After watching the kids whilie the wife was out of town, I treated myself to a 10 mile jaunt last night, with one decent blast up to about 4000 rpm in top gear. In the last mile or so, the temp gauge stopped dropping down below 210 (indicated, it's not accurate) when actually moving, and when I pulled in the driveway and shut her off, there was a nice hissing noise from underhood. Oh, and a line of drops behind the car. By IR, the upper rad hose was at 200, and after about 15 minutes of steaming, I released the pressure in the overflow tank, which was essentially empty. Jacked her up, and the junction of the WP and left block looks like the picture below. I don't think I did any permanent damage, but is this a common failure? Motor was (according to the PO) completely rebuilt about 500 miles ago, and had mentioned he'd had an issue with the WP and had to replace it with the one currently on the car. Is this junction a known weak spot on 327's? (Dumb question mode- is there supposed to be a split washer on that upper bolt in the picture?) Perhaps the bolts weren't torqued right, cheap gasket, cheapo WP, bad sealing surface on the block, or other? Thanks for any insights.
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Re: Blown WP gasket- Post mortem? (62-340)
The WP on C1's is prone to leakage due to the unique engine mounting system. Check the mating surface of the engine mount bracket (both sides). If badly pitted, you may have to replace. You can try using two sets of gaskets on each side. -
Re: Blown WP gasket- Post mortem? (62-340)
Rob -
VERY common C-1 problem, can be caused by a number of things. The mating surfaces on both sides of the engine mount bracket must be free of pits (I mean dead flat and smooth), same for the block and water pump, with sealer on both sides of both gaskets on each side, and the bolts need thread sealer, as they all go into the water jackets. If there is any slop in the assembly while it's still loose, twist the engine mount bracket clockwise as viewed from the front against the bolts before torquing them; when the engine torques, if there's any available slop in the attachment, it will tend to shear the gasket seals and create leaks. More exotic fixes like doweling both sides of the engine mount bracket to the block will also cure the torque shear, but that's pretty extreme.Comment
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Re: Blown WP gasket- Post mortem? (62-340)
John,
You are absolutely correct on the engine torque problem. I remember that exact same thing happening to many of the guys that were drag racing 62 and older Corvettes years ago. (decades ago I guess) No matter how many times they retorqued the bolts or replaced the gaskets, they would leak after evert hard pass. Finally, someone decided to "pre torque" the position of the pump and bracket as you suggested and that was the end of the problem.
MichaelComment
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Re: Blown WP gasket- Post mortem? (62-340)
one thing you do NOT want to do is use silicon sealer on these gaskets,use only non hardening permatex forma gasket. if the holes in the motor mount plate are enlarged i would get them "bushed" for a press fit in the plate and snug fit around the bolt OD. also use loc tite on the bolts along with lock washers. we always "saftey wire these bolts but NCRS may frown on this.Comment
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Re: Blown WP gasket- Post mortem? (62-340)
Those are good ideas Clem and I just thought of something else that would help, although not correct original. If I were going to lean on it from time to time, I would probably want to install at least one stud in place of the original bolts. I bet the threaded portion of the bolts may be what the motor mount bracket is using for a dowel. With studs, it would definitely have a smooth round surface for support.
If the excess stud were removed flush with the nut at the face of the w/pump, it wouldn't be real obvious that it was a stud instead of the correct bolt.Comment
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Re: Blown WP gasket- Post mortem? (62-340)
you are correct about the studs as i have seen that done.Comment
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