Exhuast Plate Gasket - 1988 XR4 150

[dsford1982]

More outboard issues.

I have to say, i have had 4 boats. 3 outboards and one I/O. All 3 outboards have had issues. Very expensive issues! While the I/O was flawless. Not sure if its just my bad luck or that, due to the performance and abuse that some outboards recieve, i just need to get something less tempermental.

Anyway, i took the rebuilt motor in yesterday because of a vibration sound through a lower rpm, that i wanted to see if was something that i could solve before it became a uge issue. The mechanic thought the sound originated from the flywheel but he said that the engine was spraying water out between the powerhead and lower unit like crazy and to come get the boat they werent interested in working on it.

after talking with them and trying to better understand the issue it is believed that the exhaust plate gasket is the culprit.

what am i looking at to replace this? Is this something i can do? Is this huge job? Why would this gasket typically fail? Warped?

the part number appears to be 27-991764.

Thank you.

 

[Chris1956]

Well, it is a nuts and bolts fix. You will need to drop the gearcase and pull the powerhead off. First locate the powerhead mounting bolts and make sure they are all tight and not stripped. If loose tighten them properly and retest.

BTW - in my opinion, an I/O requires much more routine maintenance than an OB.

 

[Dukedog]

Chris, don't need ta drop gear case on tha V6. Agree 'bout tha maintenance thing. Maybe we've just been lucky tha 40+ years.............

1. remove cowls (may/may not have trim switch on cowl that will need ta be unplugged to remove cowl). also best to remove tha long rear piece tha cowls pivot on.
2. disconnect battery leads on motor
3. unplug harness at motor (may/may not have trim switch on cowl that will need ta be unplugged to remove cowl)
4. disconnect shift arm at slide on anchor bracket. its a 7/16 nut on top of tha spring loaded slide parts....very important.
5. total of 10 9/16 nuts to remove. tha 2 in front can be a PITA but you should be able ta figure it out. locate all 10 of 'em before ya start.....
6. pull it straight up (really need tha eye) till all tha long stus clear making SURE tha shftin' arm doesn't come up with it.......see # 4.

not near as bad as it sounds. take your time and before pictures if it would help.....gl

 

[Chris1956]

Duke, I know it is not necessary to drop the gearcase, however, most of us amateurs will have difficulty reinstalling the powerhead, and mating the shift and driveshafts at the same time.

I prefer to drop the gearcase, so I can simply lower the powerhead into place and bolt it down. The last thing I install is the gearcase, as I like to the tilt the motor up and work it into place using my hands.

 

[Dukedog]

Understand what your sayin' but if ya give it shot think ya might like it. By disconnecting tha shiftin' slide at tha anchor bracket tha rod and shiftin' parts will stay intact. When ya go back with tha PH ya just gotta make sure tha slide hits tha anchor bracket. Wiggle (I'm lazy n use a remote start button for everything) tha fly wheel if necessary for it ta drop on tha drive shaft.......Just try it one time! No more wrestlin' tha pita gear case too.

 

[Chris1956]

maybe, but I am very worried about ruining the crankshaft splines, by mis-mating them with the driveshaft. I use a manual cum-along to raise and lower the powerhead. It is not the most smoothest device to use.

 

[Dukedog]

Not ta worry 'bout tha Merc. Not tha V6 anyway. Won't hurt a thing. Think that's why both drive shaft and crank are tapered. That's what we used for quite a while when we were doin' this in my garage. BigBoy, friend of mine will set a block, crank, piston, rod assembly by hand. He's a butt head show off. Nick named "Hands". Can drop a fifty cent (probably a silver dollar but haven't got one) piece thru his wedding ring.....my dirt track body guard back in tha day....