Archived 98 12v Heating during hard pull

[JTHUSKINS]

My truck is heating when I am towing up grade after the converter unlocks and full throttle is needed. I watch the guages to see that the engine temp rises first then the trans follows a few minutes later. Have factory and aftermarket temp guages and both register over 230. After pulling over and cooling with trans in neutral it will slowly go down but will quickly rise as soon as the pull continues. Trans. pickup is a dipstick mount and the engine pickup is on the Lt rear of the head. So far I have checked and changed the thermostat, replaced the fan clutch, and cleaned out all cooler fins with no fix. Right now I have the radiator out again to have it flow tested. My radiator shop said that it flows above its rating before flushing and gained 6 more gallons after. The water pump looks good and the engine is not corroded. We should be camping right now but can't go anywhere until this problem is solved. Any body else ever had this problem?

 

[Missouri Mule]

How heavy/high is your trailer?

Are you trying to maintain speed limit?

Have you increased horse power?



Seems you have covered everything on the cooling system. Were the t-stat and fan clutch bad or were you playing hit and miss?

If the water pump was bad it should overheat all the time.

 

[JTHUSKINS]

My camper is around 6k and is a tagalong. The only mods are a 4" turbo back and a KN filter. The engine is bone stock. The old fan clutch did not come on hard when temp started to rise like the new one does so the old one was not performing 100%. The thermostat showed no signs of sticking and was a 180. I was unable to locate a 180 local so a I purchased a 190 in a rush. The change made no difference. The new mopar fan clutch does come in hard when the temp hits 200. At this point the temp will continue to rise to 230 and the warning will sound. When the warning begins to sound then the transmission acts as if it is shifting up and down suddenly without reason. I have tried several different methods of driving steep grades and none prevent the problem after the converter unlocks. I have towed as much as 10k and have no problems as long as the converter is locked and RPM are low. I have noticed now that the temp begins to rise rather quickly if i get in low speed traffic where I cannot reach lockup speed even with OD off.

 

[Sticks]

I'd would also check the AC condensor and intercooler to make sure that they are not restricting air flow. The radiator can be squeaky clean but will still not cool anything if there is no air flow.

 

[BDaugherty]

Is this a new problem? I mean, have you towed under the same conditions with the same setup in the past without problems? If so and you have thoroughly checked out the cooling system, then it sounds like a transmission problem to me. If it were me, I would install a manual torque converter lockup switch. That way you can pull hard in 2nd, 3rd, or 4th at any speed without the heat caused by the torque converter slippage. Another plus is that you will probably drop 300 or so engine RPMs for a given road speed versus having the T/C clutch unlocked.



See the following link:

http://www.tstproducts.com/Torque Converter Lockup Switch.pdf

 

[JTHUSKINS]

I have owned the truck 4 years and until the fall of 2009 I just hauled loads in the bed or pulled a 1k trailer with no problems. The original owner of the truck bought it new and used it for a daily driver for 112000 miles. I discovered the problem the first time towing about 10k up the our local 2000 ft climb from Wilkes Co to Watauga Co NC which ranges from 8% to 10% grade for about 6 miles. I have to pull over and cool 3 times on this pull. I have cleaned the condensor fins as well as the cooler and intercooler then checked them thourghly with a light to find no obstruction. The torque converter slipping does make sense even though I can't feel it doing so. I will do some research on lockup switches and how to use them without breaking a trans. Thanks for the tst link.

 

[FParisi]

If the TC is not locked it makes a LOT of heat ( + not much pulling ). Do the lock-up switch, lock out OD before starting that pull + downshift as needed to keep RPM just above 2,000. Also get the trans. serviced, bands adjusted, new synthetic fluid.

If the trans. hasn't been rebuilt it might be time - go with one of the aftermarket rebuilds - the difference with the valve body + TC is amazing. (From experience with my '95)

 

[JTHUSKINS]

Just serviced the trans with the assistance of a certified mopar trans tech before the first heavy tow. He checked the band adjustment and determined it to be good. Used oem filter and fluid. haven't had any shift problems or any slippage when pulling up grades that lockup speed can be maintaned. Will a new aftermarket converter, 3 or 5 disc, help the problem without a lockup switch?. If I go with just a switch to begin with can I downshift as speed drops to where 2nd gear is needed without a tremendous jolt to the trans and driveline?

