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TR2/3/3A Correct Thermostat?

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RonR

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I took the TR3 for a 50 mile drive today, the second since the engine rebuild, and other things. I lost all the coolant from the radiator overflow pipe (no coolant in the engine oil; no visible leaks after refilling and running the engine for an extended time.)

I don’t know what thermostat was installed in the rebuilt engine, as I was not there that day.

Was the sleeve-type thermostat original to a TR3A?

Thanks.
Ron
 
Yes, a sleeve type thermostat was original. In theory, the sleeve provides a small improvement in cooling, by partially blocking flow through the thermostat bypass hose; but it's never seemed to make much real difference for me. I run a regular 180F type with no sleeve.

Did the engine boil over, or did you just lose coolant? If the head gasket is leaking, it can blow coolant out the overflow no matter what type of thermostat you have.

Also, if you fill the radiator to the top, it will always blow some coolant out when it heats up. The normal cold level is close to the bottom of the upper tank extension.
 
Thanks, Randall,

The car never boiled over. It appears 100 percent of the coolant went out the over-flow tube and was thrown back onto the exhaust pipe where it turned to steam. I didn’t notice any problem until I stopped at a traffic light 4 blocks from my home. The temp gage was down to the lowest point.

I could not find any evidence of a leaking head gasket. I suspect you are suggesting that a head gasket leaking between the cylinder and water jacket could blow the coolant out the overflow tube.
A solid copper head gasket was used during the rebuild. I have heard that this type does not always seal. I will retorque the head.

Thanks.
Ron
 
Hello Ron

Do you know if they checked that the liners protruded above the block between 0.003" to 0.0055" all around the liner?

David
 
Do you have the correct radiator cap? The length of a TR3 radiator cap is significantly longer than standard caps and the gasket face of a standard cap will not contact the sealing surface of the radiator. Temp gauge will always drop when not immersed in anything to measure.
Bob
 
David, the machine work for the engine was performed by a company that builds SCCA Formula F race car engines, so I am confident that he verified the liner protrusion.

Randall, did you end up doing anything other than retorquing the head? Would I be better off with something other than a solid copper head gasket? Thanks for the link. I will order the tool today.

Bob, the radiator cap is correct; 4 psi, 1-inch depth. I lost all coolant, not just at the thermostat housing.

Thanks.
Ron
 
RonR said:
David, the machine work for the engine was performed by a company that builds SCCA Formula F race car engines, so I am confident that he verified the liner protrusion.
Click to expand...

So, Formula F race car engines use wet liners? First I've heard of that ...

Randall, did you end up doing anything other than retorquing the head? Would I be better off with something other than a solid copper head gasket?
Click to expand...
Yeah, I tried a lot of things, including new gaskets, various kinds of dressing and so on. Finally figured out that while the liner protrusion was fine on the side I checked, the liner tops weren't actually square to the block surface, and the other side was too low. I've found that on two engines in a row (now that I know to check for it), so I'm thinking it must not be all that uncommon.

The right solution of course is to have the block machined shorter on one side; but I was in a hurry to get the car back on the road, so I tried a band-aid fix. Worked so well that I never did get around to having the block machined.
The band-aid is just a ring of .016" (26 AWG) bare copper wire, tacked in place around each cylinder opening on the stock type composite head gasket.
DSCF0014_croplight.jpg~original


IMO, you would have better luck with a stock head gasket. The solid copper ones are tough to keep sealed for long, and better suited for racing where the engine gets torn down every few seasons anyway.

As a side comment, it is more or less impossible to blow "all" the coolant out the top. If there wasn't at least a quart or two left in the bottom of the radiator and block, then IMO you have a leak lower down.

But the coolant doesn't just sit there while the engine is running. The water pump sucks from the bottom of the radiator and forces it through the engine and out the top into the top of the radiator. Any leak is going to eventually allow the level to drop until the water pump can no longer circulate what is left. Once that happens, the coolant in the cylinder head will boil almost instantly and the resulting steam will force most of the remaining coolant out the cap.
 
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