440 tranny and engine overheat

[Clyde9]

From: jdquattros  (Original Message)    
Sent: 1/12/2004 2:16 AM

I Last summer I was getting severe overheating during the following -uphill 85 F air temps, 2nd gear I think about 3000 rpm 35 mph. po installed two tranny coolers in front of rad about 300 in square. Has standard fan clutch, stock metal fan. I installed a 1000cfm electric pusher fan which did not seem to make any difference. Was the stock setup poor, adequate or would not overheat unless a part malfunctioned. The thermostat is only three years old and is the weir version.
Thanks for the help.



From: denison    
Sent: 1/12/2004 12:08 PM

Is your RV the 79 chieftain with 440? I think all of our RVs had great cooling originally, though not all cooling systems had the same amount of extra-capacity. Admittedly where you drive involves real challenges.
The heat transfer ability of the radiator decreases annually , -perhaps 5% to 10%, even if you dont use it much! Unless you positively know the rad. was out for cleaning in the last 6 years or so, that would be my first move; but I would run a cooling system cleaner through it first - just to clean some of the muck from the block. To me the radiator being clean is the overwhelming factor for good cooling. And if its not the original radiator, do you know if it is as big as the original?
I wouldn't think tranny coolers in front of the radiator would be any problem unless they were grossly dirty.
Do I recall rightly that you got a new fan clutch in the last year? Fan clutches weaken with years, and its hard to tell when they are bad. They are needed most going uphill in lower gears - when the forward motion of the RV doesn’t push so much air through the rad. Thermostats going bad in only a few years is rare, but has happened.
Most of our RVs had some kind of fan shroud on the back side of the radiator. Its effect would be important on hill climbs in lower gears or when towing. For 79 the parts catalog shows a top baffle and one on each side of the radiator, to make the air go through instead of around it.
Water transfers heat better than ethylene glycol. A 50% antifreeze mixture isnt needed if you wont be in subzero temperatures, and a mixture of 20% glycol 80% water will transfer more heat away.
Overheating can occur when the coolant flow rate is low - and there have been aftermarket water pumps that had fewer impeller blades than the originals. The 440 pump I saw had ten blades.
The parts catalog lists a radiator with the mopar # 4117799, for the 79 M300 through M600. 28 by 2.25 inches?
Overheating can also happen if your radiator caps are not holding the 15 psi, because the water in the heads gets hot enough to be boiling at atmospheric pressure -- would be more of a problem at altitudes. Does yours have the arrangement with two caps?
Halfway back along each side of the engine block, down low at the base of the water jacket there is a drain. If you can get these unscrewed and removed, you could probe in there with a coat hangar, and see if there is a lot of crud built up in the water jacket. If so, there probably is an accumulation in the engine heads too. Getting a high pressure flush right after running a cleaning solution might help. I think there are metal plates bolted to the back end of the engine heads. You can remove these and see into the water passages of the heads, to see how clean they are.
In some cases a high coolant flow rate, from high rpm, can suck the bottom radiator hose shut, even with the top of the radiator being at 16 psi. Hard to check for - but overheating would result! Some bottom hoses have a spring inside to prevent this - and some dont.
If the fan belts arent tight enough or are glazed, they could slip at high rpm, and the fan and water pump would run slower.
A coolant Overflow Recovery tank that has water in it does not always assure the water level in the radiator is high enough - if there is any tiny leak in the overflow and recovery plumbing.
The fan on my 413 has 7 fat blades.
Last but not least, ensure you timing isn’t over-advanced. I dont know about 79, but in 73 the centrifugal advance was only 12.5 degrees max @ 2500 rpm. I think distributors used in cars provide more advance at higher rpms. Used in an RV at high rpm a distributor for a 440-1 might make a 440-3 run hotter.
I hope you will let us know what it turns out to be.
denison



From: Discoverer
Sent: 1/12/2004 12:34 PM

I am not a "fan" of that clutch-fan at all. A LOT of them flat do not work......and if that clutch unit fails - it CAN shoot the fan into the rad. NOT good. I would say move those trans coolers and take OFF the clutch fan and test it from there. Sometimes - the way they operate - the clutch fan will actually impede the flow of air. ... Eric



From: UluzYarx    
Sent: 1/13/2004 1:48 PM

Over heating.

