Cris

I just finished installing the intake manifold on my '66 small block. I sealed the end gaps with Permatex Ultra Grey RTV. Whenever I use an adhesive, I run a test bead on an index card to double check the cure. After the recommended 24 hour cure, the test bead was uncured, it had not even started to cure! (I'm an engineer by trade and have worked extensively with RTV's. The Permatex RTV's cure with moisture and the death of a good cure is heating an RTV and driving the moisture out prematurely.)

I then went out and bought Permatex's Blue RTV to try a test cure against the Ultra Grey. I even monitored the humidity and temperature. Sure enough the Blue RTV cured normally, the Ultra Grey did not even set up. Bottom line, I have to tear out the intake to replace the Ultra Grey RTV. (And I am trying to get ready for a race.) Uncured RTV floating around the inside of an engine would not be a good thing. I have a hard time believing Permatex made a defective batch. Anyone seen this problem before?

Twin_Turbo

I never use the grey, always the black or red, sometimes blue.

Fast Glass

RTV is a time controlled item in aviation. I think we keep it on the shelf for 12 months before we toss it in the trash. Even if the tube has never been opened. Now if it was a freshly bought tube, I would take it back to the place you bought it with the receipt, and the receipt for your new intake gaskets and ask for your money back.

Matt Gruber

i tested some 10 year old RTV and it took a month to cure.
When i changed to oil pump on my 67 galaxie i used it on the oil pan since i only drive it once a month. worked OK.

Rebel w Cawz 2 B

Yeah, it shouldn't be too old. "First in, first out" (FIFO) has to be adhered to at the manufacturer sometimes too, though. I've seen (haven't we all?) where that rule wasn't adhered to.

Check the date on the tube. Do you still have the receipt?

"Some" RTVs seem to last longer than others. Ever seen the "clear" stuff come out of solution when a tube is first opened? Hmmm.

Just a thought.

Jeff
:flag

Cris

I haven't looked for the receipt, getting a refund for the $5.00 RTV is small potatoes compared to the hassle of pulling the intake off again. Doubt they'll send someone over to take care of that!

Most of the electronics companies I work for also pull any RTV's off the floor if they are more than 1 year old, although this is pretty conservative. I haven't looked at the fine print for a date on the Permatex tube. Seems like they should have a DO NOT USE AFTER X/X/XX in big letters. If Budweiser can do it, why can't Permatex?

ralph

I've used the gray once and it leaked. I found it didn't adhere to things as well as the black. So now it's black only for me.

WashingtonRacer

Are there any inherent differences between the Red and black? or even blue?