LB-7 Overheating

[millerman04]

Friends stock 03 LB-7 was startin to overheat. Said he stuck his finger into the overflow jug, and it wasnt very warm. We were thinkin the t-stat wasnt opening. Cheaper fix first. Next guess was the water pump. Any ideas? Or any easy tricks to know before we start? Thanks all :thumb:

 

[TheBac]

Hose out the stack, too. Its probably clogged with bugs and dirt.

 

[THEFERMANATOR]

Clean the stack out(pull the radiator and clean out the intercooler and condenser REALLY good), new stats, fan clutch(most overlook these as they should be replaced after about 75-100K miles), but 1st see if it is actually overheating or not. I have seen more than 1 coolant temp sensor fail and give a false overheat indication. Could be as simple as a dirty/bad connection at the coolant temp sensor.

 

[millerman04]

Hey Thanks!! We thought that as well to check the wiring too. As i back the truck in the garage yesterday i noticed that the gauges only bout half work. So who knows.

 

[TheBac]

on an 03, it could even be the gauge cluster itself.

 

[THEFERMANATOR]

on an 03, it could even be the gauge cluster itself.

What he said. Steppers fail ALOT. Just got done with an 04 and it was interesting on the test drive trying to drive without a speedo on 30 MPH roads with cops at every corner.

 

[millerman04]

Thats another thing i thought of yesterday. As i backed it in garage only half the gauges seemed to work. The temp gauge was pegged way past the red zone. And this was a cold start move. But the thing that has us is the water in the over flow container wasnt warm when my buddy checked it. He was pulling the stock trailer down on 81 outside of Harrisburgh Pa this past saturday evening. It apeared that the water wasnt circulating due to the overflow not being warm. Thus why we thought a t-stat, or the water pump.

 

[05_LLY]

years back i had an impeller spin off a water pump casued it to overheat so to speak but the rad was cold!

 

[millerman04]

Guess it could be possible on a totally stock truck.

 

[05_LLY]

Seen the water pumps eat the housing out bad enough that trucks would run warmer than they should as well, usually when towing.

 

[millerman04]

How nice Whats the trick to takin the black metal pipe out of the t-stat housing? Im assuming its held in with an o-ring? Seems to be a ***** to pull apart.

 

[05_LLY]

Once ya get the lil hose off, wiggle it till its turned towards the front of the truck, then just mess with it pulling it down, id have a new oring handy!!

 

[THEFERMANATOR]

How nice Whats the trick to takin the black metal pipe out of the t-stat housing? Im assuming its held in with an o-ring? Seems to be a ***** to pull apart.

Take the hose off that goes back to the turbo, take the 2 bolts out that hold it to the water pump, then rotate it outwards till you can slide it out. They can be tricky sometimes, but once you do it once or twice they aren't so bad.

 

[millerman04]

I managed to take it out in one piece. Made it harder, but i couldnt get it apart to remove it. Even tried with it out of the truck, and still didnt wanna budge.

 

[millerman04]

Got the truck bacl together. We think we found the problem. The gauge cluster is screwing up with every gauge. So we told the guy to get it fixed before we take anything else apart. We put a laser thermometer against every part of the motor during the warmup, and nothing was overheating. And during that test, the warning lights were flashing saying that the engine was overheated, but the thermometer said otherwise. Thats what led us to our decision on the guages.

 

[THEFERMANATOR]

Got the truck bacl together. We think we found the problem. The gauge cluster is screwing up with every gauge. So we told the guy to get it fixed before we take anything else apart. We put a laser thermometer against every part of the motor during the warmup, and nothing was overheating. And during that test, the warning lights were flashing saying that the engine was overheated, but the thermometer said otherwise. Thats what led us to our decision on the guages.

If it is flashing an overheat warning, then the coolant tempo sensor is reading high. The warning message is triggerred via the ECM by coolant temp, and works independant of the stepper motors that fail often. Sounds like you need to install a new CTS in it before you do anything else.

 

[millerman04]

Ok sounds good. We will add that to the list then. Thanks! And the coolant temp sensor is located in the thermostat housing right? Just making sure since no engine can be the same.