VX has oil in coolant...thought it was head gasket, could it be oil Cooler?

[mrbisset]

I have a 95 Civic VX with a dirty radiator overflow tank that gets sludge at bottom. It seems oil is leaking into my cooling system. The car runs great and has just 129K miles on it. I just learned tonight there is an oil cooler under the oil filter that circulates engine coolant around the engine oil to cool it. Is there a way to test if this is failing? Could I just remove the coolant circuit from the oil cooler and connect the IN/OUT hose lines together to see if the radiator stays clear of oil after I flush the system? I know the oil temp would be a little hotter, but I don't expect it to harm the engine? I see a new oil cooler is $200+ so if its working Ok I would hate to buy a new one to find out its not the problem...

cheers!

[theholycow]

That sounds like a reasonable diagnostic measure, although you might want to wait for someone more experienced than me to give you the OK.

If you do need a new oil cooler, I wonder if you could use an auxiliary oil cooler rather than replace the entire assembly. They do exist, and even more common are auxiliary transmission coolers that could probably substitute for the job.

[mrmad]

The D series (and B series) Honda engines are open deck blocks. Headgaskets usually blow between the cylinder and the waterjacket, where no oil is present so I wouldn't think it is likely oil in your coolant is coming from the HG. I'm sure it is possible to have the HG fail in the areas where the oil channels are, but in I've gone through 3 headgasket failures between my CRX and Integra and they have all failed between the cylinder and waterjacket.

[mrbisset]

thanks for reply's! Still having faith that its not HG problem, fingers crossed. So I guess next question is can i just connect in/out coolant hoses together of oil cooler and remove the oil cooler from system, replacing it with just the oil filter? Should I get temp gauge to monitor oil temp? I have to dig into it this week...

[mrbisset]

So I connected the oil cooler antifreeze line together to bypass the oil cooler, running the coolant together with a barb connector instead through oil cooler heat exchanger. I haven't got all the oil out of the radiator and overflow tank, so not sure if that is where the oil leak was. I have drained and refilled the radiator, and continue to wash out the overflow tank, but there is still oil residue so i can't tell if i stopped the oil leaking into coolant system or not...

Today I rented a radiator pressure tester, and put 16psi on radiator cap, with no leaks after 5+ minutes...so is it safe to say there isn't a head gasket break leaking oil into coolant while running?

[add|ct]

Have you tried using something like Prestone's radiator flush product?

That'd be a great way to clean up your cooling system for sure, along with a run on all distilled water(for a short time of course) to flush out the Prestone flush product, and then drain/refill with anti-freeze again to see if it gets as dirty as you are currently seeing it.

If it reduces the look of oil residue dramatically from what you are currently seeing it may have been left over residue.

Have you compression tested your engine? Are you loosing oil when checking via the dipstick over time? The latter may take more time to know for sure, but a compression test may help determine a blown HG the fastest without a tear down.