Is RTV really that different?

Joined
Jan 2, 2004
Messages
10,750
Location
California
So Toyota has 3 different kinds of RTV for engine/transmission sealing - 2 similar but different black RTVs and a orange one for transmission diff sealing. One of the black RTVs is is for oil pan/valve cover/camshaft housing applications, and the other is for water pumps and anything touching their coolants. I had the former RTV on hand, but I used it to seal the thermostat housing to the water pump but I also realized this part also leaked quite badly when I had Toyota Pink PHOAT coolant and it was sealed with the oil pan RTV. I plan on filling the cooling system with the old red coolant which has no organic acid inhibitors, but will I be fine or should I reseal this joint with a sealant that can do OAT coolants?
 
Your Toyota uses RTV to seal the thermostat housing?

And yes, as someone who worked with various silicone materials in the past, there are all sorts of different ones.
 
Well, Toyota's suggested RTV - basically repackaged ThreeBond 1282B is $80 list, I have the friends discount with the counterman at the local Toyota dealer - Permatex claims The Right Stuff domestic and import formulas are coolant resistant - seeing how the black "domestic" formula is specified by GM and Dex-Cool is agressive on elastomers. I might get that, a new O-ring to seal the thermostat to water bypass bridge junction and call it day...
 
Originally Posted By: nthach
Well, Toyota's suggested RTV - basically repackaged ThreeBond 1282B is $80 list, I have the friends discount with the counterman at the local Toyota dealer - Permatex claims The Right Stuff domestic and import formulas are coolant resistant - seeing how the black "domestic" formula is specified by GM and Dex-Cool is agressive on elastomers. I might get that, a new O-ring to seal the thermostat to water bypass bridge junction and call it day...


So it doesn't spec RTV for the thermostat then?
 
Originally Posted By: kschachn
Originally Posted By: nthach
Well, Toyota's suggested RTV - basically repackaged ThreeBond 1282B is $80 list, I have the friends discount with the counterman at the local Toyota dealer - Permatex claims The Right Stuff domestic and import formulas are coolant resistant - seeing how the black "domestic" formula is specified by GM and Dex-Cool is aggressive on elastomers. I might get that, a new O-ring to seal the thermostat to water bypass bridge junction and call it day...


So it doesn't spec RTV for the thermostat then?


On my engine, there is a thermostat seal for the hose elbow to housing, a O-ring to seal the junction between the thermostat housing and front water bypass bridge, and RTV is used to seal the housing to water pump inlet junction.

I called the counterman friend at Toyota and they use FIPG 103, which is relabeled ThreeBond 1207B for water pumps and thermostat housings - Toyota states not to use this for coolant sealing, but ThreeBond says it's OK for long-life coolant(Toyota Red, not pink SLLC)
 
fwiw-
One thing many folks never understand about sealants is how it cures & they think RTV's are all the same just different colors. Some think that is to blend in with your engines color...lol Yuup!!
Very important to know how the sealant cures soft/hard, fast/slow, need air to cure correctly? Its a lot to understand too and why I simply go with what the job specs because where its being used is more important than anything I'm not smarter that the people who built the machine I know. Brands are in fact different due to patent laws even though many or most brands are close to one another they do differ just enough to screw a job up sometimes.
Its **** hard to beat Toy/ThreeBond and depending on how hard the job is I sure learned the hard way use it when they say too. Do I really want to do the job twice, I never do especially a big job when I learned the hard way to use the stuff!! Can't just learned on a thermostat...grrrr! So in that sense its worth every dime to me. Do I use Toy/ThreeBond everywhere? No' but I do use it more than I have to that's for sure.
Peace

Good place I found to learn about sealants here...
 
You may find that the OE and even service RTVs and anaerobic sealants also have fast cure times as part of their spec, which you the home mechanic may not need.

I've done fine with Permatex Blue, but it's been so long it's been with normal green antifreeze, not HOAT.

Surface prep is huge. I'd go for not just clean, but scuff the surface with some sandpaper then clean and dry with alcohol.
 
Permatex Ultra Black is what I've used lately with success and is the only one I know.
A couple of gasketless pans and diff covers and some drain plug saves.

The mechanic has to know if an applied goop needs to sit before mounting and/or be tightened in stages.

The automotive world is rich in slang. All I can think of is silicone sealer is household caliber.
Gasket makers are what they are. And RTV is for higher temperatures. There are so many examples.
Is that it?
 
Back
Top