Logo
FULL SITE MENU

74 Low cylinder compression

marky1212

marky1212

Member
"As some of you have read in m

"As some of you have read in my previous post, my 454 was running up around 170 or 180 with a 140 thermostat. Well, i was just getting ready to order manifolds and risers and figured I would do a compression check. All cylinders are at 135 psi except #1 it has 80psi. I pulled valve cover and rocker arms, pushrods,valve springs and camshaft seem to be ok. Is it possible to blow a head gasket into water passage? Could this be why its running on warm side? Or maybe the temp problem has nothing to do with this. On an car with closed cooling you can determine this by excessive pressure in the radiator,but not on a seawater cooled marine engine. Any input would be greatly appreciated. Please dont tell me there is a possibility of a cracked block.
sad.gif
There is no water in oil or cylinder."
 
Mark Virbick
What doe the spa

Mark Virbick
What doe the spark plug look like out of the offending cylinder?
Bert
 
hopefully the 80psi is just a

hopefully the 80psi is just a leaky or bent valve

You pulled the valve springs ? How are you keeping the valves from dropping into the cylinders.
 
"Sorry, I meant to say I pulle

"Sorry, I meant to say I pulled the valve covers to inspect. I think tommorow I will do the squart oil in the cylinder comp. test to possibly determine if its a ring problem or valve."
 
"so by checking the camshaft y

"so by checking the camshaft you rotated the engine to check lift ? good idea.

squirting a little oil in the cyl would be a good next step.

Yes a head gasket can cause an issue, there are water jacket openings around the #1 cyl. hows' the oil look ?"
 
The oil is nice and clean. No

The oil is nice and clean. No water. Even the valve train and inside of valve covers is clean as a pin.
 
"rig up a air tank/compressor

"rig up a air tank/compressor to the compression gauge fitting and with # 1 on TDC compression stroke inject air and listen.
From carb, intake valve
crankcase, rings,damaged piston
exaust, exaust valve"
 
"Well, I worked from 9 to 3 to

"Well, I worked from 9 to 3 today and still didnt get the head off, but am very close. I had to cut off 2 exhaust manifold bolts, 2 head bolts and 1 intake manifold bolt. That sucked!!! Thank God for Dremal tools. I'm about dead. I did put air in the cylinder with both valves closed and it was leaking out the exhaust port pretty bad, so hopfully an exhaust valve is my problem. Will finish pulling off tommorow."
 
Back
Top