Compression Test Question

[PonyKiller87]

I'm in the middle of doing a bunch of stuff on my plow truck, was replacing spark plugs and wires so I decided to do a compression test. Didn't read my service manual until after I was done :rolleyes: so I kind of did a few things wrong I guess. The book says to crank the engine 4 puffs and record the number and that you need to keep the battery charged so that the starter is turning the same or all 8. It doesn't give a PSI number to expect just that no cylinder should be less than 100 PSI and the lowest shouldnt be more than 70% of the highest. Well I think I only did 3 puffs and I didn't throw the charger on till after doing all 4 on the pass side.

Ok so pass side all 4 came out at 140 PSI. Then I get to number 1 on the drivers side and its 190, next two are 160 and the last one is 170. So based on the manual this is fine because 140> 190*.7 But I'm concerned because the one side seems to be all higher than the other? I did let the gauge sit on each one for a good 30 sec and non of them leaked down at all.

So should I be concerned with the imballance from one side to the other? Is this going to effect performance once I start doing some of the bolt on mods or am I just being crazy, throw the plugs back in and call it a day?

[Prince Valiant]

I say that if you don't notice anything like blow-by, and given that the truck seems to be running fine, don't worry. Given that there may have not been the most uniform approach to testing, I say you're more than fine.

[PonyKiller87]

Well thats the thing, it does have some issues. Consumes a little oil maybe a quart every 2000 miles or so? It consumes coolant, but I'm pretty sure that is the typical intake gasket leak because it has damp spots all over the intake. It was starting to miss and throw codes for right bank running rich, but I'm pretty sure thats ignition related because distributor and wires look stock(didn't see anything for new ones in the stack of papers from the original owner), plugs werent horable but they had a fair amount of crap built up on them.

Heres my dilema, Im already tearing off the intake to replace gaskets, exhaust manifolds are coming off because there were a couple bolts snapped off that I found when taking the plugs out. All the accessories are off because Im changing the timing chain/gears. So I'm thinking it might be worth taking the heads off, clean them up, maybe have them surfaced and a valve job.... more than I was planning on doing but the damn things already ripped apart pretty far.

Oh yeah this truck has 220k on the clock.

[WickedSix]

well to that end...what would it really cost to freshenup the whole engine at this point kev?

[Anakonda69]

buy a damn duramax!!!!

[juicedimpss]

i say do the whole engine,or dont do anything other than a tuneup/intake gaskets.

[WickedSix]

buy a damn duramax!!!!

there is a standard cab long box in auto and RV for 12K right now...trade the s10 in and sell the b!tch to a good home lol

[PonyKiller87]

there is a standard cab long box in auto and RV for 12K right now...trade the s10 in and sell the b!tch to a good home lol

Thats the plan for next year, theres just not enough in the budget this year.


And as much as I hate to half ass something I'm leaning twards what Juice said, leaving the heads alone, and just doing the stuff that I have to. It will do just fine like that until I can tear it apart and do a complete build.

[Anakonda69]

just do what you need to get it running right so you have more money in the budget for a better truck.

[WickedSix]

when we putting the axle in so she isn't a 1-legged burner?

[Anakonda69]

does it have enough power to spin 2 tires? lol

[WickedSix]

well the one cyclinder at 190 psi is the little known chevrolet powerboost cylinder it accounts for 50% of the engines available power so seeing as that one is to spec i'm sure it will :rolf :rolf

[PonyKiller87]

well the one cyclinder at 190 psi is the little known chevrolet powerboost cylinder it accounts for 50% of the engines available power so seeing as that one is to spec i'm sure it will :rolf :rolf

This coming from the guy driving the shitbox s10 :durr


Measured the axles yesterday before switching rims/tires. New one will put the wheels out 1" further on each side, and the spring perches are about an inch wider too. Looks like the shocks are pretty damn close. Thinking I might have to just switch the guts to get the locker and do the brakes later when I do the front.(front is a whole other story, prob have to use the 01 spindles to make it work)

[WickedSix]

i'd measure how wide the perches are kevin...honestly i'd drill new center holes before taking all the guts out if you can. I don't believe the tolerances are going to be the same to make it a simple pull it all out and jam it all in the other axle. Think of how much quicker welding two new perches on would be compared to that if it comes to it?