Use gasket sealant when replacing thermostat?

Status
Not open for further replies.
Joined
Dec 1, 2014
Messages
1,283
Location
California
I have a 2004 Tacoma truck with 158,000 miles that runs perfectly, but I'm sure it's likely running the original thermostat. I'm contemplating changing my thermostat just for maintenance reasons - is this a smart idea? If so, I'll change the coolant as well, of course.

I guess I'm "old school" in that I typically think most gaskets and/or surfaces should have a sealant of some type to really be assured of not leaking. In my case, my thermostat "gasket" looks like a rubber o-ring from the picture - http://www.oreillyauto.com/site/c/detail/FEL0/35445.oap?pt=C0420&ppt=C0331 but I'm still wondering if it's a good idea to use some form of sealant between the water inlet housing and the block? If so, can you give me a recommendation for a sealant?

Thank you,
Ed
 
Any kind of instant gasket or permatex or hylomar would be a good idea to complement the o ring,they don't always seal perfectly by themselves
 
Originally Posted By: Trav
Nothing extra necessary, just install it with the o-ring.

+1.

To that, I would add that it is an excellent idea to use a non-marring tool to scrape off any corrosion that has formed on the O-ring's sealing surfaces.
 
O-rings rock, why didn't they do that 50 years ago?

I like the o-rings with groove in them, that you stretch over the t-stat flange.
 
Originally Posted By: eljefino
I like the o-rings with groove in them, that you stretch over the t-stat flange.

That's exactly what the OP has.
 
Gaskets suck. In all but a few applications (head gaskets, duh!) sealant is world's better. Even the OEMs do it.

On the other hand, o-rings rock. I put a light coat of silicone grease on o-rings and install. Do not use any other type of sealant in the application you are talking about.
 
Originally Posted By: Tegger
Originally Posted By: Trav
Nothing extra necessary, just install it with the o-ring.

+1.

To that, I would add that it is an excellent idea to use a non-marring tool to scrape off any corrosion that has formed on the O-ring's sealing surfaces.


Can you give me an example of a non-marring scrape tool you like?

Ed
 
350,000 miles, four thermostats (always put a new one in during timing belt service) in my 89 Honda. Never used sealant, just the o-ring. Never had any corrosion to scrape and never had any leaks.

Why make the job more complicated than necessary?
 
O-rings are designed to work without sealant. They depend on internal pressure to develop a seal, and must remain free-floating. Keep the groove clean and lightly coat the o-ring with silicone.
 
unless the sealing surface has a scratch, no need for a sealant. O-rings are so much better than gaskets. Seems this is a Toyota thing but maybe other car makers use them now too.
 
Originally Posted By: Ed_Flecko
Can you give me an example of a non-marring scrape tool you like?

A popsicle stick.
 
I've bought too many bad thermotats and radiator caps (and other parts)to change one that works for one that may work.
 
Originally Posted By: Lapham3
I've bought too many bad thermotats and radiator caps (and other parts)to change one that works for one that may work.


+1

Except I don't buy no name or cheap aftermarket parts, but I still wouldn't replace a thermostat or radiator cap as "routing maintenance".
 
I've always changed the thermostat and radiator cap every other coolant change.
Always OEM parts.
On the four Honda's I prevoiusly owned the old 'stats felt sticky compared to the new, working the plunger by hand.
 
Last edited:
Take off your old one and see if there is any gasket material. If not, then don't add any. Of course, it goes without saying, buy an OEM thermostat.
 
Originally Posted By: Trav
Nothing extra necessary, just install it with the o-ring.
No sealant required. O-rings are almost fool proof. Parker four bolt flanges use an o-ring and handle 3000 PSIG.I never saw one leak during twenty some years in power generation. You clean the surface carefully, install a new o-ring, torque to specs and the unit comes back up without a problem.
 
Status
Not open for further replies.
Back
Top