compression Baaad. now what?

[bounce]

I'll get another tester and post results...thanks fellas...

[jmortensen]

I wouldn't bother testing again. You're good to go.

[Bruce Palmer]

Or the front choke stuck in the down position.

Dang it!! I did it again. After preaching that the first thing anyone needs to do is make sure the choke cable is slack in the off position so as to not be pulling the nozzle down, I told him the start cranking on the nozzle. I'd better get to work and find steve and Pam a decent sales person who has his **** together. Is dumbass one word, two words, hyphenated or what?

Carry on..........

[Gary in NJ]

Looks like Diseazd is a good candidate for the position.

[bounce]

I wouldn't bother testing again. You're good to go.

good to go for what? a rebuild? 100psi? what what?

[jmortensen]

Compression testers shouldn't be used to see if the car has a particular amount of compression, IMO. They vary pretty wildly in readings from one tester to the next, and things like a bigger cam can drastically lower the compression numbers as tested on a gauge. What compression testers are good at is seeing if you have a problem in one cylinder. By the results of your test, you do not. It's pretty clear that your top end is sealing OK, because if it isn't you wouldn't have an equal number across all cylinders. It's also clear that the rings are equal across all 6.

If you really want to do another test to evaluate the strength of the engine, do a leakdown test. That will give you a better idea of whether or not you need a rebuild, but based on the compression test being equal I'd say that car is going to fire up and run just fine and that's about all you can expect to get from a compression tester.

Edited August 27, 2010 by jmortensen

[Gary in NJ]

A leakdown test (or differential compression test) can tell you specifically where a compression leak or problem exists. For example, if you provide a reference pressure of 70 psi @TDC, and the cylinder can not maintain 67 or more psi, you have a leak. If you hear air escaping through the exhaust you have an exhaust valve issue. If you hear air escaping through the crankcase ventilation system, you have ring blow-by.

This type of test is more involved then a simple compression test, but is much more useful for diagnosing problems.

[bounce]

splendid. Leakdown test will be the next step...

the motor does start and runs good....but I do think I'm missing some pavement eating, tire smoking power.....

thanks for all the explanations and patience....

[Shade133]

that loss of power could simply be timing, fuel/air mixture or a crudded engine. for instance. i just checked all pistons in my car, and they got a cool 8th of an inch of crud built up ontop of the pistons. the oil is dirty and broken down and needs to be changed and the engine needs to be cleaned out. i plan on seafoaming the crap out of the intake system (cleaning the pistons) the fuel system and the oil system. after that the engine hopefully will free up big time and get all of its HP back

[bounce]

I'm somewhat confused because my mechanic is telling me If he were me...he wouldn't put a penny into the car...and just drive it.... I don't know what to do....listen to him (), find another Z, or put money into it this one.....

[Shade133]

dont listen to your mechanic when he tells you stuff like that. thats just his arogant opinion. he finds no value in the car so he'd just drive it till it blows up and buy another beater because thats just who he is.

if you bought the car because you like the car and want to make it pretty and run nice. do just that. his opinion could make it sound like Z's are a money pit and nothing but trouble but in reality they arent like that at all. no car is. it all depends on how the car was taken care of from the previous owners. yours looks and sounds like it had more physically body abuse then engine mechanical. so id dress up the engine, clean it out, clean out the tranny and service it, same with diff. replace ALL bushings (180 bucks for master bushing kit from MSA) and get some springs and strut inserts (around 500 for a perfmance set) and the car will run and drive like a dream. as for how it looks thats all you. you wanna clean up the furst, fix the body damage go for it. All in all the suspension wont take more then 700 bucks to make it drive like a race car (and some hours of labor) and the engine wont take more then a few hundred to burn some rubber if done right.. Z’s always hold their value more the 240’s then anything especially if its numbers matching.

my opinion i dont care how it looks until it runs and drives good. until i get my car like that the body stays the way it is. then the body is fixed and interior.

[Bruce Palmer]

Looks like Diseazd is a good candidate for the position.

That's too funny. Guy just asked me ealier this week if I'd like to trade jobs with him. That only tells me his job has turned into hammered dog meat.....