I've got a 1998 Honda Prelude with 182,xxx miles all around that has a smoking engine bay when running at hot temperatures. It has been winter and has gotten warmer just recently, but I don't think that plays a role in the diagnosis.

I've figured so far:
Oil is leaking (at rate of approx. half a quart every 40-50 miles), and dripping from somewhere above the exhaust flex pipe (steel-woven section of exhaust that sits pretty directly below oil filter), onto the exhaust (once again, mostly around flex pipe), and burning off at hot temperatures causing it to smoke. It leaks when the engine is running, and continues to drip and smoke until about 1-3 minutes after I've turned the engine off (but this is likely excess dripping, not a continued leak). This problem had a pretty acute (sudden) onset, and I've been experiencing the same problem (doesn't seem to be worsening or improving by any substantial amount) for the past 2 weeks. When I looked a few days ago, the spark plugs also had a little bit of oil on them.

WHAT IS THE CAUSE OF MY OIL LEAK?

I've tried so far:
I've been trying as much as possible to not drive my car.
I've replaced the over-due oil filter (which also came with an oil change, not that that would do anything to fix an oil leak).
I've replaced the valve cover gasket (which also came with replacing spark plugs since they had oil on them, as explained above).


Other things I've considered but not yet done:
Replacing head gasket. This was my first guess, but it's obviously the hardest to do, so I've done other things first, hoping they would fix the problem. Not so, it's still leaking.
Examine oil lines for leak. A friend suggested this yesterday and I haven't yet taken a look at it. I don't even know if the oil lines would be over the area that I'm leaking onto.
Take it to a mechanic. I scheduled for this Monday thinking I didn't have school, but I do. So that sucks.



Any thoughts before I spend money on a mechanic diagnosing it?
Thanks guys.

 

When you replaced your oil filter, did you check to see if the old gasket was on the oil filter seat?

 

I didn't pay close attention to that, but there were other guys with me and we all looked at it and didn't see anything remarkable about the old one. So I think so.

 

Ok. Sometimes when you change out your oil filter, the gasket from the old one sticks to the engine and when you put the new one on, it screws up the seal, causing it to leak. I would take a close look at the area to see if there is anything out of the ordinary. ie: warpage, chipping, etc.

 

Okay thanks.

 

Are you able to pinpoint the location of the leak. I would start by cleaning everything up that you can get to while the engine is cool then see if you can watch to find where the leak is originating. From there you should be able to narrow down the problem. Sounds like it could possibly be a head gasket but you have several places for leaks from the rear of the engine.

 

I know this might be a little bit out of the price range and realm of possibilities but I can think of two options. Get a friend with a lift and put it in the air, a lot easier to find leaks that way. A more feasible thing for you to do would to go get some special engine oil dye (they say you're supposed to premix it with the oil and then add it but since you have already changed your oil there is no point in spending the money to doing it again). You will also need a dark spot like a closed garage at night, and a UV light. Also the special yellow tented glasses help A LOT. You should clean everything up really good before you start though because it will help you find the leak better. Just add it to the engine, turn it on, and start looking.

As far as the oil on the spark plugs go, the most common thing I see is worn piston rings. I'm not saying thats your problem, just saying thats what I see the most. It would probably be beneficial to run a compression test (dry then wet of coarse) and see what you're working with. I do understand that not everyone has a compression tester, so you might end up taking it to the shop after all. Give it some time though, really do some investigating and keep posting on here for advice. It would suck to drop a couple hundred bucks at the shop when it was something simple.

 

If your getting oil on the flex pipe section of the exhaust, being that this is an H22 with high mileage, if the oil cooler o-ring hasn't been replaced you may want to consider this. It's a rubber gasket, that just like any other rubber gasket turns into hard plastic and this may be the cause of your leak considering the location described.

 

Sorry I've been out for the weekend. Thank you guys so much for the responses. Though I haven't been responding for a few days, I have been continuing to try to diagnose the problem. I think the next thing for me to do is change the oil cooler o-ring - that seems to be the easiest, simplest, best explanation, and cheapest... so it sounds pretty good to me! Along with that part, I also ordered cam cap seals, a VTEC solenoid gasket, and a distributor o-ring. I'll be installing these as soon as they come in (expected 2 days from now, Saturday) and I have the time. More suggestions are welcome if you have other or confirming thoughts/suggestions. Thanks again guys.

 

between the block and oil filter adapter is another o-ring that goes bad alot and the oil on the plugs could be the valve stem seals.