Mercruiser 3.0xl help!!

[cyphertech]

So here is my scenario maybe someone can help me out. Replace the head gasket in a 1995 3.0l xl mercruiser. SN#0F452776 Out Drive# 0F382445

Block and head were checked for flatness. head was planed. All components clean enough to eat off of before reassembly. torqued down 90 flbs in proper order. adjusted valves as per manual (zero lash and then down an additional 3/4 turn.) replace all fluids.

Checked the timing after initial warm up with the proper shunt harness procedure. 1 deg in base timing. 12 deg out of base and with the motor running at 2500 rpm the advance moves to 27 deg.

carb setup; turn mixture screw in all the way (gently) then out 1 1/4 turns, run engine, turn mixture screw in until starts to run rough. then out little bit till it smooths out. engine dieseled a little bit after it was warmed up so I leaned out the carb a touch more. this seemed to help.

went for first test run on the water. stalled a few times after warm up. Thinking low idle was to blame. but got up on plane. and headed out ran fine for about 1/2 hour. then on the way back in tried to get up on plane and the head gasket blew again. Limped back in to the dock. and tore it down again. so Im a bit lost any thoughts as to what it could be:? :mad-new:

 

[Bondo]

So here is my scenario maybe someone can help me out. Replace the head gasket in a 1995 3.0l xl mercruiser. SN#0F452776 Out Drive# 0F382445

Block and head were checked for flatness. head was planed. All components clean enough to eat off of before reassembly. torqued down 90 flbs in proper order. adjusted valves as per manual (zero lash and then down an additional 3/4 turn.) replace all fluids.

Checked the timing after initial warm up with the proper shunt harness procedure. 1 deg in base timing. 12 deg out of base and with the motor running at 2500 rpm the advance moves to 27 deg.

carb setup; turn mixture screw in all the way (gently) then out 1 1/4 turns, run engine, turn mixture screw in until starts to run rough. then out little bit till it smooths out. engine dieseled a little bit after it was warmed up so I leaned out the carb a touch more. this seemed to help.

went for first test run on the water. stalled a few times after warm up. Thinking low idle was to blame. but got up on plane. and headed out ran fine for about 1/2 hour. then on the way back in tried to get up on plane and the head gasket blew again. Limped back in to the dock. and tore it down again. so Im a bit lost any thoughts as to what it could be:? :mad-new:

Ayuh,.... Welcome Aboard,.... What do the spark plugs look like,..?? What colors,..??

What was the reason found for the 1st blown head gasket,..??

 

[cyphertech]

spark plugs look good no deposits or erosion, dark brown in color. 1st head gasket blown for unknown reason. chocked it up to age of the motor. Thx

 

[cyphertech]

any thoughts?? guru's? I read a service bulletin here but this boat is a 95 so I don't think it applies.

http://www.boatfix.com/merc/bullet/98/98_14.PDF

 

[airshot]

Are you using genuine mercruiser parts or aftermarket gasket? I have heard of issues with aftermarket. Can you see where gasket has blown thru? Common area is between 2 and 3 cylinder so may be an issue there.

 

[fishrdan]

Why do you think the head gasket blew again, what are the symptoms or what did you find that's showing as a blown head gasket? How was it blown when it went out before? Did it blow in the same place this time?

If you're getting water into the cylinder(s), have you checked the manifold for cracks (acetone test) and check the riser and riser gasket

I always use FelPro head gaskets and never had issues with them. (Airshot, are you referring to the 3.7L engine? I've heard that one you MUST use a Mecrsuicer/Quicksilver gasket, but not the 3.0L.)

 

[cyphertech]

No Title

Here's the 2 gaskets. I used a felpro gasket. Now I was reading the manual found on this site through the Adult sticky. and it said timing is supposed to max out at 24 deg @ 2400 rpm (on page 195) and then on the next page it shows the max advance to be 27 deg? which is right? thx

 

[cyphertech]

anyone know regarding timing on the above post?

 

[pro-crastinator]

Check your torque wrench for accuracy. My first thought is that it looks like bolts were not tight enough.
worth a look

 

[NHGuy]

Was the deck checked for flatness too? Also since they milled the head you might search out a thicker head gasket to keep your compression down to where it should be. Are you sure there aren't any clean white spark plugs? That would point to water in combustion chamber.
Dieseling comes from advanced timing and heat, and can be exacerbated by too high of an idle.
Since the head is back off you'd be wise to find perfect top dead center too. Easy with pistons showing. That would help confirm everything to be copacetic.

 

[fishrdan]

Check your torque wrench for accuracy. My first thought is that it looks like bolts were not tight enough.
worth a look

Yep. that's what I thought looking at the gasket. (I was thinking it when I posted up a couple days ago too.) I would borrow a torque wrench from someone and verify your wrench is correct, torque a lugnut with both wrench's and see if they are both the same. Or, check the wrench's calibration.

NHguy gave good advice, check deck flatness, TDC on the harmonic balancer in case it slipped. Mercruiser service bulletin 95 says for the 3.0L/LX ESt ignition:

"With timing light still connected, and engine at
idle, verify that timing did advance to 12 degrees
BTDC, (? 2 degrees). At 2400-2800 RPM maximum
(total) advance is obtained and should be 27
degrees BTDC (? 2 degrees).

 

[cyphertech]

Thanks for all your help. I've taken everything in, and redone the job. I'm about to fire it up today Ill let you know the results