Installing Piston Rings?

[slimt]

383 engine.. I had a compression test done.. the engine runs strong.. but the compression starting with no1 Cyl. is 95.. the rest are 105.. Can I crosshatch the cyl. and install rings without rebuilding the whole engine? and do this with the engine in the engine bay? I realize the manifold and heads have to be removed.. is it possible?

 

[Beekeeper]

If you haven't done it you should do a leak down test before assuming the rings are the problem.

 

[451Mopar]

383 engine.. I had a compression test done.. the engine runs strong.. but the compression starting with no1 Cyl. is 95.. the rest are 105.. Can I crosshatch the cyl. and install rings without rebuilding the whole engine? and do this with the engine in the engine bay? I realize the manifold and heads have to be removed.. is it possible?

No reason to try doing that much work with the engine in the engine bay, you would just be making it harder on yourself than removing the engine in the first place.
As mentioned, do a leak down test first. It could be a valve not seating. Usually the cylinder heads need to be rebuilt before the short block, and you can do the cylinder heads with the engine in the car without too much trouble.

 

[slimt]

If you haven't done it you should do a leak down test before assuming the rings are the problem.

when you say leak test.. thats a wet/dry compression test? seems at about 60mph.. the smoke comes out the tail pipe..

 

[Beekeeper]

A leak down test I not the same as a compression test.

 

[slimt]

A leak down test I not the same as a compression test.

Could you elaborate on what I can do for this leak test? I a painter by trade.. Not a mechanic.. though Im trying the best I can.. thank you..

 

[Zeppelin264]

https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test

 

[Beekeeper]

Zeppelin has hooked you up.

 

[Cranky]

A simple check is to squirt some oil into the cylinder. If the PSI comes up, it generally points to the rings. If not, valves....but how many miles are on the engine? You could have a leaking head gasket or even a cracked head. Are you getting any bubbles in the coolant when hooking up the cylinder with an air compressor?

 

[slimt]

A simple check is to squirt some oil into the cylinder. If the PSI comes up, it generally points to the rings. If not, valves....but how many miles are on the engine? You could have a leaking head gasket or even a cracked head. Are you getting any bubbles in the coolant when hooking up the cylinder with an air compressor?

Thats the thing.. this engine was supposifly rebuilt at 60.000 miles in the 90s.. when I bought the car.. it had 63.000 miles.. Now sitting at 64.000 miles.. basically driving it from where i bought it to here.. oil preasure is high when first started.. But I can see it drops after a while of running..

 

[Cranky]

Thats the thing.. this engine was supposifly rebuilt at 60.000 miles in the 90s.. when I bought the car.. it had 63.000 miles.. Now sitting at 64.000 miles.. basically driving it from where i bought it to here.. oil preasure is high when first started.. But I can see it drops after a while of running..

Oil usually thins out some when it gets hot plus everything in the engine expands so oil pressure dropping some is normal once at full operating temp....question is, how much PSI drop does it have. Also, to only go 4000 miles in 20+ years isn't much driving time. How many short trips and start ups without going anywhere did the engine see? Both are hard on them. Short run times create a lot of moisture within the engine but driving the car for several miles helps dry them out. If the engine has had a lot of start ups without going anywhere and wasn't allowed to come up to full operating temp, it's no telling what it looks like inside....

 

[mopar 3 B]

4000 miles when driven every day will just about set a chrome moly ring set and your compression difference could be the cylinder its self being out of round. Do not confuse a rebuild with a simple ring and bearing replacement.
An other point the compression variances are within tolerences. At 200 miles a year why are you worried about it?

 

[451Mopar]

I did not know the engine was rebuilt. Sounds like the short block (everything below the heads) is likely good.
As mentioned, a leak down test gives more information.
My friends engine started loosing power, and when we did a leakdown test, the air was coming out the exhaust (both valves closed.)
The heads were stock, no hardened exhaust seats installed, and the exhaust valve(s) sunk into the head.
I have also bent intake valves (valve float) by over-reving my 383, which causes them not to seat fully.
Burning oil could be from worn valve guides/stem seals or even an intake manifold gasket problem.

 

[mopar 3 B]

I did not know the engine was rebuilt. Sounds like the short block (everything below the heads) is likely good.
As mentioned, a leak down test gives more information.
My friends engine started loosing power, and when we did a leakdown test, the air was coming out the exhaust (both valves closed.)
The heads were stock, no hardened exhaust seats installed, and the exhaust valve(s) sunk into the head.
I have also bent intake valves (valve float) by over-reving my 383, which causes them not to seat fully.
Burning oil could be from worn valve guides/stem seals or even an intake manifold gasket problem.

See post #10