I need to replace the gasket around the thermostat b/c its leaking. I have never done this so any advise would help. So far all I know is I don't know how to do it. I tried last night and it didn't seal properly and now is leaking even more than it did before I started. How do I go about draining the fluid in the block so I can clean and seat the new gasket without having coolant spilling over and messing it up?

 

Drain about a gallon of antifreeze from the radiator. You will find a drain **** on the bottom of the radiator on the engine side. Disconnect the radiator hose from the thermostat housing. You will loose the water in the hose. Remove the thermostat housing. Clean the housing and the manifold surfaces of all gasket and RTV. Be sure the surfaces are clean and dry. The thermostat goes in the groove of the housing, be sure the radiator side is in the housing. Apply a thin coat of sealer to the housing and the intake surface. I like copper coat for this but RTV will work. Install the gasket on the housing and set the housing on the intake and start the bolts. Insure that the thermostat stays in its groove, this is why I prefer copper coat as it will hold the gasket in place on the housing and that will keep the thermostat in the groove. Tighten the bolts according to specs. Reinstall the radiator hose and put in the coolant. Remember the gasket goes between the intake and the thermostat not between the housing and the thermostat. Most problems are caused when the thermostat is not kept in its groove.

 

Seal thank you once again, I will attempt this again tomorrow. I think with all the coolant that leaked out over night I might not have to drain any. The only thing that makes me confused is that when I pulled the housing off the first time the thermo was on the manifold and not in the housing connected to the tube. The seat for the thermo was on the manifold. The gasket that the parts store gave me was the wrong size. So I went back and its the one they show I should need. So I bought another and one slightly bigger. I don't know if its just b/c its not the factory motor in it. Just so I have this straight Intake>Gasket>Thermo>housing

 

I will admit that I have not seen every manifold out there but I have never seen an intake with a seat/groove cut in it for the thermostat. If you have one then the thermostat should go in the provided seat/ groove. The main thing is the gasket can not be between the thermostat and its seat/groove/recess.

 

if all else fails you could use JB Weld instead of a gasket. even if you do have a gasket you still need something to seal it.

 

Why does something that sounds so simple have to give me issues, ARGH. Oh well. I will try and attempt it again today. I bought some silicone gasket maker. I hope one of these gaskets is the correct size. I need to get this done b/c the temp is going to drop from 50 degrees today to almost freezing by tomorrow night.

 

I just did the thermostat on my truck like 4 days ago.
Its pretty simple.

1. Take and drain some fluid out of the radiator. (or do like me and just put a drip pan under the truck and clean up what you spill because I didnt want to fart around draining the stupid thing. )

2. Remove the two bolts holding the thermostat housing onto the intake.

3. Remove the old thermostat and replace with a new one. (since you are in there you better just replace it. I like the fail safe ones personally )

4. BEFORE YOU DO ANYTHING ELSE! Scrape the manifold and the thermostat housing with a flat blade screwdriver or whatever you have to get them clean. If you dont get ALL of the old sealant off it wont seal correctly.

5. Once you have the manifold and the thermostat housing all clean down to metal, then set the thermostat into the manifold.

6. Take your thermostat gasket and apply blue RTF to both sides of the gasket. A nice bead around the edges on both sides.

7. Place the gasket covered in RTF on the manifold over top of the thermostat and then slowly seat the thermostat housing down onto that.

8. Reinstall the two bolts you removed, snug to spec.

9. Refill your radiator before starting.


Hope all goes well, stay warm!

 

What about replacing the water outlet? Mine is leaking also(put a new t stat and gasket in this summer. Iam planning to replace the water outlet and upper hose when i do this. If it's leaking and it is below the fins in the radiator does it still need to be drained?

 

Well round two is so far so good. I used a turkey baster to remove enough coolant to allow me to work. I have everything put back together and so far no leaks. How long should I wait until I fire it up? I want that gasket silicone to dry before I mess it up.

 

@tooltime - Ehh Im not really sure but I would think that you would be fine. If you spill any just clean it up. lol

@pollocksn - Your RTF tube should say on it the dry time but given the cold temp it can take longer. Give it 1 hour longer than it says on the RTF tube. Then youll be fine Im sure. You can always speed up the process by using a hair dryer or heat gun. ( dont get to close )