brett14

iTrader: (3)

whatsup guys picked up a lm7 for 500$ supposedly had 80k miles on it. def doesnt look like it. anyway i wanted to do some test before i start doing anything to it so i dont waste my time.

mind you this engine has been sitting 2+ years on an engine stand.

this is my first time doing a leak down test. i had the intake manifold off.
i ran through all the cylinder

1- 25%
2- 25%
3- 45% heard air leaking the intake port.
4- 25%
5- 25%
6-25%
7-40% again heard air leaking from intake port
8-25%

than i did it again and nearly all of them were 40% + all leaking from intake port

i dont know much about internals but it seems like the valve stem maybe pushed up?

im also not 100% sure if i had the cylinders at TDC i just kept turning the crank until air stopped coming out of the exhaust.

insight please

farmington

iTrader: (14)

If the piston isn't at direct top center the air pressure will push the piston down giving bad readings.

NowhereFast

Since it's on a stand, why not pull the valve covers and make sure both valves are closed before screwing with it? I find it hard to believe EVERY intake valve is bent.

brett14

iTrader: (3)

can you give me advise on how to make sure each cylinder is at TDC. i heard of the screw driver one but the spark plugs are on the side so it cant really push the screw driver up.

yeah thats a good idea i can take the cover off and play with the valves

farmington

iTrader: (14)

make a mark on the balancer at tdc, and every 90 degrees. follow the firing order.

LFX1stGenF

Whoa! The same thing has happened to me. I purchased an LM7 from an 04 Silverado and it only had 139k miles! How did the bullsh*** alarms not go off? Okay, this is Texas, the only way you can get around anywhere is if you get on the highway so this translates to roughly 65miles/day. 65miles per day multiplied by 365 multiplied by the age of the vehicle (12yrs) = 284,700miles.

Well.. It turns out that at its last recorded oil change the vehicle had 299,5XX miles and then in March of this year the title was transferred and somehow the miles went down to 139k. :-)

F*** Me right? :-)