New To Me 1987 924S Arrived

[River19]

2 - When I get on it I get some exhaust smell in the cabin, more than ever should be. Part of me wonders if I didn't have a mouse nest in the exhaust etc. requiring the aforementioned "clearing out" and possibly still have something going on there.

Sometimes exhaust fumes in the cabin may be an indication of the rear hatch not sealing correctly.
Regarding your exhaust system questions.
I don't think there's much to be gained from a 2.5" system in a N/A car.
If you have the time, you should have a look at some of the videos from @NC944er on restoring his '88 944 N/A. He's done a great job of documenting quite a few things that may be of interest to you.



Cheers

Appreciate the response, I will check out his vids as there is always something to learn regardless of whether it applies to my car or not. My rear hatch seals appear to be in decent condition, but I will take a closer look.

I am assuming the stock exhaust is 2", and if so I agree that 2.5" probably doesn't make sense especially as the sweet spot of the 8V isn't really on the high end of the rev range like the 16v engines.

Ideally they don't find any spendy hidden issues that I don't know about, and if so I can invest in getting the thermostat/gauge issue addressed, the exhaust and shocks, that list alone will require some investment, but should yield a pretty well sorted car.

EDIT: After looking at NC944er's channel I realized I have watched a fair bit of his content, good stuff for a non-mechanic like myself, thanks again for the recommendation.

[Tom]

@PSU_Crash Thanks !!!

Regarding the fuel lines, I just glanced through the service history and saw the fuel pump was replaced in 2022, there is an outside chance the fuel lines were replaced as well, or at least I would have if it were me. We will find out in a few weeks as to what things it "needs" within reason.

My goal for the car is to invest in the things it needs to make it a reliable, enjoyable runner. I'm not looking for "performance" per se however if a modification improves the drivability or reliability I will look in that direction, things such as the MAF vs. the barn door etc.

EDIT:
Wanted to add, I have service records as well which is nice. Timing belt, water pump, fuel pump, plugs, master cylinder along with some other items have all been done in the past 2-4 years and within the past 3K miles.

The fuel pump is by the tank under the back of the car, so while some of 'those' lines might have been replaced, it's not a natural 'while you're in there' to also do the under hood lines at the same time. And, from the pictures, they look very original.

I may be in the minority here, but I'd vote against a MAF. On an N/A car, it's hard to beat the OEM smoothness of the barn door and even harder to max it out to the point where you'd benefit from the MAF. Even on turbo cars, MAFs primarily are used to increase the amount of air that can be measured -- rarely if ever to improve drivability/reliability. I'm old and jaded by a lifetime of modifications, but if reliability is a goal, it's very hard to beat stock parts in good condition. If drivability includes the fun factor, things like exhausts, struts, roll bars, short shifters can go a long way without compromising reliability. Just my two cents.

[River19]

@PSU_Crash Thanks !!!

Regarding the fuel lines, I just glanced through the service history and saw the fuel pump was replaced in 2022, there is an outside chance the fuel lines were replaced as well, or at least I would have if it were me. We will find out in a few weeks as to what things it "needs" within reason.

My goal for the car is to invest in the things it needs to make it a reliable, enjoyable runner. I'm not looking for "performance" per se however if a modification improves the drivability or reliability I will look in that direction, things such as the MAF vs. the barn door etc.

EDIT:
Wanted to add, I have service records as well which is nice. Timing belt, water pump, fuel pump, plugs, master cylinder along with some other items have all been done in the past 2-4 years and within the past 3K miles.

The fuel pump is by the tank under the back of the car, so while some of 'those' lines might have been replaced, it's not a natural 'while you're in there' to also do the under hood lines at the same time. And, from the pictures, they look very original.

