so my 94 5 speed will creep up to around 210 and then drop to 190 and creep back up again. i have changed the radiator because it had 300,000 on it and had holes, still dodnt hepl. so the next day i changed the thermostat and still does the same thing.. im not sure but is it possible for the fins on the waterpump to corrode off of on the inside not letting it flow? or do i need to replace my fanclutch? i have even opened it when it is hot to bleed all of the air out.. or could this just be another faulty gauge?

 

Does it sound like the fan kicks on and off? Is there any anitfreeze coming out of the weep hole above the water pump?

 

Water pump would be the only other thing you could try really assuming that your fan clutch is working properly

 

To answer your water pump question yes the fins can corrode off. Has it been changed? If not at 300,000 I'd do it. Hell I'd have done it when the radiator was out to make it easier. But it's to late for that now. Does this happen driving down the road or only idle, slow speeds? When do you have the problem?

 

just at idle it stays around 190.. thats if my gauge is reading correctly. and im thinking that is too high for just idling, but just driving it just creeps from 190 back to 210 and back to 190. But i havent even checked the weephole. thanks for the input fellas

 

I could be the sender but it doesent sound like it. I had a 94 with a bad sender and it would fluctuate between 200-140 while driving

 

Ok after some digging i found a spec for the cooling system temperature. The thermostat will not start to open until 181* and normal operating temp is 203* after 203* the cooling fan and air flow take over cooling temp control. So fluctuation from 190*-210* would be normal as far as i'm concerned. Considering the dash gauge may be a little inaccurate.

 

did you buy brand new radiator?

 

yeah brand new radiator and t-stat..

 

go buy the oem stat at cummins, i've had the same problem in the past. When you see the oem and the after market you will see why. I change yaerly and try to cut cost only to have to put the oem in after all.