Why is my 460 overheating?
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Why is my 460 overheating?
I just bought a '93 F-250 with a 460 engine. when I test drove it it ran out well - no problems. After a day, I suddenly have an overheating problem. I replaced the fan clutch and the thermostat, but it still overheats. Does this mean waterpump? Any suggestions?
Last edited by jimly; Nov 10, 2004 at 01:50 AM. Reason: make title bigger
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From: People's Republic of CA
Step 1- Assume nothing.
How do you know it's really overheating? How hot? Maybe just bad guage/ sender?
Is the ratio of coolant/ water correct?
Did you look for coolant flow in the radiator? No flow at op temp/ or during overheating could be bad thermostat, pump, plugged rad or block. Did you put thermostat in, facing the right direction?
Gas bubbles/ excessive pressure in cooling system? Bad head gasket(s)....
Verify ign timing (non-adjustable). Over advanced could cause overheating, but you'd hear bad pinging on acceleration.
Along the topic of engine, how's it run? Full power or lagging? Noises, missing, blubbering, etc..
Just thinkin' off the top o' my head...try above though for starts.
How do you know it's really overheating? How hot? Maybe just bad guage/ sender?
Is the ratio of coolant/ water correct?
Did you look for coolant flow in the radiator? No flow at op temp/ or during overheating could be bad thermostat, pump, plugged rad or block. Did you put thermostat in, facing the right direction?
Gas bubbles/ excessive pressure in cooling system? Bad head gasket(s)....
Verify ign timing (non-adjustable). Over advanced could cause overheating, but you'd hear bad pinging on acceleration.
Along the topic of engine, how's it run? Full power or lagging? Noises, missing, blubbering, etc..
Just thinkin' off the top o' my head...try above though for starts.
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more 460 overheat
I made sure the thermostat was put in right - spring down - and , yes the coolant level and mix is right. There appears to be some coolant flow and it will cool down and heat up rather randomly. Drives and sounds good. I'm really frustrated! The coolant in the radiator now gets hot enough to belch out if I crack the cap. As for checking the temp, I had a buddy with a sensor check it out and it was running about 200 degrees.
Last edited by jimly; Nov 10, 2004 at 02:12 AM.
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Well, 200 deg. doesn't sound bad, I think those are 180 deg. thermostats (OEM) though. Can't remember, been a while for me on those...could be a 195. At op temp, you will get some coolant spit if you open the cap on a pressurized system.
What temp stat did you put in? If you put in a 195, the temp's OK.
At 200, what's your guage say? Where's it at in the field?
If your sensor says 200 pretty constant (idle vs. 2-2500 rpm) but your guage is moving all over, it's an instrument problem.
Bottom line, if flow's normal, where it should be, at all RPMs, pump/rad/ block=OK, not plugged. Of course, coolant flow rate should be higher at 2500 rpm than idle. If not, restriction, or bad pump.
You can try a new cap if you're spittin' out the overflow during normal running (no extreme ambient temps or excessive loads), which could mean system isn't holding design pressure, due to the cap. Low cooling system pressure can lead to overheating.
If there's excessive pressure in the system, pressure test it to look for internal engine leaks or have a shop sniff the coolant for combustion gasses....
What temp stat did you put in? If you put in a 195, the temp's OK.
At 200, what's your guage say? Where's it at in the field?
If your sensor says 200 pretty constant (idle vs. 2-2500 rpm) but your guage is moving all over, it's an instrument problem.
Bottom line, if flow's normal, where it should be, at all RPMs, pump/rad/ block=OK, not plugged. Of course, coolant flow rate should be higher at 2500 rpm than idle. If not, restriction, or bad pump.
You can try a new cap if you're spittin' out the overflow during normal running (no extreme ambient temps or excessive loads), which could mean system isn't holding design pressure, due to the cap. Low cooling system pressure can lead to overheating.
If there's excessive pressure in the system, pressure test it to look for internal engine leaks or have a shop sniff the coolant for combustion gasses....
Last edited by B A dawg; Nov 10, 2004 at 02:46 AM. Reason: Clarification
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pull a hose and look at it. Maybe someone put some of that Stopleak gunk in there and it's plugging something somewhere. I don't know how you'd clean this gunk out. Like HardScrabble says, take it by a radiator shop.
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Hey Jimly,
Let us know what happens. I'd like to hear back on the results of your troubleshooting, thanks!
Let us know what happens. I'd like to hear back on the results of your troubleshooting, thanks!
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Wrap-up on 460 overheating
Well, I worried myself sick over nothing. A ground strap had worn almost through and was intermittently shorting out. It messed up all the gauges, so the temp, oil pressure and alternator gauges all read funky. It also messed up the alternator, so I did have to replace that. It now runs and indicates like a dream.
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Ahhhh....
So ALL your guages were messed up...OK..
Well, glad you found the problem, BTW, I've heard about bad grounds causing problems, I'll have to remember that one as a definite item to check next time.
Thanks for the update!
So ALL your guages were messed up...OK..
Well, glad you found the problem, BTW, I've heard about bad grounds causing problems, I'll have to remember that one as a definite item to check next time.
Thanks for the update!
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From: West Mansfield, Ohio
I've got a 95 F-150 and the Temp gauge likes to read half hot when it is 30 degrees out and once it warms up, the temp gauge buries it past hot. A couple of smacks on the top of the deash fixed this problem.
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Check the lower radiator hose, it should have a spring in it to keep the hose from collapsing which can restrict coolant flow at higher engine speed. I just replaced my thermostat and the parts guy said the stock value was 195 deg. F. but he also had 180 and 190 replacements. My Temp. gauge runs about 1/16" to right of straight up using the 195 deg. thermostat.
Ken '83 F350
Ken '83 F350
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From: West Mansfield, Ohio
That is exactly where mine is positioned too..... Some people its say its bad to have it run that "warm" but thats is the temp that the engine has to run in order for the sensors and stuff to work right.
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