Overheat Alarm at Idle - F250

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lgusto

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Folks,

Had my 2005 F250 serviced a couple of months ago. All the annual work was done but the tech said no need to replace impeller this year, looked fine.

Since the service, my overheat alarm will sound after a couple of minutes at idle. Never happened before, good water stream coming out of the engine. If I shut it down for a moment and fire it back up it's fine for a couple more minutes. Only happens at idle. RPMs at idle are about 600. Engine hours are 2,200. Runs perfect.

Thoughts? Thanks for any input.
 
Perhaps there is something blocking the ports? I have been in water where I had to idle and picked up some fillamentus algae and got this alarm. Come to think of it my 2008 F250 had this issue and it would warn over heat at low rpm. It was a faulty sensor.
 
There's an o-ring seal at the bottom of the pump housing that can slip out of position during installation. If it gets pinched off, water pressure can drop just enough to cause what you're experiencing, especially if the impeller has some wear.
 
GulfSea said:
There's an o-ring seal at the bottom of the pump housing that can slip out of position during installation. If it gets pinched off, water pressure can drop just enough to cause what you're experiencing, especially if the impeller has some wear.
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I have the same year & model you have. I just had the same problem, it turned out to be what Gulfsea is describing.
 
Only overheats at idle, but fine at speed? I'm betting Poppet valve (also known as PVC valve). Clean out or replace.
 
I had a similar issue when changing the water pump it would alarm at idle but not in gear. Ran fine in gear. Brand new but Faulty water pump housing/seal. Changed it and it was fine. Just the luck of the draw. Tear down and do the water pump again.
 
Break Time said:
GulfSea said:
There's an o-ring seal at the bottom of the pump housing that can slip out of position during installation. If it gets pinched off, water pressure can drop just enough to cause what you're experiencing, especially if the impeller has some wear.
Click to expand...

I have the same year & model you have. I just had the same problem, it turned out to be what Gulfsea is describing.
Click to expand...

When I saw the design I figured it happened quite often. Just for info, the previous mechanic apparently over-torqued the housing causing 2 bolt holes to have a faint crack. So I bought a new housing; it's only $27. But I noticed the new housing has been modified with 9 tiny tabs around the o-ring area that seem to hold the o-ring in place better.
 
bayrat said:
Only overheats at idle, but fine at speed? I'm betting Poppet valve (also known as PVC valve). Clean out or replace.
Click to expand...

Definitely check this and the thermos. if your motors have a nice strong stream coming out the pisser, it's almost definitely one of these two. You can test your thermo's by putting them in boiling water on your stove and they should pop open as the water comes up to temp. sometimes they stick... Personally I replace them every two years along with the lower pressure fuel pumps...
 
Well, I never got to checking the o-ring as the problem didn't recur. However, I did lose a piston and need a new powerhead. The rings on cylinder #5 either broke or got stuck resulting in lots of blue smoke and no power at RPMs over 3000. I'll know for sure once the old engine is disassembled but in any case it was time for a new short block. Fortunately there were no overheat codes in the computer so it doesn't seem to be cooling related. I got 2,300 hours out of the 2005 engine which I guess isn't too bad for a single F250 pushing a Gulfstream during years of offshore chartering in Maine during the summer and Florida during the winter.
 
lgusto said:
Well, I never got to checking the o-ring as the problem didn't recur. However, I did lose a piston and need a new powerhead. The rings on cylinder #5 either broke or got stuck resulting in lots of blue smoke and no power at RPMs over 3000. I'll know for sure once the old engine is disassembled but in any case it was time for a new short block. Fortunately there were no overheat codes in the computer so it doesn't seem to be cooling related. I got 2,300 hours out of the 2005 engine which I guess isn't too bad for a single F250 pushing a Gulfstream during years of offshore chartering in Maine during the summer and Florida during the winter.
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Ugh !….but as you say, after 2300 hard hours it really doesn't owe you too much.
 
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