Engine/Transmission (1994 - 1998) Engine Temp

[FD5]

With 279,000 miles on the truck I took it to the local Cummins shop to have the valves adjusted. While there they said my water pump was leaking so I had them replace it along with the idler pulley. They also adjusted the idle and pump timing. When I was heading home I noticed the engine temp approaching 210 degrees then it dropped to 140 back up to a max of 190 and cycled 140 to 190. My truck had never gone over 190 even while pulling. I realize 210 is not bad but I would like to know if someone can tell me why it goes up to 210 every time after the engine has cooled then cycles 140 to 190.

Thanks,

 

[B.W.T.]

I've got a friend that has the same problem.



Hope some one can give some feedback

 

[rjones]

Did they put a new stat in also?If so they usually go up to a certain temp then back off and cycle like that... something about a Cummins stat..... In this cold we're having mine dosent go that high,but in the summer it does and I'm using a Cummins stat... ...

 

[FD5]

They said they didn't change the stat?? Should they have??

 

[rjones]

Originally posted by FD5

They said they didn't change the stat?? Should they have?? [/QUOTE



I would have change it with a waterpump change... IMO... . Rick

 

[B.W.T.]

He changed out stat and the radiator still does same thing.

He mentioned that when it heats up like that that some coolant end up in the overflow.

 

[rjones]

Originally posted by B. W. T.

He changed out stat and the radiator still does same thing.

He mentioned that when it heats up like that that some coolant end up in the overflow.

ya might want to test the cap make sure that its blowing at the right pressure

 

[Ben Rumson]

Change the stat - with a CUMMINS stat

Sounds like the initial temp has to hit 210 to start opening the stat. From then on it does the 'ol cycling thing between 140 and 190.



The original stats were too quick to responds to temp and opened quickly - thus dumping in loads of cold water into the block when it opens.



The new CUMMINS stats uses a thicker wax inside the stat and it reacts slower - thus you don't get the hugh mass of cold water all at once. Rather, it opens slowly and lets the water keep the temp much more constant.



To be safe (because it's slower reacting) cummins lowered the temp rating to 170.



Many members have tried replacing their stat with other brands and ALL still cycle. The CUMMINS stat that myself and others have used is MUCH more constant than the others. Mine hits 170 and stays there. No more cycling!!! And the 170 still burns you out of the cab using the heater. After market will cost you $10. I got my cummins for $17 plus the two rubber gaskets = $23 total.



Do a search using my name and read my post on this from about a month or two ago.



My cummins stat runs dead on 170 all the time. Haven't pulled with it yet. One other member reported that his runs 170 empty and 180 loaded with a cummins stat.

 

[B.W.T.]

yeah we changed the stat out 2 times with different styles hoping that the one that opened at a lower temp would cycle more and cool it down. When we changed out the radiator along with the radiator cap it seemed to stop the overflowing just does'nt seem to want to circulate coolant now.



we also changed the head gasket which was bad no change, we changed out the temp sending unit (even tested temp gauge inside cab to actuall water temp maybee 5 degrees off). Took the water pump off thinking it may have took a dump its in great shape. He now has no water movement the gauge will read 200 + and the water in the radiator is cold. We can't figure it out. Our next thing we are going to try is to pull the T-stat out and try it.







If anybody has any other suggestions it would be muchly appreciated

 

[JohnG]

Temp. Cycling also

I'm the 'New Guy' w/ '95 2500 and on my trip home with my new (used) truck, I also saw the temp. cycling rather quickly. . I assumed that the temp sender or the guage had gone bad. . Glad I read this!. . I'll get the newer thermostat. . Thanks guys. . John G

 

[FD5]

New Stat

Changed out the T-stat today, big difference but still cycles. It was cycling 210 to 140, it now cycles 180 to 160 with no load, much better.

 

[FD5]

Sending unit

B. W. T.

I told the guy at Cummins what mine was doing (Temp cycling) and he said that Dodge was having problems with some of there gauges as well as the temp sending units. Your friend may want to explore that possibility.

 

[bmoeller]

I bought the new Cummins t-stat but had a chance to put it in yet. I did replace the sending unit before getting the new t-stat and it did make difference in my case. It still cycles in the winter(not as much as before) but quit doing it in summer.

 

[Dr.Bob]

Wish I had your problems , mine never gets hot enough to open the t-stat.

 

[FD5]

Not hot enough

Dr. Bob

You may be having the problem Cummins rep was talking about, possibly your gauge or temp sending unit is bad.

 

[Dr.Bob]

No, had it shot runs at 165.