RTV silicone?!?!

[Flying_gage]

Hey all,



Just replaced the lower intake gasket on the wife's 99 suburban. Done this before, (different chevy 350) so I am familiar with using too much RTV for the valleys... Well, I bought Permatex Ultra Copper High Temp and applied it. Had just a hint of "squish" factor as I torqued it down in 3 steps. Then I went on shift at the fire dept and let it sit for close to 48 hours. Got it all together and fired it up and I had a river of anti freeze down the back of the motor... F**K!



Took it all apart and lo and behold the RTV hadn't set up in the rear valley. It was still slimy. The front had set up but was still pretty soft.



The steps I took were to scrape the old stuff off, the I took and wire wheel to it, then I wiped it down with acetone no less than 6 times till I had nothing on the towel.



My question is this, is the acetone to blame? I always thought it didn't leave a residue? Is it to blame? Or, (less likely) did I get a bad tube of permatex? Help me out here. Also let me know if you have any favorites for this type of stuff.



Thanks in advance,

Pete

 

[ryecreek]

RTV stands for *room tempature vulcaniving*

maybe they got in a hurry

 

[omlambu]

I always use a product called Right Stuff I put every thing together right after application and never had a problem.

 

[B.G. Smith]

Done the intake gasket on a few small blocks in my time. I never used anything on the gasket but wheel bearing grease on both sides. I did glue the end pieces in place to keep from dislodging them in the process of installing the intake. bg

 

[PToombs]

If I put any sealer on, it's Ultra Copper RTV. I love the stuff. I've used it on exhaust gaskets, fuel stuff, everything. Always works.

Maybe the ambient temp was too cold and it didn't set up in the rear? Either that or a bad tube of it. I usually use a fine film of RTV and the gaskets in those spots.

Extra safety factor.

 

[Flying_gage]

Hmmm. Well I let it sit for 48 hours prior to starting it. I am thinking that by using the acetone there was a reaction? Literally it was still slimy when I pulled it back off.



Off to the autopart store to get some brake cleaner... .



Thanks all.

 

[B.G. Smith]

Even if the stuff you used didn't set up you should not have had a coolant leak. Better check the intake gaskets before you go back with it and see if you can detect a fault or see where a hole was not aligned. bg

 

[jakprince]

Are they plastic gaskets like they put in the 3. 1 v6

 

[chipster]

Hmmm. Well I let it sit for 48 hours prior to starting it. I am thinking that by using the acetone there was a reaction? Literally it was still slimy when I pulled it back off.



Off to the autopart store to get some brake cleaner... .



Thanks all.

I`ve been using acetone to clean surfaces before applying rtv for 30 years. NEVER had a problem. must have been a bad tube of rtv. I have had a few tubes of rtv that didn`t set up right. :-laf:-laf

 

[Skydiver]

I`ve been using acetone to clean surfaces before applying rtv for 30 years. NEVER had a problem. must have been a bad tube of rtv. I have had a few tubes of rtv that didn`t set up right. :-laf:-laf

Same here, I agree.

Store rtv in a zip-lock bag in the shop refridgerator.

Flying Gage, was your rtv new and did it get left in a hot vehicle?

 

[Hoefler]

If it didn't start leaking until you started it, I would suspect the fitting that goes to the heater core. They tend to corrode significantly and break off. It could of cracked when it was disassembled and you did not notice it.

 

[Flying_gage]

BG:

I was on the same track as you when I was taking it apart, not knowing how it could have leaked like that. Well, it looks as though in my rush, I didn't get the last bolt in the rear tightened on the last set. Therefore the gasket was not completely seated...

It's back together and all should be well now!

 

[rbattelle]

I notice you're in Illinois. Been pretty cold there - maybe too cold for the RTV to set up? Like Skydiver says, best place to store RTV is in the fridge. I think if the ambient temperature is below ~50°F it'll never set up.

Ryan

 

[jwgary]

Also if you put it all together too quickly (especially if it's cold) the RTV might not have enough time to react with the air. RTV sets by pulling moisture from the air. If you have too large of a bead or you assemble too quickly, you can get where you have the stuff where it will not set.