S_Ellzey

Hi Guys

I have been fighting with a YS 140 for a while and the biggest problem I am having is with the high temp silicon rubber that is used to seal the MACS header and tube together. It burns off in 3 runs. MACS does not specify which one to use, only that you should use it. So far Permatex high temp turns to a gray powder in three runs, and Permatex Ultra Copper is only doing slightly better, I am still done after 3 flights, but you can tell that it was RTV in a former life.

There is plenty of air flow through the engine compartment so I don't think that is it.

Is any one else having this problem, and does any one know the cure for it.

Thanks,

Steven

Kaos Rulz

Steven,

Use the clear RTV. It'll hold up to the heat. Just make sure everything is wiped clean and free of oil before applying.

Hobbsy

My Feedback: (102)

Make sure the clear does not contain acetic acid, smells like strong vinegar, it's highly corrosive. most silicon adhesives contain it.

Ernie Misner

Of all the high temp silicones I have looked at, I think the red (permatex) had the highest heat rating.... up to 650 degrees. Most modeler seem to use the red for muffler work.

How permanant do you want that union to be? JB Weld is the high temp equivalent of epoxy.

How about using a piece of Aerotrend (comes in all sizes) between the two joints?

Ernie

S_Ellzey

The joint is between a block that threads into the cyclinder head and a flex tube that threads into the block. JB-weld is a bit more permenent than I would like. I would not be able to remove the header with out burning out the JB-weld.

I am bit suprised that the clear RTV can take the temp better than the high temp stuff. Have you used it in this application?

Thanks,

Steven

Kaos Rulz

.............I use it on all my engines and after 20+ years, I haven't noticed any corrosion. At one time I tried to burn some cured RTV up with a torch----couldn't do it. It'll stand up!

S_Ellzey

Thanks, I will give it a try.

Steven

Ernie Misner

Hi Steven,

............I am bit suprised that the clear RTV can take the temp better than the high temp stuff. Have you used it in this application?.....................

We're talking about RED rtv silicone here, not clear. Go to the auto parts store and read the info on the various colors of silicone. Red is the highest temp, way up there!

Ernie