First time boat owner with a 3.0 question

[dave 7 0]

Hi i bought a 98 Bayliner with a 3.0 ser# 0L023335 .after replacing the head gasket engine will not run.I have spark Carb is freshly rebuilt Fuel psi is good.I'm thinking one of two things. The manifold gasket doesn"t fit very well (ill post pics). Also i am having problems setting the rockers. I went through once and set them, tried to start it and it would not start. Pulled the valve cover to recheck them and several were loose. I will also post a pic of the way i set them. I don't have a manual i found the info online.Thanks in advance for any help guys.

 

[Rick Stephens]

Use the Mercruiser Service manual at boatinfo.no

 

[Alumarine]

Here's the link to the manual Rick mentioned.
Don't spin the push rods to check if they're tight enough.
They will still spin easy when they are too tight. I have the T shirt.

http://boatinfo.no/lib/mercruiser/manuals/mercruiser26.html#/0

 

[dave 7 0]

thanks guys the service manual will be invaluable. I used the same procedure to set my valves. What about the gasket? Do they all fit that poorly or do i have the wrong one? Can the same gasket be reused?

 

[dlogvine]

Looks like this gasket is not right, also it is exhaust manifold and not a head gasket. As for the rockers, I tightened them all to 20 ft lbs on my 4.3 v6 mercruiser at the advice of one of the forum gurus and it worked miraculously.

 

[dave 7 0]

Yes it’s the intake/exhaust manifold gasket.

 

[TurtleTamer]

That is the incorrect gasket. Made that mistake myself.

It's likely that having set the lash without the lifters pumped up caused the valves to hang open once the lifters did finally pump up.

 

[dave 7 0]

That is possible. I did a compression test. Got 120 90 150 and 125. The 150 seems high and the 90 seems low. Not sure what it is supposed to be. Can’t find it in the manual. 120 125 seems good. When I had the head off I looked at the cylinders and I can still see crosshatch in them so I don’t think the rings ate shot. I think it’s a valve opening closing problem. I will run the valves one more time after I build good oil psi. One other question. I drain the water out of the manifold and out of the block when I pulled the head do I have to fill the engine back up with water at the thermostat housing or will it fill itself when I hook the hose pipe to the muffs?

 

[dlogvine]

Hose will pump the water much faster than the impeller. You dont need to worry about it.

 

[Rick Stephens]

Here's the Mercruiser Compression Test Service Bulletin:

http://www.boatfix.com/merc/Bullet/97/97_25.pdf

 

[dave 7 0]

thanks guys

 

[nola mike]

Here's the Mercruiser Compression Test Service Bulletin:

http://www.boatfix.com/merc/Bullet/97/97_25.pdf

Wow, a reading of 150 psi in one cylinder and 105 in another is acceptable?

 

[Rick Stephens]

Wow, a reading of 150 psi in one cylinder and 105 in another is acceptable?

Yup, that's the minimum spec.

 

[nola mike]

I've always considered 10-15% spread to be what you're after, with ~125 indicating a tired but service able engine. If I got a 45psi difference I'd be looking for problems. Hell, just got 132 psi (cold) on 3 cylinders and 120 on the fourth (131 when warm) and wasn't pleased.

 

[Rick Stephens]

That is possible. I did a compression test. Got 120 90 150 and 125. The 150 seems high and the 90 seems low. 120 125 seems good. When I had the head off I looked at the cylinders and I can still see crosshatch in them so I don’t think the rings are shot.

Seeing crosshatch means you probably have iron rings and they are what wore first. Downside of fancier ring material can be the cylinder wears instead of the rings.

Only way to tell without a tear down and rebuild is to do a leak down test and see if air leaks into crankcase or out exhaust or intake valves. I think that is the place where you are now, and the next step in your investigation.

 

[dave 7 0]

I'm on hold right now waiting on gaskets. When i get it all back together I'll run the valves again and go from there.I'll keep y'all posted

 

[dave 7 0]

Ok thanks for ll the input guys. Got my gaskets in put it all back together. Built up good oil pressure then ran the valves one more time and shes up and running fine.Now i just need to lower the idle a little and set the carb and choke and i"m set

 

[Bt Doctur]

Your assembling a motor without a manual and incorrectly adjusting the rockers too. Now did you torque the headbolts using the correct pattern to 90Ft/Lbs in 3 or 4 steps?
Guessing the gasket you need is 27-815528. The easiest way to adjust rockers is with the cylinder on its compression stroke, meaning you rotate the motor until the intake valve opens and closes, now your on the compression stroke, now you adjust the rockers to 3/4 past zero lash.

 

[dave 7 0]

90 ftlbs in 3 steps. Got the gasket sorted out i needed the small port gasket. I still have the wrong exhaust riser gasket but made it work for now to get it running and have ordered the right one.