Leak down / compression test results

[Jean]

Took the car to get the leak down test done to get an idea if it would be worth my time putting a rebuilt head or if the engine in the car has more problems. Looks like I'll need to finish my extra bottom end, and get new pistons and not waste a rebuilt head on this one...

1. 30% comp 170
2. 55% comp 160
3. 45% comp 170
4. 35% comp 170

Rings ?

[FredK]

The compression figures seem good, which indicate the rings are in good shape.

The leakdown is horrible though. I think a new engine has leakdown of around 7-8% cold. I think the head is the problem. Did the mechanic offer any advice on what to do? Like were there any whistles he could hear in the exhaust or something?

[Jean]

The printed sheet with a MotoMeter compression value in lbf/in^2 says "Crank Case" near the CLT. % numbers.

I asked how the test was done, just for my own knowledge and was told they shoot air with a machine that has a gauge to read the value off of into each cylinder through the spark plugs and check if it leaks through the crank case or oil filler cap.

I was hoping it would be the head, that way I can just slap a new head and call it good. This makes sense to me "The compression figures seem good, which indicate the rings are in good shape. " What's the factory rated compression on the m10 supposed to be ?

I wonder if it could be a bad head gasket, since my coolant gets dirty quick but oil isn't mixed with coolant....

[mcgrath]

does the car smoke on decel? If it does then you most likely need to replace the valve stem seals. Those compression numbers wouldn't scare me, the fact that they are so consistent shows the block has been wearing evenly and they really arent that low at all. I don't know what a new m10 produced, probably around 190 (someone here knows)

[Jean]

No smoking on start up or acceleration. The only time I saw smoke is when accelerating hard and shifting at redline 1st to 2nd on the on-ramp and it was more of a black smoke.