Those pesky front cover bolts

[DonaldSmith]

Friday I noticed coolant on the garage floor, from the leaking front cover bolts on my 47 DeSoto. This has been covered in a past thread, and several thread sealers were recommended, also some cone head washers and special bolts, which I don't have.

My last fix, teflon gas pipe tape and teflon pipe dope, gave out after a few months. Saturday I tore things apart and gooped the offending studs with some hardening type sealant, a Permatex knock-off. The car seemed cured, and I gave it a good run.

Last night, the fix failed, and coolant was dripping out again. I put a pan under the engine. This morning, there was a noticeable amount of coolant in the pan, maybe a quarter of a cup.

This morning I tore everything off again (radiator, fan and pulley, front engine mounting plate; I'm getting fast at this) and tried something new - o-rings.

I figured the leak started between the engine block and the front plate due to thermal expansion and contraction. In the past, it would leak when the engine was cold, but close up when the engine was warm.

So I loosened the front cover bolts and the one bolt through just the plate. I pried the plate away from the block (so I didn't have to remove the pulley and thing with the huge nut). I bought some o-rings just larger than the bolts, and fished them between the plate and the block at the three bolt holes into the water passage. (I taped each o-ring to a putty knife and held the o-ring in place while removing the putty knife. The o-rings stayed in place while I installed the studs; I had gone to studs thinking that when I drove them home they would seal a little tighter than a bolt.)

I glooped the studs thoroughly with genuine Permatex No. 2, non-hardening, and drove the studs home. Then I glooped the star washers and tightened the nuts. (Isorproyl alcohol works well to remove the Permatex from tools, hands, etc.)

I figure the o-rings, compressed between the block and the mounting plate, will try to resume their shape and will seal the joint if something moves thermally. And the Permatex should seal the treads and holes through the plate and the front cover.

I filled the radiator, and I have to put away my tools and give the car a run. Stay tuned. If you hear nothing in the next several months, the o-rings must have worked.

[Don Coatney]

If I recall correctly there is one bolt in the front timimg chain cover that had a copper 2 piece gasket (ring). I must have re-installed it correctly in my Desoto engine as I do not have any anti freeze leaks.