Overheating in city driving

[fessup]

I hope that someone can help me. I have a 99 3500 with a auto that I use for hauling and a daily work truck. I have major trouble with pulling any trailer (3,000 to 20,000) with out overheating the truck. This is only a problem during stop and go city driving at any temp over 70 deg outside. If I have a full load it only takes a few stop lights to start cooking. Has this happened to anybody else?



I believe that it is the torque converter boiling the trany fluid. The trans temp climbs first then the engine follows. The trany temp will not go less than 260 deg in city driving and can go higher than 300 with no problem. This did not happen the first year I had the truck than the dealer had to rebuild the trany under warranty. It has never been the same. The dealer said that it meets the specs but it has a lot of delay between stepping on the gas and starting to move.



Any help would be appreciated.



Ian

 

[KatDiesel]

So the transmission and the engine are both overheating?



How many miles on the truck, when is the last time transmission fluid, filter was changed? Is the coolers on the front "clean" from any restrictions?



Engine over heating, last time coolant was changed? Is your level full? Ever change the thermostat? Is the fan working? How high does the engine temp go?



Just a few questions for more info.

 

[fessup]

More info

Yes both the engine and trans will overheat.

The truck has 65,000 miles, the fluid and filter was changed 15,000 miles ago, had the problem before and after the fluid and filter change. Dealer changed the t-stat under warranty last year (not the problem). There are no restrictions in front of the cooler or radiator. Coolant level if full and in good condition. The engine will hit 240 but I usually stop before it gets that hot.



Once the torque converter locks up everything starts to cool down. I don't have much problem pulling at 25 MPH if I don't have to do starting and and stoping. Once I start from a stop light with a heavy load I can watch the trany temp do a steady climb from 140 deg. Every time I start again the trany temp will keep climbing and take the engine temp with it. Once I get on a freeway (going up a on ramp to reach 60 MPH really heats things up quickly)and the converter locks up the trans temp falls to 140 to 200 deg. then the engine also starts to cool down)



let me know if you need any more info.



Thanks

Ian

 

[JAK]

When it gets hot does the fan sound like its trying to turn your truck into an airplane? If I'm not mistaken, the viscous fan clutch should get more aggressive the hotter the coolant gets. In the stop and go traffic with insufficient air flow over the radiator, everything will get hot. But at speed, the airflow will be adequate and all temperatures will be normal.

 

[RustyJC]

If this problem started with the transmission rebuild, the root of the problem probably lies there - excessive heat is being built up at low speed due to torque converter slippage.



I had a similar problem with our V-10/automatic 3500 towing a 13,500 GVWR in Houston traffic during the summer. Engine coolant temps would climb to 230* or so. I made two modifications that totally cured the problem - last summer we had 107* ambient temperatures, and the truck only got to 195*-205* coolant temperature. These mods were:



1. Installed a B&M Supercooler (1/2" NPT inlet and outlet) transmission cooler upstream (ahead of) the radiator tank transmission cooler and the factory oil-to-air cooler. This got rid of a lot of the transmission heat load before it got dumped into the engine coolant.



2. Installed a 205* aftermarket thermal fan clutch - the factory fan clutch for the V-10 was rated 224* but didn't engage until coolant temps reached 230* or higher!



Again, I'm not proposing the above as a fix that only masks the root cause problem, but it's a nice addition for those who tow heavy trailers in stop-and-go traffic during high ambient temperatures.



Rusty

 

[Steve St.Laurent]

I don't know much about automatic's but if it's heating up bad until the clutch locks up then I'd guess a bad torque converter. When they rebuilt the transmission did they replace the torque converter or did they just put the fried one back in? Just a guess.

 

[Todd T]

I would have to agree,



its sounds like the transmission is putting all that heat into the radiator and heating up the engine with it.



at what RPM does the converter flash? to check put your foot on the brake and give it steadily more gas until you feel the truck trying to overpower the brakes.



or from a dead stop take you foot off the brake and floor it at the same time, watch the tach and you will see it stop and the truck start to move around 1700rpm's. if its alot higher than that you may have a bad converter.



when was the last time the bands were adjusted in the transmission too? are they slipping, and heating things up.

 

[Partyat33]

I had a bad thermostat in mine. Did not open fully, just enough to not totally overheat though.



Just my $. 02



Dennis

 

[Steve M]

My first thought was the thermostat. It could be another bad one. Then my thoughts went to the fan. I would seriously consider replacing the fan clutch. It should kick in at just over 190*. Mine howls at just about every traffic light launch until I hit about 35mph when it releases. It also cycles regularly on the highway in the summer heat. If you're not hearing it blowing like crazy under there, it's not doing it's job. It turns at about 15% in it's released state and about 90% of motor rpm in it's engaged state. They work great when they work and are an asset to the a/c unit as well.

The proper way to check a torque converter is to hold the brakes, put in drive, give throttle until rpm are maxed. This is the stall spd of the TC. About 2100 is good. Don't do this for more than 5seconds. It does heat up the fluid quickly.

