Cummins R2.8 97 TJ

[NDSpeed]

Alaska tent and tarp will make winter covers and summer bug covers.

 

[nuffsaid]

In both cases here, if your engines are not getting up to operating temperature it is a thermostat issue, period. Specifically, the thermostat is not closing properly, or you have the wrong temp thermostat installed. The outside temp, driving at highway speeds, bad fan clutch, etc, have no impact on the minimum operating temp of the engine, which is what the thermostat establishes.

Are you familiar with the Cummins R2.8? There is a series of hoses called out to keep air out of the cooling system flow. Even though these hoses are only 3/8 inch in diameter, they are bypassing some coolant around the thermostat. In cold weather with very little engine load it is almost impossible to maintain thermostat set point on the engine. I am on thermostat #2 on my engine with only 5500 miles. The thermostat temp is 180, my engine usually will run 170 unless it is under a load and then it will exceed the thermostat temp and run around 185-190. This isn't that unusual with a diesel because when ambient air is very cold, they don't generate very much heat unless worked. I have had this same type of issue for 40 years with multiple different diesels I have owned. You wouldn't think that a stream of coolant through a 3/8 line would have much of an effect, but when temps are well below freezing it is enough to make the engine drop to 115-120 after warmed to 170 just by idling. Without the radiator blocked off, it is much worse. The hose routing specified by Cummins is pretty strange, but there must be a reason. Trapping air in the cooling system is a definate bad idea. I might try installing some restrictors in the 3/8 lines to drop the flow down to around 1/8. I know I thought about this before, but I can't remember if I did it or not. I do know that the epansion tank I used is always full and has coolant flowing through it all the time from these 3/8 lines and they bypass the thermostat.

 

[NDSpeed]

I had a variable thermostat installed on mine.

 

[NashvilleTJ]

Are you familiar with the Cummins R2.8? There is a series of hoses called out to keep air out of the cooling system flow. Even though these hoses are only 3/8 inch in diameter, they are bypassing some coolant around the thermostat. In cold weather with very little engine load it is almost impossible to maintain thermostat set point on the engine. I am on thermostat #2 on my engine with only 5500 miles. The thermostat temp is 180, my engine usually will run 170 unless it is under a load and then it will exceed the thermostat temp and run around 185-190. This isn't that unusual with a diesel because when ambient air is very cold, they don't generate very much heat unless worked. I have had this same type of issue for 40 years with multiple different diesels I have owned. You wouldn't think that a stream of coolant through a 3/8 line would have much of an effect, but when temps are well below freezing it is enough to make the engine drop to 115-120 after warmed to 170 just by idling. Without the radiator blocked off, it is much worse. The hose routing specified by Cummins is pretty strange, but there must be a reason. Trapping air in the cooling system is a definate bad idea. I might try installing some restrictors in the 3/8 lines to drop the flow down to around 1/8. I know I thought about this before, but I can't remember if I did it or not. I do know that the epansion tank I used is always full and has coolant flowing through it all the time from these 3/8 lines and they bypass the thermostat.

Thanks for the explanation. Interesting setup on the R2, with which I am not familiar. I wonder if there is an issue with emissions if it can’t get up to op temp in cold weather. I have owned many diesels over the years and have never had an issue with operating temp, even in very cold weather.

 

[Wildman]

Thanks for the explanation. Interesting setup on the R2, with which I am not familiar. I wonder if there is an issue with emissions if it can’t get up to op temp in cold weather. I have owned many diesels over the years and have never had an issue with operating temp, even in very cold weather.

When you say very cold weather what type of temps are you talking about? I know from living in Alaska & driving truck in the western states that in very cold weather we used to run a bib on the grill to block air flow so that the engine could get up to operating temperature. But it sounds like nuffsaid might not be able to do that if he's having issues with his intercooler.

I had a variable thermostat installed on mine.

What is that? And how does it work?

 

[Rickyd]

Are you familiar with the Cummins R2.8? There is a series of hoses called out to keep air out of the cooling system flow. Even though these hoses are only 3/8 inch in diameter, they are bypassing some coolant around the thermostat. In cold weather with very little engine load it is almost impossible to maintain thermostat set point on the engine. I am on thermostat #2 on my engine with only 5500 miles. The thermostat temp is 180, my engine usually will run 170 unless it is under a load and then it will exceed the thermostat temp and run around 185-190. This isn't that unusual with a diesel because when ambient air is very cold, they don't generate very much heat unless worked. I have had this same type of issue for 40 years with multiple different diesels I have owned. You wouldn't think that a stream of coolant through a 3/8 line would have much of an effect, but when temps are well below freezing it is enough to make the engine drop to 115-120 after warmed to 170 just by idling. Without the radiator blocked off, it is much worse. The hose routing specified by Cummins is pretty strange, but there must be a reason. Trapping air in the cooling system is a definate bad idea. I might try installing some restrictors in the 3/8 lines to drop the flow down to around 1/8. I know I thought about this before, but I can't remember if I did it or not. I do know that the epansion tank I used is always full and has coolant flowing through it all the time from these 3/8 lines and they bypass the thermostat.

