idghq
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My M923-cummins 250 NHC-take a long time to warm up. Should I check or change the thermostat first?
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Warm-up issues M923-cummins 250 NHC
- Thread starter idghq
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All my 250's take a long time to warm up even when it's warm outside. You could double check with a mechanical gage and use a grill cover.
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If you don't have one a winter front or a well placed piece of card board will help with that.
gem1410
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I drove one of mine 60 miles in 40* weather in NJ last week and it never did warm up---will have to use a nose cover next time
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Use an IR thermometer to make sure it's not a gauge issue. If it doesn't warm up, change the thermostat, easy to do on the NHC 250. My M929 is at operating temperature after about 10 miles.
gem1410
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where is the thermostat in the 250 cummins--I may need to change mine--thanks
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You need to go to the TM section here and down load the -20 series. It has the complete procedure detailed.
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Ray in Florida the temp is a little higher than up north here! My 923 NEVER gets above 160 unless I am running loaded and really working it. These cooling systems are so oversized its not funny. Add in 40 deg ambient and its almost impossible to warm one up without really putting a load on the engine. At least that has been my experience in the three I have had.
As others have said, your milage may vary......
As others have said, your milage may vary......
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I have not had it not get to operating temperature since I replaced the thermostat. And I have driven it in 40 F temps (I know, HA, HA) last winter. The bypass flow is not that much, it will take longer in cold WX and If you are in real cold WX you need a cold WX front, but we don't see that in the south. A piece of card board is cheap.
Like you said, YMMV!
Like you said, YMMV!
idghq
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Thanks for the info. Looks like I don't have to change my stat. "cardboard is cheap."
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Since when do you need a "good excuse"?
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A couple of weeks ago we were down to 18° one morning with the Arctic front that blew through and never made it above freezing at all that day. I decided to try it out on the 11 mile trip to work that morning to see how it did in the cold. It fired off after about 5 seconds (almost immediately is normal for mine) without the block heater or ether. I waited my usual 10 minutes to let everything get perculating while I preformed my pre-trip checks before driving. About two miles from work I was maintaining operating temperature with toasty air coming from the vents. I go easy on the throttle until it hits operating temperature but I do have a couple of long hills along the way.
A couple of months ago when I went through the cooling system, I verified the temp gauge at the sender and checked for proper thermostat operation among other things. Honestly, it doesn't take mine much longer to get to and maintain operating temperature below freezing than at 90° in my truck.
Some of this will be common knowledge but I'll go through it anyways. The specs listed are for the NHC250 but operation and testing should be the same on other motors. On a cold engine (at least 24 hours on a motor this large), make a note of the temperature of the thermostat housing and of the radiator itself prior to starting. Start the engine and allow the truck to idle to operating temperature. During this time, monitor the temperatures of the thermostat housing and the radiator. The radiator might warm slightly but should only be a negligible amount. The thermostat should remain closed until it reaches 175° (spec from the TM) then it should open, allowing coolant flow through the radiator. If the radiator warms close to or along with the motor before reaching operating temperature the first time then the thermostat isn't closing all the way. You will probably have trouble reaching and maintaining operating temperature in colder weather with a thermostat that won't close all the way.
The fan should come on at ~190° (from sketchy memory). If the fan comes on then the cooling capacity of the radiator has been reached. The fan should come on only if the radiator can't keep up with cooling demand to maintain operating temperature. If the temp drops below 190° then the fan should disengage. If the fan stays on then you will have trouble reaching and maintaining operating temperature. I don't think I've ever had my fan come on when the ambient temperature is 50° or below. That's because the radiator is able to keep up by itself.
As I said, most of this is common knowledge. The fan and thermostat need to be working properly though to keep things warm. At some point it is just too cold and a radiator cover is needed. What kind of temps have you been driving in?
A couple of months ago when I went through the cooling system, I verified the temp gauge at the sender and checked for proper thermostat operation among other things. Honestly, it doesn't take mine much longer to get to and maintain operating temperature below freezing than at 90° in my truck.
Some of this will be common knowledge but I'll go through it anyways. The specs listed are for the NHC250 but operation and testing should be the same on other motors. On a cold engine (at least 24 hours on a motor this large), make a note of the temperature of the thermostat housing and of the radiator itself prior to starting. Start the engine and allow the truck to idle to operating temperature. During this time, monitor the temperatures of the thermostat housing and the radiator. The radiator might warm slightly but should only be a negligible amount. The thermostat should remain closed until it reaches 175° (spec from the TM) then it should open, allowing coolant flow through the radiator. If the radiator warms close to or along with the motor before reaching operating temperature the first time then the thermostat isn't closing all the way. You will probably have trouble reaching and maintaining operating temperature in colder weather with a thermostat that won't close all the way.
The fan should come on at ~190° (from sketchy memory). If the fan comes on then the cooling capacity of the radiator has been reached. The fan should come on only if the radiator can't keep up with cooling demand to maintain operating temperature. If the temp drops below 190° then the fan should disengage. If the fan stays on then you will have trouble reaching and maintaining operating temperature. I don't think I've ever had my fan come on when the ambient temperature is 50° or below. That's because the radiator is able to keep up by itself.
As I said, most of this is common knowledge. The fan and thermostat need to be working properly though to keep things warm. At some point it is just too cold and a radiator cover is needed. What kind of temps have you been driving in?
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