Hi all

I have a 1989 21' motor home E350 with a 460 efi eng. C-6 trans. 33,000 miles

When I am on the freeway with the A/C on, in hot weather 90+ degrees and going up any grade, the factory temp gauge needle points at "MA and AL". Any thing else I drive, the needle is straight up or to the left. I don't see or smell or lose any coolant. City driving is fine.

Are this readings normal with a factory gauge, I know it is the "normal" range, but it worries me that I am about to overheat.

Does anybody know what the temperature is at these readings?

If it is too hot, any suggestion?


Not sure if I hear the clutch fan kick on. temp does go down when I, turn off the A/C, reduce eng speed by coasting or slowing down.

Radiator was replaced about 3 years ago with the largest Modine, 180 degree t stat, new rad cap. Temped to put a aftermarket temp gauge in.

 

Welcome to the forum.

There is no 'A'=180* kind of correlation.
You could try shooting the thermostat housing with an IR thermometer and make a note of it.

Fords use a variable resistance temp sender that grounds to the block.
It's not very expensive. You might try changing it and seeing if it makes any difference.

The engine IS working, hauling a barge, uphill, in 90*+ weather, with the A/C on.
I'm sure the condenser coil shedding heat in front of the radiator doesn't help.
But I would say 'NORMAL' is normal.

I'm kind of surprised you have had to change the radiator with that few miles on it.

 

Thanks Jim

Yes, condensers do put out heat. And yes it is under a lot of load without a overdrive.

I could check the ohms at the sender and see what it is after warmed up idling. Would anybody know the ohms range of that sender? Sometimes a spec of like 0 (cold) - 90 (hot) ohms is available.

I get alarmed when i see that needle leaning so far to the right like that. There is not much "normal" left when it get that hot. I imagine engine overheating can occurs at 250- 260 degree range.

Regarding the clutch fan, is there a definite roar in the engine when that kicks in and can you hear it while on the freeway? How may blades should it turn if I spin check it?.

Yeah , I was surprised to when I had to replace the radiator too, a rock or something punched a hole in it from the engine side.

 

If nobody here knows, NAPA has a temp sensor cross-reference sheet that will tell you. I've used it before trying to match up a gauge with a sending unit...not fun!

 

Nothing definitive but I have read 75ohms cold - 10 ohms hot.

Ford went crazy and lawyered up a few years back, then issued DMCA takedowns on all of their TSB's that were posted online.
A certain batch of senders were bad and they had printed the values in TSB 95-13-2.

My clutch is pretty tight. I have never tried to spin check it.
You can definitely hear the fan when it locks up, but at highway speeds it shouldn't really be needed much.

I can understand a punctured rad.
I thought it might have been clogged or corroded.

 

An Auxiliary electric fan mounted in front of the condenser that is wired to run whenever the AC is on will make a huge difference. You just need to be sure you wire it to push air through the condenser, instead of pulling and fighting the engine fan. The best ones IMHO are Honda Civic fans because they are cheap ($20.00 at most U-Pull yards) they move a lot of air, and they are compact. Wire a relay in parallel with the A/C request signal on the low pressure switch (if you unplug the low pressure switch and turn the A/C on this will be the hot wire when you probe the terminals). USE THE RELAY to power the fan and make sure you provide a fused 30 amp power supply for the fan relay. The added bonus is it will tickle the engine driven fan clutch with extra heat when the engine is working hard and the A/C is on, and cause it to engage earlier to mitigate the temperature rise.

 

An oft overlooked thing with a C6 truck is that there is no TC lockup so that thing is generating a lot of heat when climbing hills and it's dumping much of it into the rad, so installing an aux trans cooler may go a long way to keeping everything else cool as well.

The fan clutch in these things has no real on or off, it's somewhat temp sensitive(tighter when hot, looser when cold) and there should always be a certain amount of slip if you try to turn it by hand. If the fan can't be moved with the engine off and cold and it roars at rpms the clutch is seized and needs to be replaced.

 

Good call on the converter. This is especially true if it stalls at 1800 or higher, because it will slip anytime going up a hill in 3rd gear unless you're doing 90. A tight 1,200 stall converter will produce less, but sill more heat than a lockup.

 

I am going to hook up a aftermarket temp so I can read what temp I am running at when I am concerned.

I need to know this first, in order to take any further action. If it ain't broke don't fix it.

Thanks all for the loads of great info info.

 

While I think it's a great idea, how much does this Honda fan draw?
I know the stock alternator can't keep up with the popular Taurus/Lincoln conversion.
I doubt the Accord fan has such a high inrush or run current, but it is something to pay attention to when adding loads to an already marginal alternator.

I have the 130A 3G from a Taurus and it will put out more at idle that the 2G can at redline.

 

Mine draws 23A during startup, but operates on about 12 A. I understand the Alternator deal! When my alternator croaked about 4 years ago, I upgraded to a GM CS144 unit. It puts out more at idle than the small 3G I originally had could max at. I also have fat 0 gauge ground and power wires hooked to it. It maxes an amp test at about 180 amps.

 

NICE!

I just have the stock Taurus 130A and 00 cables on both sides of the battery.
It will show ~150A on my inductive ammeter when loaded to test.

But my truck doesn't have A/C or anything that is a heavy load.
I figure the alternator is never working very hard or getting hot because of it.
I mostly did the swap to get away from the damned 2G that was always failing.

 

I always felt that Ford made better Starters than GM, but that GM made better Alternators than Ford. The 2G is a perfect example of that. Passing charge current through spade connectors? What a joke! I have seen many a nice Ford Truck, Crown Vic, Mustang, T-Bird, etc destroyed by alternator fires because of that POS.

 

Oh, I got the idea by the way after upgrading the 2G on my grandfather's 88 Town Car. It was a beautiful car but kept eating batteries and frying alternators. I did everything I could to make the 2G work, but it was insufficient. I finally got to thinking the 2G looked similar in size to the GM CS105 (My Alternator's little brother) rated at 105 A. I swapped the wiring and bolted it in. I needed to make a small spacer plate to bolt to the small end of the alternator to make it work. I cut and drilled a 1"x2.5" piece of 1/4" steel and bolted it right up, fit like a glove. It idle tested at 80 A and at 1500 RPM it cranked out 120 A. I kept the original charge wires (I put a solder on ring eyelet attached to the leads) and I ran an additional 4 gauge wire from the B terminal to the hot side of the Starter Solenoid. My grandfather kept highbeaming people because he would be running low beams and flick the switch when there was oncoming traffic because the lights were so much brighter after the alternator swap that with the low beams on he thought he had the high beams on!

 

Would a auxiliary fan make a difference at highway speeds?

I don't know if there would be enough room, on a motor home there is a eng. oil, trans and p/s coolers and a condenser up front.

I believe I do have a 100 amp alt. though and a 2 chassis battery set up.