Exhaust plate Gaskets

[sawbones]

I recently bought a boat with a 1990 115HP Merc, SN 0D013703. The owner had never replaced the impeller so I decided I should do it before using the boat. While I was taking off the lower unit I noticed the lower mounts were trashed giving tons of play (1/2-1"). I got new mounts and proceeded to remove the mid-section. Too late in the evening I realized there was a gasket connecting the mid-section to the exhaust plate. I put some gasket sealer on the lower surface and put everything back together. Now I don't get any water flow when I start the motor with muffs on. I pulled the lower unit off and checked my pump job - everything looks fine. I decided to check for flow without the lower unit on. I cut a piece of old garden hose and connected it to the water pick up tube (nice fit!), turned on the hose and I hear a gurgling sound like the mid-section is filling up with water. After about 45 seconds water starts flowing out the **** hole but it also comes down the hole where the drive shaft goes. My gut says I need to replace the exhaust plate gaskets but that looks like a tough job since I will have to take the weight of the motor off the transom. Any advice out there? In hind site I should have just cut the bolt heads off to get the motor mounts off and put the new ones together with the bolts backwards. Then I could have done the job without removing the mid-section.
Thanks.

 

[Laddies]

Re: Exhaust plate Gaskets

If if was working before your repair then the repair caused the problem, the exhaust plates can be a problem for the most experianced mechanic

 

[Chris1956]

Re: Exhaust plate Gaskets

Bones, I think you substitution of gasket maker for the powerhead base gasket may be your issue. Cooling water goes up the tube, and into the block under some pressure. If the powerhead base gasket is bad, water can leak into the driveshaft area, and perhaps past the crank seals into the bottom of the crankcase.

 

[sawbones]

Re: Exhaust plate Gaskets

Bones, I think you substitution of gasket maker for the powerhead base gasket may be your issue. Cooling water goes up the tube, and into the block under some pressure. If the powerhead base gasket is bad, water can leak into the driveshaft area, and perhaps past the crank seals into the bottom of the crankcase.

 

[sawbones]

Re: Exhaust plate Gaskets

Sorry - hit reply too soon.:%
Thanks for the input Chris and Laddies. It sounds like I opened a can of worms. The kids are itchin to get out on the water. I am a decent auto mechanic so I feel pretty comfortable attempting the exhaust plate gaskets. Any words of advice before I start? It looks like getting to the bolts that hold the upper mount are tough to get to.
Thanks again.
John

 

[sawbones]

Re: Exhaust plate Gaskets

Update: I bought a folding 1 ton crane from Harbor Freight Tools - on sale for $100. Worked awesome. For those figuring out the lifting eye thing, I used a piece of 1" nylon webbing, made a tight bidirectional loop around the flywheel and then tied a square not at the apex where I wanted to snatch it with the hook. The challenge with replacing the gaskets was 1) removing the bolts and 2) removing the old stubborn gasket. After that it was a piece of cake. I only had to disconnect the steering linkage. The throttle and shift cables and wiring had enough slack.

The gasket was definitely my problem. Water was leaking between the bridge separating the drive shaft and the water tube through the exhaust plate. Got it all bolted back up, fired it up and everything works great. d Stronger water flow than before. A can of Merc Powertune helped smooth out the idle.

If anyone has any questions, let me know.
John