I may be in the minority here, but I'd vote against a MAF. On an N/A car, it's hard to beat the OEM smoothness of the barn door and even harder to max it out to the point where you'd benefit from the MAF. Even on turbo cars, MAFs primarily are used to increase the amount of air that can be measured -- rarely if ever to improve drivability/reliability. I'm old and jaded by a lifetime of modifications, but if reliability is a goal, it's very hard to beat stock parts in good condition. If drivability includes the fun factor, things like exhausts, struts, roll bars, short shifters can go a long way without compromising reliability. Just my two cents.

100% Fair. Appreciate the thoughts.

The good news is the independent Porsche shop we use is very familiar with the 924/944 platform in addition to the 911s as he and his wife both have 944s they love. So I am relying on his guidance.

I have heard mixed reviews on the MAF vs. barn door swap.

[Tom]

@PSU_Crash Thanks !!!

Regarding the fuel lines, I just glanced through the service history and saw the fuel pump was replaced in 2022, there is an outside chance the fuel lines were replaced as well, or at least I would have if it were me. We will find out in a few weeks as to what things it "needs" within reason.

My goal for the car is to invest in the things it needs to make it a reliable, enjoyable runner. I'm not looking for "performance" per se however if a modification improves the drivability or reliability I will look in that direction, things such as the MAF vs. the barn door etc.

EDIT:
Wanted to add, I have service records as well which is nice. Timing belt, water pump, fuel pump, plugs, master cylinder along with some other items have all been done in the past 2-4 years and within the past 3K miles.

The fuel pump is by the tank under the back of the car, so while some of 'those' lines might have been replaced, it's not a natural 'while you're in there' to also do the under hood lines at the same time. And, from the pictures, they look very original.

I may be in the minority here, but I'd vote against a MAF. On an N/A car, it's hard to beat the OEM smoothness of the barn door and even harder to max it out to the point where you'd benefit from the MAF. Even on turbo cars, MAFs primarily are used to increase the amount of air that can be measured -- rarely if ever to improve drivability/reliability. I'm old and jaded by a lifetime of modifications, but if reliability is a goal, it's very hard to beat stock parts in good condition. If drivability includes the fun factor, things like exhausts, struts, roll bars, short shifters can go a long way without compromising reliability. Just my two cents.

100% Fair. Appreciate the thoughts.

The good news is the independent Porsche shop we use is very familiar with the 924/944 platform in addition to the 911s as he and his wife both have 944s they love. So I am relying on his guidance.

I have heard mixed reviews on the MAF vs. barn door swap.

Right, don't get me wrong -- I ran a MAF on my turbo for years. They definitely have their place, especially once you've maxed out the barn door. I was guided mostly by your comment about wanting reliability and drivability, coupled with the relatively small utility of a MAF on a 924S.

[River19]

The fuel pump is by the tank under the back of the car, so while some of 'those' lines might have been replaced, it's not a natural 'while you're in there' to also do the under hood lines at the same time. And, from the pictures, they look very original.

I may be in the minority here, but I'd vote against a MAF. On an N/A car, it's hard to beat the OEM smoothness of the barn door and even harder to max it out to the point where you'd benefit from the MAF. Even on turbo cars, MAFs primarily are used to increase the amount of air that can be measured -- rarely if ever to improve drivability/reliability. I'm old and jaded by a lifetime of modifications, but if reliability is a goal, it's very hard to beat stock parts in good condition. If drivability includes the fun factor, things like exhausts, struts, roll bars, short shifters can go a long way without compromising reliability. Just my two cents.

100% Fair. Appreciate the thoughts.

The good news is the independent Porsche shop we use is very familiar with the 924/944 platform in addition to the 911s as he and his wife both have 944s they love. So I am relying on his guidance.

I have heard mixed reviews on the MAF vs. barn door swap.

Right, don't get me wrong -- I ran a MAF on my turbo for years. They definitely have their place, especially once you've maxed out the barn door. I was guided mostly by your comment about wanting reliability and drivability, coupled with the relatively small utility of a MAF on a 924S.

