I have a odd intermittent coolant leak and would like to know if anyone else has see this. The leak, I think, is comming from the coolant temp sensor, or the thermostat neck/housing. I took the sensor out and to my supprise there is a tapered bore and an O-ring to seal it, not a tapered pipe thread like I expected. The O-ring looked OK but I put a little black RTV around the O-ring and put it back in. I still get coolant drips blown back the valve cover by the fan but only like every other time I run it. It could be the gasket under the thermostat neck?? It is not the upper radiator hose or clamp, no coolant detected here. There is a head bolt near the sensor, does this bolt penetrate the water jacket??? I can't tell if coolant is comming around the bolt head or not, when it leaks the hole area is wet on that corner of the head. Do the bolts that hold the water neck down penetrate the water jacket??? Could the leak be comming up through these threads??? Has anyone seen a similar problem or can give me any hints, the big one for me is why dosen't it leak all the time???
Thanks for the help

 

Something to check....I had the overflow hose on mine leaking. It would blow back right there in that area, and on the air filter box. I cut about on e inch of hose off and put a clamp on it. Been fine ever since.

 

I had an intermittent coolent leak from on the right side - somedays would leak the size of a plate and the next day not at all, it was not dependant on the truck being warmed up or ambient temp outside, just leaked randomly.
Since the truck is still under warrenty took it in - the dealer said it was a Y tube and needed tightening. Hope that helps...
Erik

 

i had a small leak, that would drip on the driveway, just sometimes, not all, would blow back on the motor.never did it all the time. turned out to be my water pump.it was leaking in the shaft seal, if you looked down on the pump, where it bolts to the engine block, i could see alittle staining from the coolant.
funny thing is the pump was never wet, just stained the areas where it leaked.i changed out the pump, and all is good.might not be your problem, but some thing to keep an eye on.

 

pullin hard,
I think you may have given me the info I need. I have seen coolant stains down around the water pump but I thought that it was just running down there from up top. But it could be the fan is just pushing the coolant that is leaking from the pump up to the top and makes it look like the temp sensor or the thermostat housing is leaking. I also see a drop or two sometimes down around the bottom of the AC compressor. I'll look closer at the pump now.

Erik,
I'll also check the clamps on the Y-tube.

vzdude,
Was the leak in the overflow tube right where it connects to the radiator, right behind the radiator cap?

Thanks for the help guys.

 

yup- right at the cap - kinda felt stupid after seeing it! hose looked good from the top, but the bottom bulged out enough to leak.