OT: MR2 problem.

Mr. Pockets · #1 03-20-2005, 02:57 PM

Here's a copy of the post I just wrote on the MR2OC. If you have nay advice to offer, I'd appreciate hearing it.

Quote:

Originally Posted by Mr. Pockets

I finally did what I should have done when I first bought this car last fall - a compression test. Before I get to the results, I'd like to explain what led me to do the test.

The car runs and drives great. I had an idle problem that I semed to have inadvertently solved when I did some work on the car last week. I suspect that a hose connected to the EGR valve was not actually connected. The car also burns oil. I know from the last time I replaced plugs, about five weeks ago, that cylinders 1-3 looked great and #4 was very oily. The oil burning has gotten worse lately, and sometimes when I come to a stop I am overtaken by a faint cloud of blue smoke.

Okay, so the compression test results:

#1: 170
#2: 167
#3: 172
#4: 0

No, really, zero. I had my wife turn the car over because I didn't believe it when I got out and looked at the gauge. When I watched the gauge, it never got above 20psi and dropped immediately.

I have my own thories about what could cause this loss in compression and what is probably causing it, but I'd like to hear what people with some experience have to say.

Thanks.

Not good - I have been doing a lot of work getting ready for the autocrossing season which starts very, very soon. I should have looked at this long ago so I wasn't surprised like this.

thundering02 · #2 03-20-2005, 06:06 PM

Head gasket probable...Cylider rings or Valves Most Likely... If it is the valve then do the guides and springs while you have them out. Rings well thats a full on rebuild type job....one other thought cracked head(not likely).

Mr. Pockets · #3 03-20-2005, 07:00 PM

Yep, those are all possibilities I have considered. The head gasket was replaced less than a year ago, but I see no mention of the head being machined or whether or not it needed it..

Beav · #4 03-20-2005, 07:20 PM

Normal progression at this point: Go back and check another cylinder to ensure you didn't pick up a piece of crud in the guage's schrader valve. Next step is to pour a couple ounces of oil in number 4 through the spark plug hole and re-check. If it now pumps air you have a ring problem otherwise valve or head gasket. Now if you suspect head gasket, a cylinder that has 0 compression would be pumping a lot of air into either the crankcase or cooling system. With the radiator cap off you would see a lot of bubbles. If into the crankcase you would have a lot of oil pushed out past gaskets and seals.

thundering02 · #5 03-20-2005, 08:12 PM

Thanks Beav the head gasket/ring trouble shoot it. Oh and I replaced the head gasket on my Teg and less than 2 months later had to replace it again because the head was slightly warped 15 minutes and a large file in the drive way took the new head and gasket till the bottom end went out.

Mr. Pockets · #6 03-20-2005, 08:17 PM

Quote:

Originally Posted by Beav

Normal progression at this point: Go back and check another cylinder to ensure you didn't pick up a piece of crud in the guage's schrader valve. Next step is to pour a couple ounces of oil in number 4 through the spark plug hole and re-check. If it now pumps air you have a ring problem otherwise valve or head gasket. Now if you suspect head gasket, a cylinder that has 0 compression would be pumping a lot of air into either the crankcase or cooling system. With the radiator cap off you would see a lot of bubbles. If into the crankcase you would have a lot of oil pushed out past gaskets and seals.

It's funny you should say that, because I do get a lot of oil pushed out through some seals. I just repalced the valve cover gaskets, but oil seems to just be pouring out the cam seals. It pools (no, really - pools) in the plug valley.

Other than that, I don't see other signs of a bad head gasket. No oil in the coolant and no coolant in the oil. No bubbles in the coolant, either, and I just had to go through the coolant bleeding procedure so I definitely would have seen it there.

Beav · #7 03-20-2005, 08:25 PM

Try putting all the plugs back in and cranking the engine while holding your hand or a piece of paper over the oil fill (cap off, duh.) Excess case pressure will blow the paper off or you'll be able to feel the pulse, depending on which you do.

The head is the hottest part of the engine, besides the exhaust manifold. If it has overheated the cam seals catch hel , harden and leak.

Mr. Pockets · #8 03-20-2005, 10:40 PM

I was actually given a few interesting ideas to try. I should have more details tomorrow.

Mr. Pockets · #9 03-21-2005, 09:59 AM

The prevailing theory right now is that I have a bad intake valve. I suspect this for a couple reasons.

1. I find it unlikely that a bottom end problem would cause a complete loss of compression without other symptoms.

2. I found a lot of oil in my intake about six weeks ago.

My theory is that one or both of the intake valves on #4 are bad, or the head is cracked around them. They are leaking oil and the loss of compression results in the oil being blown straight back into the intake.

A friend of mine, after I told him this theory, told me that the same thing happened to one of his cars - he had a bad intake valve and found his air filter dripping with oil.

Beav · #10 03-21-2005, 03:25 PM

Yeah, but all of what you were told doesn't preclude checking it out properly. Check your guage and do a wet test. Stuck piston rings can easily yield 0 compression. think of it like this: If they ain't a pumpin' good they ain't a suckin' good either. (In other words, if it isn't pushing air out of the cylinder it isn't sucking air in either. Makes understanding 0 comp a bit easier.)

Mr. Pockets · #11 03-21-2005, 03:41 PM

When I went home for lunch, I rechecked the compression on #3 to make sure the gauge was working correctly and then checked #4 again. #3 read a little higher than it did yesterday and #4 still read...nada...

A 'wet test' with oil in the cylinder gave me pretty much the same result. There was actually a little pressure, but it barely registered. We're talking in the neighborhood of 5psi.

I also looked in the intake hose and found the light brown oily mess that I had cleaned out six weeks ago.

thundering02 · #12 03-21-2005, 06:53 PM

My thought now Probable to the valve(at least part)

Mr. Pockets · #13 03-30-2005, 09:31 PM

Well, I got the head off. The only obvious problem I can see so far is at least .011" of warpage in the head around the problematic cylinder. The top of the #4 combustion chamber (same cylinder) practically has stalactites growing off it. The head gasket looks to be intact.

Is the head warpage enough to cause the problem? Is the real culprit the bottom end? I'll find out, I guess.

I'm taking the head to be pressure tested, hopefully tomorrow.

thundering02 · #14 03-31-2005, 01:59 AM

The head will be most of the problem(mill it flat) I also assume you checked all the valves...?

Mr. Pockets · #15 03-31-2005, 06:40 AM

I don't really know how to 'check' the valves.