And I stick with my "reliability and drivability" goal so I appreciate you throwing a penalty flag on anything that might not necessarily fall into that swim lane.

[River19]

Need a Gut Check:

So as I mentioned in previous posts I know there is something funky with the temp gauge/thermostat etc. The thermostat was replaced relatively recently prior to my purchase along with the water pump and radiator so I believe the core components of the cooling system are solid.

What I am seeing:

Within 2-4 miles of heading out on a drive (even today with temps in the mid 40s F the car will approach and go into the red on the temp gauge. It was basically pegged in the red at one point and I pulled over and popped the hood and took out my IR thermometer gun and shot the block along the Porsche logo front to back several readings all in the 195-210 range. Exhaust headers were all in the 400-550ish range but mostly all over the pipe is in the 400-450 range. The fan kicks on when I shut the car off and I believe it kicks on when required while driving.

Once I got back within <a mile from home I hammered 2nd and 3rd pretty good and watched the needle drop back into almost the mid range, so perhaps added rpm and coolant flow but.......


My working theory:

The actual mechanical coolant system and engine temp is within spec and operating as intended however the gauge is dealing with electrical interference either from a bad ground or corrosion or loose connection etc.

Another option is the belts on the pump are slipping (if that is possible) and with high revs come enough cycles to cool more efficiently, BUT I don't have any real signs of slippage, no smell of belt, no additional whine (other than the 2.5L characteristic whine). (My shop thinks this might be the case as well)

The car is headed to the shop this weekend but it is a 40mile drive and I imagine I will see plenty of temperature gauge shenanigans along the way. About every 5th time I drive it, the gauge sits in the middle like a good little temp gauge and is rock solid like nothing is wrong, and during those drives the car behaves the same as when it is pegged in the red.

Am I missing anything here? Are those temps I am seeing at the block and header "normal"? They "feel" normal to me (hell my modded diesel used to hit 1100 at the down pipe so 500 feels "cozy" to me......lol

[Tom]

Need a Gut Check:

So as I mentioned in previous posts I know there is something funky with the temp gauge/thermostat etc. The thermostat was replaced relatively recently prior to my purchase along with the water pump and radiator so I believe the core components of the cooling system are solid.

What I am seeing:

Within 2-4 miles of heading out on a drive (even today with temps in the mid 40s F the car will approach and go into the red on the temp gauge. It was basically pegged in the red at one point and I pulled over and popped the hood and took out my IR thermometer gun and shot the block along the Porsche logo front to back several readings all in the 195-210 range. Exhaust headers were all in the 400-550ish range but mostly all over the pipe is in the 400-450 range. The fan kicks on when I shut the car off and I believe it kicks on when required while driving.

Once I got back within <a mile from home I hammered 2nd and 3rd pretty good and watched the needle drop back into almost the mid range, so perhaps added rpm and coolant flow but.......


My working theory:

The actual mechanical coolant system and engine temp is within spec and operating as intended however the gauge is dealing with electrical interference either from a bad ground or corrosion or loose connection etc.

Another option is the belts on the pump are slipping (if that is possible) and with high revs come enough cycles to cool more efficiently, BUT I don't have any real signs of slippage, no smell of belt, no additional whine (other than the 2.5L characteristic whine). (My shop thinks this might be the case as well)

The car is headed to the shop this weekend but it is a 40mile drive and I imagine I will see plenty of temperature gauge shenanigans along the way. About every 5th time I drive it, the gauge sits in the middle like a good little temp gauge and is rock solid like nothing is wrong, and during those drives the car behaves the same as when it is pegged in the red.

Am I missing anything here? Are those temps I am seeing at the block and header "normal"? They "feel" normal to me (hell my modded diesel used to hit 1100 at the down pipe so 500 feels "cozy" to me......lol

My first guess would be trapped air in the system, either from the recent cooling system work or a small leak. When air gets trapped, the pump just spins in air and can't move the coolant. Classic trapped air symptom in these cars is when the needle creeps up at stop lights and drops very fast when you start moving.

