Cummins R2.8 97 TJ

Another update, after an unsuccessful deer hunt it was time to go elk hunting. The weather turned south and snowed about 6 inches and thick fog that you could only see 50 yards, Jeep did great running around with 10 psi in the tires and lockers loaded and ready, had to use both front and rear winches after sliding into a rut on a sidehill, worked perfect to keep me out of a two foot deep rut. Engine is flawless, but now the issue is trying to keep it warm enough, driving around in the cold weather with the heater going, I was lucky to maintain 150 degrees unless climbing a steep long hill and then I would touch on 180. Looks like I am getting close to 15 mpg driving around in 4 low in steep muddy country. Last year driving the same country with the 4.0 engine I was at about 5 mpg.
 
Another update, after an unsuccessful deer hunt it was time to go elk hunting. The weather turned south and snowed about 6 inches and thick fog that you could only see 50 yards, Jeep did great running around with 10 psi in the tires and lockers loaded and ready, had to use both front and rear winches after sliding into a rut on a sidehill, worked perfect to keep me out of a two foot deep rut. Engine is flawless, but now the issue is trying to keep it warm enough, driving around in the cold weather with the heater going, I was lucky to maintain 150 degrees unless climbing a steep long hill and then I would touch on 180. Looks like I am getting close to 15 mpg driving around in 4 low in steep muddy country. Last year driving the same country with the 4.0 engine I was at about 5 mpg.

What temp should it be running? With a thermostat the diesel should maintain a minimum temp regardless of the outside temp.
 
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The thermostat for this engine is 195, but this engine uses some extra coolant hoses to keep air bubbles in check. When I check the upper radiator hose with the engine running, it is cold, but maybe it is bypassing some coolant. I placed a piece of cardboard over the radiator core when hunting the other day and I was able to hold 170-195 coolant temp, so the heater was working. Once the engine reached 195, I could tell the thermostat opened as the temp started dropping quickly. Starting the engine below 32 F is a bit of a challenge, engine will fire but will only run on 3 out of 4 cylinders until it builds a little heat. I installed the cummins block heater and it will bring the engine temp up to over 100 degrees and this helps a lot, so if needed I can plug into my generator when I am hunting and it gets cold. Overall I am very happy with this engine over the 4.0 gasser.
 
The thermostat for this engine is 195, but this engine uses some extra coolant hoses to keep air bubbles in check. When I check the upper radiator hose with the engine running, it is cold, but maybe it is bypassing some coolant. I placed a piece of cardboard over the radiator core when hunting the other day and I was able to hold 170-195 coolant temp, so the heater was working. Once the engine reached 195, I could tell the thermostat opened as the temp started dropping quickly. Starting the engine below 32 F is a bit of a challenge, engine will fire but will only run on 3 out of 4 cylinders until it builds a little heat. I installed the cummins block heater and it will bring the engine temp up to over 100 degrees and this helps a lot, so if needed I can plug into my generator when I am hunting and it gets cold. Overall I am very happy with this engine over the 4.0 gasser.

It's only running on 3 cylinders in the cold? Is that common on diesels? I started mine around 10F once and yes it sounded horrible, but assumed it was firing 4 cylinders.

Block heater is a no brainer on any vehicle IMO. I'd totally get 1 for a gas vehicle too unless you park in a heated garage. I like fast heat, but that's just me.

I haven't had time to use my Jeep much at all. A lot of towing and there's a weird intermittent noise in the drivetrain of my Jeep right now and I'm too busy to really deal with it.
 
The reason I think the engine is only running on three cylinders when it’s very cold out is that there is a pronounced miss with a lot of blue smoke from unburned fuel, if I increase rpms to 2000-2500 for about a minute, engine smooths out. This could be due to low compression on one cylinder or maybe that cylinder isn’t getting the heat from the grid heater. Maybe I will test the exhaust manifold with a digital thermometer and see which cylinder it is. Maybe I should get a new thermostat to try also
 
The reason I think the engine is only running on three cylinders when it’s very cold out is that there is a pronounced miss with a lot of blue smoke from unburned fuel, if I increase rpms to 2000-2500 for about a minute, engine smooths out. This could be due to low compression on one cylinder or maybe that cylinder isn’t getting the heat from the grid heater. Maybe I will test the exhaust manifold with a digital thermometer and see which cylinder it is. Maybe I should get a new thermostat to try also

When I was stationed in AK and would start the generator that powered my whole camp it'd run rough as heck and bellow white exhaust smoke until it was properly warmed up. We had heaters to get them warmed but I had an officer who didn't want to wait so he'd always tell me to start the generator cold.
I tried explaining to him that I'd have power faster if he'd wait for the engine to get warm first.
EDIT: And this was at temps of -10* and lower.

