15 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHOil in coolant & coolant in oil
Reported or suspected cause
heads
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
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Reported cause
I was certain it was the heads but Hoffman checked them out and rebuilt them for me.
Leading evidence: 'heads' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'heads' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check /ruling out' (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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Performed · outcome unconfirmed
The last time I checked, a populated head brand new from Porsche was $3500.
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I had the "missing water pump blade" problem on my youngest sons 2002 Boxster about 5 years ago, I designed/made/installed metal mesh screens in the block to "catch" any blades on ALL my m96/7 engines ( pic below ) .
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Suggestion
the oil cooler 9 out of 10 times is not the problem supposedly, but worth checking/ruling out, for sure.
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Suggestion
Just knowing engines, would assume if engine was run with this type of head crack for extended periods, then after engine/oil pressure was shut off, the coolant system is still pressurized to 18psi on a hot engine and takes a while to cool off some.
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Performed · outcome unconfirmed
I had the "missing water pump blade" problem on my youngest sons 2002 Boxster about 5 years ago, I designed/made/installed metal mesh screens in the block to "catch" any blades on ALL my m96/7 engines ( pic below ) .
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Suggestion
Just knowing engines, would assume if engine was run with this type of head crack for extended periods, then after engine/oil pressure was shut off, the coolant system is still pressurized to 18psi on a hot engine and takes a while to cool off some.
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15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T105141Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
brown milkshake in coolant exp tank
yellow/brown dipstick
car never over-heated to my knowledge... have read about lodged water pump blade preventing proper temp reading.
now that there's coolant on the dipstick, I'm not going to start it again. Last time I started it was a few nights ago. Car sounds and runs great actually. No smoke or coolant being burned from what I can tell.
I am thinking next step is to pressure test oil cooler. If bad will run detergent thru engine and cooling system and cross fingers I guess? Idk, any thoughts? Anyone positive it's a cracked head just on info given? I have not done a compression test.
Thx as always
From what PT3 posted and explained in great detail... not an exact quote, but the general gest of it iirr...
"The crack 'usually' appears/occurs in/around the Heads oil gallery where a coolant passageway is amazing close by, and oil bleeds into the coolant passages after they crack (maybe from an broken WP impeller blockage/whatever...?). So high pressure oil escapes the oil gallery
into
the much lower pressure cooling system,,, thus only oil in coolant scenario.
Coolant in oil was a bigger problem iirr and not usually a cracked head... the oil cooler 9 out of 10 times is not the problem supposedly, but worth checking/ruling out, for sure.
Just knowing engines, would assume if engine was run with this type of head crack for extended periods, then after engine/oil pressure was shut off, the coolant system is still pressurized to 18psi on a hot engine and takes a while to cool off some. So small amount coolant might eventually be migrated/pressurized slightly into the crack and eventually contaminate the oil. , just a theory of mine. Or the crack migrates right thru to valve seat/cam area. Just a theory of mine.
I have no personal experience with this, just slept at a HI .....
maybe PT3 will chime in....
FWIW,, The cracks in my cylinders when My engine died were all at the mid stroke area.
They were almost invisible but let the engine suck coolant like crazy if started and I had
the classic white smoke cropduster thing out of the left tail pipe. Oil in coolant and a trace of
coolant it in the oil.
There is only 4 ways to have intermix on the M96/7 engines ( and head-gaskets are not one of them, although to the uninitiated that is their first assumption) .
(1) AOS (2) oil cooler (3) head crack ( 4) cylinder crack/D-chunk
1 , you can forget the AOS on yours, it can only cause coolant in the oil, will NOT cause oil in coolant ( cause is a crack in the housing of the heater chamber , note UAOS eliminates/prevents this))
2 Oil cooler , by all means always test this first, if you are extremely lucky, this could be your problem..about 1 out of 10 times
3 Cracked head...this is the most likely especially on a 3.4 , and like Allcool said, the crack is normally in the lifter oil pressure feed, and the high oil pressure while running ( 60-100 PSI ) will push oil into the coolant a lot more than the 18 max PSi will push coolant into the oil when the engine is OFF and HOT..... BUT if you drive/play araound long enough, you can get a substantial amount of coolant in the oil..
4.. Cracked cyl/D chunk, ..this usually has smoke coming from one pipe that has a sweet smell, normally you lose coolant and get coolant in the oil, but very little to NO oil in the coolant...Cylinder cracks are due to the cylinders ovaling over a long period of time untill they finally crack, or if an AOS fails by diaphragm rupture, it can hydrolock from excessive oil and crack one or more cylinders..
Car is a 01/98 build C2. Stock 3.4
Thanks for all replies-
yea Pt I drove it a bit. Maybe for 10-15 miles total after I noticed milkshake in expansion tank. Wasn't up until recently (on my last drive) that I noticed the dip stick really turn color to that brown/yellow.
I'll test oil cooler and cross fingers. if not, she'll be going away for a while...
I changed it myself ~20K ago with a metal impeller unit. When I pulled the pump that was on the car, it looked to be original (gasket was not cut) and I noticed a blade missing on the pump, but assumed that happened during the removal (I did not fully remove motor support bracket, just unloosened bolts enough to pry back and slide pump out from beneath the car...it was tight).
car ran fine for solid 20k after install
edit- you think w/p gasket is leaking???
Good news is you have wrenching skills. Skip gave you a very clear scenario roadmap. I'd go after the low hanging fruit first to eliminate the potential cause. Lets hope its a seal. But that broken blade had to go somewhere. If it's a crack in the head, let's hope an expert can repair it or worst case replace it without a rebuild. Sorry it happened to you.
The last time I checked, a populated head brand new from Porsche was $3500. Instead of removing the head, disassemble it, send it out for repair, and reassemble it, and end up with a used not as good as original unit after a month's time, I would just buy a new head and replace it. That is if it's a cracked head.
No metal impellers EVER for our engines. When (not if) it starts to get sloppy with some play, it will bore out the water pump hole and make your block/engine useless. As has been said, the usual culprit for a hot spot on the head, causing a crack, is a lost impeller blade. Good luck.
I had the "missing water pump blade" problem on my youngest sons 2002 Boxster about 5 years ago, I designed/made/installed metal mesh screens in the block to "catch" any blades on ALL my m96/7 engines ( pic below ) . Here is a link to the thread where all the Technical details were discussed, and water pumps were dissected to see what sealed bearings were in there ect...
https://rennlist.com/forums/996-foru...ght=water+pump
Water pump screens to catch broken blades
Sent you a PM but short answer is no. My car had sat for years and was in the midst of blowing up. I drove it about 200' from the delivery trailer to my garage. Blowing smoke all over the place.
I was certain it was the heads but Hoffman checked them out and rebuilt them for me. I pressurized the oil cooler and could see/hear bubbles on the other side.
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