Engine/Transmission (1994 - 1998) heating problems

[CumminsPower98]

Lately I have noticed my coolant temp running a lot hotter then I'm used to when towing heavy or even empty for that matter. Yesterday coming up the lower steep foothills out of Denver I was clear down in 3rd running about 30 mph pulling an 11,338 lb. 5th wheel and got my temp up to about 225 with only 80 deg. ambient. I have pulled this same hill with similar loads in 5th and gotten up to maybe 220 with higher ambient temps. And other places running in the mid 90s with small hills and some wind it gets up higher then I'm used too. Radiator is 100% clean inside and I have run a bug screen since installing it and also done some hosing and get hardly any bugs out. I have messed with fan clutches and thermostats. I'm starting to think I may have to go to Mopar for a fan clutch though. My last one ran way too much even when cold out and maybe not enough when real hot but not fully sure on that now. I just put on a Napa one and it's like it's not there. I got it up to 200 today just running up a slight grade with the A/C on and 95 deg. ambient and still didn't hear a huge roar like I would expect from that temp. I'm on my way to Fresno with this trailer and stopped home to work on this thing. Now I'm scared I didn't help it and I get to face the Majovi tomorrow. Wish I could afford a Horton.



Could tired injectors cause it to run hotter? I have 381k on the originals and I'm guessing they are tired weather or not that's the problem. Mileage really hasn't changed much if any. I sometimes think I may have lost a small amount of power but that's hard to tell when I drive it all day everyday if it happened slowly.



Any thoughts?

 

[JGrover]

Ive read some post in the past about the crankcase vent hose. Oily fumes get (in between) intercooler/radiator clogging them. Oil fumes cake the cooling fins causeing cooling problems. The problem effected the intercooler more though. May be worth checking very closely.

 

[CumminsPower98]

Thanks but this is a 12 valve so the crank vent is not up front like the 24 valves so no oil misting problems.

 

[JGrover]

I read them post on the 12v. Maybe they sit/smoke/idle with a little tail wind

Just passing on what I read

 

[JFaughn]

When was the last time you changed the thermostat ?
Messed with , really doesn't mean anything .
Find a shop [ preferably Cummins ] to do a combustion gas check on rad. - hopefully not but could be the beginning of a headgasket .
A basic way to check the fan clutch is with a hot eng. - not running , spin the fan by hand should have a fair amount of resistance to turning , compared to cool eng.

 

[bmoeller]

Has the water pump ever been replaced?

Running a 180 or 190* t-stat? I'm running a 180* one myself.

Is there oil on the coil on the front of the fan clutch? If it has oil on it, it might be insulating it, and keeping the coil from getting warm enough to engage the fan.

 

[hsmith]

Better check the tstat. Have seen some that have hung partially open causing the coolant not to stay in the radiator long enough to get cool.

 

[hsmith]

Forgot to say you need to stay with the Cummins stat. NO AFTERMARKET stat will compare.

 

[CumminsPower98]

I changed the t-stat once some time in the past couple years with a Cummins 180 deg. Yesterday I pulled it out and boiled it with a temp probe and it was opening up good by about 190. When the truck isn't working hard it runs at or slightly below 180 and is steady. The stat did open wide and closed back up. I tested it like this a couple times. I wasn't able to get a Cummins one when I needed it so I put in a Napa one and ended up taking it out and putting my old one back. The Napa one didn't open at 180 like the Cummins.



When I first installed my current fan clutch (carquest), also within the last couple years, I was struck by the fact that it ran way more then my OE one even when cold out it would stay engaged way too much. I got so used to it's sound that I was thinking it wasn't running enough so I got a Napa unit and put it on yesterday and couldn't believe how quiet my truck got. The problem was that today when I pulled a good long steep hill and got the truck up to 230 I still didn't hear much from the fan so I stopped and put my old one back on. Hoping Napa will take that sucker back. I made it to Barstow tonight. I had some hot pulls but none as bad as the first one with the Napa clutch.



My next move when I get home is to pull the radiator and make SURE it's fully clean of bugs. What I can see of it's clean but I can't see it all. The screen should kept most out. A few weeks ago I did take the fan off and back wash what I could but didn't see many bugs come out. I know it can't be cleaned correctly in the truck.



Water pump is original and they don't wear out to speak of other than the bearings and seal so if it's not leaking there shouldn't be a problem unless the impeller fell off and that's not common at all. If it did fall off I would probably be running a lot hotter.



I suppose it wouldn't hurt to check the HG. I haven't noticed any coolant problems like filling the tank so it seems unlikely. I'm running only 30 psi and studs torqued to 125.



Tonight when I pulled in to park I noticed the truck was missing more then I have ever felt before. I could feel it and hear it pretty pronounced at an idle. If I idled up to maybe 1k it would really shake but above that it would smooth out nicely. So I'm really starting to think I should be thinking injectors. I sure hope it's not a pump problem but I don't know how to tell. I started up after eating and didn't notice the shake... strange. We shall see how it sounds in the morning.



