HELP!! Engine heating problems

[fsthrse]

On my 99 I am seeing engine temps from 200 to 230. The problem only seems to happen when I'm making boost. . ie. . my foot in it during city driving. When I get it on the freeway and when the boost is low or none then it drops to normal of 190. If I pull my 5th wheel (8K) then I can really see the needle swing all the way over to right. The EGT's are less than 900 under the load. The dealer replaced the fan clutch but that wasn't it, my truck being a 99 already has a 180 thermostat in it factory. Any suggestions would be greatly appreciated... I'm running out of options. . this doesn't make sense. The cooling system just isn't disapating the heat. Do these water pumps gradually go out??I thought they were mechanical so it was an all or nothing deal?

 

[LSMITH]

Jay, I would replace the thermostat right off the bat. My guess is it is not opening all the way. The water pump is a fairly common failure, but if the weep hole is not weeping the odds of it being bad are really remote. By fairly common I mean it is one of the only things you hear about going bad on the Cummins side of things. The thermostat is only 3 bolts to remove, and about $17 at Cummins. That would be my first troubleshooting measure, if it is wrong you are out less than $20 and 15 minutes of your time. The cooling system is plenty for our trucks if the system is working right, 230 should never be seen IMO. Give it a shot and let us know if it fixes it.



By the way, welcome to the TDR forums!!

 

[WyoJim]

My son has a '98. 5 that got to acting like that and it was the thermostat.

 

[fsthrse]

Thanks guys, I'll let swap the thermostat and let you know how I make out. My username was changed to fsthrse, I wanted just Jay but it was taken... didn't like both first and last name being posted. Thanks again guys.

 

[Rob Thomas]

You may also want to check in front of the radiator, I had some heating issues a month ago, checked in front, and yep, it was packed full of crap,don't know what, but it was full.

There was nothing in front of the condenser or the intercooler, just the radiator, I pulled the rad out and power washed it, no problems since. BTW, my truck only had 55,000 miles on it, my freinds has 225,000 miles and there's nothing crammed in his radiator, and he claims he's never cleaned it,go figure.



Later, Rob

 

[fsthrse]

I did spray the front w/ degreaser and sprayed it out (what I could) blowing from the engine side and that didn't seem to help. At the time I was on the road w/ my fifth wheel so I couldn't pull the radiator. My truck has 72k on it now so I will pull the radiator and clean it good after I replace the thermostat, this way I'll be sure what fixed the problem. Thanks Rob, atleast now I feel more confident in my troubleshooting methods and there isn't something elementary that I'm overlooking.

 

[Rob Thomas]

Yea, fsthrse,



I tried to "cheat" also, didn't cut it. I Be carefull not to get too close to the fins, I'm sure you know what will happen.

I don't know what was in my rad. , but it was nasty lookin',I think I spent 20 min. pressuree washin' it, man it was packed!

The rad. is simple to pull out, 2 ,10 mm bolts on the top ends,upper and lower hoses,battery cable accross the top,then theres 4 (I think) bolts that hold the fan shroud on, then pull it out. Good Luck!!





Later ,Rob

 

[HEMI®Dart]

There was a bad batch of t-stats that got put into some '98-'99 trucks. I'll bet you are the lucky recipient of one.



See this TSB:



http://www.dodgeram.org/tech/tsb/1998/07_08_98.htm

 

[fsthrse]

Problems Fixed!!! =WooooHooo!

It's fixed guys!!! I printed the TSB off of the site, took it to the dealership (the one that says replace the defective thermostat), they replaced the thermostat with the part number listed for my 99 (180) on the TSB and the highest temp the truck see's towing my 30 foot 5th wheel is 190. This is great seeing how before in the same situation the truck would go to about 230. Unloaded it runs 180 solid. I don't know why the dealership didn't read the TSB's before they started diagnosing the problem but I did get a new clutch fan out of the deal as well as the thermostat. This problem was weird b/c normally a thermostat will either stick open or closed, not somewhere in between... . My truck has always had the problem (72K now) that I noticed but it wasn't that pronounced until I traded in my 4K pound travel trailer for the 10K fifth wheel. Thanks again guys, I can't wait to hit the road again now and not have to stress watching the temp gage.

 

[Big_Daddy_T]

WELL $%^# and I paid to have my bad thermostat replace. Im gonna cuss til I go to sleep.