M42 won't start

[mattdk318i]

not to thread jack but i have a bunch of M42 parts including good head and block. Just in case

[KenC]

This blows. As of Sat, my birthday. I am now in the same boat as Ken with my m42. Beginning the trouble shooting phase now. :(

Totally forgot to call you back man. If you have any more questions about it feel free to give me a ring.

[Van Westervelt]

This blows. As of Sat, my birthday. I am now in the same boat as Ken with my m42. Beginning the trouble shooting phase now. :(

[KenC]

I comp tested an M42 with 200K+ that sounded OK while running, and it comped out at 130, 90, 130, 90 psi.

All four tested at 190-210 about a month ago.

[Hick]

Nope.

What do you mean 'Nope'

If he sits there and cranks on it for a day and theres no spark the fuel will wash the cylinder walls of oil which can damage the rings and walls. Unlikely, but possible.

GL fixing it.

[FredK]

I comp tested an M42 with 200K+ that sounded OK while running, and it comped out at 130, 90, 130, 90 psi.

[Jordan]

120 is very low, 60-80 is just plain insufficient compression. When I tested my M42 last month it was:

Cylinder 1: 201psi
Cylinder 2: 195psi
Cylinder 3: 209psi
Cylinder 4: 195psi

Which I'd suspect to be pretty normal for a good running M42.

As for Ken's motor... its got a cracked/warped head or a bad head gasket. Bent valves are unlikely as I'm sure he would have noticed the noise.

[Funkmasta]

Well, the only thing i can think of that would of caused this is that the car wouldnt start from a problem but the compression issue is as a result of trying to fix the motor.

Nope.

[Hick]

Well, the only thing i can think of that would of caused this is that the car wouldnt start from a problem but the compression issue is as a result of trying to fix the motor.

[Funkmasta]

Both edges pointing up and being level should have 2 dimples in them.

With cyl 1 at TDC, both arrows on the cams were pointed straight up, and both cam lobes for cyl 1 were pointed at their 45 degree angle toward eachother like they should be.

Makes no sense to me.

Ken did mention that his last couple tanks his mpg had gone down considerably.
I guess when they go, they go. ?

[Funkmasta]

The timing is correct (at least close enough).

We tested the compression guage AND the leak down tester on the good M42 AFTER the failed readings on Ken's motor.

Cylinder 2 had the highest compression @ 120. The other 3 cylinders ranged from 60-80.

[Jordan]

The cams line up by placing a straight edge across the blocks all the way at the back of the cams so that there is no gap on the straight edge, best judgement is best, do not need to be perfect.

Both edges pointing up and being level should have 2 dimples in them.

[Hick]

The cams line up by placing a straight edge across the blocks all the way at the back of the cams so that there is no gap on the straight edge, best judgement is best, do not need to be perfect.

[KenC]

Yeah we tested the gauge on another engine to make sure that it wasn't the gauge.

I'll try those relays and swap in another FPR.

Timing:
We put cyl 1 at TDC and the arrows on the cam gears were both parallel and pointing straight out of the head. We can get a cam alignment tool.

[ak96ss]

If you tested it on another engine, and it worked, I would say the gauge probably isn't faulty, although that obviously doesn't rule out operator error. I would find it hard to believe, though, that you could make the gauge work on one engine, then totally screw it up on all four cylinders of another engine.

Unloader relays are K5 and K7, but that won't help your lack of compression.

Are you positive timing is set right?