I doubt it is running on 3 cylinders it's just not completely burning all the fuel that is being injected into the cylinders, so it runs rough until the cylinders reach sufficient temperature to burn all the fuel in the cylinder.
 
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that does sound odd. when i started my cummins in AK. it would idle rough but never three cylinders rough. and the block heater was definitely needed. always plug that in anytime it’s below 20.
 
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I always try to plug my block heater in if possible to get around the rough idle, but the block heater does take quite awhile to get the temp up too. I'm not sure at what temp I can get it with just running a generator for awhile, but it does take a few hrs or so to get it to the max temp. IMO starting a modern engine like this would get it to running ability faster than a block heater, unless you can plug in the block heater sooner, which is the best method IMO. I always use a timer plug and just plug it in when I get in and in the morning it's warm and I'm off to work and in about a mile I'm getting warm air, though the TJ isn't the greatest with insulation and ductwork.

I was recently thinking about running my generator on my track loader for the block heater, but I couldn't find a block heater the last time I looked. Of course that old piece of equipment requires A LOT of heat to start. According to the manual I need to run the glow plugs for 1 minute to get it to start under 60F and at a minimum the glow plugs aren't wired to the glow plug switch which is obviously a problem, I've just never had anything with that high of a temp that requires additional heat. I was assuming that to run a block heater that it might take 3 or so hours until I could get the temp up high enough to start that engine.
 
if your talking about a block heater for starting, a timer would be beneficial in the winter. you definitely want it on for three hours to get that heat in there.

i didn’t have my grid heater wires in. and with just the block heater running thru the night the jeep would crank right up at 0 degrees
 
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thought i had a photo of the jeep with no snow in the center of the hood. all from the block heater running thru the night.

but i also dropped a heat blanket over the hood and would run space heaters in the engine bay on really cold nights.

but that’s Alaska.
 
this is a little worrying. Blue is engine oil as far as i know. White and black are unburned diesel fuel. Color dependant on a cold or warm motor.

I have seen many times when a diesel at high altitude and cold temps will run with blue smoke that is unburnt fuel. My onan quiet diesel generator has this issue when I use it at 9000 ft and the fix is to bump the timing a couple of degrees.
On the opener of elk season, I was driving the Jeep at 10,000 ft and because of no load, the engine kept getting colder down to 120 degrees and then the blue smoke started, burns your eyes from the fumes. If I could put the engine under a load I could get the temp up to 140-150 and the smoke would go away. Cardboard over the radiator helped a lot last week, but it makes me wonder if the thermostat is defective. When the engine was brand new and I had the electric fan in, the temp would climb pretty fast to 195 and then drop to about 180 unless I was on the highway on a hot day, then it would just keep climbing towards 220. Since I installed the mechanical fan I don't think I have ever seen 200 degrees.
 
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Don't these have a grid heater or glow plug system to preheat on cold days?

The engine has a grid heater, but I am suspecting that maybe the furthest cylinder from the grid heater isn't getting enough heat to light the fuel when very cold. I need to do a test run and try it, probably not tomorrow, it is supposed to be -6 tonight, so the test will fail if I don't plug it in.
 
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thought i had a photo of the jeep with no snow in the center of the hood. all from the block heater running thru the night.

but i also dropped a heat blanket over the hood and would run space heaters in the engine bay on really cold nights.

but that’s Alaska.

If I leave the block heater plugged in it will get the engine up over 100 degrees and makes for an easy startup.
 
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The engine has a grid heater, but I am suspecting that maybe the furthest cylinder from the grid heater isn't getting enough heat to light the fuel when very cold. I need to do a test run and try it, probably not tomorrow, it is supposed to be -6 tonight, so the test will fail if I don't plug it in.

