1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

Overheating on long grades

Old Sep 30, 2012 | 07:16 PM
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splitnrag's Avatar
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Default Overheating on long grades

Ok I'm hoping that someone can point me in the right direction. I have a 89 Chevy Crew with a 93 transplant. I have had some issues since I bought the truck that on long continual grades the truck will start running hot. When this happens it's usually running high trans temps as well. The truck has an external trans cooler and the one in the radiator.

I went down to the radiator shop thinking that I should put in an aluminum radiator. The shop recommended that I stick with what I have it's a 4 core 1/2" radiator with plenty of cooling power however he thought the fan clutch was shot. I was at operating temps when I shut the truck down and the fan continued to spin. According to him when it gets hot the fan engages and should only turn about 3/4 of a turn after the motor stops. My question is, would this matter on the highway when there is air being pushed through the radiator. Any substantial tests to make sure it is really needed? Any recommendations on where and which one to buy?

Also when I pulled the radiator out of the truck I found that the PO put a piece of carpet in between the radiator and the condenser. I'm assuming he was trying to achieve the right running temps. So what are the best operating temps? 195? Any input is appreciated. Thanks
 
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Old Sep 30, 2012 | 07:30 PM
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run 190 at normal and maybe 200 going up a realy steep grade, are you using a lower gear? and do you take it out of overdrive? When I go up the pass my EGTS are 800-900*
 
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Old Sep 30, 2012 | 07:43 PM
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Yesterday coming home from a trip hauling a 30' car trailer I saw temps in the 220ish range, trans temp was up there as well but I never went over 800 egt's. I did kick it out of OD and kept the throttle at 2k on the revs.

Now another problem with my truck is that it has an automatic with a gear vendor electronic OD. I don't know if this is a contributing factor but doesn't help finding the cause and solution.

I don't know what rear gears are in it either but suspect the stock chevy gears which I believe to be 4.11s.
 
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Old Sep 30, 2012 | 07:47 PM
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hmm, 220 should be max! imho, but maybe try shifting to a lower gear and go slower? and check you antifrezze and make sure it has a good mix, and not to much antifreeze, and make sure your fins are cool, and maybe just take the garden hose and spray a lil water thru the radiator from the back to the front...
 
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Old Sep 30, 2012 | 11:34 PM
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When I went in to the radiator shop the temps seem pretty good on both side but the flow wasn't what he though it should be so I pulled it and will take it in for back flush and or rod and cored.
 
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Old Oct 1, 2012 | 12:21 AM
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You mentioned you think the fan clutch is done? Running empty on flat ground it apparently won't work in a 2nd gen to run no fan in the winter but if your towing and this time of the year you need it to pull the air through the rad.
 
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Old Oct 1, 2012 | 12:41 AM
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i didnt catch that!! they carpet can be your issue also. in the winter time I have a radiator tarp so I can block off the radiator to reach operating temp because if I dont, its a cold drive to work.... Maybe take that piece out and see how she does, because it sounds like a lack of flow, not a component problem..
 
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Old Oct 1, 2012 | 01:28 AM
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Originally Posted by RanchhandTCR
i didnt catch that!! they carpet can be your issue also. in the winter time I have a radiator tarp so I can block off the radiator to reach operating temp because if I dont, its a cold drive to work.... Maybe take that piece out and see how she does, because it sounds like a lack of flow, not a component problem..
What's odd is he has the snaps for the radiator cover in the grill. I yanked that !$!@&$ out will have the radiator cleaned since its already out replace the clutch fan and see if I can figure out how to get the serpentine belt passed the air pump as its right on the cross member.
 
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