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Can't get my 312CL to warm up to operating temperature.

Digwizz

Active Member
Joined
Dec 29, 2007
Messages
27
Location
NE Ohio
Happy New Years Folks! Looking for any ideas you guys might have concerning my current headache. My 312CL doesn't want to warm up to operating temperature. Seemed like a no brainer, must be the thermostat is stuck open right? Ya, never seems to be that easy for me. Took the old thermostat out and placed it in pot of water right beside the new one and heated it up. The way they opened and closed was pretty close to identical. "Now," I know I'm in trouble, but I put the new one in anyway, along with the new seal on one side and new gasket on the other side. I let it run for a couple hours at about 1/2 throttle, but it never came out of the white and made into the green on the gauge. I thought maybe the sending unit or gauge might be screwing up, but checked the temperature of the casting that holds the thermostat with my infrared thermometer while the machine was running and it was only 130 deg F.

Any thoughts would be appreciated!

Thanks,

Mike
 

turfblazer

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Joined
Dec 20, 2015
Messages
72
Location
niagara falls ny
Occupation
semi retired drainage ,site work , eq operator.
id feel happy with 130f measured on a outer exposed metal on a day i assume with outside temp of approx 30f with a diesel idle to part throttle that is not being worked.
when i work snow storms in my loader down into the zero's and stop for a quick 10 minute break and let it idle for a coffee and pee it'll go almost cold. diesels are a heat motor they do not like idle ( in a perfect world ).
my opinion only!
work it for 10 mins take another reading bet it goes up !!!
 

Shimmy1

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Aug 14, 2014
Messages
4,260
Location
North Dakota
No, I was just trying to verify that it would match the new one.
Check the old one again, with a thermometer in the water. If it opens close to what it's suppose to, then you maybe could assume the new stat is good. Not much to really do other than take a bunch of reading with the infrared. Maybe engine just hadn't been worked hard enough to warm up. What was the outside temp while this was going on? Does the heater put out any heat? At 130° it should be lukewarm, if it's cold, I'm going to throw out a suggestion that you might have a head gasket or crack of some sort leaking compression into the coolant and screwing with the circulation. How many hours? 312 not a very big machine, small engines with hours don't warm up very fast.
 
Last edited:

John C.

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Jun 11, 2007
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Northwest
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Machinery & Equipment Appraiser
In another thread it was mentioned that the Cat thermostats are designed to be open at 160 degrees F. The would kind of make sense for you what you are describing as the temp at the thermostat housing and operating in near or sub freezing weather. I think I would run the machine hard for a bit and see what happens. In my opinion if I had a machine running that cool I would look for a 180 degree thermostat.
 

big ben

Senior Member
Joined
Aug 22, 2010
Messages
352
Location
Vancouver Island
So is this a new problem ? What temp did it run before ?
S/N help to give better response's as to what might be going on.
Is the fan direct drive or thermostatically controlled and stuck on ?
What happens when you put it to work ?
Whats the outdoor ambient temp when you are testing this ?
 

srjd

Active Member
Joined
Dec 18, 2015
Messages
42
Location
Canada
What temp are your thermostats stamped. I just replaced mine but for different reasons. Today it was 28F out and my 320D runs 160f. Runs the same temp in the summer. I still think that's too cool. Are you getting heat out of the vents?
 

turfblazer

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Dec 20, 2015
Messages
72
Location
niagara falls ny
Occupation
semi retired drainage ,site work , eq operator.
i cant wait till wizz tells us what happens when he works the machine???
 

Digwizz

Active Member
Joined
Dec 29, 2007
Messages
27
Location
NE Ohio
I put the old thermostat back in the pot and heated it up. It's opening around 165 which is pretty close to the 160 it's designed for. I took the machine out and ran it for a little while this morning as I was summoned to a coke spill where a semi dump rolled over on an on ramp. I loaded the spilled coke on another trailer without hitting the green on the gauge. Hardly a workout since the coke is so light, but I still think it should have made into the operating range. Ambient temperature isn't likely to be the problem as she has been running cool, ( or at least appearing to run cool), for a couple months. The machine has always ran in the middle of the green since it was new prior to this. I think the temp this morning was around 28. The heater is putting out some heat, but I had the front window up and the lower glass removed today so I could see well. That makes it kind of hard to judge how well the heater is working and couldn't fool around with it since the authorities had the ramp closed and I was surrounded by troopers would wanted the clean up done and me out of the way! Maybe I should close it up and let it run with the heater on to see how well the cab warms up. It seems to me if there was a circulation problem it would get hot instead of running cold, but I have been wrong MANY times before. The SN is CAT0312CKCBA02833 and it is a direct fan, (Although that question got my hopes up for a sec). Does anybody know how to diagnose the temp sending unit,(I'm still leaning a little toward the fact the gauge might be misleading me). I appreciate all you thoughts and welcome any additional ideas.
 

