3.0l will not roll over to check vavles

[Will1974]

Hi everyone(my first post). I am new to marine mechanics but not to automotive stuff. Here is the deal I have a 1985 Thundercraft with a 3.0l 4cyl engine. I got the boat with a blown headgasket. Sent out the head and I am now in the process of setting the valves. It will only roll about 1/8 of a turn and then CLUNK. It sounds like it is coming from the rear. Do I need to disengage something? Thanks for the help in advance. I belive it says OMC.

 

[fat fanny]

Re: 3.0l will not roll over to check vavles

Welcome aboard! Is the drive in neutral? and good luck with the OMC they have been out of biz for some time.

 

[Will1974]

Re: 3.0l will not roll over to check vavles

As far as I can tell, I can spin the prop no problem with my hand.

 

[Don S]

Re: 3.0l will not roll over to check vavles

Moved to the OMC forum, it's not a Mercruiser if it says OMC on it.

If it moves 1/8 turn and locks up, remove the spark plugs and turn it over a little at a time. Sounds like you have water in the cylinders causing a hydrolock.

 

[Will1974]

Re: 3.0l will not roll over to check vavles

Thanks for moving. This is a fresh head back from the machine shop. I just came back in from the shop and I removed the head it still only moves about an 1/8 of a turn either way.

 

[Don S]

Re: 3.0l will not roll over to check vavles

Pull the outdrive, it may be locked up.