Leaky 302/5.0 water neck

[jimschulz]

Want to see if anyone has a suggestion on a coolant leak I have on my 5.0 explorer motor. I had the same issue with the origional 302 that came out before the explorer swap. The water neck seems to leak ever so slightly from the water neck/thermostat housing. It doesn't leak alot just a seep. When it sits un started for a month or two during the winter there will be a pool of antifreeze on the timing cover. I have tried a different water neck, new gasket, RTV sealant and checked that bolts are tight. Has anyone had this issue with the 5.0/302 water neck? And if so, what were you able to do to stop it.

 

[Rustytruck]

does your water neck have a step where the thermostat sits? is the step deep enough so the thermostat sits below the sealing surface? try putting the thermostat in the water neck and gluing the gasket on top so the water neck cant slip down and foul the seal.
try the bolts through the water neck and into the intake manifold without the gasket and thermostat to make sure the bolts are not bottoming out. the only time I had issues was a chrome water neck with the O ring seal they didn't cut the step for the thermostat too shallow it wouldn't seal.

 

[DirtDonk]

Same here. Never had a problem with the later model intakes or covers. Just the early ones and especially those pesky chrome ones.

 

[jimschulz]

Yeah, I tried one of the O-Ring style necks and it wouldnt seal at all. I've thought it might be the neck casting wasnt quite level. I may try doing a double gasket but it seems that would actually encourage seeping...

 

[TX-ZACH]

I had this issue and went to autozone, walked back and picked out 3 different necks. I think the one that worked was a 5/8ths inside id and fit snug enough for a hose clamp to seal. I'll check to see if the receipt and bag is still in my garage.

I beleive the issue was the neck that was on there was a slightly larger inside ID so that when the hose clamp snugged it either cut a pin hole or allowed enough gap with pressure to seep.

 

[blubuckaroo]

Check the gasket surface of the thermostat housing with a straight edge. Overtightening it may have warped the bolt ears, keeping it from tightening squarely. I've had to use a big flat file to straighten them up.

 

[TX-ZACH]

I am reporting back that still have a leak and now not sure where now other than the seal at thermostat. After researching this it seems a common problem. The housing is not chrome or painted so next step is to try a new gasket set up. Curious if the OP figured yours out yet.

 

[SevenT]

I have used this trick for 20+ years on the water neck. Take your water neck off of the intake. Clean the mounting surface thoroughly. Install the thermostat using a zip tie and a 16 penny nail through the front of the water neck (loop zip tie through the bell at the end of the thermostat and anchor with nail across the hose opening. Install gasket with sealer of choice (I use Indian Head gasket sealer) and set it aside to dry. When you install the water neck the thermostat will not slide down and ruin the seal. Cut the zip tie and pull out of thermostat. Good luck.

 

[lars]

Worth noting is that the intake manifold gasket is right above the water neck, and if it leaks it will dump coolant right down in the same spot as a leaky water neck gasket. The popular Fel-Pro paper gaskets are notorious for this. I chased a water neck gasket leak for a long time before realizing that it was the intake gasket leaking. Steel core intake gaskets solved the problem.

 

[papy]

Want to see if anyone has a suggestion on a coolant leak I have on my 5.0 explorer motor. I had the same issue with the origional 302 that came out before the explorer swap. The water neck seems to leak ever so slightly from the water neck/thermostat housing. It doesn't leak alot just a seep. When it sits un started for a month or two during the winter there will be a pool of antifreeze on the timing cover. I have tried a different water neck, new gasket, RTV sealant and checked that bolts are tight. Has anyone had this issue with the 5.0/302 water neck? And if so, what were you able to do to stop it.

Following! I am experiencing the exact same problem on my 96 explorer swap!