Robinhood 1977 dodge 440 heats up on freeway

[scottjohnwitz]

The longer you run it on the freeway the more it keeps gradually heating up. If you get off the fwy and slow down its ok. Or going down a hill cools it off quick. I have been through the cooling system... any other ideas for this old girl?

[j-d]

I was hoping the latest post in this old thread was a solution! About all I can add is that we had a Dodge One-Ton Passenger Van and the Fan Clutch locked up in Drive Mode on a trip. I called a friend and asked what to do. Where to get a Fan Clutch in a small town on a Sunday? He said "Don't - Take the Fan OFF of it and put it back together Without." Most of the trip home was open road, but we had some secondary roads getting back to the house. Didn't overheat. That said, it was a Van, not Towing, not an RV. We had a 360 engine with a wide three-row radiator from a cube van.

When we had a Class C with 460 Ford, the Fan Clutch would engage on slight upgrades on the interstate. I'd hear the noise (sounded like being passed by a gang on Harleys), notice the temp gauge had risen a little, then it'd quiet again as the gauge dropped a little. That was highway speed, with toad, with A/C running. I suppose that the temp would have kept ratcheting up if the fan clutch hadn't reacted. I was very grateful to have a good fan clutch (which I believe was original) on that coach, because I heard they were discontinued, and the aftermarket ones simply were not as good.

[badger_]

I have similar problems with my 1979 Robinhood with a 440. I had the radiator rodded, new thermostat, new hoses, new water pump, and I am still heating up. It was suggested the engine's water lines could be clogged also. I am going to pull the thermostat and test. Good luck.

[beachcomber_1]

Be sure the spring is in the lower radiator hose, keeps it from restricting the flow of water. I would not waste time and money cleaning the old radiator if it is original or more than 5 years old. If you were driving it all the time it would be more likely to be cleaner. Sitting in storage and parked camping is hard on system

[Jer_Ger]

On my 77 Dodge 360, it had a three row core. When I ordered a new one, I had them replace it with a four row. I didn't have any problems finding one in So. CA., I did have to order it though. Solved all my heating problems after that and a new clutch fan (P.O. had a flex fan on it) and thermostat.

[ron_dittmer]

I agree with Dakzuki. With such an old chassis, just replace the radiator assuming they are still available.

If a new or rebuilt radiator is not available, I would leave the original raditor mounted, but make sure the cooling fins are free of debris like grass hoppers & butterflies, grass, weeds and other air-flow-blocking material. A high pressure washer works great to force such debris through the fins, but if not careful, you will bend them.

Bent cooling fins will restrict air flow. You can buy a radiator comb, a great tool to bend fins back into their original position to get the air flow it was designed for. Here is one of many different comb designs.



So here is my check list in random order, common with many replies.
- make sure the fan clutch is opperating properly
- replace thermostat
- flush cooling system (utilize both drain plugs in the engine block, assuming it has them)
- use a Made-For-Vehicle-Cooling-System calcium & rust removing product to help remove such build-up
- clean raditor fins
- bend all fins to proper shape
- clean out the overlow bottle
- optional, recommend if it's not painful, remove and clean the heater core fins

If you pursue replacing the radiator, see if you can upgrade to a heavy duty version that provides extra cooling. An expert in chassis parts might be able to identify one for your application. I know earlier Ford chassis used for ambulances have an extra cooling capacity aftermarket radiator available. Maybe such is also available for your 1977 Dodge chassis.

About engine block coolant drain plugs, I don't think Chryslers have them but not 100% sure. Years ago my dad's 67 Plymouth Fury had a rusted out freeze plug. We removed the bad plug and out came a whole lot of crud that settled inside the belly of the engine block. If you don't have block drain plugs, I would be tempted to remove one freeze plug from each side and flush out whatever yuk is in there. It could be a source of crud that will get recirculated throughout the entire cooling system. Freeze plugs are easy to replace as long as you have relatively easy access to them.

[Dakzuki]

ScottG wrote:
That is really the classic symptom of a clogged radiator. It certainly would not be a waste of money to have it boiled out by a radiator shop and I'm sure it could use it by now.

Unless it's made of unobtainium, I'd just replace an old one. A few years back a replacement OE radiator for my F250 HD was a little over a hundred bucks on my doorstep from radiators.com.

[BobJoh]

I had a 440-3 (the truck, not car engine) in my '76 Coachman 25ft MoHo..
this engine used a larger thermostat than automotive.. I think I got it at NAPA.. also try add Redline water wetter.. and I had to renew the cuff wings around the radiator so all the air was flowed through the radiator and no blow out to the wheel wells. Also had a plywood floor at the bottom of the front frame rails so no air dove down under the radiator. freeflow mufflers and duals carried the exhaust heat away quicker.. used it all over Calif. w/o overheating problems except Palm Springs up Yucca valley grade in 103f day. Speed uses horsepower causing heat.. 10% increase speed uses 20% more power. Also when I replaced the water pump had to get a truck high volume one.(not stamped steel impellers but cast iron.

[Normk]

Problem with this theory is that removing the viscous clutch and installing the same fan onto a non-clutch hub is that fan will now turn at engine speed and all will be as with the other 1/2 of vehicles on the road. The reason for the viscous clutch has nothing to do with improved cooling. The viscous clutch is installed to allow the fan to free wheel/not require the power to drive, when cooling requirements are low.

Of course, electric fans are another improvment on this same intent.

navegator wrote:
If the unit has a viscous fan clutch, and the clutch has gone south the fan will block air from passing through the radiator.

At freeway speeds the fans with fan clutches actually turn backwards in the air stream, and you will see the temp go up if the fan is actually turning with the speed of the engine, the fan is runing to slow for the air coming into the radiator area, and actually creating a wall or air in front of the radiator.

navegator

[Gale_Hawkins]

I agree with ScottG.

What I learned was many radiators after 10+ years start becoming less effective. It can be due to cooling fin separation from the tubes/crud inside or a combo of the two.

[ScottG]

That is really the classic symptom of a clogged radiator. It certainly would not be a waste of money to have it boiled out by a radiator shop and I'm sure it could use it by now.

[navegator]

If the unit has a viscous fan clutch, and the clutch has gone south the fan will block air from passing through the radiator.

At freeway speeds the fans with fan clutches actually turn backwards in the air stream, and you will see the temp go up if the fan is actually turning with the speed of the engine, the fan is runing to slow for the air coming into the radiator area, and actually creating a wall or air in front of the radiator.

navegator

[Dakzuki]

I'm thinking restriction too. Does "been through the cooling system" mean the radiator was replaced? If not, just replace it. They are pretty cheap.

[_1Flyboy]

. . .Gradual heating up at Freeway speeds would indicate that the radiator is plugged up - suggest looking in YP for a Radiator Repair Shop!!! Also, the MoPar 440 engine REQUIRES a BALANCED SLEEVE Thermostat & WILL Run Hot if you install a REVERSE POPPET Thermostat!!! Robertshaw is the ONLY Mfg. of the Balanced Sleeve Thermostat. . . If your air cleaner is intact you will see a decal on the air cleaner stating this!!!!!!!!!!!!!

[PaulJ2]

I'm with NormK on this one. Cooling system gradually loosing ground with the normal heat generated by the engine. Partially restricted radiator probably.