See attached from the RAVE overhaul manual in the "general section". Talks about exhaust valves leaking if not upgraded.... You might want to review that section, not just the workshop manual (not saying you haven't, just tossing that in there for those who have not yet entered the RAVE world). Did they also do valve seals and valve guides and valve seats as part of the head job?

 

Does any one think that it could be the lifter? When Cyl 5 is at TDC you can see that the push rod for the exhaust valve is higher than the intake valve. and without the rocker arms on, both of the valves hold pressure just perfect but when I put the rocker arms back on the spring for the exhaust valve compresses just a little bit, and it leaks all of the air out of the tail pipe. As a side not though, this was not a problem before the head gasket job. Any and all imput is welcom. Thanks to every one that has helped so far.

 

Yes it could. Please see attached. Were lifters new or were old ones still servicable? If re-used, important that they go back in same place they came from.

Also, piston rings? Old school test was some oil in to cylinder, if compression test went up it was rings...

 

Finally able to work on the truck again. I called a rover shop and the owner told me to get in contact with his machine shop and order shims for the rocker assembly. So I did so. I installed the shims and would you know it, Cyl 5 was holding 150 psi on the compression test. But, WTF, cyl 1 and cyl 3 had no compression. Pissed off now. I took the shims out and WTF again, no compression on any cyl. The only thing that I can think of is that I am doing all of this compression testing with motor tor down to the crank case. Does any one think that the lifters are just out of pressure now? I have read and researched just as much as I can. Thank you BUZ for all of the suggestions. I feel that I have tried just about everything at this point though.

 

Well, seems like springs hold valves closed, and lifters, if not built up with pressure, just would not open valave as far. But I suppose it could be weak enough to not open at all. A good question.

 

Ok, Knew theory...
The cylinder compression tests are so inconsistent. One day it is cyl 5 with no compression, another day no cylinders have compression, and now cylinders 1, 5, 7 have great compression but not cyl 3. I am going to pull the exhaust push rods to see if all of the calendars have compression. My thought is that the valve job was not done right. I think that the inconsistency of the compression tests is do to a bad valve job. Buzz, the exhaust valves were not upgraded just cut. I think that the exhaust valves seat when they want to and don't when they want to. Or it could be the valve guides but either way, I think now, because of the inconsistency that it is the valves. Your thoughts.

 

Sure sounds like valves.

 

Hylandtk1,

Are these the heads that the 1st machine shop milled to two different plans and them you sent them out to another shop to have the equilized.
What do you think the chances are that HG were done before like around 70-80K not unheard of ?
If so your pushrods could be keeping all the valve from seating, they may all need to be shimmed. There is a limit to what these heads can be milled.
If you want a "shade tree"way to check your machine work, pull all your pushrods out, hook air to your compression guage and see if each cylinder holds air. If they do your problem is in the valve train not the valve job.

 

When milling heads...you throw off the mounting angles of the intake...

The intake and heads are made to be put together, the mating surfaces have the same angle. When you mill a head you change that angle a degree or two. The head sits just a shard lower but it is sometimes enough to make a difference.

Seen this on a minivan once...had the heads milled and the thing wouldnt run right at all. Never milled the intake to match. Once we milled the intake, it ran so smooth and all the codes disappeared.

With what your going through, I would have bought a known good set of unmilled heads and put it back together and drive it.

 

shanchevelle,

That is a valid point but I dont that is the problem here, that would make it run like crap and have vacuum leaks, his problem is with compression and intake manifold will not effect compression.