Kroon Harness for 944 Turbo

[chrischrischris]

@Dkraven I think NG got his block prepared through the 944 specialty shop in Charlotte, NC called "Edredas" and you might want to contact the shop directly to discuss options: https://www.edredas.com/

[NCGermerican]

NG, if I could hijack your thread a little - I just dug into my new to me 86 951 with milky coolant with a plan to change the head gasket, took off the head, and found bore scoring. Now I'm looking at sleeving and am curious about your experience. If you want I can start a separate thread to discuss this, but my main questions are -

Did you use flanged or straight sleeves? Assuming steel? What material were the rings on your pistons? I understand OEM rings meant for alusil cylinders don't vibe with steel liners. I'm kind of wanting to reuse my pistons but am starting to accept that I might need to get new ones.

Anyways, any tips you can give me, I'm suddenly in deeper water than I'd hoped and trying to find a lifevest.

No worries about any hijacking on Carpokes! However, I do recommend you starting a new thread on this topic. I had a new short block built by Edredas (www.edredas.com) in Charlotte, NC (I'm in Raleigh, NC). I don't have a lot of the specifics other than the cylinders were steel lined with Wossner Pistons. I need to get with Brent to get some more details on it.

[Tom]

NG, if I could hijack your thread a little - I just dug into my new to me 86 951 with milky coolant with a plan to change the head gasket, took off the head, and found bore scoring. Now I'm looking at sleeving and am curious about your experience. If you want I can start a separate thread to discuss this, but my main questions are -

Did you use flanged or straight sleeves? Assuming steel? What material were the rings on your pistons? I understand OEM rings meant for alusil cylinders don't vibe with steel liners. I'm kind of wanting to reuse my pistons but am starting to accept that I might need to get new ones.

Anyways, any tips you can give me, I'm suddenly in deeper water than I'd hoped and trying to find a lifevest.

No worries about any hijacking on Carpokes! However, I do recommend you starting a new thread on this topic. I had a new short block built by Edredas (www.edredas.com) in Charlotte, NC (I'm in Raleigh, NC). I don't have a lot of the specifics other than the cylinders were steel lined with Wossner Pistons. I need to get with Brent to get some more details on it.

Ah, so your replacement short block was a sleeved rebuild? What about the head?

[NCGermerican]

NG, if I could hijack your thread a little - I just dug into my new to me 86 951 with milky coolant with a plan to change the head gasket, took off the head, and found bore scoring. Now I'm looking at sleeving and am curious about your experience. If you want I can start a separate thread to discuss this, but my main questions are -

Did you use flanged or straight sleeves? Assuming steel? What material were the rings on your pistons? I understand OEM rings meant for alusil cylinders don't vibe with steel liners. I'm kind of wanting to reuse my pistons but am starting to accept that I might need to get new ones.

Anyways, any tips you can give me, I'm suddenly in deeper water than I'd hoped and trying to find a lifevest.

No worries about any hijacking on Carpokes! However, I do recommend you starting a new thread on this topic. I had a new short block built by Edredas (www.edredas.com) in Charlotte, NC (I'm in Raleigh, NC). I don't have a lot of the specifics other than the cylinders were steel lined with Wossner Pistons. I need to get with Brent to get some more details on it.

Ah, so your replacement short block was a sleeved rebuild? What about the head?

The head was rebuilt locally about 2 years and less than 2,000 miles ago. It was done by a pretty reputable, local cylinder head rebuilder that used to do a lot of head work on 911's and 944's back in the 90's. I had all the valve guides, seals, retainers, and springs replaced. Valves were cleaned and lapped, head resurfaced.

I just posted my latest video (not my greatest video work, unfortunately), but the leak down came back really good - 5% or less on all cylinders.

[Tom]

Watched your video and appreciate the Carpokes shout out (and it reminded me to run your banner, which I'll do shortly here).

Nothing wrong with confirming the turbo oil drain is clear, but in your case it seems like any drainage problem is the result of excessive crank pressure or too much oil flow through the turbo (or maybe both).

Once you get the rebuilt turbo back on, the first thing I'd do is check for excessive crank pressure. Pull the dip stick and put a vacuum/boost gauge on it -- I'd be curious what you see, especially after a rev or two. If you see pressure, I'd focus on finding that before running it and putting the new turbo at risk.

Just a note on leak-down tests. They are great at testing the seal when the piston is at TDC, but won't tell you if there are sealing issues at other positions -- so while the leak down is a good sign, it doesn't rule out combustion gases as the source of excess crank pressure.

Probably not what you want to hear, but since you are relatively close to edredas, you might benefit from a second set of eyes on the car. There's a chance something more mundane/boring is going on that you are overlooking -- misrouted hoses, a combination of smaller issue, sneaky leaks, etc. Having followed these deep mysteries as an air-charm internet mechanics for decades, I can't tell you how many times it turned out to be something much less exotic than suspected. Sometimes if you stare at the same thing for a long time, you stop seeing what's right in front of you. An experienced tech will also be able to let the clues guide his efforts to the most logical tests.