2 to 4 minutes is not long enough to boil all the coolant in the system, but it is long enough for steam to form in the head and send the temp sensor into the red zone. So I doubt you'll find super hot reading on your IR thermometer anywhere in that short of time (other than the headers of course) but it also sounds like you were pointing the gun at the cam tower (where the big porsche logo is). If so, that's not a good place to check temps. That's a big hollow box with where the camshaft spins, so would taka a long time to reflect the actual engine temp, if ever. You want to point the gun at where the temp sensors are. See this guide on testing the gauge temp sensor to see the location (and do the testing if so inclined).

It is possible the belt is slipping, the thermostat is sticky, the gauge/sensor or wiring is sketchy, the pump is bad, etc., etc., I'd say the odds point to trapped air. There is a little vent bolt on the front coolant neck -- try opening that when the car is running and hot (be careful -- steam can hiss out and burn so wear gloves). Rev the motor a big and let any/all steam come out until you just see steady coolant and no steam, and keep an eye on the coolant level, refilling as needed. It may take a few tries to get it all out, that's pretty common. With any luck, that might be good enough to get the car to the shop, even if it has a small leak.

One clean-hands test it to warm up the car and turn on the heater. If there is a lot of trapped air, you will often hear a lot of gurgling sounds (and sometimes no heat). Coolant won't gurgle if the system is free of air...

[River19]

Need a Gut Check:

So as I mentioned in previous posts I know there is something funky with the temp gauge/thermostat etc. The thermostat was replaced relatively recently prior to my purchase along with the water pump and radiator so I believe the core components of the cooling system are solid.

What I am seeing:

Within 2-4 miles of heading out on a drive (even today with temps in the mid 40s F the car will approach and go into the red on the temp gauge. It was basically pegged in the red at one point and I pulled over and popped the hood and took out my IR thermometer gun and shot the block along the Porsche logo front to back several readings all in the 195-210 range. Exhaust headers were all in the 400-550ish range but mostly all over the pipe is in the 400-450 range. The fan kicks on when I shut the car off and I believe it kicks on when required while driving.

Once I got back within <a mile from home I hammered 2nd and 3rd pretty good and watched the needle drop back into almost the mid range, so perhaps added rpm and coolant flow but.......


My working theory:

The actual mechanical coolant system and engine temp is within spec and operating as intended however the gauge is dealing with electrical interference either from a bad ground or corrosion or loose connection etc.

Another option is the belts on the pump are slipping (if that is possible) and with high revs come enough cycles to cool more efficiently, BUT I don't have any real signs of slippage, no smell of belt, no additional whine (other than the 2.5L characteristic whine). (My shop thinks this might be the case as well)

The car is headed to the shop this weekend but it is a 40mile drive and I imagine I will see plenty of temperature gauge shenanigans along the way. About every 5th time I drive it, the gauge sits in the middle like a good little temp gauge and is rock solid like nothing is wrong, and during those drives the car behaves the same as when it is pegged in the red.

Am I missing anything here? Are those temps I am seeing at the block and header "normal"? They "feel" normal to me (hell my modded diesel used to hit 1100 at the down pipe so 500 feels "cozy" to me......lol

My first guess would be trapped air in the system, either from the recent cooling system work or a small leak. When air gets trapped, the pump just spins in air and can't move the coolant. Classic trapped air symptom in these cars is when the needle creeps up at stop lights and drops very fast when you start moving.

2 to 4 minutes is not long enough to boil all the coolant in the system, but it is long enough for steam to form in the head and send the temp sensor into the red zone. So I doubt you'll find super hot reading on your IR thermometer anywhere in that short of time (other than the headers of course) but it also sounds like you were pointing the gun at the cam tower (where the big porsche logo is). If so, that's not a good place to check temps. That's a big hollow box with where the camshaft spins, so would taka a long time to reflect the actual engine temp, if ever. You want to point the gun at where the temp sensors are. See this guide on testing the gauge temp sensor to see the location (and do the testing if so inclined).