Maybe cycle it twice? I know my old 5.9 CTD wouldn't like it if it was really cold, and I'd let it sit for a week or more. I'd cycle it twice and it seemed to help.
 
I always try to plug my block heater in if possible to get around the rough idle, but the block heater does take quite awhile to get the temp up too. I'm not sure at what temp I can get it with just running a generator for awhile, but it does take a few hrs or so to get it to the max temp. IMO starting a modern engine like this would get it to running ability faster than a block heater, unless you can plug in the block heater sooner, which is the best method IMO. I always use a timer plug and just plug it in when I get in and in the morning it's warm and I'm off to work and in about a mile I'm getting warm air, though the TJ isn't the greatest with insulation and ductwork.

I was recently thinking about running my generator on my track loader for the block heater, but I couldn't find a block heater the last time I looked. Of course that old piece of equipment requires A LOT of heat to start. According to the manual I need to run the glow plugs for 1 minute to get it to start under 60F and at a minimum the glow plugs aren't wired to the glow plug switch which is obviously a problem, I've just never had anything with that high of a temp that requires additional heat. I was assuming that to run a block heater that it might take 3 or so hours until I could get the temp up high enough to start that engine.

I think that above zero one hour of run time with the block heater should be enough heat to get it to start. Last week when I went elk hunting I had the engine plugged in with the Jeep on a trailer with chains on all 4. I built a mount for my 3500 watt honda generator to sit inside the tongue of the trailer and my plan was to start the generator and plug the jeep in while I ran 80 miles down the road. The engine was around 100 degrees when I unplugged it and an hour and a half later it was 33! The engine started ok, but ran rough for a few minutes like it was only running on 3 cylinders, I increased rpms up to around 2000-2500 rpms and it smoothed out and ran fine until late in the afternoon when we got done packing out our elk and the jeep had been sitting for 7 hours, luckily it started, but ran rough for a bit. I just got done with first oil change at 1900 miles and switched to 5w40 synthetic oil and this helps the little engine spin over much better when it is cold out. So far my coldest start was right at 0 F and it was a hard time to start. I cycled the grid heater twice and then I had to keep the starter engaged for about 30 seconds for the engine to finally take off. For what it was worth, my 2017 duramax didn't crank over very fast, but it came to life immediately and only rough idled for about a minute. It got new batteries as soon as I got home as the ones in it were the oems.
 
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My duramax is also very forgiving in cold weather.it doesn't need the glowplugs until 20* out. Interesting bit about high altitude diesels running blue when cold. Most i see is 7-8000ft.
 
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I think that above zero one hour of run time with the block heater should be enough heat to get it to start. Last week when I went elk hunting I had the engine plugged in with the Jeep on a trailer with chains on all 4. I built a mount for my 3500 watt honda generator to sit inside the tongue of the trailer and my plan was to start the generator and plug the jeep in while I ran 80 miles down the road. The engine was around 100 degrees when I unplugged it and an hour and a half later it was 33! The engine started ok, but ran rough for a few minutes like it was only running on 3 cylinders, I increased rpms up to around 2000-2500 rpms and it smoothed out and ran fine until late in the afternoon when we got done packing out our elk and the jeep had been sitting for 7 hours, luckily it started, but ran rough for a bit. I just got done with first oil change at 1900 miles and switched to 5w40 synthetic oil and this helps the little engine spin over much better when it is cold out. So far my coldest start was right at 0 F and it was a hard time to start. I cycled the grid heater twice and then I had to keep the starter engaged for about 30 seconds for the engine to finally take off. For what it was worth, my 2017 duramax didn't crank over very fast, but it came to life immediately and only rough idled for about a minute. It got new batteries as soon as I got home as the ones in it were the oems.

What battery do you have for the R2.8?

The R2.8 is an unusual diesel engine in my limited experience. It has a lot of crankcase (I think that's the right terminology) pressure and seems to blow a fair amount of oil into my intake piping from the crankcase. I kinda wonder if you're getting some oil from there.
 
What battery do you have for the R2.8?

The R2.8 is an unusual diesel engine in my limited experience. It has a lot of crankcase (I think that's the right terminology) pressure and seems to blow a fair amount of oil into my intake piping from the crankcase. I kinda wonder if you're getting some oil from there.

Sounds like you might want to install a catch can?