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I have a 351M in my 77 F150 4X4, C-6, NP205. Anyways, I have changed to a 180 degree thermostat, replaced the water pump, and just finished flushing the system, and it still idles up from 210-230F, and on a hot day, 240F. I have been through alot of the posts, and a few of them mentioned the tranny slippage might be causing the engine to overheat. I am running Dexron III - Mercon tranny fluid. Anyone have any suggestions?
...forgot to add I am running 70/30 coolant mix. Also, I put in a mechanical temp gauge, and in doing so used teflon tape. I read somewhere not to use this on sensors??? Can someone explain?
Also, on this engine the sensor is located next to the oil filter, but on another engine I had, it was on the front of the block. Should I move it?
Well Good News ... Your not over heating ... that port next to your oil filter is an oil port not water .... so your oil temp is 240 Dreegs not your water .. Your water port should be next to your water pump on the front of the motor ....
Additionaly, I am reading the installation instructions for an Autometer temp guage. They recommend that you use Teflon tape on the the threads. Sounds like you are all set to go.
Thanks for the info. I had been racking my brain all week. I moved the fitting for the temp gauge to the water port next to the water pump. Drove it around town and the temp stayed around 205F.
However, as soon as I stopped, the temp ran up to 215-220F. :-( If I increased the rpms, the temp went back down to 210.
What could cause this?
Also, I have a tranny oil cool which sits partially in front of the right left side of the radiator. Could this be causing the increase in temp?
No the Tranny cool would slow the cooling down a little but not that much to be noticable. I'd say try to make your mixture more 50/50. I know up north here that's what's the pro's say to run.
Too much antifreeze is just like not enough when it comes to cooling, the 50/50 mixture is just right. And then make sure you have all the air out of the system and it's not vapor lock in the heater core.
Pure wate is actually a better coolant than any antifreeze mix but does not lube and prevent corosion. If you get hot at idle you might need more fan or a smaller water pump pulley. Got your shroud on there?
My cooling system is pretty up to snuff. I think what is causing the overheating at idle is the malfunctioning vacuum advance. I do need to locate another shroud though.
If your worried about over-heating at idle, I would recommend a electric fan. They are far superior to a mechanical fan, and as for driving, any driving over 45 mph the cooling fans are not really needed as enough air is being forced in. I would agree with Shazam with the 50/50 mixture.
Thanx
1980 short-bed with 351c-2v Custom F100
"The joy of violent movement, pulls you under"!
I would add two other items to the excellent advice you have already rece'd-----if you still have some amount of over heating check into a larger fan clutch---AND ideally , you should mix anti-freeze with DISTILLED water---this will minimize the formation of the chemistry that will eventually inhibit the free flow of the coolant in your radiator!!!!!!!!!!fd :-X11
I was wandering if the fan clutch came factory on all broncos, because my 79 F150 came factory with a straight drive fan. This is one of my next upgrades.
Had the Same Problem, turns out I had the Wrong Thermostat !
Because the Coolant Bypass on this engine is Internal, the Thermostat has a special design. The Bottom of it where the temp semnsor is should have what looks like a brass "collar" around it. This extends and blocks the By-Pass when the thermostat opens.