454 Help

I'm hoping someone can shed some light on a littel problem I have, I have a 87 454, number 3 cylinder has 90 pounds of compression and number 5 has 60 pounds. I squirted some oil in the cylinders and ran a check again, Number 3 jumped up to about 120 and held there and number 5 jumped up to about to just over 90. I know this would tell me I have a ring problem but it the cylinder was warped would it hold a steady amount of preasure or would it bleed down ? The motor was free and I don't know if I want to deal with a big rebuild job compared to just doing a ring job. Any help would be appreciated.

Its time to do a leak down test on that motor.
You will need to listen for where the air is going too. Like down past the rings into the pan, or up thru the intake like a bad intake valve, or out the exhaust valve, maybe a tuliped valve. Or over to the next cylinder , like a bad head gasket.
Just my .02 worth
Good Luck

huh that sounds familiar. I wonder where else I have heard of this problem. Maybe some of the more experienced motor guys like Info etc can chime in here.

I concur, do a leak down, first before you do that can you run it, and get it to temp & then do the comp test?
You should never do it on a cold motor, valves will, & do at times bend slightly after they have been run then cooled down in an open position so it is very important to get things tested at operating temperature FIRST. In years past I found that with enough lift I had terrible comp tests until I ran the motor, the valves would straighten out once they got warm due to spring pressure & good seats that kept their shape and magically the comp test was fine. Do it warm & post the results.

Yep leak down test for sure.

Thanks guys copey70 is a friend of mine. He was asking some questions, a lot of questions. I pretty much told him to do a leakdown. I wanted to see what more of you had to say so I told him to post on here.
He is pretty much getting a free motorhome. He wants to know if it is going to be worth it or not since he does not have a lot of time to spend working on it.

Oh...to keep in the motorhome? Yeah, do a leakdown.
At first glance, I thought he got a free motor (for a boat) with two dead cylinders and was wondering if he should do a leakdown...to which I wold say "just tear it down; it's that time of year anyway."
LO
[ September 24, 2003, 07:06 PM: Message edited by: LakesOnly ]

Yes the motor is in a free motorhome I got. It wound up being a cracked head.

whats up Dave. I have a set of heads for it like we talked about. I will be back from Vancouver on friday. Let me know if you want to come out.

whats up Dave. I have a set of heads for it like we talked about. I will be back from Vancouver on friday. Let me know if you want to come out.