If it pulls ok but gets hot, I would suspect the fan or T-stat. Hold you hand in front of the radiator of a Dodge Cummins that's engaged and feel the airflow. It really moves alot of air. They're engaged when they're cold until you drive it and disburse the silicone fluid in the clutch.

 

[Don M]

I would begin by checking the fan clutch first. Sounds like she is slipping a tad and not moving enough air.



You mentioned the truck gets hot when city driving but is ok on the freeway. Sounds like your fan clutch again.



Transmission heat could get the radiator warm but causing it to overheat sounds very extreme. The fluid is only going into the side tanks of the radiator not completely through it.



If your transmission fluid is getting to 300 degrees. You are gonna be getting yourself a new one real soon. That is alot of heat for the fluid and it will break down fast at 300.



1. check the fan clutch for proper operation.

2. check into getting an auxillary transmission cooler.

3. change the trans fluid soon. it is smoked.



Don~

 

[Bob Wagner]

you need to talk to the big guy

best transmission cooler on the market www.dieseltrans.com



If you want transmission advice talk to the guru Bill K. 604-504-4002



Those transmission temp are abnormal

 

[Ram_Kowboy]

I agree with the others, I think the torque converter in the unlocked condition, creates most of the problem. I can duplicate your problems in my truck.



Condition 1:

With a horse trailer on a long steep climb on a dirt road, my temp. will climb up and up. Solution: put truck in low range, this will run your RPM's around 1500 to 2000. You will be able to see your temperature fall right back down.



Condition 2:

Working at the race track pushing sprint cars. Extremely hot outside air temperatures. ( Forcast high 90's, temp. on overhead console 120 ) Push a car out then return for next car on and on for about 10 sprint cars. Temp will really climb. Solution: Overdrive off, gear selector in 2. Get the RPM's again up to about 1500 - 2000.



I have replaced my thermostat trying to solve the problem, no help. Others have suggested a horton fan and I believe that would help. But the problem comes around to infrequently so I have learned how to operate the truck to avoid the situation.



Bottom line for me, I want one of the "neater than neat" low slip torque converters that you buy from Bill K.

 

[DMcGalliard]

Torque Converter temp buildup

Hello,

I have a temp gage on the transmission and setting waiting for light WILL heat-up the transmission. I can watch the gage move. If I am pulling a heavy load and the transmission is already hot, I move the slector to neutral and the transmission will cool down. It is a pain, but it helps to keep the transmission cool.

 

[JMoglia]

untill you find the problem I would be driveing around with my hood latch released that way the hot air has somewhere to go,check it out, also do check out t/stat again you may have a bad one,it really isn't hard to change,I know when I change mine I also make sure the giggle pins line up with coolant flow I don't know if it matters but it can't hurt.

good luck !

 

[fessup]

Fan Clutch

I think I will replace the fan clutch and the T-stat first. Any sugestions on where to get a 190 deg fan clutch?



Yhanks for the help

 

[dvieira]

how to tell fan clutch is bad ??????

lot's of good info on above, but, how

can you really know if your fan clutch is

bad or going bad, other then waiting for it

to "come on", when the temps are high ?



thanks

dave vieira

antioch,ca

 

[Steve M]

Pep Boys carries a severe duty fan clutch for our trucks. You can also borrow the wrench needed to change it. It's in the ford wrench set but it works. If no pep boys close by, almost any good parts house has fan clutches.

To tell if it's bad, you can block off the radiator with cardboard and use an a/c thermometer to watch the temp rise between the radiator and fan. At about 190 it should start to roar noticably. Also, it should be locked up in the mornings for the first acceleration down the road. If not, it might be getting weak. Look for any silicone fluid leaking around the seal too.

 

[dusty]

overheating in the city

I may be way off base and do not usually post anything but; for a long time I had the exact same problem and fkor a lont time I swore that condition was wrong. I searched all over for a fix in the form of a thermostate believing that was the problem. Cause when it was anywhere near 80 degrees outside the engine temps would go to 190 and above. When this occured the transmission would also heat up and all this happened mostly in stop and go traffic as well as towing. I searched high and low for a thermostate and even the dealer told me the wasn't one. Then low an behold I found this TSB 07-08-98 and my engine temps droped 30 degrees and the transmission never get hotter than 160 after installing and aditional cooler behind the front bumper behind the licence plate. A lot cheaper than the other suggestions.

 

[fest3er]

Re: Fan Clutch

Originally posted by fessup

I think I will replace the fan clutch and the T-stat first. ...

Yup. Fan clutch and t-stat. Also, have you tried shifting out of OD until you're up to 50 or so?



Fest3er

 

[fessup]

Dusty

Is the TSB calling for a additional trany cooler? Did you install a Mopar or aftermarket trany cooler if that is what it called for.



I don't hear the roar that everyone is talking about so I will replace the fan clutch. What is the wrench that I need for replacing the fan clutch.



Ian