I remember you dealing with this after your install. Have you contacted cummins about a possible cold weather configuration or any other advise from them?

 

[NDSpeed]

When you say very cold weather what type of temps are you talking about? I know from living in Alaska & driving truck in the western states that in very cold weather we used to run a bib on the grill to block air flow so that the engine could get up to operating temperature. But it sounds like nuffsaid might not be able to do that if he's having issues with his intercooler.



What is that? And how does it work?

when i get to the garage next time i will take a photo.

i can dial in the temp i want the thermostat to open

 

[Wildman]

when i get to the garage next time i will take a photo.

i can dial in the temp i want the thermostat to open

That is cool. Didn't know there was such a thing.

 

[NashvilleTJ]

When you say very cold weather what type of temps are you talking about? I know from living in Alaska & driving truck in the western states that in very cold weather we used to run a bib on the grill to block air flow so that the engine could get up to operating temperature. But it sounds like nuffsaid might not be able to do that if he's having issues with his intercooler.
…

Well, not Alaska cold for sure, but New England and Colorado cold. We even get sub-zero here in Nashville occasionally. But point taken.

 

[Wildman]

Well, not Alaska cold for sure, but New England and Colorado cold. We even get sub-zero here in Nashville occasionally. But point taken.

When it was only for a few days I did the cardboard trick but when it's below zero for a month or more the cold weather fronts are nice. The nicer ones you could adjust the opening to get your temperature more where you wanted it. While I didn't need it my Ram dually came with one because it had the cold weather package.

 

[NDSpeed]

i didn’t drive the jeep much in the deep cold. and fairbanks is only 2 miles by six miles. no point in driving a diesel in that. it would never warm up. so i had the gas car for the winter

 

[Wildman]

i didn’t drive the jeep much in the deep cold. and fairbanks is only 2 miles by six miles. no point in driving a diesel in that. it would never warm up. so i had the gas car for the winter

In Barrow it was leave it running or plugged in... Or hook up the dog team.

 

[NDSpeed]

In Barrow it was leave it running or plugged in... Or hook up the dog team.

i’ve got some friends on the north slope. they only shut down for the oil changes

 

[nuffsaid]

I just got done making a winter front for the TJ. I used some black naugahyde and put three snaps on the top and two snaps on the bottom. I took my digital thermometer and tested temps in the engine bay. After 30 minutes of idling the coolant temp on my murphy gauge read 118 degrees and my dash showed 110, they rarely read the same even though the sensors are in the same place in the thermostat housing. With a thermometer in the dash vents with heat on high, I am getting 80 degrees out of the vents. Temps outside are around 20 degrees F and it was -7 last night. I tested the radiator with the digital thermometer and it was around 40 degrees. The expansion tank closely matched the murphy gauge reading. Engine just isn't producing enough heat at idle to get the coolant up to thermostat temp. Due to the fact that directly below the thermostat housing is a port for the air bleed off that gets a 3/8 hose, and this goes to the expansion tank. Do to the low temp at the radiator inlet, I don't think the thermostat is bypassing much coolant. With the new winter front installed, there will still be ample air flow over the intercooler to keep the charge air cooled.

 

[nuffsaid]

Well, with the new winter front on I can get the engine up to 172 after driving 65 for about 3 miles. I back flushed my heater core with compressed air and now I can get 120 degrees out of the dash vents with the engine at 170+. Once I get into town and drive slow my coolant will slowly drop down to 140+-. It has been cold out, temps not getting much over 15-20 degrees and -10 to -18F overnight. Plug in the block heater for an hour or so and the engine temp comes up to mid 40's. Once the temps get a little warmer it might be time to head to the Big Horn mountains and play in some deep snow. The heater works much better when the engine is getting worked a little.

 

[Jake kozlowski]

Good reads all around. Just got back from a glacier trip and it was roughly 10 degrees out all day.

Highway speed cruising at 70mph I maintained 180f on the Murphy gauge.

Now when I would park the jeep after wheeling and idling it would drop down to 125F.

When the motor has zero load it's just cold. Thermostat is working properly since it opens up around 183 on the freeway, zero issues.

 

[nuffsaid]

Good reads all around. Just got back from a glacier trip and it was roughly 10 degrees out all day.

Highway speed cruising at 70mph I maintained 180f on the Murphy gauge.

Now when I would park the jeep after wheeling and idling it would drop down to 125F.

When the motor has zero load it's just cold. Thermostat is working properly since it opens up around 183 on the freeway, zero issues.

Pretty much what I see

 

[NDSpeed]

@nuffsaid what part of WY are you in?

 

[nuffsaid]

Worland, in the Big Horn Basin, Big Horn Mountains to the east and Absorka Mountains to the West

 

[NDSpeed]

And it’s been about three years so i wonder if @Jake kozlowski is still in Anchorage.

i still haven’t done anything about the grid heater. i don’t drive the jeep in winter. so i’m not worried about it yet.

and looking at getting a new battery this year. group 31 battery. i was thinking something that has closer to 1200cca