98 4.3L mercruiser valve adjustment

[Aquatron]

Need some help. Putting on my rockers on my 4.3 mercruiser. The problem I am having when I follow the mercruiser service manual it tells me to just put rockers on and tighten to 22 ftlb. The problem I am having when I follow the manual and tightening them down and try to turn the motor over by hand it locks up. The interesting part it only affects one side of the heads. I first thought it was the head so I swapped heads and still doing the same thing only different side. It looks like the valves are kissing the top of the piston.

So now what I am doing is rotating motor and waiting for piston to be on the down stroke then adjusting well that's not working.

If it jumped Timing would only one side be affected? Am I grasping at straws any help would be much appreciated.

 

[Don S]

Re: 98 4.3L mercruiser valve adjustment

Did you replace the head that keeps causing the problem? Sounds like you have one head for a much earlier model 4.3

 

[Aquatron]

Re: 98 4.3L mercruiser valve adjustment

I was thinking that, but both heads are off a 98 Mercruiser and i am only having the problem with one head.

If the block is a volvo penta but still a 4.3 would that make a difference?

My next step is to take a spare head that i have and see if that makes a difference. The reason i don't want to use them is because they are 95 prevortec.

Racking my brain on what could be wrong with this one head.....I cleaned them up and cheeked seats and guides along with replacing the oil seals and valves move with no issues.

Any suggestions??

 

[Don S]

Re: 98 4.3L mercruiser valve adjustment

Look at the rocker studs on the two heads. You should have a step just under the threads on a head you just torque the rockers on. No step, and you have to adjust them. Who knows what "Volvo" head was installed. They have used different years too.

 

[Aquatron]

Re: 98 4.3L mercruiser valve adjustment

Ok thanks I will check....

 

[Aquatron]

Re: 98 4.3L mercruiser valve adjustment

Just checked and there is no step rocker bolt screws into a flat surface. I use mercruiser manual #18. What am I missing or do I need to go and find a service bulletin or a different manual?

I would like to find a procedure so I don't screw it up?

Thanks, Don

 

[Don S]

Re: 98 4.3L mercruiser valve adjustment

Just checked and there is no step rocker bolt screws into a flat surface. I use mercruiser manual #18. What am I missing or do I need to go and find a service bulletin or a different manual?

I would like to find a procedure so I don't screw it up?

Thanks, Don

You have the wrong head for your engine. You shouldn't have one side that needs adjusted and the other side needing torqued.

 

[Aquatron]

Re: 98 4.3L mercruiser valve adjustment

Sorry I guess I wasn't real clear Both heads have the same look no step. You just screw the bolt with the rocker into the hole..

Both heads came off of a 98 4.3 mercruiser.

I hate to be a pain but I am having trouble understanding why one head is doing this. I like you approach on needing adjusting I hate just tightening them down.

 

[Don S]

Re: 98 4.3L mercruiser valve adjustment

Sorry I guess I wasn't real clear Both heads have the same look no step. You just screw the bolt with the rocker into the hole..

Both heads came off of a 98 4.3 mercruiser.

I hate to be a pain but I am having trouble understanding why one head is doing this. I like you approach on needing adjusting I hate just tightening them down.

I don't know either, but I also can't look at things like you can. Only thing I can see is what you type.

 

[Bt Doctur]

Re: 98 4.3L mercruiser valve adjustment

manual 18 is the balance shaft/roller rockers .Is that your motor.
"Sorry I guess I wasn't real clear Both heads have the same look no step. You just screw the bolt with the rocker into the hole.."

Did you mean "nut" .there are no bolts to screw in fror the rockers unless your doing a Chrysler 318

 

[Don S]

Re: 98 4.3L mercruiser valve adjustment

Manual 18 is for 93 to 97, Manual 25 is for a 98 motor. But the info is the same, they should have stepped screw in rocker arm studs that you just torque the nut to 22 ft. lbs.

The 92 and earlier were adjustable and had pressed in rocker arm studs.

 

[Aquatron]

Re: 98 4.3L mercruiser valve adjustment

Don,

You are correct they are screw in and I am thinking that they might be to long. When I screw them in they bottom out. I need to look in my parts catalog and see if different sizes were used.

When you say step screw please explain? I might be missing something.

I also have mercruiser service manual 25 and once again you are correct the same procedure.. UGH