 

[FParisi]

The switch should work. You can unlock to downshift then lock it up again, it is hard on the TC if it's locking up under heavy throttle especially at peak torque - around 1600rpm.

I changed to a DTT upgrade - single disc + upgraded throttle body for higher fluid pressures + some upgraded hard parts. It made a world of difference!

Lots of info on here about the transmission upgrade religion ;-)

 

[Rams-n-Hogs]

Do you have an EGT gauge? If your EGT's are high, they will cause water temp to go up, also.

 

[Nigel]

I was thinking along the same line as Jim. Maybe you have a boost leak causing high EGT. Does it blow a lot of smoke when you get on the throttle?



Nigel

 

[JTHUSKINS]

No EGT or Boost gauge yet. Have considerd high EGTs and restricted exhaust. Installed the 4" turbo back MBRP system after the heating problem was diccoverd and found that my CAT was partially clogged. It made no difference in temp but really improved top end. Have never noticed heavy smoke under any condition but without a boost gauge I have nothing to compare to for a loss. Do not hear any noise that would make me suspect boost loss. I have tried to move the waste gate by hand and cannot do so. Should I be able to move it that way or will it require air pressure to test?

 

[Missouri Mule]

The wastgate will require air to move it.

Lockup switch sounds like a good idea.

 

[JTHUSKINS]

Thanks to all who responded with info. Going to order some parts tomorrow to clean up some oil leaks,KDP kit, all new coolant hoses. Checked all intake boots and found one that is worn into the fiber so a set of boots will be on the list also. Maybe in a week or so i will have it back together with a lockup switch to make another test run. I think that I can rig a tester for the waste gate using my paint gun pressure regulator to see if it is working.

 

[SMorneau]

30 years ago I replaced a water pump for a buddy and the only thing I asked him to do was fill the system. He poured straight antifreeze in it and it over heated right away. He got all mad wondering what I did wrong. I finally convinced him straight AF was not good and he drained half of it out and poured in water. After that it was fine and he has to suck it up and apologize. I trust that is not your problem.

The water pumps are cheap you may want to replace it.

 

[FParisi]

Always good to check the basics!

 

[rrl989]

My original Mopar bottom radiator hose had a wire skeleton insert, my aftermarket replacement did not. Is it possible that maybe your bottom radiator hose is collapsing a bit under load, thereby restricting flow enough for you to notice your condition ?

 

[SMorneau]

I noticed the same missing insert on the lower hose when I replaced mine. This is worth checking or replacing. I watched the hose on a 460 ford collapse when the engine was reved out in neutral and he had big time heating problem because once it collapsed it want to stay collapsed.

Good suggestion RRL989.

 

[JTHUSKINS]

Still working on it. Went ahead and pulled the head while I am going over everything. All good, had the head tested & serviced. Replaced the water pump due to a very slight seepage at the weep. While going over the entire underhood area I have discovered that my wastgate accuator is leaking all preasure so the wastegate was non functional. Also the thermostat from NAPA that I was running which is the same type that was in the truck when I bought it is 7/16 smaller flow area than the Cummins replacement that I am installing. Went ahead and bought all new coolant hoses, fuel return line, and fuel pump while everything is easy to reach. Hope to have it back together this week for a trial run and maybe me and the wife can hit the road soon. Will let you all know what the out come is. And to answer the question about the bottom hose and coolant mixture, Yes the spring skeleton is in place and will have to be used in the new hose,the coolant mixture was in the truck when I purchased it so I don't know. Using new 50/50 CAT coolant after repairs.

 

[JTHUSKINS]

Got her fixed! Wow! I have a totaly different truck now. Installed a Banks stage 3 plate and their Bighead waste gate actuator while it was down. Hooked up the ole camper and went for a test run down the mountain and back up. Blew a stock boost boot near the top. Limped home. Installed BD performance boots and clamps from Genos and went for another run. Engine temp never exceeded 200 and trans temp ran 180 to 200 with the converter locked in third gear. Gained 10 MPH and one gear on the same pull that was once a nightmare. I was able to keep the EGTs at or below 1000 by backing out of the throtle with 30# boost. RPM was lowered to the engines torque range by using the lockup switch. Again I say WOW! I still have a rough slow idle after a hard run so now I will work on solveing that problem. Any ideas? Thanks again to all who posted advice and got me going. A camping we will go and have already been.