I hate the water neck (thermostat housing)

[bennylava]

I recently did a coolant flush on my 94 GT, and to really get all the old coolant, you need to remove the thermostat. I dreaded doing it because I knew the trouble I would get. I have dealt with this awful water neck (aka thermostat housing or elbow) on the 302 before. When I did this job 12 years ago, I broke the stock one trying to get it tight enough to stop leaking.

Luckily the Doorman waterneck (with gasket) I got as a replacement 12 years ago, somehow managed to seal up the leak. But after this recent flush, upon reinstalling it, of course it leaks.

So I thought "Dorman worked before, maybe it will work again". I thought maybe the new water neck will be flatter, or perhaps it's just the gasket they come with. But no such luck. Now instead of leaking from the side, it's dribbling water out of the bottom.

I don't know what to do. My best theory is it needs a thicker gasket. Could doubling up gaskets help? Or maybe I'll have to make my own gasket out of god knows what.

 

[Terrorist 5.0]

I recently did a coolant flush on my 94 GT, and to really get all the old coolant, you need to remove the thermostat. I dreaded doing it because I knew the trouble I would get. I have dealt with this awful water neck (aka thermostat housing or elbow) on the 302 before. When I did this job 12 years ago, I broke the stock one trying to get it tight enough to stop leaking.

Luckily the Doorman waterneck (with gasket) I got as a replacement 12 years ago, somehow managed to seal up the leak. But after this recent flush, upon reinstalling it, of course it leaks.

So I thought "Dorman worked before, maybe it will work again". I thought maybe the new water neck will be flatter, or perhaps it's just the gasket they come with. But no such luck. Now instead of leaking from the side, it's dribbling water out of the bottom.

I don't know what to do. My best theory is it needs a thicker gasket. Could doubling up gaskets help? Or maybe I'll have to make my own gasket out of god knows what.

Aftermarket (especially chrome) water necks are known to not be that flat and leak. If you still have your stock one, use it.

You could use some sealant, but I try to do that as a last resort. You shouldn’t need any. Are both mating surfaces clean? Do they have any deep scratches?

 

[ttocs]

I use a gasket and a line of RTV around the edge myself.

 

[bennylava]

Aftermarket (especially chrome) water necks are known to not be that flat and leak. If you still have your stock one, use it.

You could use some sealant, but I try to do that as a last resort. You shouldn’t need any. Are both mating surfaces clean? Do they have any deep scratches?

The new dorman water neck is likely pretty flat, but I suppose I could try smoothing it further. There is some small pitting on the intake, but to me, it doesn't seem like a problem. Because when I changed from the old dorman to this new dorman waterneck, the small stream of coolant that was spewing out changed locations.

It was clearly only coming out of the top right hand side, now it's doing it from the bottom. The top right has stopped leaking. I might look into that "make your own gasket" rubber. From searching this site, it seems like other people have gone through 3 or 4 different gaskets until one mysteriously started working.

 

[07GtS197]

Put a straight edge on the intake and water neck. One of them is likely warped. And as Scott said rtv along with the gasket will likely fix the issue.

 

[RAU03MACH]

Trouble sealing the thermostat housing.

I have tried twice to install the water neck and new thermostat and got a leak each time. I used the following procedure: - put sealant on the water neck - put gasket on the water neck - put a little sealant on the water neck where the thermostat fits to hold it in place during assembly -...

www.sn95forums.com

how many times are we getting this
we gave info on how to repair

 

[bennylava]

Put a straight edge on the intake and water neck. One of them is likely warped. And as Scott said rtv along with the gasket will likely fix the issue.

I guess you're pretty screwed if the intake is warped... I don't see an easy means to sand it flat while it's attached to the engine.

 

[07GtS197]

I guess you're pretty screwed if the intake is warped... I don't see an easy means to sand it flat while it's attached to the engine.

I’m sure if you get a file in there at the right angle it can be done.

 

[ttocs]

I was going to say the same thing. Stuff a rag in the intake for both water/air openings and it should not take long.

 

[CobraRGuy]

If you're going to try to file the surface of either piece flat, avoid using a bastard file. I have a long wide flat file that is single cut, not cross cut (bastard), for just such purposes.
Also, I've never had a thermostat housing leak on my 351W, and I believe they use the same part as the 302. You should still be able to buy these new from Ford. I use a FelPro gasket with Permatex Permashield Gasket Dressing & Sealant #85420. Permatex used to call this Hylomar HPF (High Performance Formulation) but renamed it. This is a very modern non-adhesive non-hardening sealant designed primarily for sealing paper gaskets, and it works fantastic. I been using this on almost every single paper gasket in my engine, even the FelPro head gaskets, for many years, and I've never had a leak. A huge benefit of this stuff is that I can reuse paper gaskets because they don't stick to the pieces, they just easily pull off in one piece. Use nitrile gloves and smear it onto both sides of the gasket with your fingers. Coat the inside edge of gaskets as well. The sealant soaks into the paper, effectively eliminating seepage. Sometimes a small amount will get squeezed out of the joint and be visible as a blue bead around the outside when the parts are tightened down. I use GoofOff to wipe it clean. Don't worry about a little bit of this getting into your engine because it is totally benign.
Make damn sure that the thermostat itself is seated properly in the water neck recess.
YMMV (Your Mileage May Vary).

