1999 Honda Accord oil in radiator


I have 1999 Honda accord that just started leaking oil from the cooling system. The car has about 207,000 miles but I have done all of the maintenance work on. The car is a Manual transmission and the oil level was low when I went to check on it. We have not had any problems with the car and it has been running normally with the exception of the oil problem, none of the lights were on and temperature was normal. I saw something on the net about a problem with the porosity of the block on this model car but I cannot seem to find any other problem, check the spark plugs, compression check and all look good. Do you have any ideas? Is there anything that I can do to determine the problem?


If there is in fact oil in the cooling system, you have a leaky head gasket, end of story.

Are there any other signs that I should look for, bubbles in the coolant, water in the oil pan or ?gunk? on the oil filler cap? It seems that the head gasket is always the response but I have my doubts. Honda?s generally do not seem to have a head gasket problem, unlike Toyota especially when the car has not been driven hard and has been maintained.

What exactly do you mean by “it leaks oil from the cooling system?” If there is oil in the coolant (which would be brown scummy stuff floating on the coolant when you look in the reservoir bottle or take off the radiator cap) then the only place where the oil and coolant are close enough to leak one into the other is the head gasket. You may also have coolant in your oil, which would result in the oil looking foamy instead of smooth and amber-brown.

However, if the engine is leaking oil onto the ground, then it is not coming from the cooling system, but could be coming from somewhere nearby.

I only bring this up because your question is worded a bit oddly.

Sorry for the confusion, the oil leak was from the radiator over flow tank. When I removed the cap, it was full of oil and then when I removed the radiator cap, it too, had oil in it. The dip stick and the oil cap do not show any signs of water in them. The oil in the radiator looked was black and thick, not foamy. It looked like about two quarts of oil was pumped into the cooling system, but the oil light never came on.

2 quarts is a lot to lose all at once. Was your oil level low by the dipstick? The oil light may not come on until you’ve lost more than 2 quarts. If your oil level was not low by the dipstick, I might suspect someone was playing a prank or vandalizing you. (Of course, if the oil mixed with some coolant you might have lost a quart or less and the rest was coolant mixed in, maybe.)

You could flush the coolant and hope it was vandalism. Otherwise, it can really only be the head gasket or a cracked head or block, since that’s the only place oil and coolant can mix. (You are hoping for the gasket, of course!)

I had same problem with my 1999 honda accord. After Flushing 3 times and changing hoses, (had hit a deer and damage the radiator and trans. cooler). After 6 month decided it must be head gasket. When it was changed learned that nothing was wrong with gasket with either. Then was told there was a defect with engine between water passage and oil passage.