Help on normal operating temps on daily driver OEM 5.0

[FastDriver]

I don't know if the heater core will flow with the tstat closed. That's a good question. Hopefully someone else can chime in.

However, if the top radiator hose is getting hot, then that's not the problem. Does it open inward toward the motor or outward toward the radiator?

 

[MrPerfect2]

I am going to try a high flow 180 Tstat by Motorad - it claims to have a jiggle pin to remove air ? But says it also flows more coolant with bigger opening - I can’t be sure the previous owner actually changed the stat ...

 

[Blown88GT]

I think that is not a 'bleeder plug' , it is still too low I think. Most use it for an aftermarket gauge, on older models it had a vacuum thingymabob on it for the old thermactor emissions stuff.
i just jack up the front end as far as I can and squeeze the lower hose several times to pump the air out. Works every time.

Actually, that plug was for a temperature switch. I had to drill & tap for a larger size, since could not find a switch with the correct temp range for the e-fan. With PWM fan controller (DCC) now the switch only serves as a plug. I still have some of those switches.

The 198/189°F (92/87°C) fan (temp) switch (823 959 481 F) is manufactured by Wahler and is used on a 1979-83 VW Rabbit. Use this switch with a 180°F thermostat. Use the 180°/171° (82/77°C) temperature switch 823 959 481 82 with a 160°F thermostat. These switches will require drilling out the existing 3/8" NPT hole in the thermostat Housing with a 3/4" drill bit and threading with a metric M22-1.5 tap.

I never had a problem with air pockets. If you leave the radiator cap off while idling, it will self purge all air.

Unlike other vehicles, there is no heater control valve, so there is always coolant flowing through the heater core. You get no heat inside the car because the vacuum damper covers the core so no air flows over it.

High performance (high flow) t-stats have a slightly larger opening. There are many different ones, mine is a Mr. Gasket.

Mr. Gasket 4364 Mr. Gasket High Performance / High Flow Thermostat - 180 Degrees

Mr. Gasket High Performance Thermostats are designed to resist large variations of coolant pressure at high RPM (revolutions per minute). This allows them to fully open at correct temperature consistently regardless of engine RPM. The design also provides the high flow that engines operated a...

www.holley.com

 

[TOOLOW91]

Buy a stock motorcraft t stat . Drill a small hole at 12 and 6 . You will almost never have an air pocket again . Have it this way in my car . It makes a fair amount of horsepower and it’s worked every time I have re did the car and refilled with coolant

 

[General karthief]

Most quality t stats have a hole or a loose button at the 12 o'clock position, I like them to be a wee bit bigger.

 

[TOOLOW91]

Most quality t stats have a hole or a loose button at the 12 o'clock position, I like them to be a wee bit bigger.

Me too

 

[MrPerfect2]

After some troubleshooting and testing - I believe the thermostat was changed recently ( some clean sealant around the joint is visible ) I don’t think it was sticking closed , I think some air pockets formed an obstruction and did not allow good water circulation thru the heater core . May have had some air pockets near thermostat to give a high false reading for a brief time as well . So I parked car idling at 180 degrees . It pointed nose up at very steep incline and I opened cap after tstat opened ( before boil point ) tried the heater ( it was 100 degrees, luke warm at best ) coolant level was at brim , revved up and level dropped about 4” and brief bubbles , filled up to brim again and repeated a few times . Then capped it . Drove it in to work today 45 min drive - cruised mostly and brought revs up harder on going up some hills and down some hills - temps stayed between 195-215 - heater blowing 130 degrees - also did some heat gun testing - when temp gauge in car was 185 and circulating of coolant these are heat gun readings : top of radiator 190 ; middle area 160 ; top rad hose 165 ; bottom hose 135 ; tstat housing 165 - fluid circulates strong in radiator from inspection in the cap opening . After the heater core circulated the coolant was not at green ( the heater core probably still had straight distilled water from the rinse after the cleaning flush )

 

[General karthief]

Some things here are strange, upper hose heat gun reading 165*, top of radiator 190* ? Middle of radiator 160*, lower hose 135*
and your gauge is reading 185*.
Where is the sending unit located?
did you use teflon tape on the threads?
Now the 'top of radiator' reading could be air pocket at the top of the tank reading hotter than the coolant, also the beam is reading the metal so it will read hotter than the liquid.
Also you could have some coolant passages in the lower potion of the radiator plugged that would account for the lower temp readings but the 135* at the lower hose dispels that, I'm thinking your gauge is reading higher than the actual temp, I have some numbers someplace for temp sending units resistance to temp readings, I was fighting a similar gauge reading verses actual temp stuff on my car.

 

[MrPerfect2]

The top of radiator was the top metal plate - the coolant was same temp as the upper hose - the bottom hose was indeed approx 20-25% cooler though , is that ample cooling for running through a radiator at idle? I am thinking air pockets measure hotter than parts touching coolant - I used the the thread sealer for temp senders in a tube - it is possible that the gauge in car may not be accurate ( but they are suppose to be a reputable company) on a mechanical gauge - does the cord that connects to the sender take heat readings as well as the sender ( if it is sitting on hot valve covers , will it throw off accuracy ? ) I will take some more temp gun readings if temps run high again - this time I will write down and not use my beer hazed memory , lol

 

[General karthief]

Yeah, I didn't factor in the ' beer hazed' memory thing

 

[Blown88GT]

BTW, a heat gun generates heat; a non-contact temperature measuring device is what you are using.
It uses infra-red technology to measure heat.

 

[MrPerfect2]

Yeah ... since you are a founding member , I totally agree with you , lol

 

[MrPerfect2]

45 min drive home in 87 ambient air: most of ride was 190 - ended up at 215-220 with some hard throttle here and there , city drive : did another burp on incline when home produce some bubbles , but only small drop in fluid ( heater running strong and hot ) - top hose temp 230 ; bottom hose temp 190 - so far I am comfortable at these levels - car seems to run smoother and more responsive at 220 btw

 

[FastDriver]

Sounds like you've ironed things out.

I guess drilling out the tstat works for folks, but I've never needed to, FWIW.

 

[MrPerfect2]

Thanks for all the advice - fast , Wayne , blown , General , and a few others ( can’t rem all who helped ) the air pockets were a hidden problem I never would have thought of .

 

[Rt jam]

I'm am also against thermostat drilling. The quality thermostats with a hole? I've only seen them with a check valve. This will allow to remove air after the 1st coolant refill to rid of air and seal the rest of the time. Sealing is important because it promotes fast warm up. A hole a the same as a thermostat that never closes.

Air can be a hassles after the 1st refill but a coolant recovery system will rid of air after a couple of cold to hot to cold cycles.

A good system should start from dead cold, warm up before 5 minutes of driving then stay at thermostat temperature the ENTIRE time.
If it's going below the thermostat is open or has too big of a hole. If it goes above, the thermostat is wide open so it has nothing left to offer and the radiator is sending coolant that is too hot, back to the engine. If this is during highway driving, this can be a bad radiator, like old or too small. If it's during idle when stopped, there is not enough fan.

 

[Blown88GT]

Sounds like you've ironed things out.

I guess drilling out the tstat works for folks, but I've never needed to, FWIW.

I never had a problem either.
Just changed the radiator, coolant, et al.