Hello everyone I am new to the site and I could use some help with a figuring out what exactly went wrong with my truck. I was driving home and after driving for about 50 miles (all highway) my EOT and ECT temps jumped up very high. My ECT was at 215 and my EOT temp went to 225. I have never had any signs of something being wrong. The coolant seems to be completely out and I noticed the top of the engine had coolant residue. The residue did not seem to be a lot though not as much as if it all came out of the degas bottle. The degas bottle had very little residue around it. I pulled the EGR and it had some DRY carbon build up but nothing of a real concern. As I mentioned it was dry no moisture. I am hearing a screeching sound that seems to becoming from the front right side. I was leaning towards the water pump might be shot. Or the Head gasket went, but I have had head gaskets go before and there was always a sign before they went. Any thoughts would be a big help.

 

Since you have a noise and already suspect water pump, why not pull the belt and check the water pump bearings? Maybe the impeller inside is coming apart not able to move enough coolant to keep it cool.

 

I agree with Checking the water pump. Your delta is still only 10 degrees so I would think that the pump failed also.

 

"EOT ECT high out of nowhere" You might want to check your fan Clutch. If you have a Scan Gauge program a gauge to monitor the Fan Speed Sensor FSS.
I'm having a similar problem with the ECT & EOT when the fan clutch fails to engage after about a hours running around town. I don't have a fix yet but I will say that as long as the fan engages my temps stay around the low 190's. "JR"

 

Fan Clutch? I did not think of that. That makes sense as well. Come to think of it the screeching noise sounds like it is coming from that area. Maybe I should take it to the dealer and have them diagnose my problem and go from there. I would hate to start replacing a bunch of stuff that is still in working condition. I just hate giving money to the dealers they make enough money already from selling us their vehicles.

 

More logs for the fire. When my ECT and EOT and Coolant PRESSURE goes to 16PSI, (Normally about 12-14 psi at 195 temps) the fan speed FSS is being reported at around 420 to 480 RPM. When the fan works normally it ranges from 600 to over 1800 rpm. and when it roars it it's near 2000 RPM. When I pull over and sit at idle for a couple of minutes then idle up the engine the fan begins to function again. There are 5 mechanical items in the fan drive, the pump, (could be the impeller or the bearing) the bell shaped pulley housing, (glazed over and slipping) the belt, the belt tensioner, (having just replaced the alternator I will rule out the tensioner), and finally the clutch.
If anyone out there has any ideas about how to test these components speak up.

 

I wouldn't rule out the tensioner just because you replaced the alt. I'd remove the belt and hand turn each part paying attention to rolling resistance. The part that looks glazed over and slipping is a very good candidate, its resistance it higher, why the belt isn't just rolling over it.

 

Just out of curiosity, is your EGR valve plugged in? If not they have been known to cause issues with clutch fan operation.

 

Yes, EGR is plugged in and I cleaned the connector, it had some foreign residue on the pins and in the female pin sockets. took several sprays with CDC electronic contact cleaner to get rid of the residue. Haven't been able to do a test run because of "honey do's" required in advance of family visit.

 

It seems as though you have three problems:


1. Overheating
2. Loss of coolant
3. Noise from something associated with the serpentine belt.


As to the overheating, I had a similar "out of nowhere" increase in ECT's to around 220 degrees F. When I let the truck cool overnight, the problem disappeared. Did you check your temps again after a cold soak?


I replaced the water pump and thermostat. With 90K on the truck, the pump looked virtually new. However, the thermostat was cruddy and I concluded that the thermostat had jammed closed and then reset itself overnight.


If you can check your fan RPM's with a Scan Gauge or other device, I would look at the thermostat next.