99EXDude

I have a D16Y8, 99 civic EX with 304k miles.
The story: For a long time I have suspected a head gasket issue (oil in coolant, smell in exhaust, bubbling sounds after engine turned off) but never had overheating issues so I've been living with it. Recently the lights were pulsating badly so I changed alternator+plugs+plug wires+cap+rotor. Prior to the change that same week I began to feel a slight acceleration hesitation/ that went away after the new parts [note here: only 3 out of 4 plugs were changed initially because #2 was stuck] so I figured the hesitation had been due to electrical since it went away. A week later the car was hesitating badly and misfiring. I had it towed to a local mechanic who adjusted the valves and it made it slightly better but still misfiring after warming up. He thought I may have a burned valve issue. I took the car home to figure out what to do.

If the engine was a goner, I decided to chance breaking the stuck spark plug and torqued it out (and found out it was cross-threaded) then replaced it (figuring it would be the last set of plugs for this engine anyways).
Before I put the new spark plug in I performed a dry compression test and got: cyl 1: 150 psi, cyl 2: 150 psi, cyl 3: 170 psi, cyl 4: 180 psi

These numbers seem okay to me, although it may show a leak between #1 and #2. However, now the misfiring seems gone. I've been turning the car on each night, letting it warm up then driving it around the neighborhood and stressing it uphill, etc. with no issues. Now the question is whether I have a burned valve still. I'm thinking of checking with a leak down test.

I would ask for the group's advice on a few questions:

1. Can I be sure I have a burned valve without taking the cylinder head out?
2. If it turns out I have a valve leak/burned valve, how much might it cost to have a valve job done at a machine shop?
3. If I don't have a valve leak and don't address the head gasket, can I continue driving it? It this something that will eventually kill the engine?
4. Would a head gasket leak cause misfires?

I'm trying to keep this car running past winter until we're ready to purchase a new car so your thoughts on this would be helpful. Thanks so much!!

ezone

You didn't mention that it was setting misfire codes up until the last spark plug got replaced.....
So now that's cleared up, and you've erased fault codes from the computer. Right? Right.

First and foremost: Is it still setting misfire codes?



Those engines do blow the head gasket. It's a MLS gasket and it the early stages it typically SLOWLY pushes coolant out of the radiator and overfills or overflows the reservoir. Slowly--meaning it could be many hundreds of miles from onset until anyone notices anything unusual.

If it's REALLY mixing fluids, I'd expect the head would be warped (meaning it overheated at some point).

99EXDude

ezone, you're right. I was trying to be brief. To clarify:

Before changing the alternator I was getting some hesitation (didn't know it was misfires at the time) with the 3 out 4 new spark plugs. After the alternator I got some misfire codes (P301, P302, P304, I believe - was even getting some P1399) which prompted me to change plug wires and distributor cap. I hadn't done the last spark plug yet due to fear of breaking it. Only after the really bad misfires/stalling and the valve adjustment did I change the last spark plug. I didn't actively reset the codes after these changes, unless the mechanic who did the valve adjustment did.

The check engine light has not come on since the last new spark plug but I have not put the OBD reader to it yet. The car has been running well since. I'll check tonight if there are any pending codes.

What do you mean by mixing fluids? When the coolant and oil become the sludge? I don't have that yet, only the coolant getting some oil.

99EXDude

UPDATE: The car has been used for short drives just about every day for about almost a week now and no issues and no codes. Next thing is doing the leak down test to see if I have a bad valve. A local machine shop quoted about $450 for checking for cracks, valve job and seals (plus parts or valves if needed) if I decide to do the head gasket. I'm thinking it might be worth it.

ezone

or blown between two cylinders. Wait, did you have a charger on the battery (or good strong battery) while doing the compression tests? Starter speed has to be consistent throughout the tests, because slower cranking rpm as the battery runs down can cause lower test results.

You might want to recheck compression, and do it on a hot engine.
If numbers still aren't fairly even, check and adjust valve clearances....then run it til hot, then recheck compression again.

Then if still screwy, try a wet comp test.

Exactly how much? What do you see?

99EXDude

Yes, the battery was brand new. I also did the test in the sequence of 1 to 4. If the battery was low I suspect it would have been lower for at least the last cylinder. no?

I can try again. My plan will be to only do cylinders 1, 3 and 4 since I don't want to remove the spark plug for #2.

How would you describe screwy? As I understand the fact that it's in the mid to upper 100s it's decently good but that they're not within 10% of each other that is screwy.

I've seen a decent film in the reservoir. enough to make the walls of the reservoir sticky.

Thanks ezone!

ezone

Ok, good.
Battery issue eliminated, now I'd be interested in checking valve clearances.....if none are too tight, move to something else.
I'd also want to do a wet compression test to assess the rings before considering removing the cylinder head. IF it gets to that point.

You did say it's been hot so it may still get to that point...but I'd want to be certain. I hate doing unnecessary work.
If it's no longer setting misfire codes that says a whole lot right there. The differences in compression apparently aren't enough to upset the PCM so you might reconsider how much time and effort you want to put into this right now.
That's probably not really oil. IDK what it really is but there has been some discussion before. Many cars seem to have that film stuck to the plastic but no outward symptoms of anything really wrong.

Engine oil in the cooling system will make rubber swell.
Like the gaskets on the radiator cap would be swollen and mushy if it was really oil.
Hoses would eventually get the same way.





Hope I was thinking of the correct thread when I wrote this post lol