Thermostat Cover Leak

One of the cars that I care for is a 1930's Ford Roadster with a 550 drivetrain. I am relocating the non-stock temperature gauge sensor to the thermostat cover to get the gauge to read correctly. To do this, I bought a new cover from Ricambi, and had a small bung welded into it and threaded for the sensor. I am also installing a new thermostat. I am using new a new gasket/o-ring and a new small o-ring.

So I put the o-ring on the thermostat, put the thermostat in the cover, press it in so it stays, put the gasket/o-ring in the groove in the water pump, and tighten the screws. Pump my pressure tester up to 5 psi, and get a small leak between the surfaces of the water pump and the cover.

I have tried putting the small o-ring in the groove in the cover, and putting it on the thermostat. I have tried different new o-rings. The o-rings are new from Ricambi. All of the surfaces are straight and clean. Went back to the old thermostat. Still leaks. I am baffled.

Except for the bung/sensor, this is a thermostat replacement! Ricambi has not heard of any issues with the "hundreds" of thermostats/gaskets that they have sold.

Is there a secret to this?

Thanks,

Chuck

 

Good grief!!

This sounds interesting - pictures, please.

 

I used loctite sealant and coated the o ring with it. I let the o ring sit In the housing to slightly cure then torqued down the bolts equally. The leak disappeared.
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There is a thermostat housing for our 65 degree V12s (early 575M) that already has a temperature sensor fitting. Not sure about your leaks. Any possibility the welding warped the housing?
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+1 on pics (perhaps video?) of this beast please!

Ruben

 

Tazandjan nailed it. The o-ring that seals the thermostat to the cover is only about one mm in diameter and must fit very precisely into a little groove, and we believe that the welding for the bung distorted the groove. After farting around with various sealants and trying different o-rings, we put the old cover back on. No leak. We then drilled out and tapped the bleeder screw hole to 1/8" NPT for the sensor.

Picture attached.
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Really pretty car. Looks like a cross between a Kurtis and an Alfa 2900.

 

That is the car (named the Torpedo) that Eric Zausner commissioned Moals in Oakland, Ca to create. It graced the cover of Autoweek magazine after it was done: https://autoweek.com/article/car-news/when-worlds-collide-eric-zausners-torpedo-blend-classic-ferrari-and-hot-rod

Eric used to joke that he gave Moals an unlimited budget to build the car and they exceeded it.

I did all of the wiring for the fuel injection and ignition system, mating the Ferrari/Bosch systems to the hotrod portion of the harness, and serviced the car after it was done. The engine and gearbox are from a Ferrari 456, not a 550 (although, Eric liked to claim that they were from a 550). Due to the chassis and engine mounting, servicing the engine is very difficult. I replaced the cam belts a couple of times, and it is no fun.

Working on the car is made more difficult by the fact that Moals like to use SAE stainless fasteners for everything, so if you drop a nut or bolt, you cannot use a magnet to retrieve it. For some reason Moals did not like metric fasteners and would refer to them as "Communist " bolts. There are belly pans that cover all of the bottom of the car, so it is very difficult to raise up. Removal of the belly pans is an exercise in frustration, as there are a myriad of screws that hold them on, and they didn't use captured nuts so you have to use a wrench on all of the nuts.

You have to remove the front fenders in order to take the front wheels off, which is also not an easy process. A special socket was fabricated in order to remove the knock-offs, I don't know if it is with the car. If you need it, I can check to see if Patrick Ottis still has it.

Moals built a bunch of special cars for Eric, and this one runs the best. It weighs 1,000 pounds less than a 456, so it goes pretty well.

Let me know if you have any questions about the car, as I have a bunch of experience working on it and sorting it out. I still have all of my notes regarding all of the wiring.

Brian Brown
San Francisco Motorsports

 

I remember seeing that car and Eric at Patrick Ottis's in Berkeley. I can't remember who it was that introduced me, might have been Jim Groom.