This side of the pond we can buy an electric water pump for around £125.
It has a flow rate of around 4 to 16 gallons per minute.

For a further £80 we can buy a controller that senses the engine temperature and adjusts the pump rate flow according.
Together they keep the water pump running at full whack when your engine slows down as you pull up hill.
It even keeps the water pump running when you stop the engine if the water is still hot.

Twin electric fans instead of the viscous fan gives a similar advantage, your fans run at full whack when your motor slows down under load.
Our fans continue to run after the engine has stopped if it is hot.

Try www.merlinmotorsport.co.uk

All the best - Dave



From: jdquattros    
Sent: 1/14/2004 12:26 AM

Probably original radiator-took to rad shop last year. they did not rod it out-worried that caps would not hold up but unclear about how clean it was. You mentioned parts manual- I have service manual but no parts. Do you have sources for parts manual. The vehicle came with dash ac and no auxiliary trans coolers and I assume it could climb some hills stock so I thought there must be one major part not functioning. I am considering just buying a new, replacement radiator. Also, if anyone could explain or point to website regarding details of automatic transmission fluid control and flow I would appreciate it particularly how the flow is regulated to cool it.

Thanks
JD-



From: Tymhoff    
Sent: 1/14/2004 10:21 PM

If the auxiliary trans coolers are mounted directly in front of the radiator, then perhaps they are keeping it from getting sufficient airflow. Obviously if they are not mounted directly in front of the radiator, then that wouldn't be a concern. My bone-stock Indian has the same motor and it does tend to run a little on the hot side, but I've never had a problem with it overheating, even when we go to the desert and it's 95 degrees out. The only thing that I did to help the cooling system was a complete flush and I added some Red Line brand "WaterWetter".



From: denison    
Sent: 1/15/2004 9:10 AM

If your current radiator doesn't have two fittings in its bottom tank for an internal tranny-oil cooler, then I suspect its not original. I looked in the parts catalogs, both for the 78-79 and for my 72, but alas, none of their radiator pictorials show transmission coolers in the bottom radiator tank - even though my two two 1972 winnies with their original systems both have the tranny cooler in the bottom of their original radiators. The parts catalog doesn’t show anything about it but its there and its stock!
The nice thing about the cooler in the bottom of the radiator is that it goes on cooling even when your rig is crawling slowly up a grade. A limitation on auxiliary coolers is that when the tranny oil is getting the hottest, like towing a car up to Leadville, the rig is probably going slowly, and you might want a fan blowing air through the auxiliary cooler. Same would be true for an auxiliary engine oil cooler.
If you replace your radiator, I would get one as big and thick as would fit in there, and one that had the tranny cooler available in the bottom tank. It might cost plenty.
External to the transmission the fluid flow is straightforward. The oil comes out of the line near the bell housing, flows through the tubing to the cooler and returns to the fitting nearest the rear of the transmission. On most of our vehicles it ran into the heat-exchanger in the bottom of the radiator -because thats the coolest part-, then back to the tranny. It is under no great pressure, and there is no control of the flow by the tranny. None. If you have a fancy auxiliary cooler it may have a thermostatic valve to bypass the cooling coils when the oil is cold. Like below 160?
I replaced my tranny cooling lines because one began to leak from rust, and replaced the rubber hoses connecting it to the cooler in the radiator due to old age seepage. I made up my own lines and hoses.
Manual sources: I only have the one hard copy of the 78-79 chassis parts catalog, which I got via dumb-luck from ebay. It was inside a very thick and battered looseleaf binder of other truck parts manuals, but was not itself listed in the contents. I sometimes will bid on such manuals if the price is low and no one else bids, just so they won’t get thrown away. I have seen another copy of the 78-79 chassis parts catalog since, but it had other bidders already. It is also apparently available on a CD, from www.moparmanuals.com, for $85, titled: 1978-1979 Dodge Motorhome Parts Book. I would say its worth it. If you search on ebay for it, the correct title from the cover is; motor home chassis parts catalog. It is pub # 81-690-1412. Irv Bishko of Bishko books in Ohio might have xerox copies for sale too. He is sometimes an ebay seller, you could search for his dodge motor home manuals.
Another other source of unusual tranny heat would be slippage of the clutches or bands. If that is happening your tranny fluid would be turning brown faster, and I dont think there is much to do except save funds for a rebuild.
denison