SOLVED (i think) P0128 and DexCool consumption

[DirtyBacon04]

I've noticed as of lately my truck is drinking dexcool. Some red mist covering front of eng blcok. No illuminated CEL, but i hit the scan anyways showing a P0128. Now if my research is correct, these are 2 seperate problems with one component. Perhaps the tstat is stuck open, and the seal has failed. At first I suspected water pump for leak. I took the tension off the water pump pulley to try and wiggle the pully, but shows no play. The bottom of the pump is relatively dry, so i dont think it's coming out of the weep hole. I dont have a mirror, so can't say for sure.

Here you can see it pooled up in the corners of the alternator and coating the front of block.


Got the best pic I could of the bottom of the water pump. Seems dry to me.






ALSO... unrelated... but what is this thing?

[Cable810]

CPAS in the last picture...

[fishsticks]

Looks like a water pump leak to me. A failed thermostat seal would more likely leak downwards and air from the fan would blow coolant to the rear of the motor.

The bearing could be fine right now (no movement) but the internal seal shot, which means the bearing won't be far behind.

Also check your radiator cap, it may be leaking and the coolant is falling down into the accessories. Your fan blades appear to have coolant on them, which supports this theory as well.



Regardless of what it is, you cooling system isn't holding pressure, and a system that can't pressurize won't hold temperature properly. Hence P0128.

[DirtyBacon04]

Checked cap already, it's solid. I was hoping it wasn't the water pump, but just more experience under my belt, I suppose. Thanks for the opinion fish. Any experience changing that? Is it one of those "seemed easy on paper" jobs?

[fishsticks]

Amazingly, my 2002, 120k mile water pump and fan clutch are both still going strong, even after the abuse I've doled out on that truck.

They don't LOOK hard...

[NC_IslandRunner]

Amazingly, my 2002, 120k mile water pump and fan clutch are both still going strong, even after the abuse I've doled out on that truck.

They don't LOOK hard...

I'm knocking on wood, 156k and no issues so far with fan clutch or water pump. Fingers crossed!

[djthumper]

Once you get the fan clutch off the water pump is a piece of cake. I have had to replace my water pump twice now and once was in the middle of the night in our church parking lot.

[bdp1978]

Once you get the fan clutch off the water pump is a piece of cake. I have had to replace my water pump twice now and once was in the middle of the night in our church parking lot.

Exactly, as long as the fan clutch breaks loose its an easy job. Im on my 3rd water pump and this one now has a slow leak. (2nd came with a wobbly shaft out of the box) so Im really only on my 2nd, but 3rd time of doing it. My truck has eaten Fan Clutches, Water Pumps, and Air Injection Pumps. 3 each of the above and Im only at 115k.

[DirtyBacon04]

Well took the time today to try and fix the leak. Sure enough, it was the water pump. I'm fairly unfamiliar with working on this motor, it took me a while to discover which one was the water pump. The fact that there are no coolant lines going to it, really threw me off. Anyways, the water pump was easy, once you get the friggin fan clutch and housing off! That part was a PITA!! All them special tools and stuff. Put it all together with a brand new water pump w/ lifetime warranty, started it up, checked for leaks. None. PERFECT!! Or so I thought... I went to drive it around to warm up xmsn when I very quickly noticed a horrible vibrating noise around 2400 rpm... Sure enough it was the sound of vibrating plastic that coincided with the RPMs... a few of you can see where this is headed...
It was the fan clutch bearing. So that needs to be replaced now. But at least I know how it's done, and shouldn't take me nearly as long.

My dad came out to help me. (Suprised how much working room one gains by removing the airbox and washer resevoir!)


Here you can clearly see it coming out of the weep hole


New one installed and torqued down. Anit Seize seemed like a good idea.


So now as soon as I can afford a new fan clutch, I'll be tearing it all back apart...

[bdp1978]

My 1st fan clutch went bad after I replaced the water pump as well. It was fine before then, put it back together and it jet engined. Weird???

[DirtyBacon04]

Same here. It must just be in it's own happy world before we touch it... It's like waking up a sleepwalker. Never ends up good for anyone.