Compression

[stgninja]

I have completed a compression check and I have made peace with the findings.

#1 = 155, #3 = 40, #5 = 55

#2 = 125, #4 = 162, #6 = 175

So as I tear down to do my first head & intake gaskets which looks like an engine rebuild to me, I will be cruising along asking for tips along the way.

1st ?

Asside from the obvious gaskets and machine shop sevices, any other repairs or replacements I should do along the way.

thanks in advance

[maxwedge]

What engine, what general condition, what mileage?

[stgninja]

Originally Posted by maxwedge

What engine, what general condition, what mileage?

Oops, sorry, My '95, 3.1, APV, w/115,000. It was an ebay purchase 3 years ago and after research discovered it was a repo and possibly spent some time partially submerged in water. None of this showed up on carfax. I have spent the last three years doing routine maintenance and replacing electrical components as they malfuntioned. Changed water pump and T-stat upon delivery.

[tblake]

could bad head gaskets really cause compression readings that low? sounds almost like a valve not opening right to me.

[tblake]

i see now, if 3 and 5 cylinders are leaking into eachother.

[richtazz]

Yep, you have a head gasket leaking between 3 and 5, or a cracked head. Definitely take the heads in and have them pressure tested and resurfaced. Make sure you do both, not just the one. Replace the t-stat, while it's down, it's due. I believe while tracking this down, you tuned it up, so those parts should be ok to re-use. Change any filters you haven't already done, and make sure you have a good torque wrench for re-assembly.

[stgninja]

Originally Posted by richtazz

Yep, you have a head gasket leaking between 3 and 5, or a cracked head. Definitely take the heads in and have them pressure tested and resurfaced. Make sure you do both, not just the one. Replace the t-stat, while it's down, it's due. I believe while tracking this down, you tuned it up, so those parts should be ok to re-use. Change any filters you haven't already done, and make sure you have a good torque wrench for re-assembly.

Thanks Rich, I am planning on doing both sides, I have always done things in pairs. Especially here since working from the easy side to the back will make doing the backside easier. I also am replacing most vacuum lines as I rebuild and will probably add a reman'd T-body. The radiator also has a leak so it is coming out to be repaired or replaced. I should have plenty of room to work and hopefully have a well running van after this. Been saving egg cartons and cardboard to stay organized and have some bus tubs for holding/cleaning large parts.

When the heads go to the shop, does the intake also benefit from going to the shop?

By good torque wrench I hope both current ratcheting Craftsman (inch #s & ft. #s) qualify. I did have to special order a set of female torx sockets.

Thanks again

[jeffcoslacker]

Also remember if any coolant went into the combustion chambers, either from the leak or from the repair, the o2 sensors will get crapped up, if it's running silicated (old style) anti-freeze.

[richtazz]

Craftsman definitely qualify as good ones. Good luck, and don't forget to ask for help if you run into any issues as you go. After all, that's what we're here for. Good suggestion Jeff, o2's and antifreeze don't play well together.

[stgninja]

Thanks to both Rich and Jeff, I was planning on replacing all sensors especially the ones that are hard to reach.

? for Rich in Parts. Is it possible to order the complete set of vacuum lines from GM. I like the preformed a/k/a idiot proof way they are molded to where they go. Of course if I run flexable line they won't be so brittle in winter.

[richtazz]

The emissions control vacuum harness is GM part #10146885 and is still available. Dealer retail is $40, and it includes everything but the tube to the PCV valve, which is part #10065462, and runs $6 at the dealer. Since these parts aren't Delco (they're dealer only), I couldn't sell them to you any cheaper once you factor in shipping.

[stgninja]

Thanks dude, That is good to know, Just need to decide if idiot proof is worth the winter brittleness that has some lines broken and repaired w/heatshrink.

[stgninja]

Thanks dude, That is good to know, Just need to decide if idiot proof is worth the winter brittleness that has some lines broken and repaired w/heatshrink.