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Discussion Starter #1
My 85' 308 QV seems to be

My 85' 308 QV seems to be running a bit warmer for 45-55 deg. weather. It seems to gradually creep up after the t-stat opens. It will get up to 3/4s before the fans come on. Then it will stay around that area. Here are the items I address:
Istalled 180 Thermostat
Radiator Rodded out and Cleaned
New Waterpump
New Temp. Sending Unit
Fresh 50/50

It still will climb. Could it be in the gauge itself? The gauge is reading 3/4s when the fans come on and on my other 308 they come on at 195 so this made me think it could be in the gauge.
My other thoughts are that I have an ANSA with a Aftermarket Cat that is installed. Could this casue excess heat? The engine and radiator don't feel like they are in the 210 degree range when the gauge shows this.
Is there a way to test the gauge? Any other ideas on what to check or test the actual coolant temp? Any info would be appreciated. Thanks.
 
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Discussion Starter #2
Replace the switch that turns

Replace the switch that turns the fans on, it is located on the pass. side bottom portion of the radiator. About $15 from GT Car Parts if I remember right.
 
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Discussion Starter #3
>>Replace the switch t

>>Replace the switch that turns the fans on,<<

agree...the fans must come on @ 190/195 or below no matter what.

sounds also like there may be more air trapped.

could be the gauge though, you should check the radiator temp with an infra-red thermometer at the point the fans come on against the gauge reading to see if the 2 readings match.

Regards, JRV
 
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Discussion Starter #4
Thanks Guys. I agree it would

Thanks Guys. I agree it would be best to check temp at rad. as the fan switch could be ok and the gauge could be off or it could just be the fan switch coming on way too late. I will go ahead and get a new fan switch just to be safe.

Does anyone have a resistance value that the sending unit would send out for 195 on the gauge? Thanks.
 
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Discussion Starter #5
How about testing the sending

How about testing the sending unit in a pot of hot water with a candy thermometer or meat thermometer? Then you can verify it's operation without having to go out and buy another one? Only problem is what to plug the opening in your radiator with. Did you keep the old sender?
 
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Discussion Starter #6
Dave are talking about the sen

Dave are talking about the sending unit or the thermal switch? I replaced the sending unit already for the gauge. I think you are talking about the rad. fan thermal switch. That is a good idea to check it. I actually have the rad. out of the car now so I could put the thermal switch in a pot of hot water and test for continuity and when it opens up read the temp of the water. It should open up at 85C and close at 76C. Thanks for the info.
 
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Discussion Starter #7
I just checked my thermal swit

I just checked my thermal switch and it opens at 190 deg. F. So it must be an air pocket or a faulty gauge. When my fans come on my gauge reads 3/4s when it should read 195 unless it is reading an air pocket or ?. Thanks Again.
 
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Discussion Starter #9
Not to be an alarmist here bu

Not to be an alarmist here but if your cooling system is clean, the heater controls have been opened fully, all of the air has been purged, all of the components are operating correctly and you are still running hot then I would stick an exhaust gas analyizer in the opening of the cooling header tank to check for monoxide/dioxide gasses in the system.

If the test is positive then there may be the possibility some combustion gasses are escaping into the cooling system via a bad head gasket or crack.

DJ
 
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Discussion Starter #10
DJ,

your head gaskit scenar


DJ,

your head gaskit scenario is not out of the bounds of possibility as the 308 engines age. Time can have it's effects on engines just as use or abuse can.

Regards, JRV
 
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Discussion Starter #11
I was thinking of an old Ford

I was thinking of an old Ford truck from years ago that would not run cool no matter what we did. The radiator cap keep venting continuously. While it was running we took the radiator cap off and saw bubbling in the coolant. That was the dead give away.

Sure enough, we pulled the heads and we had a blown gasket. This was an extreme case but it always stuck in my mind as a possibility.

I really hope this isn't the case on your car.

DJ
 
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Discussion Starter #12
I hope not either. That thoug

I hope not either. That thought did come into play and I did a compression check and should no large variations in cylinder pressure that would be unusual. Wouldn't I noticed at least a 30psi difference if it was a head gasket? I haven't done a leak down as I thought the compression readings were close enough together to not warrant one. What do you guys think? Plus my car runs around 3/4s and doesn't seem to go above that not correct me if I am wrong but wouldn't the head gasket cause it to go up to max on the gauge? Any info would be appreciated. Thanks.
 
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Discussion Starter #13
Also would it hiss everytime y

Also would it hiss everytime you opened the expansion tank even after sitting for a few days?
 
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Discussion Starter #14
Try getting a heat sensing gun

Try getting a heat sensing gun (infra) and check the temp at the rad. and the block. If within range and gage reads high then you found the problem. If all is the same then it may be the thermostat even if it is new. And if all else fails then do the co2 test in the water tank. I use a 165 stat which runs at that most of the time.it goes to 195 with AC and in traffic in the summer and the fans turn on. They usually bring the temp down and turns off the fans. Then when I get up to speed the temp usually goes down to 165-170. 77 308 gtb
 
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Discussion Starter #15
Where did you get a 165 therm?

Where did you get a 165 therm? Thanks for the info. I am going to look for an infra. heat gun.
 
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Discussion Starter #16
"Also would it hiss everyt

"Also would it hiss everytime you opened the expansion tank even after sitting for a few days?"

Possibly but after things cool down the system pressure should go down too.

DJ
 
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Discussion Starter #17
Yes but if you are getting exh

Yes but if you are getting exhaust gases in the coolant then even after one day of cooling down it should have air in the system. This is just what I have always heard.
 
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Discussion Starter #18
Hi Guys,

A well sealed cool


Hi Guys,

A well sealed cooling system can hold pressure for days. This shoud present no problems I'm aware of.

Regards, JRV
 
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Discussion Starter #19
Ok, well that is good as I wou

Ok, well that is good as I would hear a hiss after I had let it sit for 2-3 days. Here is the good news. I removed the thermostat and put it in a pan with water and 2 therms. Well my 180 deg. F thermostat didn't open until just over 200 degrees and this was confirmed by another therm. So I guess it goes to show that just because you buy a new part and replace it they may not always work properly. Thanks for the help and please let me know where you guys have been getting you 160s.
 
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Discussion Starter #20
"Yes but if you are gettin

"Yes but if you are getting exhaust gases in the coolant then even after one day of cooling down it should have air in the system. This is just what I have always heard."

Agreed!

I also find I can bleed air from my cooling system every 300 miles or so. I wonder if that would indicate a problem or just a normal phenomena in 308's. My temps stay under 195f.

Thats really good news on the thermo test! Makes me wonder if the thermostat wasn't misstamped or misboxed. That wouldn't be a first.

DJ
 
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