Overheating problems
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Elder User
Joined: Dec 2003
Posts: 586
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From: East Palestine, Ohio
Overheating problems
Been having trouble with truck overheating recently. I had the radiator flushed out last summer, new water pump, hoses, 195 degree thermostat. Didn't have any trouble until a couple of weeks ago. Temp gauge has always run between 205/210 degrees. Seemed ok then all of a sudden temp went to 240 and started to boil over. Today i put in a 160 degree thermostat and within 2 miles it heated up to 210 degrees. that is to hot with that thermostat. Came back home and parked it. The truck still has the original radiator but has been re-cored. I am planning on taking back to the radiator shop and having it flushed out again. Don't know what else to do but a new radiator.
I was wondering if anyone has any suggestions.
Thanks
Terry
I was wondering if anyone has any suggestions.
Thanks
Terry
Senior User
Joined: Apr 2005
Posts: 207
Likes: 0
From: Burkburnett, Texas
Several thing to check...
Do you have a fan clutch? If so, it could be bad. Also, your waterpump may be shot inside. Any sign of leakage around the weep hole? It could appear that it is turning, but inside the shaft may be sheared. Also make sure that none of your radiator hoses are kinked or sucking flat; sometimes the springs inside them can rust away and cause them to collapse. You might also check your radiator cap. How does the antifreeze/water look? Also try to post you motor and year so we all know what we're working with.
Good luck,
Vernon
Do you have a fan clutch? If so, it could be bad. Also, your waterpump may be shot inside. Any sign of leakage around the weep hole? It could appear that it is turning, but inside the shaft may be sheared. Also make sure that none of your radiator hoses are kinked or sucking flat; sometimes the springs inside them can rust away and cause them to collapse. You might also check your radiator cap. How does the antifreeze/water look? Also try to post you motor and year so we all know what we're working with.
Good luck,
Vernon
Fleet Mechanic
Joined: Jun 2004
Posts: 1,757
Likes: 37
From: Minnesota
Look at the antifreeze while the truck is running for air bubbles. If you have a leak in a head gasket that is pushing air into the radiator it would cause the truck to overheat. Can a shop pressurise the system while it is in the truck and look for leaks? I have never tried it but that may turn something up also. Also make sure the fan belt is tight and not slipping.
Lead Driver
Joined: Apr 2002
Posts: 8,813
Likes: 13
From: Littleton, New Hampshire
Terry,
Does it heat up just idling or when at speed? Generally in the absence of a mechanical problem with the engine, when the overheating occurs at idle the cause is not enough air flow (no fan, too small fan, not enough blades, not enough pitch on blades, no shroud) and when it occurs at speed it is usually because the radiator is clogged. If you had it recored recently and have been keeping antifreeze and antirust in it, it shouldn't be clogged already.
Vern
Does it heat up just idling or when at speed? Generally in the absence of a mechanical problem with the engine, when the overheating occurs at idle the cause is not enough air flow (no fan, too small fan, not enough blades, not enough pitch on blades, no shroud) and when it occurs at speed it is usually because the radiator is clogged. If you had it recored recently and have been keeping antifreeze and antirust in it, it shouldn't be clogged already.
Vern
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Elder User
Joined: Dec 2003
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From: East Palestine, Ohio
The truck has a 1970 302 with c4 auto and 2 barrel carb. The engne was rebuilt in 1989. It has about 14000 miles since rebuild. It Heats up at highway speed. Does not have a clutched fan but does have a fan shroud. Let it run with cap off and did not see any air bubbles. All the hoses and water pump were put on new last year.
Thanks for the replys.
Terry
Thanks for the replys.
Terry
Fleet Owner
Joined: Jul 2004
Posts: 27,283
Likes: 1,046
From: NM
What specific water pump did you buy? If it is a rebuilt, some of them come with really cheap impellers, just stamped sheet metal "alternator fan"-type impellers. Did the problem start when you replaced it? Are the belts tight?
That it heats up to 200 in 2 miles seems to indicate something with timing, an air bubble in the engine, etc. Can you pin down exactly when this started (relative to any other work)?
That it heats up to 200 in 2 miles seems to indicate something with timing, an air bubble in the engine, etc. Can you pin down exactly when this started (relative to any other work)?