Thanks for the replies

 

[JFaughn]

Sounds like a fuel problem , I know that the gassers would run hot if they ran lean .

 

[CumminsPower98]

Yeah, I'm starting to wonder if injector problems are contributing. No more missing today like I had last night. I have always had the slightest of misses that 's almost undetectable. Sometimes it would be slightly worse then others. Lately I have also been noticing a bit of a shaking or vibration when pulling moderately, loaded or empty at lower rpms. Feels a lot like small bumps in the road and it's real hard to tell which it is for sure. Today though I was getting it up hill and not really down hill so I'm really thinking it's a slight miss I'm feeling at times. Doesn't seem to do it all the time either. I have been trying not to hold it much if at all at 1200 as I don't need a single injector melting me down. I checked all cylinders with a temp gun and they were all real close except for #2 that was a bit cooler if I remember right and I forgot how much but I think it was less than 10 deg different. I changed #2 back at 247k miles when I did my HG because it had a slight leak in the threads where the two halves screw together.

 

[fest3er]

I might think your system is slightly out of balance. An engine running too hot is pert near due to thermostat and fan clutch. If the t-stat doesn't open enough, there won't be enough heat from the radiator to engage the clutch. When my t-stat was bad a few years ago, the internal water temp was around 230F, while the radiator was relatively cool. And the temp gauge did not reflect the internal temp. Put a new Cummins t-stat in, regardless of how the current one seems to be working. I can say the Bumper-to-Bumper t-stat is junk; damn thing never closed, and the engine would never warm up even in the mild winters we have here in VA. Then make sure your fan clutch is working right.

As to injectors, you don't say how 'old' they are. At 147K miles, one of my 215s was acting up. Blue Ridge Diesel gave them a mild looking over, and found one injector's pop-off pressure was wrong; it cost about $70. I put them back in and the 'ratty' sound and feel was pert near gone. If one injector is acting up, you'll use more fuel to compensate for the power difference. And since you have one cylinder that's running cooler, the others are likely running hotter because they are doing more work to compensate.

Fix the injectors, check/adjust the valve lash, install a new Cummins t-stat, and make sure the fan clutch is working right.

And if you are using more engine lube than you might expect, remove the filler cap and cleverly install some PVC piping to relieve the crankcase pressure. I was using about 1 qt every 1K miles until I did that. Now I'm back to about 1 qt every 5K miles (2 qts if I'm towing and running 10-20 PSI boost rather than the more normal 5-10 PSI boost).

 

[ANG012]

I have a 97 12v and i have the problem of oil clogging up the fins on the radiator. The bug screen will not stop the oil from clogging up the radiator. The temp on mine would climb up when you got on a pull. One thing i had to do to mine to keep it from over heating was have radiator shop pressure flush the radiator with air and water. There is alot of crud that will not come out of your radiator by just draining and refilling. I had mine done when mine would get hot and it made a big difference in cooling temp.

 

[CumminsPower98]

I do plan to get another Cummins t-stat. I will also pull the radiator to make sure it's clean. I don't have any oil problems on the radiator as my truck is pretty much leak free and clean. My fan is running more than is should so I don't think I have a problem there. I'm going to do a more careful check of my exhaust port temps and record what I find.



My injectors are the originals except for #2 as noted earlier. They now have 383k on them so even though it seems to run smooth most of the time and gets pretty good mileage I could still have a problem.



Does anyone know of any injectors that would be better then the stock 215s? I am on a stock turbo running about 300 RWHP so I really can't deal with much more fuel as I can get hot easy in the mountains. I guess what I'm asking is if there is anything that will give me the same or more power but less heat (more officiant). I also can't afford to pay a huge amount like some of the performance models cost.



fest3er, that's interesting what you say about oil consumption, I had never heard of that but it makes since. Right now mine uses about 1 qt/3000 miles running OTR so not too bad. Before I started driving it would use 1 qt. to about 6000 miles just putting around town and of course it had fewer miles.

 

[JFaughn]

I would think that if your not ready for a turbo [ or upgrade maybe $400 ] that stock injectors if they test bad , being that the turbo seems to be a choke point , at this point , bigger injectors will only make it worse .
Find a shop that can do a combustion gas test on the radiator , no parts with out testing .

 

[Katmandu]

Better check the tstat. Have seen some that have hung partially open causing the coolant not to stay in the radiator long enough to get cool.

BINGO !!!!!!!

This is a known issue with our 12V T-Stats! The rubber O-ring deteriorates over time and pieces of it will JAM in between the T-Stat opening!

This EXACT same issue happened on my truck last fall.

Here's pics to prove it!

Here's a link to more pics of my T-Stat. -->>

http://www.katmanduonline.net/pics/CTD/Thermostat/

Notice the little YELLOW arrow and circle in the pic below!

#ad

 

[Katmandu]

#ad

 

[CumminsPower98]

My original stat came loose like that and wouldn't let the truck warm up 200k miles ago. Friday I pulled the radiator and got a few bugs out but not a lot as expected. I installed another cummins stat even though mine seemed to be working fine so we shall see what it does now.