I 2 am having the same problem with the wacky gauge as raven2 is from the cycling temperature post. I recenly replaced the fan, themostat and water pump in my 91 xlt with 99,000 miles on it and the temp gauge flops up and down between the "o" in Normal and the half way point. The thing that is killing me though is that the heat does not get as hot or blow out as strong as it used to. After driving my coolant reservoir is empty after filling it with coolant up to the line. I dont get it, is there enough coolant in the system could it be a bad themostat, could the system have air in it along with the heater core? Please help cuz its freezen here in Cleveland,Ohio.
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TEMP GAUGES FLUTUATES&LOW HEAT
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I'm not sure if the other board mentioned this, but there are a couple theories as to why it maybe fluctuating. The first deals with how the thermostat was placed in the housing. There is a small release hole in the thermostat that must be placed at the top of the housing (At a 12 o'clock position). I have heard that this has been a fix for fluctuation when someone incorrectly installed it and then replaced it in the correct position. Another solution wasa to replace the radiator cap which seemed to solve the problem for others. I replaced my thermostat about a month ago with no problems, I hope this helps you!
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Tim Y.
1996 Ford Explorer
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Tim Y.
1996 Ford Explorer
Ira
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Raven,
This is all theory but it is my thoughts about your problem. Maybe someone else can correct me if I am wrong.
Is it possible that you have a leaking head gasket? The reason I am thinking this is as follows: As the engine is running, you have very high compression in the cylinders. If you have a weak spot in your head gasket, the compression (air) can leak from the gasket into the water passages in the form of air. This may be happening in small amounts. As the engine runs for a period of time, the air tends to accumulate and gets into the heater core causing your sloshing sound. Since the air (from compression) is under much higher pressure than the coolant when it goes into the coolant, the pressure will build and the radiator cap will release the excess pressure in the form of coolant to the reservoir. This would be a continual process while the engine is running. The longer the engine runs, the more air in the system, thus you have more coolant expelled into the reservoir. Over a long drive time, the reservoir will actually overfill and excess coolant will drain out to the ground while driving. While the engine is off for extended amounts of time, (overnight), the coolant will cool and actually contract as opposed to the expansion while it is hot. As it cools, it is drawn back into the radiator. Keep in mind, you have lost coolant thru the overflow each time the engine is allowed to run for long times. Because of this, the overflow reservoir will eventually be emptied of coolant during the night and you will have air added to the radiator. This is probably where your coolant is going and why it is a slow process.
Due to the compression being under higher pressure than the coolant, it is possible none of the coolant is actually being pulled into the cylinders and burnt. You may possibly pull your spark plugs and not see any sign of water because of this.
I would say that the thermostat being old or new, along with the radiator cap, would have absolutely no effect on this at all. Nor would the temp sending unit. As the air eventually travels thru the system and gets around the temp sensor, it will actually cause the temp sensor to sometimes read the air temp instead of the coolant temp. This would cause your temp fluctuation on your gauge. The air in the heater core would cause an insulating effect and cause you to have a reduced amount of heat.
Like I said, this is theory but is very possible. I have seen this in outboards and jet skis. Many people assume that when a head gasket is leaking, water is getting into the cylinder but it is not necessarily true. When water gets into the cylinder due to a head gasket leak, you have a larger leak and the engine performance is reduced. With a small leak, the engine performance will not decrease and you would not think it is a head gasket.
Well, enough about this. I have to stop and cool my typing fingers down...they are smoking by now. Anyone else have a comment about this (the theory part, not my smoking fingers Dead Link Removed)?
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Ira
91 XLT 4x4
What do Playboy and National Geographic have in common? Just a couple of the places I will never get to visit Dead Link Removed
[This message has been edited by Ira (edited 02-04-2000).]
This is all theory but it is my thoughts about your problem. Maybe someone else can correct me if I am wrong.
