Archived Truck Won't Warm Up

[stover]

Need some help please. I deliver storage sheds for work and after I made a delivery and after I got out on the interstate I noticed that my temperature gauge was down at 140. So I soon pulled over and checked things out and everythings seemed okay so I drove on home. After I got home I checked my radiator and it was full and I could immediately touch my coolant it was warm but not hot. Pulled the dipstick and nothing got into that. So I figured it was a stuck open thermostat. Replaced it with a cummins one and is still doing the same thing. If I put my plow on and go down the highway at 70mph it will heat up to around 175-180 but as soon as I get off the highway and exit I can watch my gauge drop. Without my plow on going down the highway it will only go up to 140. I took one of those infared heat gauges and pointed it at the thermostat housing, the lower cooler hose housing and different places on the block and it all read around 5 degrees of 130. I even pulled the new thermostat and and put it in hot water and it is opening. I even put a new radiator cap on. My fan cluctch seems to be okay; no looseness and I don't hear the roar like it would be staying on. Oh and it is around 20-30 degrees outside. I never had the truck overheat prior to this and it has never acted like this before so I am kinda stumped . I haven't posted very much and I thought my truck specs would come up. It is a 95 Dodge diesel 5-spd 4x4 with a #6 plate 3k gsk kdp tapped timming @17 Afe proguard 7 intake 4" turbo back exhaust, gauges.

 

[Nightram]

This is an odd issue. Here is a TSB on it:



NO: 07-07-94



GROUP: Cooling



DATE: Sep. 30, 1994



SUBJECT:

Engine Slow to Warm Up in Cold Ambient Temperatures



MODELS:



1994 - 1995 (BR) Ram Pick Up



NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 5. 9L CUMMINS DIESEL ENGINE.



SYMPTOM/CONDITION:



The vehicle may not warm completely, especially in cold ambient temperatures. This condition may be due to a thermostat that is stuck in the partial open position by debris in the cooling system.



NOTE: THE COOLING SYSTEM USED ON THE CUMMINS DIESEL ENGINE EQUIPPED VEHICLES PROVIDE FOR THE CAPACITY AND PROTECTION OF THE HIGHER GVWR AND GCWR RATINGS AVAILABLE ON THESE VEHICLES. OWNERS SHOULD BE ADVISED OF THE NORMAL SLOWER WARM UP AND LOWER ENGINE OPERATING TEMPERATURES ASSOCIATED WITH DIESEL ENGINES.



THE COOLANT TEMPERATURE GAUGE WILL FLUCTUATE ON DIESEL ENGINE EQUIPPED VEHICLES. IT IS INFLUENCED BY VEHICLE LOAD, OUTSIDE AMBIENT TEMPERATURE AND EXTENDED IDLE TIME. THIS FUNCTION IS CONSIDERED NORMAL.



GAUGE FLUCTUATION WILL BE NOTICED MOST OFTEN UNDER STEADY STATE (HIGHWAY) DRIVING USING THIS THERMOSTAT (P/N 4796869). PLEASE ENSURE THAT YOUR CUSTOMER IS AWARE OF THIS NOTE PRIOR TO RELEASING THE VEHICLE.



PARTS REQUIRED:



1 4796869 Thermostat, 5. 9L Diesel

1 4761292 Seal, Inner

1 4761291 Seal, Outer



REPAIR PROCEDURE:



This bulletin involves the replacement of the engine thermostat.



WARNING: DO NOT LOOSEN THE RADIATOR DRAINCOCK WITH THE SYSTEM HOT AND PRESSURIZED. SERIOUS BURNS FROM THE COOLANT CAN OCCUR.



NOTE: DO NOT WASTE REUSABLE COOLANT. STRAIN THE COOLANT INTO A CLEAN CONTAINER FOR REUSE.



1. Disconnect the negative cables from both batteries.



2. Remove the accessory drive belt.



3. Drain cooling system until the coolant level is below the thermostat.



WARNING: CONSTANT TENSION HOSE CLAMPS ARE USED ON MOST COOLING SYSTEM HOSES. WHEN REMOVING OR INSTALLING, USE ONLY TOOLS DESIGNED FOR SERVICING THIS TYPE OF CLAMP (SPECIAL CLAMP TOOL # 6094 OR SNAP-ON CLAMP TOOL # HPC-20). ALWAYS WEAR SAFETY GLASSES WHEN SERVICING CONSTANT TENSION CLAMPS. A NUMBER OR LETTER IS STAMPED INTO THE TONGUE OF THE CONSTANT TENSION CLAMPS. IF REPLACEMENT IS NECESSARY, USE ONLY AN ORIGINAL EQUIPMENT CLAMP WITH A MATCHING NUMBER OR LETTER.



4. Remove the radiator hose clamp and hose from the thermostat housing. A special clamp tool must be used to remove and install the constant tension clamps.



5. Remove the hose clamp and check valve hose at the thermostat housing.

















6. Remove the two upper generator bracket mounting bolts (Refer to Figure 1).



7. Loosen but do not remove the generator lower pivot bolt.



8. Position the generator to gain access to the thermostat housing and the housing bolts.



9. Remove the thermostat housing mounting bolts.

















10. Remove the thermostat housing, thermostat, inner and outer seals and lift bracket (Refer to Figure 2).



11. Clean the mating surfaces of the thermostat housing and the cylinder head.



NOTE: THE THERMOSTAT SHOULD BE INSPECTED FOR DEBRIS. IF THE THERMOSTAT IS DETERMINED TO HAVE DEBRIS IN IT, THEN DRAINING, FLUSHING, AND FILLING OF THE COOLING SYSTEM IS REQUIRED.















