Heating up at idle! FINALLY...IT'S FIXED!!!!

[Bucks45]

Took the boat out for the first time today. It ran pretty well, but was heating up at idle. It would start cooling off when I increased the rpm's. I didn't let it get past @ 175-180. The impeller and pump were new last spring, as well as the thermostat. I'm assuming it has to be the water pump on the engine. Do you guys agree? If so, where do I get one? Can a automobile pump be used? It's a 1987 Mercruiser 5.7 (260). Thanks guys!

 

[ruggles]

Re: Heating up at idle!

Re: Heating up at idle!

I had the same problem and it was a combo of a leaky drain valve on my heat exchanger and a leaky rad cap. yes I know the boat doesn't have a rad.

 

[RepoMan207]

Re: Heating up at idle!

Re: Heating up at idle!

What outdrive do you have?

 

[havasuboatman]

Re: Heating up at idle!

Re: Heating up at idle!

How many hours on the new (last spring) impeller? was the housing replaced along with the impeller? Do you beach your boat?
Your engine requires an annual service. Part of that service is the removal of the drive and Inspection of the impeller with automatic replacement every other year.
I am a marine mechanic. I know a LOT of other marine mechanics but I don't know ANY marine mechanics that put a year old impeller back into an outdrive.
My point is; you probably need a new impeller and housing. You could have a damaged or missing blade (which would be caught in the P/S oil cooler, restricting water flow), worn wear plate, or worn housing. If you run your fingernail along the the side of the housing that the impeller blades seal against and feel grooves or ridges (anything but smooth), the housing needs replacing.
You are in Ohio right? You don't put your boat in salt water much? Is water leaking out of the little hole under the circulating pump? If not, it's fine.

 

[Bucks45]

Re: Heating up at idle!

Re: Heating up at idle!

Thanks for the quick replies. The drive is an Alpha I. The boat is new to me, but from what I understand there were only about 15 hours put on the boat last year. The PO only had the boat a couple of months and sold it due to family issues (divorce). He didn't know much about it. I found the guys name that he bought it from on the title and called. He was a super nice guy and I had a hard time getting off the phone with him. He told me that it heated up a little during idle. He said that he replaced the water pump, impeller, and thermostat. I don't believe that the boat has been in salt (atleast it doesn't look like it has) and I haven't had it long enough to beach! I have an impeller and housing that I bought before I spoke to the original owner. If the circulating pump isn't leaking (I'll check it later), I'll just replace the impeller. Thanks again.

 

[tomcat51]

Re: Heating up at idle!

Re: Heating up at idle!

Took the boat out for the first time today. It ran pretty well, but was heating up at idle. It would start cooling off when I increased the rpm's. I didn't let it get past @ 175-180. The impeller and pump were new last spring, as well as the thermostat. I'm assuming it has to be the water pump on the engine. Do you guys agree? If so, where do I get one? Can a automobile pump be used? It's a 1987 Mercruiser 5.7 (260). Thanks guys!

Check your cooling flow...I had the same thing happen..replaced everything but found blockage in cooling system...exhaust and mineral deposits..had to tear it down and clean...dirty job but the only cost was the gaskets to put it back together...

 

[Bucks45]

Re: Heating up at idle! Update

Re: Heating up at idle! Update

Checked the circulating pump and it wasn't leaking so I took off the lower unit to replace the water pump and impeller. The housing is smooth and the impeller looks brand new, but one of the gaskets appeared to have a piece missing and the tube was melted. I'm assuming this would cause the problem, correct? What would melt the tube like that? Thanks again guys.

 

[Bucks45]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

OK.....so I replaced the water pump and impeller and it's still over heating. I haven't let it get above @ 185. I ordered a new thermostat even though the PO told me he replaced it. If it's not the thermostat the cooling system has to be clogged. How do you flush it?

 

[Don S]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

The melted tube is because you don't have water in the exhaust. As far as the broken gasket, something looks wrong in your second picture, not sure what, can't really tell what I'm looking at.
Everyone want's to post such closeup pictures you can't see what something goes to or anything else.

 

[Bucks45]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

The melted tube is because you don't have water in the exhaust. As far as the broken gasket, something looks wrong in your second picture, not sure what, can't really tell what I'm looking at.
Everyone want's to post such closeup pictures you can't see what something goes to or anything else.

Don...Thanks, I was hoping that you would respond. It is pumping water out. The second picture is the bottom half of the water pump housing. I took the picture because a piece of the gasket was missing when I took the pump out (no, it wasn't stuck to the top half). Thanks for your help.

 

[Don S]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

If the housing is not damaged, I would put a new OEM impeller kit with gaskets and impeller in it.
I can't place what the problem is right now, but something looks really wrong with that gasket, and I am not referring to the missing part. But it probably is the cause of your problem.

PS. Where at in Central Ohio, West Jeffeson was my home for many years.

 

[backyard mechanic]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

Replace the WP gasket and put the unit back together... That impeller housing/plate looks good. If the impeller has not taken a set you're good there.

Once back up and running open the elbow drains while you are running on a hose. Water coming out at a good clip or just dribbling? How's the drain flow at the heat exchanger (if FWC).

I'd bet you are plugged with sand or dirt in the elbows. Back flushing helps but you may have to pull the elbows/manifolds to get the sand out.

Next point is all about if you are FWC or not.

 

[Bucks45]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

If the housing is not damaged, I would put a new OEM impeller kit with gaskets and impeller in it.
I can't place what the problem is right now, but something looks really wrong with that gasket, and I am not referring to the missing part. But it probably is the cause of your problem.

PS. Where at in Central Ohio, West Jeffeson was my home for many years.

Really? I've lived in London for almost 40 years! I've got alot of friends in West Jeff. PM me, I'm sure we know some of the same people.

 

[havasuboatman]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

That metal plate in your photo is the wear plate that the impeller rides on and seals to. I can see two different diameter grooves worn in that plate. It needs to be replaced. What did the gasket on the other side of that plate look like? how about the impeller? Are there grooves in the impeller housing opposite that as well? One thing is certian, That pump has a lot more that 15 hours on it.
Do yourself a favor and buy the whole water pump kit and buy it from Merc ad Don said. It will come with everything including the plastic piece.
That plastic piece isn't the water tube, by the way. It's just a guide to make assembly of the upper and lower unit easier.
If you try to cheap out here, you are going to regret it later.

 

[Bucks45]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

Havasu.......I replaced the housing, gaskets, and impeller. I also went ahead and replaced the thermostat even though the old one tested good on the stove. I'm at a loss for what could be wrong. It seems to have good flow. The circulation pump isn't leaking. The only leak I can find is a very minor one (a drip every 1-2 seconds) here. It says that it's my oil and power steering pump cooler. Is this something that can get clogged?

 

[havasuboatman]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

Yes it is. You could have a piece of old impeller caught it there.

 

[Bucks45]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

Yes it is. You could have a piece of old impeller caught it there.

Thanks.........what do I search when I try to order one? Whats it called? Or do I just take it off and try to clean it? I really appreciate all the help you guys are giving.

 

[Bondo]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

Whats it called? Or do I just take it off and try to clean it?

Ayuh,... It's the P/Steering Cooler,... Yes, remove,+ repair...

 

[Bucks45]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

Thanks Bond-O!

 

[Bucks45]

Re: Heating up at idle! UPDATE

Re: Heating up at idle! UPDATE

Guess I'm back to square one. Took the oil cooler off and it was clear. Took the circulating pump off, just because I'm out of ideas, and it looks fine. So...new water pump housing and impellor. New thermostat (165 degree), and circulating pump looks fine. Any ideas guys? Thanks again.