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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHFoam at coolant tank cap
Leading reported evidence
Check condition of the coolant
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Suggestion · Original poster
Actually I just had the attached oil report done by Blackstone, and it's the slightly elevated sodium and potassium that had me checking the condition of the coolant.
Leading evidence: 'Check condition of the coolant' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check condition of the coolant' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
But you should go ahead and be prepared/start a discussion on a top end repair..( AOS or oil cooler causing intermix is a very very low probability but should be checked first)
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Suggestion
You can have an expert Aluminum welder with m96 experiance repair the crack for $750 ( Lenn Hoffman)..The rest of the cost is labor and gaskets/seals...Have your mechanic do an estimate for you..
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Suggestion
In any case, you need to drain it completely and replace with Porsche approved coolant mixed with distilled water.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
Right underneath these cracks are the coolant passages.The small channell that is cast in and circles the spark plug hole has 50-100psi of oil pressure when running but the coolant has only 0-15psi, so oil is much more likely to into the coolant passage and very little coolant will go into the oil passage..
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Check condition of the coolant
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion · Original poster
Actually I just had the attached oil report done by Blackstone, and it's the slightly elevated sodium and potassium that had me checking the condition of the coolant.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
But you should go ahead and be prepared/start a discussion on a top end repair..( AOS or oil cooler causing intermix is a very very low probability but should be checked first)
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
You can have an expert Aluminum welder with m96 experiance repair the crack for $750 ( Lenn Hoffman)..The rest of the cost is labor and gaskets/seals...Have your mechanic do an estimate for you..
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Right underneath these cracks are the coolant passages.The small channell that is cast in and circles the spark plug hole has 50-100psi of oil pressure when running but the coolant has only 0-15psi, so oil is much more likely to into the coolant passage and very little coolant will go into the oil passage..
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
20 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T155324Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
1999 996 4. I removed the cap at the coolant tank and noticed that it was covered with a yellowish foam/froth. Coolant hasn't been changed in about 7 years. Yearly mileage on car about is about 1,500 miles. Bad coolant
, or cap or other possible issues to be concerned about?
It could be the wrong coolant or bad water used to dilute the coolant. In any case, you need to drain it completely and replace with Porsche approved coolant mixed with distilled water. It will be a lot easier to fill this if you have a vacuum filler. Or just take it straight to your Indy tech and let them do it.
Pull the oil dipstick as see if the oil looks ok.Then take an oil sample and send to blackstone or Speed Diagnostics or OilView to be analyzed ..
Google "intermix" and you will find all the info you need...If your oil test comes back OK then the worst case is a top end repair...
Actually I just had the attached oil report done by Blackstone, and it's the slightly elevated sodium and potassium that had me checking the condition of the coolant. Wondering if I should have this checked out now by a Porsche mechanic rather wait another 1500 miles and another oil analysis.
Ok that's actually great... Your Lab report is excellent with just slight coolant and NO bearing damage ( that means the entire bottom end is OK)
So next is to have your Porsche Tech remove and test the AOS and oil cooler just to rule them out. But you should go ahead and be prepared/start a discussion on a top end repair..( AOS or oil cooler causing intermix is a very very low probability but should be checked first)
The top end repair will consist of R&R the engine, and R&R the heads and send them to Lenn Hoffman for repair..
Because ... he does not drive it enough. Like me, he gets in, starts the car, backs it out to the driveway, shuts it off. Do that 10 times and you will get left over water in the oil.
Right underneath these cracks are the coolant passages.The small channell that is cast in and circles the spark plug hole has 50-100psi of oil pressure when running but the coolant has only 0-15psi, so oil is much more likely to into the coolant passage and very little coolant will go into the oil passage..
Its no big deal if you attack the problem properly. You can have an expert Aluminum welder with m96 experiance repair the crack for $750 ( Lenn Hoffman)..The rest of the cost is labor and gaskets/seals...Have your mechanic do an estimate for you..
Just watch out for the "while your in theres"...Thats where most people go off the rail or go bankrupt...
Thanks for those pics, makes it crystal clear what happens to m96 engines on a all too regular basis.
iirr, From what Charles, or maybe its Lenn, says, approximately 6 months or so after a overheat/needed water pump replacement, head cracks almost always happen... IIRR, Len Hoffman the 996 head guru posted in one of his blogs, the parts of the impeller that have broken off come blasting out of the head when he pressure flushes them. These impeller parts block up the coolant passages causing hot spots promoting head cracks in weak areas.
Do you agree PT3..?
You are better off replacing the composite impeller pump as part of regular maintenance than risk the metal impeller machine the block, which then won't allow any pump to operate properly. You'd have to put a new engine in then.
