what do you think? engine problems.

Quail season is just around the corner. Time to prep the old jeep. She has been sitting for a year now (after the electrical fire). I pumped some WD40 in the cylinders and pumped out the old gas put 2 gallons for fresh juice in her and WHAM! she started right up! I am in the middle of putting a SM420 transmision on her but i wanted to see if it would be worth the while since i have a doner buick 350 in a skylark.. so i did the compression test.. she is tired, real tired.. she is puttin out 120 psi on each cylinder except for number 6.. its shooting only 95 psi.. a little bit more oil and she came up to about 100. I figure worn rings.

So... do you think its worth going out and buying a new clutch, flywheel etc and hoping this beast will get me through quail season?
will the clutch be interchangable between the V6 and the V8?

or should i go ahead and throw in the buick 350.. (i need to run a compression test on her too.. sheesh).

and whats the best way to do a compression test?


-help!
1969 CJ5, 1979 Cheroke (parts) 1964 cherokee? and one more 1978 chief.

 

Welcome from Oh, avnet. Are you in California? I think dove/quail season starts Sept. 1st there.

I've had good luck with AutoZone's screw-in comp. tester for 25 bones.

 

Your compression may be close enough. Better results when tested hot. IIRC, 10-20% variation is acceptable --or is it 15% max (??)

AFAIK, The Bu-ha 350 is a good swap and should bolt right up since the 225/231 is pretty much a short 350 Buick.

 

I wish I had more experience with the wet compression test, but 5 psi doesn't seem like a lot when comparing wet and dry. I'd try the other cylinders wet and see what kind of change you have. Consider a leak down test - easy if you have a compressor. You can make the adapter; check on the web for instructions. One bad cylinder makes me more suspicious of a burnt exhaust valve.

A 350 fits right except you have to trim the grille "tunnel" and move the radiator forward. You'll also have to find a flywheel if the Skylark has an automatic - IIRC the V6 flywheel won't work.

If you don't have a knock, consider an overhaul of the V6. Overhauls were common 50 years ago, and typically included new rings, rod bearings and grind the valves. I can say more if you're interested.

Welcome from Boston - what's your 20? Post up some pics in the intro section!

 

Yeah, me too. Instructions in the package. A remote starter switch makes the test go a lot faster.

 

I would work on/rebuild what you have currently, like Tim says.
Easiest, quickest, prob cheapest too.

Dove season opens Sept 1st
Quail opens 3rd Sat in October here

 

Regarding compressions tests....here's what I remember from my auto tech classes...When performing a compression test, your be looking at variations "within" each cylinder and also "across" all cylinders..

A: Do the test AFTER the engine has been run at normal operating temp.

B: Per cylinder, record the first and 4th stroke of the needle on the compression guage (you have to look at the guage for the 1st stroke of the needle... the needle on the guage will stay on the 4th stroke until you release the valve on the guage).

The readings...
Typically want less than a 10% variation "within" and "across" the cylinders. Service manual will tell you want compression should be within the cylinder (believe less than 80 is typically not good)

Within each cylinder, if the first stroke is more than 10psi lower than the last/4th stroke, add oil to the cylinder and retry. If the 1st stroke is better on the retest, there's typically a ring issue. If no change, look for valve issues.

If readings are low and identical on two cylinders next to each other, check for head gasket issues.

A vacuum guage is also good for checking the engines health (when running) as is a cylinder leak down test.

Good luck

 

I was reading somehwere that its best to bring the engine up to running temperature then remove all spark plugs and run a compression test that way.
I did have my plugs in when i did my compression test. And admit it probably was a "cold" test.
I will run another test this weeked using the above methods. And post the result then.

thanks

avnet
Mesa, AZ