Temp heats up as RPM increases
08-03-2003, 09:39 PM
#1
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Temp heats up as RPM increases
My temp gauge normally reads 160*-175* when I cruise 3200 rpm or less.
The past couple weekends I`ve noticed that if I run 3500-4000 rpm or more, the temp creeps up to 200* or so within a minute or two.
If I hit WOT, the temp goes from 175* to 210*+ within seconds. If I hold it wide open, the temp will hit 230*+ within a minute. If I slow down, the temp slowly decreases back to normal.
I replaced the thermostat (140*), no difference.
I am running a water pump cross-over also.
I`m not sure that the engine is actually getting hot. It doesn`t really feel much hotter than normal while it reads hot.
Any suggestions?????????
The past couple weekends I`ve noticed that if I run 3500-4000 rpm or more, the temp creeps up to 200* or so within a minute or two.
If I hit WOT, the temp goes from 175* to 210*+ within seconds. If I hold it wide open, the temp will hit 230*+ within a minute. If I slow down, the temp slowly decreases back to normal.
I replaced the thermostat (140*), no difference.
I am running a water pump cross-over also.
I`m not sure that the engine is actually getting hot. It doesn`t really feel much hotter than normal while it reads hot.
Any suggestions?????????
08-03-2003, 10:30 PM
#2
Donman, I had kind of the same problem as you. I had brand new water temp gauges that I had bought from Gaffrig. I even bought the sending units with the gauges. One is accurate and the other is showing that I am getting too hot, but touching the engines during operation they feel fine to the touch, however engines can get REAL EXPENSIVE in a hurry when they melt down so we took the engine hatch off and used a point and shoot laser temperature reading gun. Just point and squeeze the trigger and where ever the little red laser dot is at that is where it takes a an immediate temp reading that shows up in a small digital window. We took readings from ALL OVER the engine----thermostat housing, water lines, oil lines, fuel lines, oil coolers, power steering cooler, block, intake manifold, primary tubes on the headers, heads, tailpipes, etc.
It takes ALL the pain in the butt guess work out of trying to figure out what is going on. The tool may not be the answer to your problem, but it might help you solve it much sooner. Turns out that the temps showing up on the gauge and what we were getting from the temp gun were two different readings---the engine was running NORMAL water temps. It was the new gauge that was NOT working correctly! We removed the engine hatch and took the readings under normal boating/operating proceedures (on plane and at various RPM ranges)----as I drove my cousin took the temp readings.
You might try running your engine without a thermostat and see what happens, but I don't really know if that is good/safe advice. Perhaps someone else can chime in here and help you out. Best wishes
It takes ALL the pain in the butt guess work out of trying to figure out what is going on. The tool may not be the answer to your problem, but it might help you solve it much sooner. Turns out that the temps showing up on the gauge and what we were getting from the temp gun were two different readings---the engine was running NORMAL water temps. It was the new gauge that was NOT working correctly! We removed the engine hatch and took the readings under normal boating/operating proceedures (on plane and at various RPM ranges)----as I drove my cousin took the temp readings.
You might try running your engine without a thermostat and see what happens, but I don't really know if that is good/safe advice. Perhaps someone else can chime in here and help you out. Best wishes
Last edited by KAAMA; 08-03-2003 at 10:33 PM.
08-04-2003, 01:18 PM
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First check the Sea Strainers if you have them.
Usually turns out to be a worn or damaged raw water impeller. It can flow just enough water to keep cool at low R's but at higher R's it cannot keep up. Also look at oil cooler.
Good Luck
Usually turns out to be a worn or damaged raw water impeller. It can flow just enough water to keep cool at low R's but at higher R's it cannot keep up. Also look at oil cooler.
Good Luck
08-04-2003, 03:26 PM
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Also if it is a bravo, check the elbow where the water pickup hose hooks to the transom assembly. These can become plugged or if the hose is loose you can suck air.
BT
BT
08-04-2003, 05:24 PM
#9
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Originally posted by BUDAH
Don man check timing if its to low 20* total it will heat quick like that !
Or as you add throttle heat goes up and pressure in combustion chamber and if headgaskets blown it will do this ,,,,
or I've had allot with poor circulation do this ie. stopped up oil cooler ,bad impeller ect.
I don't think it lean unless you've made some big changes
sorry it took so long ,,and let me know if you find it
Don man check timing if its to low 20* total it will heat quick like that !
Or as you add throttle heat goes up and pressure in combustion chamber and if headgaskets blown it will do this ,,,,
or I've had allot with poor circulation do this ie. stopped up oil cooler ,bad impeller ect. I don't think it lean unless you've made some big changes
sorry it took so long ,,and let me know if you find it
I`ve just replaced both head gaskets due to a small leak from coolant passage into cylinder.
I have not leaned it that much, (dropped 2 jets on rear, 4 sizes down on front) since prior lake runs. Plugs look fine.
I am suspecting a clogged oil cooler. If not that, possibly a worn impeller...
08-04-2003, 05:30 PM
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Originally posted by hot water
First check the Sea Strainers if you have them.
Usually turns out to be a worn or damaged raw water impeller. It can flow just enough water to keep cool at low R's but at higher R's it cannot keep up. Also look at oil cooler.
Good Luck
First check the Sea Strainers if you have them.
Usually turns out to be a worn or damaged raw water impeller. It can flow just enough water to keep cool at low R's but at higher R's it cannot keep up. Also look at oil cooler.
Good Luck
I am really suspecting the impeller or oil cooler.
I just replaced impeller in early part of summer. It might have maybe 25 hours on it. Could it be bad already? Could something have gotten in the pump and possibly damaged the impeller? Can a damaged impeller flow OK below 3500 rpm and then not keep up at R`s above 3500 ?
To check oil cooler, do I just need to disconnect hoses and back flush it?
Thanks guys, you`re very helpful!