[NCGermerican]

Watched your video and appreciate the Carpokes shout out (and it reminded me to run your banner, which I'll do shortly here).

Nothing wrong with confirming the turbo oil drain is clear, but in your case it seems like any drainage problem is the result of excessive crank pressure or too much oil flow through the turbo (or maybe both).

Once you get the rebuilt turbo back on, the first thing I'd do is check for excessive crank pressure. Pull the dip stick and put a vacuum/boost gauge on it -- I'd be curious what you see, especially after a rev or two. If you see pressure, I'd focus on finding that before running it and putting the new turbo at risk.

Just a note on leak-down tests. They are great at testing the seal when the piston is at TDC, but won't tell you if there are sealing issues at other positions -- so while the leak down is a good sign, it doesn't rule out combustion gases as the source of excess crank pressure.

Probably not what you want to hear, but since you are relatively close to edredas, you might benefit from a second set of eyes on the car. There's a chance something more mundane/boring is going on that you are overlooking -- misrouted hoses, a combination of smaller issue, sneaky leaks, etc. Having followed these deep mysteries as an air-charm internet mechanics for decades, I can't tell you how many times it turned out to be something much less exotic than suspected. Sometimes if you stare at the same thing for a long time, you stop seeing what's right in front of you. An experienced tech will also be able to let the clues guide his efforts to the most logical tests.

Thanks Tom! I'm already preparing myself to have another set of eyes looking at it - it doesn't mean it has to be 944 specific. My aim would be to find a local "old school" mechanic that was used to resolving issues like this. Many modern mechanics need to rely on a scan tool to figure out what's going on. Brent would be my worst case scenario, mainly because I would have to trailer the car 2.5 hours to his shop and it might be months before he has an opening. The short block was easy - that went right in the back of my wife's Durango.

I'm definitely going to put a gauge on the dipstick when I get it back together. I just need to figure out what a "normal" reading should be. I DO have a Lindsey Racing catch can/breather still new in the box in my garage. I don't want to use it, mainly because I feel like I shouldn't have to - it feels like it would be a band-aid for anything other than consistent high boost use.

The thing I can't get over is many of the issues are the same as when I had the old motor in - it was the same when I had the original motor (that was confirmed to have blow-by). So if there's STILL crank case over-pressure, then it would have to be somewhere else in the oiling system.....or at least that's what my brain is pointing towards.

[Tom]

Watched your video and appreciate the Carpokes shout out (and it reminded me to run your banner, which I'll do shortly here).

Nothing wrong with confirming the turbo oil drain is clear, but in your case it seems like any drainage problem is the result of excessive crank pressure or too much oil flow through the turbo (or maybe both).

Once you get the rebuilt turbo back on, the first thing I'd do is check for excessive crank pressure. Pull the dip stick and put a vacuum/boost gauge on it -- I'd be curious what you see, especially after a rev or two. If you see pressure, I'd focus on finding that before running it and putting the new turbo at risk.

Just a note on leak-down tests. They are great at testing the seal when the piston is at TDC, but won't tell you if there are sealing issues at other positions -- so while the leak down is a good sign, it doesn't rule out combustion gases as the source of excess crank pressure.

Probably not what you want to hear, but since you are relatively close to edredas, you might benefit from a second set of eyes on the car. There's a chance something more mundane/boring is going on that you are overlooking -- misrouted hoses, a combination of smaller issue, sneaky leaks, etc. Having followed these deep mysteries as an air-charm internet mechanics for decades, I can't tell you how many times it turned out to be something much less exotic than suspected. Sometimes if you stare at the same thing for a long time, you stop seeing what's right in front of you. An experienced tech will also be able to let the clues guide his efforts to the most logical tests.

Thanks Tom! I'm already preparing myself to have another set of eyes looking at it - it doesn't mean it has to be 944 specific. My aim would be to find a local "old school" mechanic that was used to resolving issues like this. Many modern mechanics need to rely on a scan tool to figure out what's going on. Brent would be my worst case scenario, mainly because I would have to trailer the car 2.5 hours to his shop and it might be months before he has an opening. The short block was easy - that went right in the back of my wife's Durango.

I'm definitely going to put a gauge on the dipstick when I get it back together. I just need to figure out what a "normal" reading should be. I DO have a Lindsey Racing catch can/breather still new in the box in my garage. I don't want to use it, mainly because I feel like I shouldn't have to - it feels like it would be a band-aid for anything other than consistent high boost use.

