STILL with T-Stat Gasket Problem

94GTLaserRC · May 9, 2004

It's not like this is the first time for me.

BUT. I changed the gasket a couple of months ago, and last week, there started showing a small puddle of coolant on the water pump. SO, I decided to change it before the summer heat.

I changed the gasket yesterday, cleaned the intake port and water neck port really well, sucked the coolant out of that area, put a little RTV on the water neck side and pressed the gasket into it. THEN, put a layer of RTV on the intake side of the gasket, bolted it up, and waited about 3 hours to put any coolant back in.

I filled it up, put in a bottle of W/W ($7), got all the bubbles out, kept checkng the water pump...FINE.

I took it for a 5 minute test drive, and when I pulled up, COOLANT ON THE WATER PUMP dripping from under the neck where I just sealed it.

I dont know If I should let the RTV dry, THEN put the neck on, or put the neck on right away, then let it "dry into the crevaces" around the neck or what.

Im pretty sure I did everything right.. Should I DOUBLE THE GASKETS between the water neck and the intake or what??

ANY ANSWERS?

RC

Venom351R · May 9, 2004

wow that sucks. Its funny how things work, I have a crappy gasket on mine gooped w/ RVT seal and it dosent leak at all.

HoofnIt · May 9, 2004

What thermostat housing are you using? Is it the FRPP chrome unit? If so, I tried to use one on my last 5.0 and could never get it to stop leaking. I tried everything, including using two gaskets and also 'roughing' up the mating surface of the housing, nothing seemed to work. I got tired of changing it out, so I went back to the stock unit.

94GTLaserRC · May 9, 2004

HoofnIt said:
What thermostat housing are you using? Is it the FRPP chrome unit? If so, I tried to use one on my last 5.0 and could never get it to stop leaking. I tried everything, including using two gaskets and also 'roughing' up the mating surface of the housing, nothing seemed to work. I got tired of changing it out, so I went back to the stock unit.

I have the second WT gauge unit in the top bolt, so I dont want to change it.

Travis: When you "gooped it" and put it on, did you put seal it wet and tighten it, then let it dry, or did you let it dry, then put it on?

I went 2 months last time without it leaking, so I should be able to get it to seal.

Thanks
RC

Venom351R · May 9, 2004

94GTLaserRC said:
ITravis: When you "gooped it" and put it on, did you put seal it wet and tighten it, then let it dry, or did you let it dry, then put it on?

RC

I belive we put it on the housing and just let it dry when bolted on. I cant remember for sure b/c we did it a yr ago when we swaped out the old Intake for the cobra. I reused the same Thermostat gasket and needless to say it dident make it all in once peice from being taken off an old inake and put on the new one, I dont know how the hell its not leaking but that Sealent we used must be some good stuff.

jmuva44 · May 9, 2004

You should probably wait till its dry or else you will just be mixing coolant in with the sealant rather than the solid sealant blocking the coolant and acting as a gasket.

Also, when you remove the tstat do you know if the tstat is still centered? I had a problem once with the tstat sliding down in the housing so that the lip of it was sitting in between the tstat housing and the intake thus creating a leak.

What i've been doing to fix that is sanding the housing down on a flat surface to make sure there are not any inconsistancies that would create a bad mating surface, then I'd add a small bead of silicone between the tstat and the tstat housing and letting that sit for 15 minutes (this will make it seat properly and not slip when installing the whole thing). Then silicone both sides of the gasket evenly and immediately installing the whole thing to the intake. Then I let it sit again for about 15 - 20 minutes. Never had a problem since. Everything stays together, in alignment and the silicone is dry and acting as a sealant.

Good luck. I HATE working with the cooling system.....

94GTLaserRC · May 9, 2004

jmuva44 said:
You should probably wait till its dry or else you will just be mixing coolant in with the sealant rather than the solid sealant blocking the coolant and acting as a gasket.
.....

I meant if the RTV was dry when you put it on..Not Mixing coolant..That is a given, that it must be dry before the coolant is added.

Thanks.
RC

jmuva44 · May 9, 2004

oh sorry, but yeah still cuz it needs to bond to the intake.

1105 · May 9, 2004

RC, I just put a new t-stat housing on a few days ago, just used a hell of a lot of RTV on it because I didnt have a gasket and I'm not getting any leaks... Of course the intake was off my car and sat for 2-3 days before it got put back on. I used the red high temp RTV and I know it was dry when I fired up my car... Maybe something you might want to try. Let it sit over night or something.

hillie16 · May 9, 2004

My brother is a mechanic, and he brought some stuff he uses at work when I did mine, it's red and it sprays on. Sprayed it on one side, stuck the gasket to it, sprayed it on the other, and put it together. Let it dry overnight. We had to take it back apart for some reason, and it shredded the gasket to pieces when we pulled it apart. I have NO LEAKS with this stuff. I'll try to find out what it was.

94GTLaserRC · May 9, 2004

Here is the scoop....

