holeshotmoe
Well-known member
Are 1G and 2G valve cover gaskets identical? Sticking to OEM to reduce the variables, part numbers for the perimeter and wells (1G, MD125939 & MD125940) and (2G, MD186784 & MD186785).
So are they different in dimensions, material formulation, or did they just revise part numbers with the models? I noticed the rubber half moon plug numbers are the same. I looked around a lot! Everyone (e.g., here, tuners, et al) seems to agree the DOHC covers are interchangeable, heads are interchangeable. But most stores and aftermarket brands distiguish the gasket p/n's too.
I'm asking because I have never had a 4G63 valve cover that didn't leak after a year or so (most times less). I started to see trails down the sides of the head. This was true on 90 & 91 GGSXs (NTs), two VR4s with multiple swapped heads, and a 90 EGSX. BTW, and oddly, I've never found any leaks into the plug wells. Also, all of my covers have been 1Gs. Some sat assembled for months before being started. I only used sealant at the cam seal cap edges as per svc manual.
I usually use OEM, but I've tried felpro and others. Always, I've cleaned the head surfaces and cover grooves spotless, using paint thinner, alcohol, acetone, washing with soap and water first, on and on. These cars were daily drivers, but definitely doing some pulls. Is there a secret to perfectly sealing them? Are these gaskets maintenance items after 10K miles? So tempted to try a thin film (not gobs) of RTV, or hardening gasket sealer all the way around. Compare with oil pan sealing techniques.
So are they different in dimensions, material formulation, or did they just revise part numbers with the models? I noticed the rubber half moon plug numbers are the same. I looked around a lot! Everyone (e.g., here, tuners, et al) seems to agree the DOHC covers are interchangeable, heads are interchangeable. But most stores and aftermarket brands distiguish the gasket p/n's too.
I'm asking because I have never had a 4G63 valve cover that didn't leak after a year or so (most times less). I started to see trails down the sides of the head. This was true on 90 & 91 GGSXs (NTs), two VR4s with multiple swapped heads, and a 90 EGSX. BTW, and oddly, I've never found any leaks into the plug wells. Also, all of my covers have been 1Gs. Some sat assembled for months before being started. I only used sealant at the cam seal cap edges as per svc manual.
I usually use OEM, but I've tried felpro and others. Always, I've cleaned the head surfaces and cover grooves spotless, using paint thinner, alcohol, acetone, washing with soap and water first, on and on. These cars were daily drivers, but definitely doing some pulls. Is there a secret to perfectly sealing them? Are these gaskets maintenance items after 10K miles? So tempted to try a thin film (not gobs) of RTV, or hardening gasket sealer all the way around. Compare with oil pan sealing techniques.
