my 91 gt gets to 230-240 and does not wanna cool down, it seems to stay at 180-190 until i start pounding on it or turn ac on, but when it gets hot even easy highway cruisin with no ac it stays high, could my thermostat be stuck open not allowing radiator to do its job? any suggestion, did a pressure test yesterday and it stayed at 16 lbs even put new rad cap on
getting too hot!!!
- Thread starter 91whiteponygt
- Start date
TheBocSez
New Member
Do you have the lower air deflector attached still? Makes a big difference when driving.
If you still have the stock clutch type fan, it may also be the fan clutch going out
If you still have the stock clutch type fan, it may also be the fan clutch going out
Flavadave4
Active Member
afast93stang
Founding Member
Are you using an aftermarket tmep guage or the stock one? If your using the stock one its horribly off.
According to my autometer guage I usually run between 185-195 depending on traffic and if I have the A/C on. I also have a Mark VIII electric fan.
According to my autometer guage I usually run between 185-195 depending on traffic and if I have the A/C on. I also have a Mark VIII electric fan.
RaceDvr50
New Member
When you are cruising down the highway you should'nt need the fan to be kicking in unless you have some high compression motor or really deep gears making your engine work overtime. The thermostat might not be opening all the way that is one place to look, I'm assuming that your coolant is full and somewhat fresh?? The thermostat opens to let the radiator do it's job, not the other way around.
RaceDvr50
New Member
91whiteponygt said:
If the thermostat is stuck open the engine won't warm up properly. You won't have any cooling problems unless the thermostat won't open or won't open all the way.
To diagnose a cooling problem it might be a good idea to first understand how the cooling system works.
Just to clarify -RaceDvr50 said:
When the stat is removed the coolant can circulate through the radiator so quickly that it does not have time to dissipate heat. In this situation you end up with hot water coming out of the radiator.
So the thinking that a t-stat that is stuck or sticks at wide open could cause such a problem is reasonable.
Whether that is the case or not in this instance is not clear though.
I recommend a coolant gauge. You can go all out and get an autometer (or other good brand).
OR you can just pick up a parts store special. They are supposed to be pretty decent.
If you have access to a thermocouple, that would work as well for a quick verification of the stock gauge readings.
There may be a way to test the gauge via the sending unit, but I am not smart enough to know how to do that.
jason
I would confirm temps, add a real gauge so you dont have to guess anymore (might be part of the first thought).
You can change your stat if you want. The stat in and of itself is a restriction, even if the stat is stuck open. This works and is demonstrated on cars with a stat rating way below that of the fan on-temperature.
Your radiator simply might not be able to reject enough heat, especially if this just popped up as temps have gone up.
Good luck.
:OT: Jason, did you read about the 6 stroke prototype engine? I figured you'd dig the physics behind the idea.
You can change your stat if you want. The stat in and of itself is a restriction, even if the stat is stuck open. This works and is demonstrated on cars with a stat rating way below that of the fan on-temperature.
Your radiator simply might not be able to reject enough heat, especially if this just popped up as temps have gone up.
Good luck.
:OT: Jason, did you read about the 6 stroke prototype engine? I figured you'd dig the physics behind the idea.
RaceDvr50
New Member
vristang said:
WTF? Remove the stat if you want, the more coolant you move through the engine the better. The radiator is a heat exchanger it absorbs and disperses heat by transferring it the the air it doesn't hold the coolant and wait to release it until it cools. If you can pull the radiator cap and watch a healthy wash of coolant flow through the radiator you are probably golden as far as flow goes. Then look for something else, is this a stock fan? I have seen someone put in a fan that was pitched the wrong way and it stalled the air going into the radiator and overheated quickly. Also, do you run cats? A plugged cat can cause a hot running engine.
RaceDvr50
New Member
The spring should go into the intake manifold. That way the engine temperature coolant is in contact with the bi-metal spring.
RaceDvr50 said:
I am not trying to say that excessive flow is the source of this guys problem. I am just saying that this is a possible condition.
Think of it this way. If you had to grab a hold of something bare handed that you thought would be hot enough to burn you, what would you do?
Most likely you would touch your hand to it very quickly. The less time you spend in contact with the hot object, the less heat will be transferred to your hand.
Heat transfer is a function of time.
Another example... A hot cup of coffee will not cool to room temp instantly. Time is needed to transfer heat from the coffe, into the cup, then into the surrounding air.
It is the job of the t-stat to slow the flow of coolant through the radiator. Not only does it only open when the coolant reaches a "warm" temp, but the stat also acts a restrictor even when the stat is fully open.
Several guys have posted here about having trouble with keeping their coolant temps down. A few questions later and we find that they had removed the t-stat completely.
I also seem to remember a few instances where removing the stat was all a guy could do to keep temps down (this was in very hot parts of the country though).
:OT:
JT- I have not read anything on that 6 stroke engine. Thanks for bringing it up though
I will look into it.
jason
afast93stang
Founding Member
GT_Rich
Member
I will second Jason's claim that a stuck open thermostat could cause higher operating temps than a properly functioning one. Hopefully he's explained this well enough for others to get it.
My truck started running 20 degrees hotter last summer, and I knew right away it was the t-stat stuck open. I thought this was more of a common knowledge.
My truck started running 20 degrees hotter last summer, and I knew right away it was the t-stat stuck open. I thought this was more of a common knowledge.
RaceDvr50
New Member
Yeah sure ok because as the engine gets hot, the thermostat opens, as it gets hotter it opens more and once it opens too much the engine just gets hotter and hotter and then BANG the laws of physics catch of to you and nothing you have just said makes any sense in the really real world. The coolant flows through the radiator and it absorbs and releases heat you can't move it too fast. Did nobody else here take three years of Physics in college?
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