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Having oil leaking into my coolant but not vice versa. Compression is good, no overheating, car runs fine, and no coolant in oil. Ended up taking the head off, checking block flatness, decked the head, and replaced HG. But oil continues to show up in the coolant even after multiple flushes.
This is driving me crazy!! Anyone have any suggestions on what else I can check here?
Cracked head? I had that once in a BMW 2002 engine. I used a dye process, and the crack was discovered. I didn't heli-arc the head, but looked for a good used one.
You might have water/coolant in oil, just not enough to show. In my case oil looked great, but I anm loosing coolant slowly, Oil analysis confirmed it.
Google OEM Honda S2000 oil heater/cooler weld failure issue. Cross contamination could be coming from there.
Could be a crack in the head as mentioned. Good idea to check for that when pulling the head for this type of issue.
It can be getting there via the head, the head gasket or less likely, a crack between a water jack and oil in the block somewhere. Did you follow the shop manual procedure carefully when re-installing the head? There is a specific tq + angle procedure for torquing and that process changes depending on if you use new head bolts or reuse the old ones. Did you measure the original bolts to make sure they were good to re-use if that was the case?
Could be a crack in the head as mentioned. Good idea to check for that when pulling the head for this type of issue.
It can be getting there via the head, the head gasket or less likely, a crack between a water jack and oil in the block somewhere. Did you follow the shop manual procedure carefully when re-installing the head? There is a specific tq + angle procedure for torquing and that process changes depending on if you use new head bolts or reuse the old ones. Did you measure the original bolts to make sure they were good to re-use if that was the case?
I did the head gasket twice now, but this time I just went with OEM head gasket and arp head studs
Oil in coolant at end of last race season. Tough to say when it happened as the engine ran flawlessly. But the engine is pushed at the track, and it was very cold at the last event (large ∆T swings = larger thermal expansion shock, perhaps enough to compromise the high-pressure oil feed seal in the 100k, 25 year old HG). I removed the head and the seal around the oil feed did not look good, but not sure how much can be drawn after lifting the head.
I had the head completely checked and rebuilt by a reputable shop. Had them remove no more than 0.003" to retain ideal timing chain geometry. Valve wobble was out of spec so I replaced all valves and guides (not relevant...). New HG, hoses, thermostat, head bolts, etc. Meticulously cleaned, assembled, and torqued exactly to spec. Car runs perfect, but slowly started to see some oil in the coolant after about 100 miles – enough to make me second guess..
That said, I am now doubting I got all of the oil out of the system the first time around (especially the radiator and heater core) and this – see later picture – could very well be residual oil. I obviously changed the oil after the rebuild and am doubtful the fresh oil would mix with the new coolant to create a light brown residue so quickly? Looks more like old residual oil…
I bypassed the coolant loop for the oil cooler, then ran clean distilled water through the coolant side and into a bucket for inspection. Did this for all different temperatures and varied the RPM. At first there was a light sheen of oil in the water, but it quickly went away with more flushing and now it’s spotless. This doesn’t exactly replicate the pressure, heat, and flow of coolant, but the oil cooler is likely fine.
This past week I completely cleaned out the cooling system in-situ. I added 1/3 Simple Green HD (aluminum safe) and 2/3 distilled water. Ran the engine for a bit. Then flushed with distilled water (fill, run engine, bleed, dump, repeat) about 5 to 6 times until clear. As confirmed with the scope – see picture – oil clings to the radiator channels, hoses, etc and is VERY hard to completely remove. Have to keep this in mind going forward; just because I see oil in the coolant, doesn’t mean it’s fresh. What a pain… but praying the HG fixed the original problem. I have never heard of a confirmed case of block porosity issues with an F20/22, and I highly doubt the block/head is cracked.
Not trying to hijack your thread, just hoping this info can help anyone else with a similar problem.
Oil in coolant at end of last race season. Tough to say when it happened as the engine ran flawlessly. But the engine is pushed at the track, and it was very cold at the last event (large ∆T swings = larger thermal expansion shock, perhaps enough to compromise the high-pressure oil feed seal in the 100k, 25 year old HG). I removed the head and the seal around the oil feed did not look good, but not sure how much can be drawn after lifting the head.
I had the head completely checked and rebuilt by a reputable shop. Had them remove no more than 0.003" to retain ideal timing chain geometry. Valve wobble was out of spec so I replaced all valves and guides (not relevant...). New HG, hoses, thermostat, head bolts, etc. Meticulously cleaned, assembled, and torqued exactly to spec. Car runs perfect, but slowly started to see some oil in the coolant after about 100 miles – enough to make me second guess..
That said, I am now doubting I got all of the oil out of the system the first time around (especially the radiator and heater core) and this – see later picture – could very well be residual oil. I obviously changed the oil after the rebuild and am doubtful the fresh oil would mix with the new coolant to create a light brown residue so quickly? Looks more like old residual oil…
I bypassed the coolant loop for the oil cooler, then ran clean distilled water through the coolant side and into a bucket for inspection. Did this for all different temperatures and varied the RPM. At first there was a light sheen of oil in the water, but it quickly went away with more flushing and now it’s spotless. This doesn’t exactly replicate the pressure, heat, and flow of coolant, but the oil cooler is likely fine.
This past week I completely cleaned out the cooling system in-situ. I added 1/3 Simple Green HD (aluminum safe) and 2/3 distilled water. Ran the engine for a bit. Then flushed with distilled water (fill, run engine, bleed, dump, repeat) about 5 to 6 times until clear. As confirmed with the scope – see picture – oil clings to the radiator channels, hoses, etc and is VERY hard to completely remove. Have to keep this in mind going forward; just because I see oil in the coolant, doesn’t mean it’s fresh. What a pain… but praying the HG fixed the original problem. I have never heard of a confirmed case of block porosity issues with an F20/22, and I highly doubt the block/head is cracked.
Not trying to hijack your thread, just hoping this info can help anyone else with a similar problem.
Caleb
Thanks for the reply! I saw you commented also on this post;
I was looking at Billman's comment on how he discovered a breach in the HG between the main oil feed hole and ended up closing it up with "adhesive M." Was that something you looked into for your situation? When I pulled the head, I wasn't sure what to look for that would indicate that being the root cause.
Oil leaking into coolant
