Help with Compression test results
 

I just finished testing. Tell me what you think of these findings. 86' na
1st cyl - 145
2nd cyl - 145
3rd cyl - 170
4th cyl - 200
The first and second cyl. took about 6 strokes to build up each, where as 3rd and 4th only took about 4 strokes each. I thought that I had blown a head gasket, because of coolant in th oil and rough running. I'm not sure now. Thanks for the help.

How're your valve timing & timing belt?
Are those readings "wet" or "dry"?
When running, what vacuum readings show?

Im not sure, but I think they are all supposed to be within 10 lbs or so of each other....I know theres a percentage spec for this...the 200 sounds really weird (too high). THe 145 seems a little low (not too bad tho) -- I think 170 is OK. I know you want consistant numbers thru-out....if you readings are accurate - i think somethings amiss...Good Luck

The spec for an na (early) is 145, I don't know what it is for an 86 (late) 944 ...
The 200 and 170 sound too high to me!!!

Repeat the test, using the same number of strokes per cylinder. Write down the results, repeat. If the second results are pretty close to the first time, then I would say they are more reliable. 200 sounds way too high but 170 is close to 180 which is the low side of the +-10% range from 200. From what you have now, I would about say you do have a blown head gasket across 1 & 2. A head gasket can be blown across the compression side as well as the oil/coolant passages. Good luck.

Dave951M

I'm gonna try again. There is a loud metal on metal clapping sound. I think that it is a valve problem. Everything was running ok engine wise and then i put fuel injector cleaner into the tank with a fill up. Since then, I have had nothing but problems. Another thing I thought was interesting was that when I took out 3 and 4 sparkplugs, there was oil on the metal band behind the threads. I'll let you all know how the next test comes out.

If it is a loud metal claping noise it could be a rod bearing, hope not for your sake.

Whoa...
while the plugs are out examine the valve
time/align marks and TDC. Metal-on-metal
sounds could be piston to valve.

Is that anywhere in the haynes. Could you give me a quick lesson on how to do that?
If it is a head gasket problem, I know it will be a lot of work. I trying to look at it as a learning opportunity because I have never taken the head of a 944. A gasket I can deal with, but more worried about having to do a valve job, or removing the engine etc...

During the buyers inspection my mechanic came up with these numbers for my '86 NA...which he indicated were very good for a car with 120K on the clock.

#1 170
#2 165
#3 168
#4 170

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1986 944 NA

Aceman...yes, Haynes describes the valve
timing/belt alignment check; so does Chilton
Import book. I prefer the Haynes, usually.
Be sure alignment marks line up at (top dead
center)TDC of compression stroke--rotate the
engine (plugs out)so they do. Be sure cam belt tension is good; might as well examine
balance shaft belt while you're at it. Are
you confident your pressure gauge is good,
by the way?