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Low coolant temp = engine damage?

15K views 17 replies 7 participants last post by  92 Ram 350  
#1 ·
I just bought a 92 Ram D350 with 5.9 L turbo. I've been reading a lot about how low engine/coolant temps can damage the engine by causing fuel not to burn completely which causes the unburned fuel to wash the oil away from the cylinder walls and apparently the unburned fuel can also get into the crankcase and dilute the oil there.

One of my questions is: Okay, if you follow that line of logic, then isn't it true that every time you cold start a diesel, until the temp reaches operating temp (140 F from what I've read), then the period of warm up is causing engine damage?

I discovered a few days after I bought it, that the fan is running pretty much all the time, and the temp gauge is staying just slightly right of the "C" mark. I put cardboard over about 3/4 of the radiator (not the intercooler) and it does get up into the normal range, but it takes about 15-20 mins of driving to reach that temp.

Any voices of experience would be appreciated.
 
#2 ·
per cummins there is 500 times as much wear with cylinder walls at 100* than at 180*. cummins and others tell you do not let the engine idle to warm up because diesel is sow efficient it takes to long to warm up. start the engine, keep the rpm low until it smooths out and start driving under light load and lower rpm until it gets up to operating temp.
 
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#3 ·
In addition to Carl48's answer, cool engine operation does not evaporate off condensation in the oil which creates the whitish sludge you sometimes see. This happens on all internal combustion engines, not just our cummins diesels. I've heard that excessive idling (tracked by the computer) on big trucks can void the warranty.

Most of the engine wear that accumulates over the life of an engine occurs at startup. It's one of the reasons that over the road truck and taxi engines last so long.

Steve g
 
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#9 ·
Idle time doesn't VOID warranties, but the engine hours added up will run the engine out of warranty long before the miles will.
For example on a little cat the warranty was 3 years, 150k miles or 3600 engine hours. When one of those were reached it was out of warranty.

I think you're too worried about idle time causing wear and low temps causing damage. I've never seen an engine wear out from too much idle time or not running warm enough. I understand in colder climates you have to use winterfronts to maintain engine temp, but REAL engine damage comes from abrasive wear and overfueling from injectors and overheating. I've got 5 cummins, the only one I worry about idle time is the 08 because of the dpf. If it's hot out it stays running for the a/c. Cold out and the heat stays on.
Cold start wear is too minimal to concern yourself with.
 
#4 ·
If you are using the trucks stock gauges in the dash you will probably be surprised if you put a aftermarket gauge. After time all the gauges and speedometer will quit or not read right. I thought my oil pressure was about 40 when cold and put a gauge on and found out it's really 75PSI.
 
#12 ·
I'll yield to your reasoning. Here in Texas there's no such thing as winterfronts and problems maintaining engine temp. I always forget to keep in mind where different folks are from. You're just a little north of me here in San Antonio.
I've never been to canada but imagine snow is on the ground most of the time. We haven't seen snow here since 85 and we shut the roads down when it freezes cause people cant drive. We thought 19 was bad last year. Down here we worry about our temps going the other way too far.
 
#14 ·
I've never been to canada but imagine snow is on the ground most of the time.
You'd be imagining wrong. Our summer temps are not much off yours, frequent mid 90*'s, occassion 100*+. This time of year we're usually just above freezing, dropping below over night. We'll reach our coolest Dec/Jan at around 5*F. Starts warming up again in Feb. Where I spent most of my life, middle of the prairies in Winnipeg it wasn't quite as warm in the summer, but still pretty warm. Winters though frequently reached -35*F. We see both sides of the scale up here.

Steve g
 
#15 ·
The coldest I've ever seen is 10 and that's only for a few hours out of 1 or 2 days a year. But there's a huge difference between 100 and 115. And when you walk out the door in he morning and it's 90, you know it's gonna be one of those days where you gotta peel your soaking wet drawers off at the end of the day. And down here window tint is one step away from painting the windows black.