Northstar Engines and System Technical Discussion Discussion, ETC Crossover Leak in Cadillac Engine Discussion; 94 ETC. Leaking coolant where crossover joins head. Pressure tested at 15psi has steady drip. Is this a gasket or ...
The gasket at the joint is a plastic substraight with a molded silicone bead. Relatively easy to replace, actually.
Even easier is to simply refresh the cooling system with fresh 50/50 and install two tubes of the BarsLeaks "golden seal" powder or 6 of the GM coolant supplement pellets installed into one of the radiator hoses NOT the surge tank. The sealer will easily seal up a seepage at the coolant crossover gasket and prevent any further repair. Possibly there is a scratch on the gasket surface or something like that and the original dose of the cooling system sealer at the factory prevented a leak all this time. The sealer/coolant supplement needs to be replenished just like the coolant itself.
Nothing to loose trying this as the coolant needs to be refreshed occationally anyway and the sealer should always be installed. If it seals up the seepage there is little or no risk as the joint will never fail catostrophically...i.e..the plastic substrainghted gasket is very robust and will not ever "blow out"...it will just seep if the silicon bead does not seal. In fact, if you do take it apart, the surest fix at that joint is to clean up the parts, reuse the original gasket and just apply a thin skim of RTV to each surface/side of the gasket and reassemble. Allow the RTV to cure overnight before refilling the cooling system and it will be fine forever.
Thanks for the replies sts96 and bbob ....Disassembled and found the aft/upper seal (by the EGR Valve) cracked. (Lasted 10 years and 140,000mi....good enough.) Cleaned seal surfaces and replaced all four seals with GM P/Ns 12562046 & 12562047. New 50/50 coolant and the recommended dose of pellets....Good to go. Thanks for the info........cm