Compression test

[Bextreme04]

I did the compression test this morning. I warmed the engine up first. On first attempt to start it lock up. I knew #3 had water in it before. I pulled #3 and water ran out. I mean a lot. It started after #3 was cleared.
Readings are as follows.
1 - 150
3 - 135 water in this cyl.
5 - 155
7 - 140
2 - 160
4 - 80
6 - 85
8 - 150

Agree with Fast 99. Wet test on 4 and 6 to tell you the condition of the short block. If a wet test brings them up near the others, you basically need to rebuild the whole motor. If not, you probably have two blown head gaskets and/or cracks in the heads. Either way, intake manifold and heads need to come off and you need to inspect the mating surfaces as you go to see if you have a leak somewhere. Have the heads cleaned/magnafluxed/inspected by a reputable shop or just bin them and replace with some good quality aftermarket heads.

 

[Terry Wilkerson]

Wet test on 4 and 6. No change on compression. If I go with heads and problem does not go away I should be able to use the heads on a short block??

 

[Terry Wilkerson]

Another interesting thing this problem started all the sudden. I immediately knew something was wrong. Does this tell anything?

 

[1979 c20]

I would be considering another long block at this point if it were me. I don't have time to fiddle fart around trying stuff for the sake of trying it but discovery is fun too.
Disassembly should show the why soon enough.

 

[Bextreme04]

Wet test on 4 and 6. No change on compression. If I go with heads and problem does not go away I should be able to use the heads on a short block??

Well, that tells you that you aren't losing compression due to bad rings. Two cylinders having almost the same low compression right next to each other like that usually means the head gasket blew between the two cylinders. At this point you have to take the intake and heads off both sides and inspect the heads and head gaskets for damage. Heads will need to go to a machine shop for cleaning and inspection. They will likely find the passenger side head is cracked and will need to be replaced, but it could be from a head gasket blown to a water jacket hole as well. If you need it up and running with minimal down time, you will probably need to just buy a new set of good quality heads and head gaskets and swap them right out when you pull the old ones.

 

[85K304SPD]

If its just a "yard dog" and sits in your yard most of the time, then you can just swap the heads out, but if you ever use it, then this would be a good opportunity to freshen the whole thing up.
It sucks doing all that work changing heads and then it still runs like crap or has 10 lbs of oil pressure when it warms up, or the timing jumps around, or it still leaks oil or starts leaking from rear main seal.
Take a little more time and save up your money and rebuild it or get a rebuilt engine, put it in right, with all new accessories and you will be more happy and never look back and say "I should have..."
Just my opinion based on experience.