5.0 overheating

caniborrowit

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Jul 26, 2012
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5
First post, new boat owner as of 2012. I have a '89 Baretta Phaser with a 5.0 Ford and OMC drive that I bought last year. 2 weeks into owning it the coupler burned up. Got it fixed and everything was fine the rest of the summer. Get it out this summer and no problems until 2 weeks ago I started losing power and reading through the forum it sounds like I have a spun hub in my prop. Put on a new prop, fixed the problem.

Last weekend we take the boat out, go across the lake about 3,000 rpms and a 10 minute cruise no problem. Park at the beach for a couple hours, get back into the boat and head back across the lake. Into a pretty stiff wind so was at about 3,500 rpms. All of a sudden smoke starts coming out of the engine compartment, look at my guages. Temp around 240, oil pressure seemed a bit low also. I panicked, cut the engine, got towed to the dock and am wondering what to do.

I can handle most automotive repairs so I'm fairly mechanically inclined but know nothing about boat engines. Through reading on the forum I gather it could be the water pump, thermostat, risers?

A couple specific questions I have I would love some help with: Would this have ANYTHING to do with the coupler? Is it possible something could be plugging the water flow through the engine? Would overheating cause problems with any other components? What are specific steps I can take to diagnose the problem?

The boat is a lot of fun when it's working correctly and in the water, not when it's sitting in my driveway or at the shop. I'm not ready to quit on it yet if it's easily fixable but if it's gonna cost a bunch of $ I may have to cut my losses. Please help, thanks.
 

RogersJetboat454

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Jul 9, 2010
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2,964
Re: 5.0 overheating

Welcome to Iboats.

Has nothing to do with the coupler, unless the new one failed and wasn't spinning the drive shaft, but you would have been "stuck in neutral" on the water.

First step is to check and replace the impeller in the drive. Not a complicated job, and has to be done every couple years. If when you lay your eyes on the impeller you find pieces of it missing, you need to look for the pieces in the cooling passages.

Chances are also high that since you baked her pretty good, the rubbers for the exhaust, and flappers in the exhaust need replacement.
 

caniborrowit

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Jul 26, 2012
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Re: 5.0 overheating

I don't know if it was one, the other, or a combination of both, but I replaced the pump impeller and the thermostat. The impeller was a little chewed up and the thermostat was a little corroded so $30 and some new parts and I'm back on the water and no overheating. The exhaust seems fine so I'll leave it at that for now.

Love this forum and all the info at my fingertips.
 

caniborrowit

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Jul 26, 2012
Messages
5
Re: 5.0 overheating

Well I thought I had it fixed, but it overheated again. Seems to only have problems when at idle speed too long. When I get going the temp cools dramatically. Is there a reason it's not circulating enough water while idling? How can I fix this?
 

caniborrowit

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Joined
Jul 26, 2012
Messages
5
Re: 5.0 overheating

Well I tried fixing the issue again last night. Took the impeller off and backflushed from the thermostat intake and got 4 dime size pcs of what look like impeller pcs of rubber but the impeller I replaced was not chewed up that bad. So I put the impeller back together and started it on the muffs and was getting good flow to the thermostat. connected the hose, started it and it overheated. Pulled the thermostat, started it, temp gauge didn't move. Tested the thermostat on the stove and it opened fine, put it back in the boat, started it and overheated again. Thouroughly upset by now, pulled the stat, started it, temp gauge didn't move again. Decide to take it out on the water and see what happens with no stat in. Get 50 yards away from the dock and overheated. Now it's in my driveway and I am out of ideas. I'm praying that someone can help or point me in the right direction. Is there something else I should be checking? I don't want to take it in but I have no idea what to do now. Please help, thanks.
 

RogersJetboat454

Commander
Joined
Jul 9, 2010
Messages
2,964
Re: 5.0 overheating

Well I tried fixing the issue again last night. Took the impeller off and backflushed from the thermostat intake and got 4 dime size pcs of what look like impeller pcs of rubber but the impeller I replaced was not chewed up that bad. So I put the impeller back together and started it on the muffs and was getting good flow to the thermostat. connected the hose, started it and it overheated. Pulled the thermostat, started it, temp gauge didn't move. Tested the thermostat on the stove and it opened fine, put it back in the boat, started it and overheated again. Thouroughly upset by now, pulled the stat, started it, temp gauge didn't move again. Decide to take it out on the water and see what happens with no stat in. Get 50 yards away from the dock and overheated. Now it's in my driveway and I am out of ideas. I'm praying that someone can help or point me in the right direction. Is there something else I should be checking? I don't want to take it in but I have no idea what to do now. Please help, thanks.

Are the manifolds getting hot? Have you tried flushing through the manifolds? Not uncommon for the manifolds to either get restricted with foreign debris, or rust up and restrict flow. Any coolers on board (oil, power steering)? It's a good idea to disconnect hoses from them and other items, and directly back flush.
 
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