Motor temperature concerns..

[98fleetwood]

My temp gage is running hot. I have 1300 miles on my rebuilt 98.5 Cummins 24 valve.
First trip, temp gage stayed under 1/2 the whole time. Highest egt's. I seen was 1140 or so..
2nd trip the temp gage stayed under 5/8 or so. The highest egt's I seen was right at 1200..
3rd trip the temp gage went up to 3/4 or so. The egt's went up to 1240 before I let off to not see 1250 (the melting point of aluminum)...
Each trip was around 400 miles, early in the morning so road Temps were about the same, and roughly the same road grades...
What could cause this??
I am wondering if I can put a lower tempature thermostat in it??
Any and all advice will be greatly appreciated!

[jacwjames]

Best thing I did was get an engine moderating system. I have a VMSpc which shows all the engine perimeters.



Hot engine>>> first thing to check is how clean the radiator is!!

[wolfe10]

Actually, how clean is the FRONT of the CAC??


That is where most of the dirt and debris will be "filtered out" before that air gets to the radiator which is behind the CAC.

[98fleetwood]

Originally Posted by wolfe10

Actually, how clean is the FRONT of the CAC??


That is where most of the dirt and debris will be "filtered out" before that air gets to the radiator which is behind the CAC.

I had everything out, taken apart, pressure washed, and then put all back together 1300 miles ago...

[98fleetwood]

Originally Posted by jacwjames

Best thing I did was get an engine moderating system. I have a VMSpc which shows all the engine perimeters.



Hot engine>>> first thing to check is how clean the radiator is!!

I am going to flush it...
When I had it out nothing came out of it to make me think it might need to be flushed...
Looks perfect.. I know looks can be decieving...

[CRV2]

Are you seeing the high temps only with the EGT or is the engine coolant temp also high? If only EGT then there are other possibilities than the engine's cooling system. ~CA

[98fleetwood]

Originally Posted by craigav

Are you seeing the high temps only with the EGT or is the engine coolant temp also high? If only EGT then there are other possibilities than the engine's cooling system. ~CA

Coolant temp went up each trip...

[wolfe10]

If the cooling package (CAC and radiator) are clean, next thing I would do is change the thermostat. They can hang up-- not opening all the way.

[Wild Card]

What are you doing when this occurs?
This is not flat land EGT's.

[98fleetwood]

Originally Posted by Wild Card

What are you doing when this occurs?
This is not flat land EGT's.

Traveling over the pass.. 10 mile hills.. ETC..
I see 900 to 1000 degree EGT's all the time on mostly flat slightly hilly terain...
Here in Washington nothing is flat...

[98fleetwood]

Originally Posted by wolfe10

If the cooling package (CAC and radiator) are clean, next thing I would do is change the thermostat. They can hang up-- not opening all the way.

A radiator flush, and a new thermostat are the only things I can think of...

[jwprosser]

When you rebuilt, did you also replace your water pump? All the suggestions so far are on the money.

[98fleetwood]

Originally Posted by jwprosser

When you rebuilt, did you also replace your water pump? All the suggestions so far are on the money.

Yes the water pump has 1300 miles also..

[98fleetwood]

Thx for all the suggestions.. I am going to work on it soon.. next trip is in a couple weeks..