The thing I can't get over is many of the issues are the same as when I had the old motor in - it was the same when I had the original motor (that was confirmed to have blow-by). So if there's STILL crank case over-pressure, then it would have to be somewhere else in the oiling system.....or at least that's what my brain is pointing towards.

I didn’t realize edredas was that far away from you, so totally understand your reluctance on towing.

That said, if you get it back together and see meaningful crankcase pressure, I’d definitely consider looping the engine builder back in. That starts to point toward ring seal, and sleeved 944 motors can be tricky to get right—many very good engine builders have had headaches galore.

I had originally assumed you were working from a known-good block, but since this is a sleeved rebuild, I think it has to stay on the table if you confirm pressure at the dipstick. There just aren’t many other explanations for pressure building quickly in the crankcase along with what you’re seeing.

I’d hold off deciding next steps until you do that dipstick pressure test. If the dipstick shows meaningful pressure with everything hooked up and the motor running/revving, I’d focus all energy on understanding why. At that point it's highly likely to be either poor ring sealing or the AOS not venting properly.

If the dipstick shows slight vacuum or virtually no pressure, then you’re likely looking at a different path—possibly a combination of smaller issues. I'll see if I can test my motor just to give you a point of reference...

On the flip side, things like rebuilding the oil thermostat are probably just going to burn time without getting you closer to an answer.

Re an old-school shop—nothing wrong with that in general, but I'd vote for someone familiar with the 944 -- or at least German cars from the same era. If anyone sees your 944 and gets out a scan tool, you know you're in the wrong place. If you do end up with measurable crankcase pressure, I’d lean toward the builder -- but either way I'd look for someone familiar with these engines if possible, even if it means a bit of a tow. Again, just my two cents...

[NCGermerican]

Watched your video and appreciate the Carpokes shout out (and it reminded me to run your banner, which I'll do shortly here).

Nothing wrong with confirming the turbo oil drain is clear, but in your case it seems like any drainage problem is the result of excessive crank pressure or too much oil flow through the turbo (or maybe both).

Once you get the rebuilt turbo back on, the first thing I'd do is check for excessive crank pressure. Pull the dip stick and put a vacuum/boost gauge on it -- I'd be curious what you see, especially after a rev or two. If you see pressure, I'd focus on finding that before running it and putting the new turbo at risk.

Just a note on leak-down tests. They are great at testing the seal when the piston is at TDC, but won't tell you if there are sealing issues at other positions -- so while the leak down is a good sign, it doesn't rule out combustion gases as the source of excess crank pressure.

Probably not what you want to hear, but since you are relatively close to edredas, you might benefit from a second set of eyes on the car. There's a chance something more mundane/boring is going on that you are overlooking -- misrouted hoses, a combination of smaller issue, sneaky leaks, etc. Having followed these deep mysteries as an air-charm internet mechanics for decades, I can't tell you how many times it turned out to be something much less exotic than suspected. Sometimes if you stare at the same thing for a long time, you stop seeing what's right in front of you. An experienced tech will also be able to let the clues guide his efforts to the most logical tests.

Thanks Tom! I'm already preparing myself to have another set of eyes looking at it - it doesn't mean it has to be 944 specific. My aim would be to find a local "old school" mechanic that was used to resolving issues like this. Many modern mechanics need to rely on a scan tool to figure out what's going on. Brent would be my worst case scenario, mainly because I would have to trailer the car 2.5 hours to his shop and it might be months before he has an opening. The short block was easy - that went right in the back of my wife's Durango.

I'm definitely going to put a gauge on the dipstick when I get it back together. I just need to figure out what a "normal" reading should be. I DO have a Lindsey Racing catch can/breather still new in the box in my garage. I don't want to use it, mainly because I feel like I shouldn't have to - it feels like it would be a band-aid for anything other than consistent high boost use.

The thing I can't get over is many of the issues are the same as when I had the old motor in - it was the same when I had the original motor (that was confirmed to have blow-by). So if there's STILL crank case over-pressure, then it would have to be somewhere else in the oiling system.....or at least that's what my brain is pointing towards.

I didn’t realize edredas was that far away from you, so totally understand your reluctance on towing.

That said, if you get it back together and see meaningful crankcase pressure, I’d definitely consider looping the engine builder back in. That starts to point toward ring seal, and sleeved 944 motors can be tricky to get right—many very good engine builders have had headaches galore.

I had originally assumed you were working from a known-good block, but since this is a sleeved rebuild, I think it has to stay on the table if you confirm pressure at the dipstick. There just aren’t many other explanations for pressure building quickly in the crankcase along with what you’re seeing.

I’d hold off deciding next steps until you do that dipstick pressure test. If the dipstick shows meaningful pressure with everything hooked up and the motor running/revving, I’d focus all energy on understanding why. At that point it's highly likely to be either poor ring sealing or the AOS not venting properly.

