Holler,

I have a little problem my coolant manifold's leaky.

So, I already got new pair of rubber o- ring on it... But can put on the rtv on it, like a little on it? Before put intake manifold.

You shouldn't need any RTV. With all surfaces clean and new o-rings that should do the trick. I suppose you could use a small amount of 518 but that's it.

The block surface often corrodes under the old O rings and even new O rings may not seal properly.

Wire brush the corrosion off as much as you can, clean the mating surfaces and put some Indian Head Gasket Shellac on the block surface before putting the new Orings in the grooves. Put some I/H on the manifold surface and install. Do not over-tighten the bolts, they will strip easily.

 

http://www.permatex.com/products/automotive/automotive_gasketing/gasket_sealants/Permatex_Indian_Head_Gasket_Shellac_Compound.htm