After replacing head gasket my Mercruiser 3.0 wont Start, Help!

[Alvin7575]

I am in need of some serious mental help. I replaced the head gasket on my 1991 Mercruiser 3.0 and now it wont start, it will start with a little forward throttle but runs really really ruff and puff burst are coming from the carburetor, when I place the throttle in neutral the motor dies.

I installed the head gasket and replaced everything in reverse order using the required 90 lbs torque specs for the head. I marked all the spark plug wires so I could place them back in the correct order. I also performed a compression by removing one spark plug at a time. The results were,

Cylinder 1: 120 (facing bow)
Cylinder 2: 120
Cylinder 3: 120
Cylinder 4: 130

I also left each cylinder pressurized for a short time to see if there was a drop in pressure and all seemed fine. My neighbor says it may be the timing, he also stated that I should have placed cylinder 1 to top dead center before taking the head off (which I did not do).

After putting the head back on I then installed all eight push rods starting at cylinder 1. I tightened the rocker arm bolts as specified in the service manual to 3/4 turn after zero lash starting at cylinder 1.

I am lost here, does this sound like a timing issue, should I have placed cylinder 1 to top dead center prior to removing the head? I would say that the cylinders are not firing in order.

All help is appreciated?

 

[Fun Times]

Re: After replacing head gasket my Mercruiser 3.0 wont Start, Help!

Hi there, sure sounds like it would be the firing order is out of order.

The best thing to do at this point is start at step one at finding top dead center of the compression store and follow the service manual titled ignition system, should be under section 4E I believe.

Good luck.

 

[Alvin7575]

Re: After replacing head gasket my Mercruiser 3.0 wont Start, Help!

Hi Fun Times,

Great! Got it, I found the ignition system in section 4B and this is where I will start after finding TDC for cylinder 1 . I will report my findings. THANKS!!

 

[Walt T]

Re: After replacing head gasket my Mercruiser 3.0 wont Start, Help!

After Fun times post you could almost hear Alvin exclaim "Timing? Whats that?" Then looks it up " O crap!" Just pokin a little fun at ya Alvin glad you found it

 

[Bt Doctur]

Re: After replacing head gasket my Mercruiser 3.0 wont Start, Help!

http://www.boatfix.com/merc/Servmanl/13/13B4R2.PD

 

[Alvin7575]

Re: After replacing head gasket my Mercruiser 3.0 wont Start, Help!

After Fun times post you could almost hear Alvin exclaim "Timing? Whats that?" Then looks it up " O crap!" Just pokin a little fun at ya Alvin glad you found it

Exactly! I was just as puzzled as my neighbor explained cylinder one being at top dead center. I did some reading after Fun Times pointed me to the Ignition System and confirmed cylinder one being at TDC. It's raining hear in Spring Hill, FL so I hope to jump on this tomorrow.

Fingers X

PS: Bt Doctur the link returned a page not found

 

[thumpar]

Re: After replacing head gasket my Mercruiser 3.0 wont Start, Help!

Make sure you are at TDC on the compression stroke. It sounds like you already know this but just a reminder.

 

[Alvin7575]

Re: After replacing head gasket my Mercruiser 3.0 wont Start, Help!

Just want to update this thread to inform anyone that are having the same issues.

I finally found the issue. This one had me scratching my head for a while due to me not having removed the timing belt or distributor. So I back tracked and did some heavy thinking. It turns out that the issue was with me adjusting the rocker arm nuts a bit to tight.

The Mercruiser service manual that I was using was for a newer motor and the rocker arm adjustments called for 3/4 turn past zero lash. I found that an older service manual called for 20 lbs of torque for the rocker arm nuts, after adjusting the rocker arm nuts to 20 lbs I attempted to start the engine, it ran better then the first try so I knew I was on the right track.

In the end what I did was to adjust the rocker arm nuts when the push rods were at there lowest point by turning the engine over re checking the rocker arm for play each time and adjusting the rocker arm nuts as needed, I did this multiple times to insure that the rocker arm nuts where not to loose or to tight.

I then started the motor and adjusted the idle after the engine was at optimal operating temperature.

I can now say that it is Fixed. Next step is to go out for a test run to see if all is well. If all seems good I will recheck/re torque the head bolts to 90 lbs after 20 HRS and I will also check the rocker arm nuts and push rods for any play.

THANKS!!