Logo
FULL SITE MENU

Vortec 5.7 Motor Roller Lifters Question

M

marragtop

New member
I have a 05 235 Bayliner with a Mercruiser 5.7 Vortec engine. Recently the motor started running poorly and a compression checked revealed no compression on cylinders 4,6, and 7. Pulled the valve covers and was able to get it running by adjusting the valves. However, I couldn't adjust the valves what I consider the proper way (remove lash, and tighten extra 3/4 turn). I ended up having to adjust the valves by ear with the motor running. The motor is running fine, but I'm concerned about what caused this problem and future big time damage.

I pulled the intake and verified that it has roller lifters. When adjusting the valves and watching the lifters, it appears the lifters are pumped up all the time and are not compressing. The engine is sludge free but the lifters don't appear to be compressing. Has anyone come across this before and is there a different method to adjusting roller lifters on a 5.7?

Thanks in advance for any and all replies.
 
If lifters are not compressing then oil is not getting to rocker arms.If you are getting oil up to the top then they are compressing,unless of course somone put solid lifters in there.Or your rollers are worn,or nuts for adjustment are not staying locked in place and backing off.Hope this helps.
 
Did you have to loosen the rocker arms to get it running? If yes, its time to shut her down and pull the head. The valves could be tuliped and ready to brake.
 
Ditto Chris's suggestion if you had to back-off on the rocker nuts.
Valves that are wearing into the seat some (or are tuliping), position the valve stem higher in the cylinder head, thus causing the rocker arm to place cam follower plunger towards bottoming out!
We have approximately .080" to .100" plunger travel within the cam follower body (aka lifter).

What we're actually doing when adjusting...., is setting the depth of the plunger (or piston) within the body.
If the previous person who set these favored the bottom side of the plunger travel, it may have caused an issue.

ciscokid, when the cam follower is coming onto the ramp, the oil is checked or trapped.
Since we can't compress a liquid to any measureable amount, basically there is no compression of the oil.
This is normal, and is what causes the lift.
Oil is sent up/thru the push rod only during the low side of the cam lobe.

marragtop, I'd check your compression again.... if OK, you may have dodged a bullet.
If not, then I too would be removing the cylinder heads.


.
 
Last edited:
Back
Top