Is it possible that you have a leaking head gasket? The reason I am thinking this is as follows: As the engine is running, you have very high compression in the cylinders. If you have a weak spot in your head gasket, the compression (air) can leak from the gasket into the water passages in the form of air. This may be happening in small amounts. As the engine runs for a period of time, the air tends to accumulate and gets into the heater core causing your sloshing sound. Since the air (from compression) is under much higher pressure than the coolant when it goes into the coolant, the pressure will build and the radiator cap will release the excess pressure in the form of coolant to the reservoir. This would be a continual process while the engine is running. The longer the engine runs, the more air in the system, thus you have more coolant expelled into the reservoir. Over a long drive time, the reservoir will actually overfill and excess coolant will drain out to the ground while driving. While the engine is off for extended amounts of time, (overnight), the coolant will cool and actually contract as opposed to the expansion while it is hot. As it cools, it is drawn back into the radiator. Keep in mind, you have lost coolant thru the overflow each time the engine is allowed to run for long times. Because of this, the overflow reservoir will eventually be emptied of coolant during the night and you will have air added to the radiator. This is probably where your coolant is going and why it is a slow process.
Due to the compression being under higher pressure than the coolant, it is possible none of the coolant is actually being pulled into the cylinders and burnt. You may possibly pull your spark plugs and not see any sign of water because of this.
I would say that the thermostat being old or new, along with the radiator cap, would have absolutely no effect on this at all. Nor would the temp sending unit. As the air eventually travels thru the system and gets around the temp sensor, it will actually cause the temp sensor to sometimes read the air temp instead of the coolant temp. This would cause your temp fluctuation on your gauge. The air in the heater core would cause an insulating effect and cause you to have a reduced amount of heat.
Like I said, this is theory but is very possible. I have seen this in outboards and jet skis. Many people assume that when a head gasket is leaking, water is getting into the cylinder but it is not necessarily true. When water gets into the cylinder due to a head gasket leak, you have a larger leak and the engine performance is reduced. With a small leak, the engine performance will not decrease and you would not think it is a head gasket.
Well, enough about this. I have to stop and cool my typing fingers down...they are smoking by now. Anyone else have a comment about this (the theory part, not my smoking fingers Dead Link Removed)?
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Ira
91 XLT 4x4
What do Playboy and National Geographic have in common? Just a couple of the places I will never get to visit Dead Link Removed
[This message has been edited by Ira (edited 02-04-2000).]
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Here's a link for those having problems with disappearing coolant:
Dead Link Removed
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Tim Y.
1996 Ford Explorer
Dead Link Removed
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Tim Y.
1996 Ford Explorer
forbyfiev
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Try checking the coolant level in the RADIATOR instead of the reservoir. I just had similar problem that ended up being an intake manifold gasket leak. I kept filling up the reservoir, but the temp was still wrong and I had no heat. No matter how much coolant I put in the reservoir, there wasn't enough pressure in the half filled radiator to draw from the reservoir.
J.B.
J.B.
Thank you for the reply and the time for that long post.
It does sound logical, I do not have any puddles, odor, moisture on the oil cap, or signs on the dipstick.
The only advice I got on the swishing sound under the dash (which I assume is air in the heater core ) is that the cap is bad (and it was old) and not letting enough pressure build to push any air out, I tried a new cap but still have the swish.
Thanks again,
Tim
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91 Sport
It does sound logical, I do not have any puddles, odor, moisture on the oil cap, or signs on the dipstick.
The only advice I got on the swishing sound under the dash (which I assume is air in the heater core ) is that the cap is bad (and it was old) and not letting enough pressure build to push any air out, I tried a new cap but still have the swish.
Thanks again,
Tim
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91 Sport
Ira
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Raven2,
I would try disconnecting the heater core and try flushing it out. You may have some sort of partial blockage that is preventing the air from escaping. Another thought, I am not very familiar with heater cores, but if the inlet and outlet hoses were reversed, could that also cause the problem?
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Ira
91 XLT 4x4
What do Playboy and National Geographic have in common? Just a couple of the places I will never get to visit
I would try disconnecting the heater core and try flushing it out. You may have some sort of partial blockage that is preventing the air from escaping. Another thought, I am not very familiar with heater cores, but if the inlet and outlet hoses were reversed, could that also cause the problem?
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Ira
91 XLT 4x4
What do Playboy and National Geographic have in common? Just a couple of the places I will never get to visit
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