Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

[on_ice]

Hello.

I am having some overheating issues with a 1988 Mercury 45 HP. I've already changed the impeller and there is no poppet valve assembly nor a thermostat on this engine. After reading the thread linked below, it looks like I need to remove the exhaust plate cover and search for potential blockages. I've never done such a thing so I was wondering if you guys had any tips or suggestions before I start. Are any of the bolts torque to yield and need to be replaced? Are the gaskets reusable? I'm going to start soaking nuts/bolts in PB blaster in hopes of loosening them up a little.

http://forums.iboats.com/mercury-mariner-outboards/mercury-classic-50-overheating-582893-2.html

 

[mercurymang]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Bolts are not torque-to-yield. Do not re-use gaskets.
Also there is a trick to getting frozen bolts out that a lot of people use. If you have an impact wrench, you can put it on the lowest setting and just start banging away at the offending bolt switching between forward and reverse at first and then once it gives just reverse. Just be sure it's on the lowest setting.

 

[Laddies]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

...

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Any other options? I've never pulled a power head or this exhaust plate so I want to make sure I try everything before tearing apart an otherwise great engine. It runs really strong and if this alarm didn't go off I would have said it was perfect. What about dropping the lower unit again and trying to backflush it somehow?

 

[Laddies]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

...

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

And then what? Hope to find something in one of the coolant passages on the bottom?

 

[Laddies]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

...

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Laddies, for some reason I can now only see the first 4-5 letters of each of your posts (including previous posts). Is this an issue on my end or yours? Happens in 2 different browsers.

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Now all I see are "..."! I knew I should have saved that image you posted!

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

I'm kind of wondering if it's a blown headgasket now... I'll do a compression check tonight and let you know.

 

[mercurymang]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

I don't think that motor has a headgasket. But still do run a compression test.

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

So it would be a cracked block/head? I'll keep you guys updated.

What happen to Laddies?

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

After reading Boatinfo - Mercury Service Manual for 45jet-50-55-60 hp and refering to the top part of the water tube connecting to a "clamp" I am wondering if this is the source of my issues. My water tube is pretty loose, in fact it popped out the first time I pulled the LU. Also, when running the boat in a 44 gallon garbage pail, I noticed leaking from :
225px-Merc_50_hp_zpsc0cfdae9.jpg Photo by blueovalstanggt | Photobucket

Could it be that? I don't even know how I would access that to tighten anything.

 

[sjoefl01]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

When I was fighting a heating problem I found a video on Utube that showed a classic 50 running and the stream was much stronger than mine. When I ficed the problem the stream looked like the one on Utube.

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Sjoe, did you have to use permatex to seal any of the exhaust ports?

 

[sjoefl01]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Yes. I used high temp gasket sealer and we gooped a lot of high quality anti seize compound on the bolts. We blew a lot of sand out of the various passageways.
Some black tar ball thing fell out. We never could figure out where it came from.

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Yes. I used high temp gasket sealer and we gooped a lot of high quality anti seize compound on the bolts. We blew a lot of sand out of the various passageways.
Some black tar ball thing fell out. We never could figure out where it came from.

Where did you use the gasket sealer? Mine has a rubber gasket that joins the exhaust tube to the lower unit and I thought maybe the gasket sealer wasn't neccesary. It was also not there when I removed the lower unit.

 

[mercurymang]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

My understanding is that you want to install these gaskets dry. I think the main reason is that using sealant may cause the gasket to "slide" when tightening things up. I installed mine dry and had no issues. You're probably ok but only time will tell.

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

Are you talking about the water pump gasket or the powerhead gasket?

 

[on_ice]

Re: Removing exhaust plate cover on 1988 Mercury 45hp Pro Fifty - how to

To confirm, if I ran the motor with the lower unit off and a hose hooked up to the water tube. Exhaust/water should only be coming out of the tell tale and the exhaust tube...not the area around the exhaust tube. Correct?