It is possible the belt is slipping, the thermostat is sticky, the gauge/sensor or wiring is sketchy, the pump is bad, etc., etc., I'd say the odds point to trapped air. There is a little vent bolt on the front coolant neck -- try opening that when the car is running and hot (be careful -- steam can hiss out and burn so wear gloves). Rev the motor a big and let any/all steam come out until you just see steady coolant and no steam, and keep an eye on the coolant level, refilling as needed. It may take a few tries to get it all out, that's pretty common. With any luck, that might be good enough to get the car to the shop, even if it has a small leak.

One clean-hands test it to warm up the car and turn on the heater. If there is a lot of trapped air, you will often hear a lot of gurgling sounds (and sometimes no heat). Coolant won't gurgle if the system is free of air...

Thanks Tom.

I spoke with my shop guy today to confirm I can drop off Saturday, his guess is the belt might be slipping. But trapped air is certainly a possibility.

As far as the heat system goes........from past over heating situations with a Subaru I was running the heat for giggles thinking I was at least giving it a place to go, and thus I was doing the same in the 924......I can report no abnormal sounds, no gurgling that I noticed and plenty of steady heat from the system.

I believe I know the vent bolt you mentioned, I saw a "bleed the system" video today so I think I can give that a try tomorrow or the next day, weather dependent. I can take it for a quick spin, which is usually enough to get the funky gauge behavior going and then I can crack the bolt. I assume I just crack it, right? if steam comes out that indicates air/vapor in the system we need to bleed that out........if coolant comes out then that would suggest the system is at least in solid shape from a air perspective.

Am I thinking about that right? (and thanks again)

[Tom]

Need a Gut Check:

So as I mentioned in previous posts I know there is something funky with the temp gauge/thermostat etc. The thermostat was replaced relatively recently prior to my purchase along with the water pump and radiator so I believe the core components of the cooling system are solid.

What I am seeing:

Within 2-4 miles of heading out on a drive (even today with temps in the mid 40s F the car will approach and go into the red on the temp gauge. It was basically pegged in the red at one point and I pulled over and popped the hood and took out my IR thermometer gun and shot the block along the Porsche logo front to back several readings all in the 195-210 range. Exhaust headers were all in the 400-550ish range but mostly all over the pipe is in the 400-450 range. The fan kicks on when I shut the car off and I believe it kicks on when required while driving.

Once I got back within <a mile from home I hammered 2nd and 3rd pretty good and watched the needle drop back into almost the mid range, so perhaps added rpm and coolant flow but.......


My working theory:

The actual mechanical coolant system and engine temp is within spec and operating as intended however the gauge is dealing with electrical interference either from a bad ground or corrosion or loose connection etc.

Another option is the belts on the pump are slipping (if that is possible) and with high revs come enough cycles to cool more efficiently, BUT I don't have any real signs of slippage, no smell of belt, no additional whine (other than the 2.5L characteristic whine). (My shop thinks this might be the case as well)

The car is headed to the shop this weekend but it is a 40mile drive and I imagine I will see plenty of temperature gauge shenanigans along the way. About every 5th time I drive it, the gauge sits in the middle like a good little temp gauge and is rock solid like nothing is wrong, and during those drives the car behaves the same as when it is pegged in the red.

Am I missing anything here? Are those temps I am seeing at the block and header "normal"? They "feel" normal to me (hell my modded diesel used to hit 1100 at the down pipe so 500 feels "cozy" to me......lol

My first guess would be trapped air in the system, either from the recent cooling system work or a small leak. When air gets trapped, the pump just spins in air and can't move the coolant. Classic trapped air symptom in these cars is when the needle creeps up at stop lights and drops very fast when you start moving.

