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Triumph TR6 - Coolant Loss

Hello all...
The car is a '73 TR-6 with a bit of a "situation". I'm going through aboui 1 cup of coolant in 400 mi. or so, measured at the overflow reservoir. There is no visible sign of a leak anywhere, and the car does NOT run hot under the most severe conditions.No leakage evident at the heater matrix and associated hoses, and the plugs and exhaust pipes are normal in colour.In fact all is fine with the exception of the coolant loss. Anyone have any comments/suggestions/advice re what is normal, OR what could be the problem?
Thanks in advance.

Any sign of a puff of white smoke when starting up?

Ken Shaddock

Hi Dave,
If you have access to a pressure tester check for slow leaks...pump it up to 14lbs and let it sit for a couple of days and see if the gauge drops.. a pin hole leak at one of your hoses or you may have a leaking head could be leaking slowly but not enough for you to smell coolant in the exhaust or affect the idle of the car.

Charlie B.

Hi Dave,

check around the water pump for any leakage out the main seal... put a tissue below and in behind the drive pulley and see if there are traces of coolant there. My experiences in this realm have shown leakage here while the car is running and up to temperature . An easy check. Hope this helps,

Rob Gibbs may be right. Time for a [long] pressure check. If that is negative....perhaps on to a leak-down check. If THAT is negative, then.....? The fact that each plug is normal in appearance would seem to negate a head gasket problem. [I hope!]

Rob...good idea, I'll check the water pump area when the whole thing is hot.Dry as the proverbial bone when cold though. What IS considered to be a "normal" fluid loss in a TR-6 anyway?

Thanks all.....


quote: "What IS considered to be a "normal" fluid loss in a TR-6 anyway?"

That's just it...fluid loss is normal in a TR-6!

c.a.e. emenhiser

I am curious about something. You say you measure this cup of coolant loss at the overflow bottle. I am curious how you do this. The overflow bottle is just overflow bottle.
My overflow bottle has not seen a drop of coolant in 7 years (since the restoration) and I do not expect to see any. Why is coolant going from your rad to the overflow bottle? Is your rad OE? Does it need a good flush or even a re-core? Maybe when you top off the rad you are overfilling it and indeed it overflows into the bottle.
Usually rads overflow when they are about to "blow their top" yet you say she does not over heat.

Rick Crawford

Hi Rick.
I mark the fluid level on the side of the overflow jar,out of the car, sitting on a level surface, when everything is stone cold, ie sitting overnight...15 hrs. or so after a drive.Also marked down is the odometer reading at that time.Four-five hundred miles later I repeat the whole thing.The level is always down a bit...a little work with a graduated cylinder [one of my wife's measuring cups] gives me the variation from the first reading.Always down a bit, but where its going is the $64.00 question.To anser the next question.....the overflow bottle is ALSO bone dry at all times. I also went to the trouble of cleaning, drying, and checking it with naptha [about 1/2 filled] to see if I could induce and spot any leak at the bottle seam. Not a bit!

What a pain,although so far a minor one.

Thanks all.



I had some coolant loss after installing a new heater valve and the pipe which attaches it to the head. I wouldn't have noticed it if I hadn't been trying to tune the carbs, since the water drips down onto the exhaust manifold and hey presto, no trace of the leak! Some drips land on the head first, but they evaporate pretty quickly too. I solved it with something in a tube that said plumber's something-or-other. Might be worth a look?


Well blow me away! This is weird. Coolant DOES NOT go from the bottle back to the rad and you say it does not leak.

I Am confused (does not take much:)

One sentence from your last post you say "The level is always down a bit...a little work with a graduated......." then you say "To anser the next question.....the overflow bottle is ALSO bone dry at all times." Splain yourself please.

Alistair has a good splanation. That makes sence to me Alistair.
Rick Crawford

Gotta take issue with one item of the coolant heats during start up and normal operational temp. is achieved, the coolant expands and is forced past the outlet valve in the rad cap and into the bottle. After shutdown as the coolant [in the rad/block]drops in temperature it contracts and sets up a lower vacuum which draws the coolant BACK into the rad past the INLET valve.Actually the valves are the rad cap spring [outlet] and the flexible rubber ring [inlet]..kinda crude, but they work.

Re the overflow bottle being "bone dry" at all times...I should have clarified.....bone dry on the OUTSIDE at all no visible leaks. Mea culpa!

Alistair, thanks for the tip, however no joy! Just as dry as can be.

Several years ago there was a movie called "The Exorcist"....could THIS be the answer?

Thanks all.


time flies! "the exorcist" is DECADES ago.
back to coolant, I hardly need any coolant filled.
Paddy Kan

Dave, here's a way to check out Rick's answer. Don't worry about the coolant in the bottle. In fact, empty it. Check the level at the radiator. If it goes down just a bit, don't add any yet. Drive for a week or 2, checking at the radiator cap occasionally. All you really need is a full radiator (still coolant in the top tank). It doesn't have to be right at the top of the fill neck.

It doesn't sound like time to panic about where the coolant is going just yet. Just keep checking all the fluids.

Some time ago I replaced the radiator cap from 7 psi to the correct 13 psi. Since I've doen that, no overflow to the bottle. Before I saw the lever of the bottle go up and down, constantly refilling etc.
Dave , are you using the correct radiator cap with the correct pressure ? Just a thought :)

Eric de Lange


I meant "level of the bottle".
Eric de Lange

Eric,, correct[13 psi] cap.

Tom...I just might try your thoughts, however it could add to the mystery.If the coolant continues to go down in the rad....where is it going? If not...why and how is it disappearing from the overflow bottle?

Paddy...Right on, DECADES ago, but I suspect the "Old Boy" is still around.Why couldn't He go pick on some M.G. somewhere?....Why me??

Thanks one and all.


I'll add a bit more to your mystery...the MGB that I had in a previous life (be quiet Rick C) had a leaking head gasket that would only leak into the water jacket. When it was running, it would run hot, because of the hot gases superheating the coolant, but never leaked enough coolant back into the combustion chamber to be detected. Like it sealed itself as it cooled. Rodded out the radiator, new water pump, t-stat, then pulled my hair out. (That's why I shave my head now) Talking to a guy at the radiator shop convinced me to pull the head, and that was it. Leaking gasket acted like a thermostatically controlled valve, letting combustion gasses into the cooling system, no great amount of coolant lost, but it would drop a bit over time.
I would take Tom's advice, don't worry about the bottle....check your coolant level in the radiator after it cools off, that's the one you want to worry about. Go for a drive, cool it down, check the level. If it stays the same, start looking at the bottle and hose.
happy moToRing!
Rod Nichols

This thread was discussed between 19/06/2007 and 22/06/2007

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