Mercruiser 233hp Slight over Heating. Is this Impeller bad enough? Pic.

boxchevyman

Seaman
Joined
Mar 16, 2014
Messages
61
Hi guys just bought this boat took it out, works pretty good. Noticed that the temp gauge was just ever so slightly in the red zone. So I shut her off let her cool down then took her home. I am getting water out of the ports by the transom on muffs. But I decided to pull the lower unit and take a look at the impeller. Here is a picture. The fit is somewhat snug but not near as a snug as a new impeller.

Do you think it?s bad enough to cause overheating or should I look somewhere else?

Thanks all,
James
20150702_211443.jpg
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
you will find the service life of the Alpha impeller is 2 years ,dosent matter if its used or just sits
 

NHGuy

Captain
Joined
May 21, 2009
Messages
3,631
Yes, replace it. But to your question, no it probably won't solve your heat issue. Keep looking. Undo the water lines that lead to the motor and back flush or back blow them.
Then hook up water straight to the engine and run it in the driveway for a check.
 

boxchevyman

Seaman
Joined
Mar 16, 2014
Messages
61
Hi all,
So I took a garden hose to all the hoses on the engine and I got good flow back out of the corresponding exhaust hose. (Good flow being defined as filling the diameter of the hose and making me soaking wet.) I also took off the thermostat housing cover and there was no thermostat in there. So I decided to just run it with a hose strait to the intake line. It ran cold the entire time. Never once did the temp gauge go to green. Which makes sense because it doesn’t have a Tstat.
So I guess this proves that my impeller is in fact bad? Just want your guys nod before I put another one in.

Thanks for your time,
James
20150703_093021[1].jpg

Edit: The exhaust manifold logs were warm to the touch. I could keep my hand on there indefinitely so I believe the temp gauge is at least somewhat accurate.
 
Last edited:

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Yes your impeller is bad, with the fins being bent so badly it cannot create water pressure to circulate the engine..by the way put a 160 thermostat in to running a engine that cold will make for bad power and economy. It sure looks like someone took out the stat just so the engine could run without overheating thats how bad that impeller really is.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Yes your impeller is bad, with the fins being bent so badly it cannot create water pressure to circulate the engine..by the way put a 160 thermostat in to running a engine that cold will make for bad power and economy. It sure looks like someone took out the stat just so the engine could run without overheating thats how bad that impeller really is.

Yes. Replace that impeller, and do not operate the engine without a T-stat:thumb:
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
From what I have heard no thermostat can cause problems with flow within the engine and can make hotspots . Get it replaced. If you got into the red it was overheating pretty bad. Mine had numbers on the gauge I don't think it gets to red until after around 250. You should be running around 160-170 or maybe 175 as a high. Whenever you remove an impeller you might as well replace it. They are cheap. Make sure the housing is in good condition. If the housing is worn water won't pump as needed. You might try backflushing the hose from the thermostat housing back to make sure there is no old impeller parts in there.
 
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