12. Install a new outer seal into the machined shoulder on the thermostat housing (Refer to Figures 2 and 3).



13. Install new thermostat into the machined shoulder next to the outer seal. Note the direction of the thermostat from Figures 2 and 3.



14. Position the inner thermostat seal with the shoulder towards the thermostat housing.



15. Install the thermostat, lift bracket, seals and housing to the engine as an assembly. Install and tighten the mounting bolts to 24 N-m (18 ft. lbs. ), torquing the short bolt first and then the two longer bolts.



16. Position the generator to the thermostat housing. Install and tighten mounting bolts to 24 N-m (18 ft. lbs. ). Tighten the pivot bolt to 43 N-m (32 ft. lbs. ).



17. Install the check valve hose and hose clamp at the thermostat housing.



18. Install the upper radiator hose and clamps to the thermostat housing and to the radiator.



19. Install the accessory drive belt.



20. Connect negative battery cables to both batteries.



21. Fill the cooling system and check for leaks.



22. Program the radio and set the clock to the correct time.



POLICY:

Reimbursable within the provisions of the warranty.



TIME ALLOWANCE:Labor Operation No: 07-40-01-90 0. 6 Hrs.





FAILURE CODE: P8 - New Part





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Try this, this may help you out. This is an odd issue, that is for sure. Good luck!

 

[stover]

What seems weird is that it has never acted like this even in colder weather. I did a search and someone mentioned an overflow valve. Is this the valve that is in the housing just before the thermostat with a rubber hose going to another port or valve after the thermostat? I got a vise grips and pinched the rubber line and then drove around and it didn't seem to make a difference.

PS Is the thermostat to be balanced? The reason I say that is when I hold the thermostat in my hand and turn the middle it wobbles? I guess my next step will be another thermostat. ??!!!??

 

[Nightram]

That would maybe be it, because that should be tight in the middle, it should be under spring pressure. an old trick is to take the thermostat and out it in water with a temperature gauge, and watch to see when it opens as you boil the water. Not knowing the exact opening temp, it should open usually somewhere between 190-200 degrees. With the middle loose, I would take it back and try another t-stat!

 

[stover]

I did put the thermostat in boiling water and it opened but at what temperature;I don't know. I thought I had a themometer but couldn't find it. I did notice when it is closed there is a small gap open on the one side (maybe a 1/16). Is that normal?? I went to napa and carquest to see if they had one in stock to look at but they didn't.

 

[Nightram]

I did a quick on-line search, and autozone and advance auto say you have to order it also. The thermostat should seal completely shut when cold, so I would say you have a bad thermostat. That is why it has the bleed valve on the top so it doesn't have to stay open.

 

[stover]

I guess it won't hurt nothing to just keep on running it. I will probally put some cardboard up front to help get a little heat. Talked to my friend who works in parts at dodge dealer and he won't be able to get another cummins thermostat till tuesday. So I guess that will be my next step. Thanks for the replies!

 

[Nightram]

No problem! Let me know what happens, and stay warm

 

[2-ND TIME]

If you have a farm store around the round baler belting works well for a rad shutter as does the big mud flaps and they don't burn or get wet as cardboard does. Have used it for years.

 

[TWennrich]

I've had the same problem going on with my '92(see thread in 1st gen discussions). I'm as stumped as you because before all previous winters the truck warmed up nicely and stayed consistently hot. I've replace my thermostat twice(although not with a cummins one) and it does not seem to make a difference. Even throwing a cover over the radiator doesn't seem to help too mcuh. Keep me posted if you have a breakthough.

 

[stover]

I've put cardboard in front of my radiator and that helped some. My new thermostat is to come in tomorrow morning so am anxious to see if it makes any difference.

 

[Nightram]

I would try a full cooling system flush, and I would also take the hoses off the heater core and backflush the heater core. Make sure to check the thermostat housing to be certain it is not cracked near the coolant bypass and allowing more coolant to flow through there than designed.

 

[Slow Six]

I had similar problems on my 94. I finally ended up with a 195* Napa Superstat which I left in year around, towing and every thing else. I was real happy with that set up. I noticed an improvement in mileage in the winter as soon as I warmed the old cumapart up. You need a weather front as well when it gets cold. . It can be frustrating getting it right but stick with it. I got real good at changing thermostats in the old girl. Good luck.

 

[stover]

Got It Fixed

Thanks for all the help guys! I put a new cummins thermostat in this afternoon and I have my heat back. It does seem to cycle a little more than my original one though. Will see what it does when I pull my trailer again.

 

[TurboFan]

When you say it "does seem to cycle a little more" what temps are you talking roughly?



Mine cycles between 145-170. really frustrating as I just put in a Cummins t-stat part number 3934373, which was supposed to stop the large temp fluctuations I thought.



Thanks

Greg

1996 2500 5spd

 

[TowPro]

Greg, in my 98 (5 speed) in the dead of winter in SE pa (warmer then dead of winter in other places) I would see swings of 145-180 or so (temp gauge is not a calibrated instrument). On highways I could watch the truck heat up to around 180, thermostat would open and temps would drop back to around 145 and start the process all over again. (I was running a cummins 180 thermostat)



In my 2002 (automatic) I don't see the temp swings as bad as the 98 did. My thoughts is the auto trans generates more heat and actual helps keep the anti freeze warmer while driving in the winter.



In my 98 I used a Lund Cold front and it helped a good bit. I hate the idea of putting cardboard in front of the radiator because your also blocking air from over the intercooler.

 

[stover]

I live up by Erie, Pa and so I have been running around with my plow on since I changed my thermostat. With the plow on it doesn't seem to cycle very much but with the little driving that I did do with the plow off it seemed to cycle between 150-180 I would guess. The guage wasn't moving up and down very fast though so I guess I won't worry about it.