merc 470 out of boat for 2 years, removed rocker cover, rusty rocker arms....

the engine has been out of the boat for a couple years. it's been in a garage with the oil pan off and a few cloth painter's cloths covering it. i'm going to replace all hoses and gaskets. took the valve cover off and found some rust (old and wet with oil) on some of the rocker arms. i want to clean them up.

the valve lash on this engine is set by installing different length pushrods. i've found a couple spec's for this gap. from my oem manual it's 0.075" - 0.175". another spec i've found is 0.111" - 0.211". the latter spec i found in the seloc online manual and also on some forum, can't remember where. could have been on this forum somewhere.

i'm inclined to go with the oem manual spec. there is some overlap between the two, so i could actually get in the correct range for both spec's with the correct pushrod lengths.

here's my real question, the valve lash on my engine right now is way under either spec. the question is how can this happen? i want to remove the rusty rocker arms and clean them up. even the other rocker arms without rust don't seem to be within the correct valve lash spec, so i'd have to get new pushrods for the whole engine in order to bring the whole thing into spec. what has happened to mess up the valve lash?

thanks for any help,
monte

Re: merc 470 out of boat for 2 years, removed rocker cover, rusty rocker arms....

Valve lash is measured with the lifters collapsed, takes a special tool to collapse them. I would assume that you are OK as long as you don't mix up the pushrods. All you have to do is take them off and clean them up then retorque them. You do however have to retorque the rockers in a specific sequence: Here is the manual: Boatinfo - Mercruiser Service Manual nr. 8 - 1985-1989 - Mercury Marine 4 Cylinder Engines

Re: merc 470 out of boat for 2 years, removed rocker cover, rusty rocker arms....

yeah, if your lifters aren't collapsed that will give you false numbers. Unless you've changed cams/pushrods/ lifters, I doubt that you need to mess with the pushrods...
Oh, and my "special tool" (no, not that one...) is a hose clamp and pry bar...

Re: merc 470 out of boat for 2 years, removed rocker cover, rusty rocker arms....

stonyloam said:

Valve lash is measured with the lifters collapsed, takes a special tool to collapse them. I would assume that you are OK as long as you don't mix up the pushrods. All you have to do is take them off and clean them up then retorque them. You do however have to retorque the rockers in a specific sequence: Here is the manual: Boatinfo - Mercruiser Service Manual nr. 8 - 1985-1989 - Mercury Marine 4 Cylinder Engines

Click to expand...

thanks. i've finally figured out how they are "adjusted" and just took them off, cleaned them and re-installed them using the firing order.