2 to 4 minutes is not long enough to boil all the coolant in the system, but it is long enough for steam to form in the head and send the temp sensor into the red zone. So I doubt you'll find super hot reading on your IR thermometer anywhere in that short of time (other than the headers of course) but it also sounds like you were pointing the gun at the cam tower (where the big porsche logo is). If so, that's not a good place to check temps. That's a big hollow box with where the camshaft spins, so would taka a long time to reflect the actual engine temp, if ever. You want to point the gun at where the temp sensors are. See this guide on testing the gauge temp sensor to see the location (and do the testing if so inclined).

It is possible the belt is slipping, the thermostat is sticky, the gauge/sensor or wiring is sketchy, the pump is bad, etc., etc., I'd say the odds point to trapped air. There is a little vent bolt on the front coolant neck -- try opening that when the car is running and hot (be careful -- steam can hiss out and burn so wear gloves). Rev the motor a big and let any/all steam come out until you just see steady coolant and no steam, and keep an eye on the coolant level, refilling as needed. It may take a few tries to get it all out, that's pretty common. With any luck, that might be good enough to get the car to the shop, even if it has a small leak.

One clean-hands test it to warm up the car and turn on the heater. If there is a lot of trapped air, you will often hear a lot of gurgling sounds (and sometimes no heat). Coolant won't gurgle if the system is free of air...

Thanks Tom.

I spoke with my shop guy today to confirm I can drop off Saturday, his guess is the belt might be slipping. But trapped air is certainly a possibility.

As far as the heat system goes........from past over heating situations with a Subaru I was running the heat for giggles thinking I was at least giving it a place to go, and thus I was doing the same in the 924......I can report no abnormal sounds, no gurgling that I noticed and plenty of steady heat from the system.

I believe I know the vent bolt you mentioned, I saw a "bleed the system" video today so I think I can give that a try tomorrow or the next day, weather dependent. I can take it for a quick spin, which is usually enough to get the funky gauge behavior going and then I can crack the bolt. I assume I just crack it, right? if steam comes out that indicates air/vapor in the system we need to bleed that out........if coolant comes out then that would suggest the system is at least in solid shape from a air perspective.

Am I thinking about that right? (and thanks again)

Right on the venting, though it sputter and spit for a while so look for a steady stream of bubble/steam free coolant rather than closing it the minute it starts to flow. Even then, sometimes you need vent, drive, vent, drive a few times to get at all the trapped air.

Steady heat from the heater is curious though. That would bump the odds of stuck thermostat. After the car runs a bit, but the IR gun on the top and bottom radiator hoses.... Both should be hot.

Slipping belts are not all that common on these cars since the pump is turned by the cam belt. If the belt is slipping, the cam belt might be loose or glazed, which would be critical to fix asap. The factory made a special tool to tension the timing belts, which cost well over $1000 these days, so lots of home (and shop) mechanics try to tension by feel (90 degree twist or other subjective measures -- heavy sigh...) -- so if you belt was done like that or is just old, belt slip is more likely (though still not all that common on these cars).

Fingers crossed venting helps. Might want to have some distilled water or compatible coolant on hand when you try. If there are big pockets, the reservoir can empty fast...

[BennSport]

Need a Gut Check:

So as I mentioned in previous posts I know there is something funky with the temp gauge/thermostat etc. The thermostat was replaced relatively recently prior to my purchase along with the water pump and radiator so I believe the core components of the cooling system are solid.

What I am seeing:

Within 2-4 miles of heading out on a drive (even today with temps in the mid 40s F the car will approach and go into the red on the temp gauge. It was basically pegged in the red at one point and I pulled over and popped the hood and took out my IR thermometer gun and shot the block along the Porsche logo front to back several readings all in the 195-210 range. Exhaust headers were all in the 400-550ish range but mostly all over the pipe is in the 400-450 range. The fan kicks on when I shut the car off and I believe it kicks on when required while driving.