Digwizz

Active Member
Joined
Dec 29, 2007
Messages
27
Location
NE Ohio
Just to satisfy Turfblazer, I promise I'll move a couple piles of dirt around tomorrow! :)
 

Shimmy1

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Aug 14, 2014
Messages
4,260
Location
North Dakota
Find the sensor and shoot the casting around it with the infrared. I would think even though the coke was light, running and operating it should get it up to temp. Good work verifying the old stat was opening properly. Could you tell if it looked like it was sealing properly?
 

turfblazer

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Dec 20, 2015
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72
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niagara falls ny
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semi retired drainage ,site work , eq operator.
even with the light working ya gave it today and now a little history of over the last couple months i would conclude you have a sending unit going out of calibration. over all my years of temp issues and after 1st always changing stats to be safe ( they used to be a regular maintenance item !!! ) but who does that these days ???
#2 to look at is the sending unit. i'am really racking the old noggen but i cant remember a electronic sending unit fail with a reading hotter???. use the infrared dig the dirt, sending unit is cheap. running cold is better then hot !!!
 

turfblazer

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Dec 20, 2015
Messages
72
Location
niagara falls ny
Occupation
semi retired drainage ,site work , eq operator.
i forgot to mention clean contacts at sending unit with some wd 40 wiggle or push off and on a few times to insure good contact before buying new sending unit. in the old days ya could just ground the positive wire and gauge would go to hot but ya can't do that now
 

lantraxco

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Jan 1, 2009
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Elsewhen
Some engines have too large a bypass line so you always get coolant flow to the radiator, even with the thermostat totally closed.

Try covering the lower half of the radiator with cardboard, just don't block the oil cooler, see if that doesn't help. Adjust to suit, works just like the winter fronts you see on the highway trucks.
 

big ben

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Aug 22, 2010
Messages
352
Location
Vancouver Island
Ok so start it up, leave it idle and when your up to the 130 temp it only seems to get to, touch the upper rad hose and see how warm it is.

It should still be coldish but if it is also at 130 then you are leaking coolant by the thermostat

As mentioned they are not a perfect seal so there will always be some bypassing but should not be at the same temp as the engine before the thermostat opens
 

srjd

Active Member
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Dec 18, 2015
Messages
42
Location
Canada
How's your coolant level. If it's a bit low you will have now heat. Probably not your issue but check it out its happened to me before
 

Digwizz

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Joined
Dec 29, 2007
Messages
27
Location
NE Ohio
Today I moved dirt for half a hour. The cab warmed up nicely, but the gauge still didn't come into the operating range. Took an infrared shot in the heater vent which was 122. The temperature at the water jacket next to the temperature sending unit made it up to 154 and the top radiator hose was at 89.
 

Nige

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G..G..G..Granville.........!! Fetch your cloth.
From those numbers it would appear that the thermostat isn't opening, the temp you see on the top hose is the small amount of coolant flow that is bypassing the closed thermostat. You didn't take the temperature of the bottom radiator hose by any chance..? If that temp is say 20 degrees or more lower than the top hose temperature then you would benefit greatly by blanking off at least 50% of the radiator area. For the purpose of a test a piece of cardboard would work fine.
 

turfblazer

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Dec 20, 2015
Messages
72
Location
niagara falls ny
Occupation
semi retired drainage ,site work , eq operator.
I personally would not do any radiator blocking at this point with temps in the 20,s.
Let the stat do it's job!
Blocking rads are a primary practice for vehicles that travel down a road and have air forced thru the rad. I do not block my loader rad in winter ( I have a fixed fan) unless it's 10f or below , one time I blocked 100% it was -20f and snowing very hard, ice was building up on blades of fan and hitting the shroud, ya needed the blow back heat to keep the fan turning.
 
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