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Discussion Starter #1
1968 XR7, 302 J code:
PROBLEM: heater does not heat well. temp gauge stays just above the "cold" mark....never indicates warmer temp than that. Valve to heater core opens and closes as it should. New water pump, new thermostat. Radiator recently cored/rodded. new antifreeze.
Any ideas? could the heater core be plugged?

Chris
 

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Feel your heater hoses, if they are not both the same temp. you may have a air lock. (some place to start)
 

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The core could well be in need of replacement. I always do when I am going through a car. 9 times out of 10 they need replacement from age or hard water (mineral) buildup blocking the tubes.
 

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I think the the water flow is from manifold through the heater to water pump, you, could remove the hose at the water pump and check flow. Take hose off before starting, have a catch can ready, then have someone start the car, this will releave a air lock (if there is one) and you can see how much flow. Watch out for fan.
Another thing is, remove the hoses from manifold and water pump and blow through them to check for restriction.
 

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It's pretty easy to get the stat in back asswards --- DOHHH....just sayin.
 

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Also, the laser temp thingies are getting to be pretty cheap, you might want to get one of those, and you can see exactly where your temp changes.
AND! Did you drill a tiny hole in the top of the T-stat? That has cured many a temp issue for me over the years. It lets the air vent out, and make it easier to pump coolant...
 

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Discussion Starter #8
Ok......

Disconnected heater core hoses attached water hose and water flowed through core just fine; no restriction at all; unit is relatively new.

Attached water hose to in-line Prestone "T" and back washed the entire system out trough radiator inlet on top.

Refilled system with antifreeze. started car with radiator cap off. Visible flow of coolant through radiator.

Heater still does not heat well. Temp gauge, which is working, still reads Cold. If I let the car run/warm up, turn it off, let it set for a few minutes and restart it temp gauge reads 1/3 above cold and almost immediately drops to cold.

Any further suggestions? Hate to remove thermostat again to verify it is in correctly....99.9% sure it is installed correctly........

Looks like it's going to be a cold Cougar Winter!
 

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Did you try and drill a hole in the top? It does seem to help...
 

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Sounds to me like you are running without a thermostat. Either in upside down or it is stuck open. If you heater core were plugged you should be running hot! Not cold.
 

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im with harvey...or if its in/in correctly, what temp t stat is it? if its super low it could be giving u these fits too
 

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Discussion Starter #12
Ok...
So what is the recommended stat temperature for this engine?

Guess I need to R/R the thermostat a second time... can't think of anything else....
 

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I'm trying to guess from memory which aint so good but I think we used to run a 165 in ours?
 

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Sound like the thermostat is hanging open. When the new one was put in it might of stuck open now it just acting as there is none in place. If the thermostat was in backwards I would think it would overheat, maybe. The temp should reach whatever rating thermostat you are using 195,180,165 etc. When the heatercore is airlocked usually the engine will heat up and show on the temp gauge if I remember correctly. Some newer thermostats have an "anti failure" type device built in that will cause the thermo to hang open when overheating occurs, I would replace it to see, probably the cheapest place to start.
 

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My bet would be thermostat, replace with a Robertshaw 180 degree.
 

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I have had good luck using Stant SuperStats. They only cost a few bucks more. Sucks they are not available for more applications. 192-195F T stat was used from the factory, same as almost every car ever made. Using cooler T stats usually will not fix an overheating condition. It will just delay the overheat slightly. BB Cougars might want a 180 F stat because the radiators are too small and the extra time might get you by. Not really a fix though, really need a bigger radiator. Restomod time? The downside to using cooler T stats is increased cylinder wall wear do to lower average engine temp. IMO run a 192-195 F stat if you can. Stant SuperStat PN's for most old school Fords including W,C, FE, 335 and 385 series engines. 45359 (195º), 45358 (180º) and 45356 (160º) http://www.stant.com/Consumer-Products/Thermostats/SuperStat--Thermostat/

Bill
 

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Discussion Starter #17
Problem resolved. Thanks to all.

Thermostat was "anti-failure" type and kept locking open.
Replaced with a new 195 degree regular thermostat and all is well.....it's going to be a warm Winter afterall.............
 

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Anti failure..? = no stat then huh? Never heard of that one. Not gonna look for one either!! Glad you wont be freezin your cajones now!
 

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Anti failure..? = no stat then huh? Never heard of that one. Not gonna look for one either!! Glad you wont be freezin your cajones now!
An Anti failure thermostat means if it goes bad, it failures in the open position, to ensure circulation and to not overheat, most new thermostats is of this design
 
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