Once I got back within <a mile from home I hammered 2nd and 3rd pretty good and watched the needle drop back into almost the mid range, so perhaps added rpm and coolant flow but.......


My working theory:

The actual mechanical coolant system and engine temp is within spec and operating as intended however the gauge is dealing with electrical interference either from a bad ground or corrosion or loose connection etc.

Another option is the belts on the pump are slipping (if that is possible) and with high revs come enough cycles to cool more efficiently, BUT I don't have any real signs of slippage, no smell of belt, no additional whine (other than the 2.5L characteristic whine). (My shop thinks this might be the case as well)

The car is headed to the shop this weekend but it is a 40mile drive and I imagine I will see plenty of temperature gauge shenanigans along the way. About every 5th time I drive it, the gauge sits in the middle like a good little temp gauge and is rock solid like nothing is wrong, and during those drives the car behaves the same as when it is pegged in the red.

Am I missing anything here? Are those temps I am seeing at the block and header "normal"? They "feel" normal to me (hell my modded diesel used to hit 1100 at the down pipe so 500 feels "cozy" to me......lol

My first guess would be trapped air in the system, either from the recent cooling system work or a small leak. When air gets trapped, the pump just spins in air and can't move the coolant. Classic trapped air symptom in these cars is when the needle creeps up at stop lights and drops very fast when you start moving.

2 to 4 minutes is not long enough to boil all the coolant in the system, but it is long enough for steam to form in the head and send the temp sensor into the red zone. So I doubt you'll find super hot reading on your IR thermometer anywhere in that short of time (other than the headers of course) but it also sounds like you were pointing the gun at the cam tower (where the big porsche logo is). If so, that's not a good place to check temps. That's a big hollow box with where the camshaft spins, so would taka a long time to reflect the actual engine temp, if ever. You want to point the gun at where the temp sensors are. See this guide on testing the gauge temp sensor to see the location (and do the testing if so inclined).

It is possible the belt is slipping, the thermostat is sticky, the gauge/sensor or wiring is sketchy, the pump is bad, etc., etc., I'd say the odds point to trapped air. There is a little vent bolt on the front coolant neck -- try opening that when the car is running and hot (be careful -- steam can hiss out and burn so wear gloves). Rev the motor a big and let any/all steam come out until you just see steady coolant and no steam, and keep an eye on the coolant level, refilling as needed. It may take a few tries to get it all out, that's pretty common. With any luck, that might be good enough to get the car to the shop, even if it has a small leak.

One clean-hands test it to warm up the car and turn on the heater. If there is a lot of trapped air, you will often hear a lot of gurgling sounds (and sometimes no heat). Coolant won't gurgle if the system is free of air...

Thanks Tom.

I spoke with my shop guy today to confirm I can drop off Saturday, his guess is the belt might be slipping. But trapped air is certainly a possibility.

As far as the heat system goes........from past over heating situations with a Subaru I was running the heat for giggles thinking I was at least giving it a place to go, and thus I was doing the same in the 924......I can report no abnormal sounds, no gurgling that I noticed and plenty of steady heat from the system.

I believe I know the vent bolt you mentioned, I saw a "bleed the system" video today so I think I can give that a try tomorrow or the next day, weather dependent. I can take it for a quick spin, which is usually enough to get the funky gauge behavior going and then I can crack the bolt. I assume I just crack it, right? if steam comes out that indicates air/vapor in the system we need to bleed that out........if coolant comes out then that would suggest the system is at least in solid shape from a air perspective.

Am I thinking about that right? (and thanks again)

Ditto on what Tom is saying regarding the radiator hoses. Severe overheating can throw the thermostat out of spec or in a completely stuck closed position. Newer engine thermostats have preventative measures to be stuck open in a failed state, but we unfortunately don’t have that luxury.