I bought a new Tstat (only $4) and gasket. Took the stuff apart again, and cleaned everything.

1. Put the tstat on centered with a bead of RTV and let cure for about 15 minutes.
2. Put a thin film of RTV around the housing, but a little thicker at the bottom, and then worked in the gasket.
3. Smoothed out the bottom to even out the bead of RTV.
4. While that was sitting, I cleaned the intake port.
5. "Roughed" up the bottom 1/2 of the inlet.
6. Vacuumed it out and dried it well.
7. Inserted the screws through the holes of the housing and in to the inlet on the intake, but not letting the gasket touch the intake inlet. (after about 20 min)
8. Tightened down both screws until the housing was about 1/2" away from the inlet.
9. Then I pushed up the housing onto the inlet ( I did this instead of pushing the housing up at the beginning and then trying to find the holes for the screws...I think when you do that, the housing slides around)
10. Tightened everything then put the bypass hose and upper back on.

I finished that at 5:30. It is now 6:40, and I need the car in the AM, so Im going to fill it back up with fluid. I think that should be long enough, since the RTV was already slightly firm when put it back together at 5:30..

Wish me luck

RC

1105 · May 9, 2004

I put the RTV on then immediatly put the bolts through the holes, screwed it a little onto the intake, then pushed the t-stat housing on then tightned upthe bolts all when the RTV was still wet.

Hillie, I know that stuff your talking about, used it to hold the gasket to my elbow and the upper to lower gasket inplace. Stuff works great.

94GTLaserRC · May 9, 2004

Thanks Zach for your "serious" posts this time

CHANGE OF PLANS.

Im gonna just walk to work tomorrow so that the gasket/housing has a full 24 hours to sit. I was also able to rig up a 1/4" hex screw to my ratchet so I could tighten the bolt better than if I just used the allen wrench.

RC

1105 · May 9, 2004

94GTLaserRC said:
Thanks Zach for your "serious" posts this time

I'm always serious RC

jmuva44 · May 9, 2004

RC....it should be good by the morning. But I understand that you just want to make sure it is done right. I only let mine sit for like two hours and drove it away and it has been fine since. I can imagine that 12 hours would be more than sufficient. Either way, I hope it works for ya.

urban96 · May 9, 2004

man i feel lucky after reading all you guys problems. last year when i changed to a 180 thermo i just cleaned off the stock gasket, and used a little bit of silicon to hold the thermostat inplace in the housing and used a cheap paper gasket that i got from pepboys and havnt had a leak yet. maybe the area on your lower intake where it bolts up isnt perfectly flat

94GTLaserRC · May 9, 2004

urban96 said:
man i feel lucky after reading all you guys problems. last year when i changed to a 180 thermo i just cleaned off the stock gasket, and used a little bit of silicon to hold the thermostat inplace in the housing and used a cheap paper gasket that i got from pepboys and havnt had a leak yet. maybe the area on your lower intake where it bolts up isnt perfectly flat

I think it's actually that chrome water neck...There have been many reported issues with that..mainly the top bolt hole leaking and the screw in bypass nipple. (the stock one is welded)

If this doesnt work, Ill change the housing and try to polish a stock one up.
Thanks
RC

Badlilstang · May 9, 2004

94GTLaserRC said:
I think it's actually that chrome water neck...There have been many reported issues with that..mainly the top bolt hole leaking and the screw in bypass nipple. (the stock one is welded)

If this doesnt work, Ill change the housing and try to polish a stock one up.
Thanks
RC

Although I didnt read all the posts.. Ill tell you right off dont use that chrome water neck.. I went through the same crap and could never get it to stop leaking.. even my ford suplier told me they are known for that issue.. I took my stock one and did a little polishing.. I use a small amount of silicone on the lip the thermostat sits on and put the thermostat in place.. I allow this silicone to dry.. this holds the thermostat in place.. if the thermostat slides down when installing it will either leak or crack the water neck ( if cast ). I used a thin layer of RTV silicone on each side of the felpro gasket then installed it... I let it sit for 2-3 hours befor I attempt to put any water in it.. I havent had a problem since and ive repeated this on my freinds cars with no problem.. You can also try taking the water neck to a machine shop and have them surface where the gasket sits... this will make sure its flat. Good luck man.. I know its a PITA.

94GTLaserRC · May 10, 2004

I dont have the stock one, but as I said above, I have a cast one from Disc Auto that has an opening in the top. If this doesnt work this time, I will polish that one up and use it.

Thanks
RC

Venom351R · May 10, 2004

hillie16 said:
My brother is a mechanic, and he brought some stuff he uses at work when I did mine, it's red and it sprays on. Sprayed it on one side, stuck the gasket to it, sprayed it on the other, and put it together. Let it dry overnight.. I have NO LEAKS with this stuff. I'll try to find out what it was.

Oh yeah I know what you mean, Ive used that before as well, really good stuff

STILL with T-Stat Gasket Problem

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