Engine oil in coolant

[California98Civic]

Asking for pro-tips and pointers...

"Black and Green" has engine oil in its coolant reserve tank. It has been a minor phenomenon for a loooong time, but in the last year it seems to have become more significant. So, I am planning to replace my head gasket during my daughter's spring break.

This will be the first time I will ever have done this job.

I understand that when the head gasket fails, generally oil escapes into the coolant and not the other way around because the oil is under higher pressure.

I have not noticed white smoke from the tailpipe, indicating coolant in the combustion mix, but I also have not seriously checked (and can't right now).

How likely is it that I also have coolant in the engine? How would that happen and how might I check? And how should I check for damage when I get into the head?

Thx

[19bonestock88]

It would largely depend on where the gasket failure(if that’s the true fault) is... if it were between a large oil jacket and a small coolant jacket then there wouldn’t be a huge likelihood of coolant in the engine...

Best way to check is when the head is off to check for signs of water(rust or other deposits that aren’t carbon or oil)... while the head is off it wouldn’t be a horrible idea to have it magna-fluxed (check for cracking) and possibly shaved to correct any potential warping/pitting(a sign of water)

Has the engine developed a misfire of any kind? Have you checked compression?

[Frank Lee]

"You got chocolate in my peanut butter!"
"You got peanut butter in my chocolate!"

If you see what looks like cappuccino froth on the dipstick or under the oil fill cap that could be coolant in the oil (or condensation from multiple short trips in sub-freezing temps).

[19bonestock88]

I had totally missed that, I assumed you were referring to the combustion chambers and the like

[California98Civic]

Good suggestions. I'll ask around for places here that can look at the head and check it. That sounds like a good move.

Originally Posted by 19bonestock88

... Has the engine developed a misfire of any kind? Have you checked compression?

No misfires. I checked compression two years ago, and it was really good for 250,000 miles. Stock being about 180 or 185, mine was still in the 170s. One cylinder was maybe 169, IIRC.

Originally Posted by Frank Lee

... if you see what looks like cappuccino froth on the dipstick or under the oil fill cap that could be coolant in the oil (or condensation from multiple short trips in sub-freezing temps).

Nothing like that. Oil blackens, but no "froth" or otherwise off color.

[Frank Lee]

If a head gasket is leaking compression you might see bubbles in the coolant when the engine is idling.

[Stubby79]

Could it be getting in there by other means? If you're not losing coolant (out the tail pipe) and not getting any water in with your oil, and it's not a significant amount either...might not be your head gasket?

If its engine oil, and it's only going one way, it would have to be oil under pressure...or it would go both ways or the other way. A crack or a leak somewhere between the oil pump and anything it supplies.

I assume you have a manual trans with those kind of MPG numbers...but if you didn't, it could be the oil cooling line for the trans in through the radiator. There any other possible routes of contamination that come to mind?

[ksa8907]

Does that car have an integrated oil heater/cooler in the radiator?

[Gasoline Fumes]

Originally Posted by ksa8907

Does that car have an integrated oil heater/cooler in the radiator?

I've never seen that on a Honda, but some Hondas do have coolant-to-oil heat exchangers between the block and oil filter.

[jcp123]

Others have already covered what I was going to say.

While you're in there anyway, I know these have a 105k timing belt change interval. But it's a pain, might as well slap a new belt/water pump/tensioner on. And if you have the feeler gauges, adjust the valves when you're getting 'er back together.