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Worries about overheating


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Anonymous Poster
todd@datacomponents.net

Jan 18, 2009, 10:34 AM

Post #1 of 6 (1387 views)
post icon Worries about overheating Sign In

Hi everyone,

My name's Todd and I drive a 1988 Ford Bronco II. It's a 2.9L V6 engine with roughly 97,000 miles on it. It's been kept in great condition with repairs and regular maintenance over the years. I use it to drive back and forth to college, roughly 100 miles each way.

For a couple of months now, I've been driving without any problems and I notice my engine temp gauge will sometimes point up towards hot but not in the red. It points up roughly 3/4 of the way and after a minute or less, it'll go back down to normal. Just recently the heater doesn't blow any warm air out of the dash. After a while of driving it'll blow some warm air out but it eventually dissipates and doesn't.

I'm concerned about the engine overheating and I think it's the thermostat. The problem is that I have to head back to school tomorrow morning and have EXTREMELY little time to get it repaired. When I come back for spring break in the end of February, I'll take it to my mechanic.

So my question is, would I be able to drive it back to school without any problems or should I get it repaired ASAP?

The engine runs well and hasn't given me any trouble nor have I seen any noticeable changes. I just don't to break down on the highway and have my engine cease up.

Would it still be okay for travel from time to time?

--Todd


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 18, 2009, 11:06 AM

Post #2 of 6 (1385 views)
Re: Worries about overheating Sign In

You gotta check this out before you go back Todd.

This could be explained by low coolant in radiator despite what reservoir says. Check both! Keep it full and carry spare mixed coolant (antifreeze) for an emergency.

Heater will quit when overheating or low on coolant. Just a hill up or down might slosh low coolant to do what you described.

OK: Things to check right now.......

Check levels as said. Check for wobble of fan which is mounted on water pump. Not much is allowed. Check for leaks under the pump. When cool - run your finger UNDER connections and the pump - should come back dry. High chance this is leaking somewhere as a guess.

I wouldn't risk going back to school with a known bad pump OR a mystery loss of coolant. There's no good time for troubles but worse if enroute someplace!

Check away and get back to us or make an appointment. It will really help to NOT overheat this any more than it has or repairs could get worse,

T



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Anonymous Poster
todd@datacomponents.net

Jan 18, 2009, 11:18 AM

Post #3 of 6 (1383 views)
Re: Worries about overheating Sign In

I don't think it's low coolant since I had my radiator checked in just this past December. I had the coolant checked and my radiator checked too. I don't smell any coolant when I drive or any other smell.

It's a rather inconsistent thing. I'll drive for about 10-15 minutes and then the temp will point up to about 3/4 of the gauge, and then within 30 seconds or less, it'll go back down to normal. It'll do this inconsistently but little heat comes out of the dash. It will usually come out for a couple of minutes if I keep the blower off and then when the heat's gone it blows cooler air.

My mom owned the car before me and said the thermostat was replaced twice before and suspects it might be the case now.

Nonetheless, I'll talk to my mechanic tomorrow morning and see if I can get it in early. How long would it usually take to replace a thermostat in a car like that? I know there are always specifics like where it's located and how easy it is to get it out but on average, how long would it take, just the labor alone?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 18, 2009, 11:35 AM

Post #4 of 6 (1377 views)
Re: Worries about overheating Sign In

Having checked it weeks ago means nothing right now! The problem is now and totally consistant with low coolant level!

There aren't that many faulty thermostats like you may think and it could be but not high on the list. If so it isn't that big a job at all. Almost while-u-wait for some.

Gotta check it. The reason for heat fluctuation is possibly air which doesn't throw heat either from being low or bubbles from boiling - hot as that is - it's air and doesn't transfer that heat to a heater core to air again - you gotta believe me!

T



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Anonymous Poster
todd@datacomponents.net

Jan 18, 2009, 11:42 AM

Post #5 of 6 (1372 views)
Re: Worries about overheating Sign In

Okay, I just checked the coolant and it's filled completely.

It's not that I don't believe you I am just mechanically inexperienced. Would there be a way to remove the trapped air in the system? Also, how could you tell it's not the thermostat? Not that I don't trust you but I just want to know how to diagnose whether or not it's really the thermo or if its something else.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 18, 2009, 1:30 PM

Post #6 of 6 (1366 views)
Re: Worries about overheating Sign In

If you checked the system and found it full at the radiator it's probably fine with that. Small amounts of air would be self purging and no more would enter unless there was a problem or when recently serviced.

The temp spiking like you say and then being able to be normal isn't a good thing for the moment. I really hope it is just a thermostat and with it being erratic the only way to know is a new one when all else seems ok.

One way YOU could test thermostat is to start from cold, feel the upper radiator hose at the radiator end. It should be cold to the touch and stay that way till the gauge reads close to normal. NOTE! OF COURSE IT CAN GET VERY HOT AND YOU CAN GET BURNED SO USE GOOD JUDGEMENT IN TOUCHING PARTS AND STAY AWAY FROM MOVING PARTS. PLAIN DON'T IF IN DOUBT. If that stayed cool/cold and temp went higher than it's "normal" spot then I'd seriously blame the thermostat - they do have faults but not as common as you think.

There could be a problem with the radiator itself being marginal or partly plugged, there's a fan clutch that could be erratic or not capable of handling loads but could straighten out at easy higher speeds as the air flow would be enough without - say a long climp or towing etc.

Need to know what ambient temps you are in and dealing with. Most of N. America is cold right now and the complaints are coming in fast and fuious about heater problems. It's not a likely time of year for marginal radiator or fan clutch to be the trouble as if you are asking for heat it's probably cool out where you are.

There's a long checklist still to do and I understand you aren't a tech but should be familiar with the general operation of a vehicle.

Water pump could be worn such that lower rpm driving it can't circulate enough. That's hard to nail down. The belt that drives it could be slipping and must be known good.

What you don't want but need to know is if the head gasket is ok. Those can be intermittent and add air then may quit it for a while and drive you and techs nuts if it won't stay broken for testing. Finding cooling system full is a great sign so far.

Catching whatever it turns out to be can save you an unnecessary head gasket job from severe overheating - that's why it's so important.

There are other things that can cause this too - like missing shrouding both around the fan and underside where they get torn off so easily. Those do make a difference at speed but not much just slow or sitting there.

It's also wise to know the freeze protection you have. If not enough it could be slushing up in radiator and thawing when you slow down. Almost all vehicles should be set to -34F which is a 50/50 mix. Way too strong isn't helpful at all especially in hotter weather for cooling the engine.

One more - If there tons of debris in radiator - bugs, leaves - whatever - that too is a problem. If this has A/C check between parts - hard to see easily but there's a radiator up front called a condenser for A/C and looking similar the radiator for the engine which has the coolant and runs the heater.

Wish you luck and no breakdowns. Check or get it checked before your return is the suggestion "du jour"

T







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