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TR2/3/3A TR3a Coolant Loss

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RonR

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Hi Folks.

This pass week, we were on a 1500 mile road trip in our TR3A.
Everything went well, including the engine temperature maintaining no more than 160 degrees (a 160 degree thermostat is installed).
About 45 miles from home, we were in construction traffic and sat still for several minutes. The engine temperature started to climb.
By the time we were moving again, the temperature was at over 200 degrees.
Withing a few minutes, we lost coolant, and ended up being towed home the final 45 miles home.

I looked under the hood while at the side of the highway, and did not see anything in the way of split or broker hoses.

The engine was rebuilt a couple of year ago, including all new hoses.
Could the elevated engine temperature caused a hose to fail?

Any suggestions on what may have failed within the cooling system?

Thanks.
Ron
 
Ron - just wondering out loud ... if the engine got so hot the coolant may have reached the overflow tube at the top of the radiator (near the cap).

Tom M.
 
Hi Tom.

Coolant was coming out of the vents in the hood near the windshield.
I doubt coolant from the overflow drain hose would have made its way that at up.

Thanks.
Ron
 
RonR said:
Hi Tom.

Coolant was coming out of the vents in the hood near the windshield.
I doubt coolant from the overflow drain hose would have made its way that at up.

Thanks.
Ron
Click to expand...
That sounds like a leak in the heater hose/valve or under the neck of the radiator. The fan will then splash it all over the engine compartment. If there’s enough, it may come out the hood slots as you mentioned.

Take a look at your oil… does it look creamy? If so, blown head gasket.
 
The logical thing to do is:
Open the hood.
Look for any obvious leaks.
If none seen, then remove the radiator cap and refill the radiator with water. Replace cap.
Look for leaks.
If none, then start the engine . And watch for leaks. Run engine either until a leak is found or 5 minutes.
Then ask your questions.
Charley
 
These cars only have a 4 psi cap which doesn't raise boiling the point very much. My guess is your coolant loss is a result of boiling. Once the coolant begins to boil, the cooling system basically stops functioning. I would refill the coolant, retorque the head, make sure the cap is functioning correctly, and drive on.
 
Folks,

An update and a couple of question:

It appears the coolant loss with my TR3A was from a leaking freeze plug at the rear of the cylinder head.
Moss offers both steel and brass. I am thinking brass is better. Any thoughts?

Since I have to pull the head to replace the freeze plug, what are the recommendations for a replacement head gasket.
Moss offers steel, copper, and some other materials.

Thanks.
Ron
 
RonR said:
Folks,

An update and a couple of question:

It appears the coolant loss with my TR3A was from a leaking freeze plug at the rear of the cylinder head.
Moss offers both steel and brass. I am thinking brass is better. Any thoughts?

Since I have to pull the head to replace the freeze plug, what are the recommendations for a replacement head gasket.
Moss offers steel, copper, and some other materials.

Thanks.
Ron
Click to expand...
The freeze plug is likely best to be steel.

The head gasket is best copper then center material and copper. Make sure you place the overlaps facing up.
That is standard and my opinion.
Charley
 
The sneaky freeze plug is the one under the valve cover, If one is bad, do both. This one will ruin a motor
by letting antifreeze into the oil. It is threaded in and machined flat. Sealing the threads is a must.
Mad dog
 
Hi Mad dog.

Thanks for the reply.
The threaded plug was replaced when the engine was rebuilt around three years ago.
The freeze plug was replaced too, but yet it has failed, even though the work on the cylinder head was performed by a friend that built Formula Ford engines.

I will remove the plug and add new thread sealer.

Thanks.
Ron
 
I like to set freeze plugs with some metal bonding epoxy covering the inside. Paint is not
water proof but epoxy is. This makes a perfect seal every time.
Mad dog
 
also, Freeze plugs come with a rubber expansion joint on the outside. You put the plug in and tighten it in place. It should work for a tr3 with the low pressure and the head should be able to stay in place.
 
Hi Mad dog. I have friends that used Jen Weld at freeze plugs. That seems like it would make it difficult to remove the freeze plug if it became necessary in the future.

sp53, I have seen the type of freeze plug you described, but they are not original to most British cars, nor does the usual sources of British parts seem to sell them. It is a good idea, but it does not help me get the old plug out without removing the head.
 
The perfect freeze plug is never "serviced" it is for the life of the car. I am only suggesting that the backside
can rust over time and a protective finish is salubrious. Paint is NOT water proof and will peel off faster than
you might think. Epoxy is the ounce of prevention here.(IMHO)
Mad dog
 
My sister bought an old ford once baxk in the 80ites where someone had dumbed some caustic acid?cleaner? into the cooling system. I replaced every freeze plug.
 
Update:
It was a bit warmer this past week, so I investigated the freeze plug issue.

The freeze plug in the back of the cylinder head was completely gone.I found it laying on top of the bell housing.
It appears it may not have been replaced when the engine was rebuild.

I looked into the adjustable freeze plugs. They are either rubber or copper. They appear to be for "cup" type freeze plugs and not the flat type used in the TR3. Here is what NAPA and other s have:


Since the TR3 head has a lip of sorts for the freeze plug to set into, I am uncertain if the head has enough surface inside the freeze plug hole for one of these to seal against.

Maybe I should jut clean up what I have, set the freeze plug in either JenWeld or silicone sealant, and try to get back into the hole.

Thanks for any additional suggestions.
Ron
 
If the plug was out, then it was not the plug's design. It was the wrong one or improperly installed.
 
Hamish Racing,

The head on my engine was done by a professional too.
I don't want to remove the head, or pull the engine, but I do not see anyway to get anything behind the head to "whack" the freeze plug in.

The two options on new, no adjustable, freeze plugs, are steel and copper.
Steel is what fell out, but I doubt the problem was because of the material.
 
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