Help Diagnosing 0 Compression!

[b4christ15]

What's up guys? I have a little dilema going on right now. I'm in the process of fixing my car that spun a rod bearing back in January. The car was sitting till last month when I picked up a used, but good condition short block to replace the one with the spun bearing. The short block had cross hatchings still visible and even included a good condition ACT 2100. The guy I bought it off said the car it came out of had good compression and a 12 sec. 1/4 mile under its belt. I picked up a BSE kit from slowboy and sent everything over to a mechanic I've known to have it all put together. With everything in, I got a call today that a compression test revealed 0 compression on all cylinders. I talked to the guy I bought the block from and he said he thinks something is set up wrong with the timing part of the motor. Any other thoughts on to what could cause a reading of 0 compression? The head was rebuilt in November and only has maybe 1k miles on it. Mechanic said that its not causing the problem and that he thinks its in the short block. Im wondering maybe doing the BSE wrong could cause no compression to build. I need some helpful responses from the DSM gurus of this site. Any insight is greatly appreciated. BTW, profile is up to date.

 

[b4christ15]

Are they using a starter, etc to pull the motor over while checking compression ? The only cylinder testing that I personally do while the block is 900miles from a starter is a leakdown.

Unless I just didn't understand if the block was put in the car, and towed or w/e to your mechanic.

Im not sure what exactly your asking but ill try to respond. The car was towed to my mechanics and he replaced the block that had the spun rod bearing with a used short block I bought from a local dsmer. The motor was put back in and I was told today that a compression test revealed 0 compression on all cylinders.

 

[GVR4592]

0 compression on all cylinders would most likely be the timing.

 

[b4christ15]

Okay, making more sense.

When you did the BSE, did you re'align the timing, etc, when putting it all back together?

Did the shortblock look really good? No cracks on the pistons, etc?
Did you have the head mag'd (inspected for cracks) ?

I would think that only the head gasket, or something wrong with the head could be your major problem. Nothing really can go 'that' wrong on a shortblock, and get 0 across all the cylinders.

Not exactly sure but I would imagine my mechanic did the timing. The short block looked pretty damn good. Cross hatchings were still visible and it has about 20k on a rebuild. The previous owner said it came from a strong running car with good compression. I had the head rebuild back in Nov and it only has about 1k miles.

 

[oldman]

Unless there is a big hole in each cylinder which would have been visible during the initial visual inspection, 0 across all fours probably means bent valves most likely caused by incorrect installation of the timing belt/components.

This of course is assuming the mechanic knows how to compression test, you never know.

 

[b4christ15]

0 compression on all cylinders would most likely be the timing.

This is what the previous owner of the short block said. I told my mechanic thats what it could be so he's gonna be checking and double checking it tommorow.

 

[b4christ15]

Unless there is a big hole in each cylinder which would have been visible during the initial visual inspection, 0 across all fours probably means bent valves most likely caused by incorrect installation of the timing belt/components.

I sure hope this isnt the case as i stated before the head has a fresh rebuild with only about 1k miles on it.

 

[oldman]

I sure hope this isnt the case as i stated before the head has a fresh rebuild with only about 1k miles on it.

Let's hope that he doesn't know how to compression test instead, I don't see how timing can be off by so much as to produce 0 compression without bending valves.

 

[b4christ15]

Let's hope that he doesn't know how to compression test instead, I don't see how timing can be off by so much as to produce 0 compression without bending valves.

When I got the bad news today, the first thing I asked him was the condition of the head. He said it was fine. I'll find out more info tommorow and update. Thanx for all the help.

 

[GVR4592]

Let's hope that he doesn't know how to compression test instead, I don't see how timing can be off by so much as to produce 0 compression without bending valves.

I agree and that's what I meant to say in my first post. The only time I've seen 0 compression is when the valves were bent....or that one time the valve head snapped off and went through the piston, but that was only one cylinder.

 

[b4christ15]

0 compression on all cylinders would most likely be the timing.

Just got the news that this was the cause. I was told that timing was wayyyy off and that the car runs good now.

 

[GVR4592]

I think you should do another compression test to be safe. Maybe take it to a different mechanic this time.