Over Heating Engine

Tiny
COULDBEJIM
  • MEMBER
  • 1984 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 102,000 MILES
I have a 1984 Ford F150 with a 302 engine. The other day it got over heated and I thought the thermostat was stuck. I removed the thermostat and thought that I'd just run it for the summer w/o one. I also replaced the old radiator cap. The engine is still running hot. That led me to believe that I possibly had blown the head gasket, but when I run it sitting I can see no sign of a leak at all. The radiator is curculating water through it just fine. Do you know what the possible problem is? I'm stumped. Thank you in advance.
Thursday, June 2nd, 2011 AT 3:13 PM

7 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If the overheating occurs only when driving at high speeds, the cooling efficiency is poor and it could ba due to a clogged radiator.

If the overheating occurs no matter what condition, it could be due to poor circulation due to restricted passages or weak water pump.

Have you checked the cooling fans?

Removing the thermostat does not necessarily mean the temperature would be lower. The coolant can accumulate heat when coolant is not being cooled sufficiently before it re-nters the engine and this would result in the temperature gauge increasing with the time the engine is running, especially when engine speed is high.
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Thursday, June 2nd, 2011 AT 3:41 PM
Tiny
COULDBEJIM
  • MEMBER
  • 3 POSTS
It is over heating when the driving speed is kept below 30mph. The only thing that seems a bit unusual is the radiator seems to be pumping the water through quite fast. Fast enough in fact to "spit" water out when the engine is cold and just started if you leave the radiator cap off.
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Thursday, June 2nd, 2011 AT 4:07 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
That seems to indicate a blown head gadsket or clogged radiator. It is not moving fast enough.

Have system pressure tested to ccheck for bad head gasket.
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Thursday, June 2nd, 2011 AT 4:33 PM
Tiny
COULDBEJIM
  • MEMBER
  • 3 POSTS
Would the engine run good with a blown head gasket? The engine starts and runs fine at both low and high speeds. It just starts getting hot after running for a few miles. BTW: I really appreciate the help. I'm disabled and live on a very fixed income.
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Thursday, June 2nd, 2011 AT 4:47 PM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Hi guys. Let me just add a couple of observations. First, that fast circulation and spraying coolant is from having no thermostat. There's nothing to limit how fast the coolant circulates. A fully-opened thermostat still adds a lot of needed restriction.

Second, a missing thermostat CAN also cause overheating because the hot coolant doesn't stay in the radiator long enough to give up its heat. Put the correct thermostat back in, then continue with the diagnosis, otherwise you will have two problems and conflicting symptoms.
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Thursday, June 2nd, 2011 AT 5:18 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi caradiodoc, thanks for the additional input.

Engine can still run well with a blown head gasket if there is only minimal compression leaks but it is going to get worse.

You need to confirm if pressure is building up in the cooling system and if coolant is being pushed out of the radiator to the recovery tank.
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Thursday, June 2nd, 2011 AT 6:31 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
Hey fellers, what about a radiator hose being sucked flat by the water pump. Seldom do you find 'em with a anti-collapse spring anymore.

Around these parts, 10 years and you gotta get the radiator torn down and professionally rodded, to get rid of the restrictive mineral deposits.

Are you running coolant, mixing it properly, then pouring it in. Not pouring it in, and guessing what the mixture might be

KHLow2008. Please do not thank me for input too.I'm getting too used to "Socket Man", "Wench Baby". Or whatever, trying to throw me off of a post!

Nice to see a little 2carcourtesy w/ doc, or even me. Even if my input might be useless!

G'Day to the 3 of ya'll

The Medic
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Thursday, June 2nd, 2011 AT 8:48 PM

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