 

[bennylava]

If you're going to try to file the surface of either piece flat, avoid using a bastard file. I have a long wide flat file that is single cut, not cross cut (bastard), for just such purposes.
Also, I've never had a thermostat housing leak on my 351W, and I believe they use the same part as the 302. You should still be able to buy these new from Ford. I use a FelPro gasket with Permatex Permashield Gasket Dressing & Sealant #85420. Permatex used to call this Hylomar HPF (High Performance Formulation) but renamed it. This is a very modern non-adhesive non-hardening sealant designed primarily for sealing paper gaskets, and it works fantastic. I been using this on almost every single paper gasket in my engine, even the FelPro head gaskets, for many years, and I've never had a leak. A huge benefit of this stuff is that I can reuse paper gaskets because they don't stick to the pieces, they just easily pull off in one piece. Use nitrile gloves and smear it onto both sides of the gasket with your fingers. Coat the inside edge of gaskets as well. The sealant soaks into the paper, effectively eliminating seepage. Sometimes a small amount will get squeezed out of the joint and be visible as a blue bead around the outside when the parts are tightened down. I use GoofOff to wipe it clean. Don't worry about a little bit of this getting into your engine because it is totally benign.
Make damn sure that the thermostat itself is seated properly in the water neck recess.
YMMV (Your Mileage May Vary).

Yeah that is one thing I noticed, the thermostat seats in the neck. Then the paper gasket ends up going between the thermostat and the intake. Because the hole in the gasket for the thermostat, is not as big around as the thermostat itself.

I wish there was an easy way to get it to stay centered in the neck while you're putting it back on. Cause you're right, it could slip down and get pinched and be the cause of a leak.

 

[94IndyPace]

Yeah that is one thing I noticed, the thermostat seats in the neck. Then the paper gasket ends up going between the thermostat and the intake. Because the hole in the gasket for the thermostat, is not as big around as the thermostat itself.

I wish there was an easy way to get it to stay centered in the neck while you're putting it back on. Cause you're right, it could slip down and get pinched and be the cause of a leak.

Ignore the coolant line part. Most don’t realize that the thermostat will lock into the housing.

 

[ttocs]

I thought if after you inserted the thermostat if you give it a slight twist it would stay in place?

 

[94IndyPace]

I thought if after you inserted the thermostat if you give it a slight twist it would stay in place?

Exactly it does

 

[Terrorist 5.0]

This must be for certain thermostats because mine didn’t lock in no matter which way I twisted it.

I saw people talking about twisting it to lock it in but I guess mine didn’t have that feature.

To answer above, no sealant should be necessary. If it’s still leaking with a new gasket then you gotta check if anything is warped. I put mine no sealant, and not a drop leaked.

 

[ttocs]

oh absolutely no sealant should be needed I always thought of it as a back up myself but I have never had a leak.

We had a similar situation recently where upon closer inspection of the neck it was found to have a small crack in it, might be the same situation here. Give it a very close inspection next time it is out to be sure there are no cracks.

 

[bennylava]

This must be for certain thermostats because mine didn’t lock in no matter which way I twisted it.

I saw people talking about twisting it to lock it in but I guess mine didn’t have that feature.

To answer above, no sealant should be necessary. If it’s still leaking with a new gasket then you gotta check if anything is warped. I put mine no sealant, and not a drop leaked.

Your name reminds me of that old video game, can't remember the name, where you had teams and everyone ran around shooting each other. You could be the taliban or something, and fight the americans. If they won, it would say something like "TERRORISTS WIN!!" ... LOL

 

[bennylava]

Well anyway, it seems that it stopped leaking after this last attempt to fix it. For anyone who searches this problem in the future, here's what I did:

Gently used a file on the intake (i don't think this actually did anything in my case)
Sanded the waterneck flatter using sand paper taped to a mirror (i don't think this actually did anything either)
Tried a third gasket, the MotoRad brand part number MG50EA, which is a peel and stick gasket. This might have fixed the leak
Only tightened to the recommended torque spec, which is 12-18 foot pounds. This might have fixed the leak, I may have been overtightening just enough to cause a slight bend in the waterneck.

 

[ttocs]

I was just thinking a light guide-coat on the spot you were making sure was flat would have been helpful. Of course I only have good ideas when the work is over. Congrats on the fix though the simple little ones like this that just when you think is fixed, you find it leaking again have been enough to make some people sell their car.....

 

[Daryl]

Same frustration recently. My last gasp try was to finally take it in the shorts and pay $35 for a Mr Gasket aluminum rubber molded gasket. But I was at my whits end and desperate. Thin coat of their gasket sealer on water neck side; let that set up 24 hrs; thin coat on the remaining (motor) side; install ever so gently using bolts as locator pins; hand-tighten to snug; alternate sides torquing down to the 18-20 ft lbs as recommended. THEN…. Let it set up and seal for 48 hours before dribbling distilled water into the upper radiator hose connection port to check for leaks again. No leaks? Button that bitch up, top off the radiator and call it done! Thank god and I hope I NEVER have to do it again! How can something seems so easy be such a PITA cluster-f*ck?!!