Loss of Power - Fresh Head Install

[incrediblened]

I just put the boat on the water. It started off great, we cruised for about 1/2 mile, and all of a sudden we lost power. I just installed new head gaskets.

I haven't checked compression yet, but I'm thinking one of the new head gaskets blew. Any quick thoughts before I jump in to the engine.

Thanks,
Ryan

 

[Alpheus]

Re: Loss of Power - Fresh Head Install

Sure. What kind of engine???

Check the oil.

Perform compression test and leak down. If there is a leak the leak down test will find it...

 

[incrediblened]

Re: Loss of Power - Fresh Head Install

1997 Mercrusier 4.3. Oil is clean. But actually it's OVER the full line! Could this be the problem?!

 

[incrediblened]

Re: Loss of Power - Fresh Head Install

Ok, I found the problem. I pulled the valve covers off and all of my rocker arm bolts were loose! This is crazy!

The mercruiser manual says to torque them to 20ft/lbs. But it doesn't give a lot of detail after that. Is that the same for valve open / valve shut? The rocker arms themselves look like they have a lot of travel and i would assume that the torque depends on the position of the cam/lifter/rod.

Would someone give me a little info on this... I may still take out the boat tonight if I get a quick reply. lol.

 

[1ruralmailman]

Re: Loss of Power - Fresh Head Install

not sure with out looking,but i know from fresh experience that the lifters have to be adjusted in a certain order on a fresh rebuild,with no.1 at tdc,then one complete turn then the rest. would think might be same for rocker.

 

[Adirondack]

Re: Loss of Power - Fresh Head Install

Those are adjustable lifters. They don't torque to anything. Get back into your manual and find the valve adjustment procedure. Follow that to the letter, and you should be all good.

 

[incrediblened]

Re: Loss of Power - Fresh Head Install

Those are adjustable lifters. They don't torque to anything. Get back into your manual and find the valve adjustment procedure. Follow that to the letter, and you should be all good.

Not true. The manual procedure for my engine (1997) says to torque them to 20 ft/lbs. This is what I did. It now runs great.

Earlier year 4.3's have a rocker arm lock-nut that is adjustable. The 1997 just has a normal threaded bolt that has to be torqued down.

 

[incrediblened]

Re: Loss of Power - Fresh Head Install

Hey everyone, I got it working. Thanks for your help. I torqued all of the rocker arm nuts down to 20 ft/lbs and she ran like a dream the next morning. (Yeah, I didn't go out to the lake at 2am after torquing the bolts down, lol).