Engine/Transmission (1994 - 1998) Why does it get so danged hot?

[Stranger]

When towing up a grade in 3rd Direct, keeping the EGTs below 1250 and boost around 34lbs. , the water temps climb to well over 210. :--) Then we open the windows and turn on the heater to cool it down. Next hill it starts all over again.



Here's what I'm thinking is going on. With 34 lbs of boost and stock injectors I'm giving too much air and it's leaning out. However a friend thinks that just the opposite is happening and that I need to pump more air.



Oo. What's really happening, any ideas?

 

[illflem]

Could it be your fan clutch isn't engaging? Somewhat common problem. You'll know it when the fan engages, that sucker screams and pulls 23 hp. Nothing wrong with 210°, it's on the high side but has a long way till overheating.

 

[Stranger]

Well...

I put a new fan clutch and fan on it. (Don't want to get a Horton unless it's last resort.



After we turn on the heat it still gets to about 230 and then I'm moderating the throttle to try to get the temps down while still keeping the EGT's and boost where I like them.

 

[JohnE]

Get your tranmission checked.

Do you have a fluid temp gauge?

 

[Boldt's Wagon]

How much weight are you pulling up that grade, at what speed, and what percent grade? With 34 lbs boost and 1250 exhaust temperature your transmission is no doubt operating with an unlocked torque converter. The computer reads the TPS and unlocks the TC clutch. Even with the DTT, operating the TC unlocked will increase the temperatures drastically. The transmission heat is dumped into the engine coolant with the water cooled exchanger below the exhaust manifold. If you are operating with the TC unlocked, this is probably the source of your high coolant temperature.



Either back off on the speed up the hill, get a mystery switch, or get a smart controller and pull the hill in 2nd locked TC.

 

[dieselburner]

Been there, done that. I recently replaced all of my hoses and the serpentine belt and figured I would replace the thermostat with the newest and greatest one. I flushed the cooling system and got all of the new parts in there and hooked up my 13. 5K fifth wheel and hauled it up to the mountains. The sucker over heated at the first big pull. I have never had a overheating problem before so I figured it must be the thermostat. Pulled it when I got back and put it in a pan of water on the stove along side the old one and a calibrated guage. The new thermostat opened much more slowly and later than the old thermostat and it never fully opened at all. I stuck the old one back in there and all is well again. No temps over 190 pulling real hard up the hills. I'll see if I have the numbers written down somewhere on these thermostats.

 

[Diesel Freak]

Originally posted by Stranger



Here's what I'm thinking is going on. With 34 lbs of boost and stock injectors I'm giving too much air and it's leaning out. However a friend thinks that just the opposite is happening and that I need to pump more air.

You can't run a Diesel to lean.

 

[Stranger]

Here's some of th things we've done

We scale at right around 20K, I had the transmission built for 25K AND 250hp but since then I'v heard that I may be putting out 300+

Installed DTT's Smart TC Box, (totally different truck, snaps the neck going into OD ) It and the PAC-Brake are always on until about 1/4 mile from destination. (It's great to let off the throttle and have the front end dip).



Haven't yet towed with the box but early signs show a 125 RPM gain @ 70mph. I used to run 70 @ 2K RPM and 8 lbs of boost empty. Now it 1875+/- and 6 lbs. if I'm in a light throttle application and it shifts into OD and I apply just a touch more pedal I think the TC is shuddering. Should I change fluid type or...



BTW: I'm getting 3 more gauges (that makes 5!), Trans temp off the line from trans to cooler, Post Turbo EGT and Post turbo boost for back pressure when PAC-Brake is on.

 

[BPINE]

Hey Stranger, we have talked about this in the past. You might not have any troubles at all, any thing over 1150 degrees will start building heat in the radiator and by 1300 the temps will keep climbing until you over heat. Remember we have drastically increased the HP and have not increased the cooling capacity along with it. In temps above about 80 degrees I have the same problem. The longer the hill the bigger the problem, So far I have kept things in check by slowing down a bit when I have to.



I have been told there is a pin in the small outlet from the thermostat housing I think called a jiggle pin and if that sticks you can not control the temps no matter what. Does anyone have any experience with that?

 

[Berrigan]

Stranger,



Whats the ambient temp during these pulls?

I agree with another reply that 210 is fine. I pull hills in Arizona when its 100 plus degrees and both of my CTD trucks will hit 220-230 at the top of a long hard hill. Say 7 of 8 % grade that is 7 miles long with a good sized trailer in tow.

 

[CUMINNTSTRKN]

another thing to think about is. when you have 34psi going thru your intercooler it is heatsoaking. my temps didn't really used to climb with a single charger, but with twins my cooloant temp is 20 degrees hotter 190 to 210, but i'm also able to use more hp with the twins.



are you hearing your fan coming on? it will sound like a jet engine trying to take off when it engages.



jim

 

[pkennedy]

I had the same problem with the 91 pulling hard in the hills all day, the horton fan clutch is not going to give much more cooling. Like the other guys stated your radiator is built for X amount of heat transfer so possible solution is get a rad with 1 more core built- Big$$$$. These engines are a bit of a contradiction in design in that they pull real well at lower RPM's than the other guys but you will also generate substantialy more heat especially if it has been cranked. One does not reach maximum cooling ability until 2600-2800RPM where the fan/coolant are moving at high rates and manifold pressure starts to drop off dramatically. The horton fan will be slightly more efficient here because it is direct drive vs. the viscous at 95% lockup. The 2003 have a plastic fan which is supposed to be more efficient drawing more air through less rad so maybe one will fit the older hub and lighter too. The large trucks went to this design many years ago because they were also experiencing cooling problems with high torque low RPM designed engines. If all else fails when pulling big hills back off the throttle as to lower your manifold PSI (20) but maintain higher RPM (2500) to allow the air to flow. My old 380HP 3406 Cat would drop 420HP to the ground but it would warm up pretty good on the mountain passes and dropping back to max RPM and 25PSI( max 46PSI) manifold would pull there all day. PK

 

[PHaller]

I think your problem is an unlocked TC like Boltd's Wagon said. When unlocked pulling a hard grade with a trailer you are shearing transmission fluid which generates heat. Lots of heat! That heat from the transmission is transfered to the water in the engine via the oil to water cooler in the radiator and more indirectly from the oil to water cooler mounted under the manifold on the engine. Your water temperature will rise and it will take a long time for it to drop.

Try locking that TC with a mystery switch.

-Paul R. Haller-

 

[Reb.B]

okay, if u are pulling these hills a lot, then this is what u need to do. Get a CO2 tank, build aluminum tubes around and cross ways infront of the intercooler. Put really small holes all around it and put out a larger hole at the end of the tub, have it pointed down toward the road. Then when u pull the hill, hit the button that activates the solenoid to the tank, and your temps will go down forsure

 

[Stranger]

Thanks for the feedback...

Boldt & Paul; I think you've hit it. I'm now locking the TC with the smart box, I just haven't gotten to tow with the box.



pkennedy; But... . , I don't wanna slow down!!Oo. Besides, my cousin has a DMAX and the same size trailer.



CUMINNTSTRKN; Thinkin' about putting some nozzles in front of the intercooler and shooting water through them, I've seen the "Desert Cooler" in TL.

Also thinking about one of my Dad's old tricks from when he used to race midgets. Water injection. Only using a mix of water and methanol.



Berrigan; Mid 70's sometimes to 90's, sometimes higher depending on where we are. And I've put that into the mix of my question.



BPINE; I foggily (is that a word) remember this conversation . I also remember sprint cars and sprint boats too!



Does anybody have a wastegated 14 housing they want to get rid of?