Topic: Any Cummins experts here?

Hey All,

I'm having a strange problem with my LeMons tow vehicle, I've Googled a bit with no luck.  Thought I'd reach out to the community here for expertise.

The vehicle is a 2001 Dodge Ram 2500 w/5.9 Cummins 24v td.

Background - A couple of months ago, on a very hot day, the serpentine belt shredded driving up I5 from LA.  I caught the red alternator light almost immediately, I was literally just approaching an off ramp, so I drove it off the highway slowly and into a McDonalds parking lot.  The temperature got pretty high, but not pegged, and no steam from under the hood.

AAA flat bedded it home, where it sat for a month.  I finally got around to installing a new belt a few weeks ago, neglected to check the coolant level.

A couple of weeks ago I took it out for a drive, and noticed it wasn't coming up to temp.  Turned on the heat, and wasn't impressed by what came out.  Oh oh, low on coolant.  I pulled into a Walmart parking lot, and checked coolant levels.  Radiator was full, overflow bottle almost empty.  I grabbed some 50/50 and topped up the overflow bottle.  Drove it home, still not coming up to temp.

Took it out again today, and the temp came up a little bit, but still well below normal.

There is no oil in the coolant, nor coolant in the oil.  Truck starts immediately and runs and drives as normal.

I've searched online for bleeding instructions, haven't seen any, even in those instructional videos that describe water pump or thermostat replacement.  But it sure feels like the coolant system needs bleeding.

Any hints?  The online videos simply show pouring in coolant, no vacuum evacuation.

Any help or tips are greatly appreciated.

bs

Re: Any Cummins experts here?

Have you checked your thermostat? - could be stuck open thus not allowing truck to ever heat up before pushing cool fluid through it.

Re: Any Cummins experts here?

J10495T wrote:

Have you checked your thermostat? - could be stuck open thus not allowing truck to ever heat up before pushing cool fluid through it.

I have not.  Other than popping the radiator cap and overflow caps, I haven't cracked the system.  Good suggestion, I guess if things got a little hot it could have jammed in the open position.  With 125k on the motor, can't hurt to throw in a new one.

Thanks,

bs

Re: Any Cummins experts here?

Was going to say the same - thermostat.  I have an '02 2500 Cummins.  Never a problem with the coolant system - it is pretty simple.  Only think I could think of that would cause it to stay cool like that is thermostat.

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Re: Any Cummins experts here?

FYI many thermostats will default to fully open if they ever see temps way beyond normal. Any time you have an engine overheat it's best to replace the thermostat.

Re: Any Cummins experts here?

Thanks All,

And also to Dan, a Cummins professional who wasted a half hour of his precious time talking about this, everything else I should be paying attention to on my truck, LeMons, and life in general.

Thermostat will be changed hopefully before the weekend.  I'll report back my findings.

I love this community.

bs

Re: Any Cummins experts here?

All righty!

Quick update, and sadly a couple more questions.

The update - I swapped out the thermostat, no apparent difference.

While I was trying to run it up to temp, I noticed a couple of things:

First, the engine fan was spinning at engine speed from startup.  During our discussion, Dan seemed to indicate that it should be on some kind of electric clutch?

Second, I noticed a pair of broken wires, passenger side of the engine block, looking like they were heading towards the radiator.  They are in a place that could very easily have been taken out when the belt let go.

I'm guessing that these wires go to some kind of switch that disengages the fan?

I'm going to have to shuffle the truck around to get to these wires to repair them.  Hopefully this weekend.

I don't understand why, even with the fan running at engine speed, it wouldn't eventually come up to temp.

Comments?

Thanks All,

bs

Re: Any Cummins experts here?

FWIW I have the same motor stuffed into a '92 Ford F250.  The motor does not get warm enough to run the fan - EVER - in my truck; but I still have the old 7.3 IDI radiator in it.  It is about the size of a medium duty truck radiator from what I've seen.  I have an electric fan clutch from a medium duty truck, a fan controller from Dakota Digital and a toggle on the A/C switch for when I get stuck in heavy traffic - only used it twice so far.  These motors don't make a lot of heat unless they're being worked from what I've seen.

If your fan clutch is stuck on I can see the motor not heating up (my motor came with a thermostatic clutch - didn't think the electric clutch came until the Common Rail motors).  I know that my truck would not come up to temp if the fan were on.

Nick
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Re: Any Cummins experts here?

All righty!

Haven't yet found the time or the motivation to crawl under this thing yet to fix those wires, but had to take it out for a couple of errands yesterday.  Apparently it needed to do a little work - it came up to temp as normal, and stayed there.

Looks like it was in fact the thermostat.

Thanks again all, and especially Dan for taking the time on the phone.

Cheers,

bs

Re: Any Cummins experts here?

I have an '01 Ram 3500... the fan is 100% mechanical.

Can you freewheel the fan by hand?

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