Krampas! Lol. I think he's decided to become a randomly appearing year-rounder...PSU_Crash wrote: Sun Dec 21, 2025 9:57 amOof... hate to see that Tom! Perhaps Krampus came early this year. I don't believe in coincidence, but I'm not sure what makes sense there.
Years ago I had a similar issue, although with a new build, where one of the alignment dowels was holding the head up ever so slightly. Compression and leak down looked good, then when at temp it would weep. Not your situation this time, unfortunately.
Like t36 said, we all look forward to your detailed tear down and rebuild report
Coolant Leak at Oil Filter Housing Console
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blueline
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dr bob
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Hi Tom --
Sorry to hear about the leak.
The leaking gasket like that is exactly the symptom I saw after using Dexcool in the German Ford engine 30 years ago, and the reason for regular diatribes on getting it out of any car you love. In my experience, the finger points to the coolant you took out, rather than the G40 or G48 you just put in. It's hard to impossible to believe that the proper coolant in there for just a week or two would eat through a head gasket.
You'll find out when the gasket gets replaced.
My too sense...
Is there any coolant in the oil?
Sorry to hear about the leak.
The leaking gasket like that is exactly the symptom I saw after using Dexcool in the German Ford engine 30 years ago, and the reason for regular diatribes on getting it out of any car you love. In my experience, the finger points to the coolant you took out, rather than the G40 or G48 you just put in. It's hard to impossible to believe that the proper coolant in there for just a week or two would eat through a head gasket.
You'll find out when the gasket gets replaced.
My too sense...
Is there any coolant in the oil?
dr bob
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1989 928 S4, black with cashmere/black inside
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928 Owner's Club Charter Member
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Free Advice and Commentary. Use At Your Own Risk!
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Tom
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There's no sign of mixing or combustion chamber leaks, but I'm going to put a scope in through the spark plug holes before tearing it down to take a look. When I pull the head, it's always hard to know if coolant was already in there, or if it spilled in from the head when pulling things apart.dr bob wrote: Sun Dec 21, 2025 10:21 am Hi Tom --
Sorry to hear about the leak.
The leaking gasket like that is exactly the symptom I saw after using Dexcool in the German Ford engine 30 years ago, and the reason for regular diatribes on getting it out of any car you love. In my experience, the finger points to the coolant you took out, rather than the G40 or G48 you just put in. It's hard to impossible to believe that the proper coolant in there for just a week or two would eat through a head gasket.
You'll find out when the gasket gets replaced.
My too sense...
Is there any coolant in the oil?
In my experience, if the fire-ring is compromised, it will pressurize the cooling system and spit coolant out the overflow tube. I had none of that. Although, if the Dexcool had been eating away at the sealing bead on the gasket, it's possible the fire-ring failed and the gasket seal just blew out before the coolant reservoir cap. Time will tell. This motor does not have a lot of gaskets with the embedded rubber/silicon bead, but the oil thermostat housing comes to mind as another, so I'll plan to change that and the neck gaskets on the head while I'm at it. Will be interesting to see if they look crinkled up like some of the dexcool cautionary tales on the interweb. Sigh. I'm going to mostly leave it until after Christmas... Hey, at least there's only one head on this motor.
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Tom
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Well I scoped two cylinders this afternoon and at least there was no pooled coolant in either of them. I'm going to wait until after Christmas then pull the head. If nothing else, I'm very curious to see if the Dexcool compromised the sealing bead...
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Thom
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Well, so sorry to hear this, especially with the previous leaks that took you a while to figure out (dowel pin). Such an issue cannot really make for an enjoyable Christmas present.
Pressurising the coolant circuit to 14 psi may have been asking a little too much from it though?
Pressurising the coolant circuit to 14 psi may have been asking a little too much from it though?
'90 944 turbo
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Tom
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In the end, I think my early head gasket problems were primarily a tuning issue (too much timing) and probably a knock limit well below my boost pressures. It held for years on e85 and water injection (with less timing and better logging tools), but I'm looking for less fuss these days. I'm going to change this hg to get it on the road without and super long delay, then work on rebuilding the 2.5 motor that came with the car. Plan to pick @michaelmount123's brain for his Nikasil/piston/ring approach.Thom wrote: Mon Dec 22, 2025 4:27 am Well, so sorry to hear this, especially with the previous leaks that took you a while to figure out (dowel pin). Such an issue cannot really make for an enjoyable Christmas present.
Pressurising the coolant circuit to 14 psi may have been asking a little too much from it though?
Re the pressure test, I've always tested to 14 or so, since that's just under the lowest-rated cap for the coolant tank (and well under the 1.5B that came with my car). I've probably done it 100+ times. Loose hoses and leaky seals show up nicely that way, but this one is a first for me. I figure if the factory put a 15 or 21psi cap on the tank, that's kind of the de facto spec for how much pressure they expect the system to hold before springing a leak. In this instance, curiously, it held 14psi just fine when I finished flushing the coolant, and after a few shake-down drive -- then started dripping a week or two later just sitting in the garage with no pressure.
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Tom
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I have one, but my cylinder tops are o-ringed so I'll have to take a close look to see if it will work. I'm kind of doubting it will, but we'll see.Fejjj951 wrote: Mon Dec 22, 2025 8:23 pm Tom,
The SCE Cut ring gasket is a great option to consider!
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Just curious if you tested for exhaust gasses in the coolant?
Cheers
Cheers
Brian
'88 944 Turbo S / Silber Rosa
'88 944 Turbo S / Silber Rosa
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Tom
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With Santa duties in the rear view mirror, I had more time to spend investigating this leak this morning. It's hard to get my bearings using the little iphone scope thing, and I was determined to see the leak with my own eyes before tearing the head off. Very glad I did 
It's a Christmas miracle! 
The leak is actually coming from the oil filter console gasket. It was wildly deceiving because it shoots a little stream out (under pressure) that bounces right into the head gasket joint. I couldn't tell which way the coolant was actually spraying either, so could not tell which gasket was actually the source. I finally found a angle where I could see it with my bare eye, and confirm the source -- see video below showing the oil filter console-to-block joint. Not super excited about doing the oil seals, but it's better than the head gasket, so I'll take it! That gasket's been in there since building the motor in 2007, which I'd still consider a pre-mature failure, but suppose 18+ years isn't too late for a full refund.
It's a Christmas miracle! The leak is actually coming from the oil filter console gasket. It was wildly deceiving because it shoots a little stream out (under pressure) that bounces right into the head gasket joint. I couldn't tell which way the coolant was actually spraying either, so could not tell which gasket was actually the source. I finally found a angle where I could see it with my bare eye, and confirm the source -- see video below showing the oil filter console-to-block joint. Not super excited about doing the oil seals, but it's better than the head gasket, so I'll take it! That gasket's been in there since building the motor in 2007, which I'd still consider a pre-mature failure, but suppose 18+ years isn't too late for a full refund.