If the dipstick shows slight vacuum or virtually no pressure, then you’re likely looking at a different path—possibly a combination of smaller issues. I'll see if I can test my motor just to give you a point of reference...

On the flip side, things like rebuilding the oil thermostat are probably just going to burn time without getting you closer to an answer.

Re an old-school shop—nothing wrong with that in general, but I'd vote for someone familiar with the 944 -- or at least German cars from the same era. If anyone sees your 944 and gets out a scan tool, you know you're in the wrong place. If you do end up with measurable crankcase pressure, I’d lean toward the builder -- but either way I'd look for someone familiar with these engines if possible, even if it means a bit of a tow. Again, just my two cents...

In regard to the venting, I took a quick look in the vacuum manifold inside the AOS specific line. It wasn't pretty, but didn't look blocked. My plan is to hit it with a good pipe cleaner and see if that helps. Outside of that, I do have a LR catch can (that is vented) and I could try that. However, when I did have the AOS line disconnected from the J-boot (before I plugged it), there was no difference in the vacuum reading.

As for the oil thermostat - I've already bought it and if it at least totally crosses that off from being an issue, then I guess I'd be that much closer to a resolution.

Lastly, given the amount of oil on those plugs and what was coming out of the intake manifold and charge pipes, looks like I'll need to give the intercooler a good cleanout as well.

[Dkraven]

NG, if I could hijack your thread a little - I just dug into my new to me 86 951 with milky coolant with a plan to change the head gasket, took off the head, and found bore scoring. Now I'm looking at sleeving and am curious about your experience. If you want I can start a separate thread to discuss this, but my main questions are -

Did you use flanged or straight sleeves? Assuming steel? What material were the rings on your pistons? I understand OEM rings meant for alusil cylinders don't vibe with steel liners. I'm kind of wanting to reuse my pistons but am starting to accept that I might need to get new ones.

Anyways, any tips you can give me, I'm suddenly in deeper water than I'd hoped and trying to find a lifevest.

No worries about any hijacking on Carpokes! However, I do recommend you starting a new thread on this topic. I had a new short block built by Edredas (www.edredas.com) in Charlotte, NC (I'm in Raleigh, NC). I don't have a lot of the specifics other than the cylinders were steel lined with Wossner Pistons. I need to get with Brent to get some more details on it.

Thanks for the reply! I think he uses LA Sleeves and the Wossner Pistons would've come with their own rings. In concept, sleeving my engine is simple, but the details to cover are many. I hope you figure out your oil issue, have been enjoying your videos! Production is good, your narration is well done without too much "hey you guys this is my channel" type vibe and also not too dry. The little fun clips are just enough seasoning I'd say.

I have a Storch MAF that I liked on my NA, which got wrecked, which is why I'm now onto a 951 project car, and Julius actually modified the NA MAF for my turbo. Looking forward to eventually running it when I have a working engine.

Patience and doing it right is everything, though I long to drive the car!

[NCGermerican]

NG, if I could hijack your thread a little - I just dug into my new to me 86 951 with milky coolant with a plan to change the head gasket, took off the head, and found bore scoring. Now I'm looking at sleeving and am curious about your experience. If you want I can start a separate thread to discuss this, but my main questions are -

Did you use flanged or straight sleeves? Assuming steel? What material were the rings on your pistons? I understand OEM rings meant for alusil cylinders don't vibe with steel liners. I'm kind of wanting to reuse my pistons but am starting to accept that I might need to get new ones.

Anyways, any tips you can give me, I'm suddenly in deeper water than I'd hoped and trying to find a lifevest.

No worries about any hijacking on Carpokes! However, I do recommend you starting a new thread on this topic. I had a new short block built by Edredas (www.edredas.com) in Charlotte, NC (I'm in Raleigh, NC). I don't have a lot of the specifics other than the cylinders were steel lined with Wossner Pistons. I need to get with Brent to get some more details on it.

Thanks for the reply! I think he uses LA Sleeves and the Wossner Pistons would've come with their own rings. In concept, sleeving my engine is simple, but the details to cover are many. I hope you figure out your oil issue, have been enjoying your videos! Production is good, your narration is well done without too much "hey you guys this is my channel" type vibe and also not too dry. The little fun clips are just enough seasoning I'd say.

I have a Storch MAF that I liked on my NA, which got wrecked, which is why I'm now onto a 951 project car, and Julius actually modified the NA MAF for my turbo. Looking forward to eventually running it when I have a working engine.

Patience and doing it right is everything, though I long to drive the car!

Thank you for the kind words and I'm glad you enjoy the videos! I'm trying to convey that I am no expert on these cars (or any other), but it's just a documentation of my experience doing these types of DIY projects. Not only are they not "HOW TO" videos, many times they are "DON'T DO WHAT I DID" videos!