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Following my recent incident with what I think turned out to be a sticking cam follower I have been putting some miles on the car to confirm that all is well.

The one thing I have noticed is that the engine - according to the temperature gauge appears to be running hotter.  Since the only thing I have done is remove the head and the radiator but without changing anything that could affect the running temperature, I suspect that I have an airlock somewhere in the system.  Is there any way to confirm this and more importantly get rid of it?

Over the last couple of weeks I have covered a couple of hundred miles at varying speeds but not above 65mph bearing in mind I am running in new cam followers. The engine warms up very quickly and runs with the temperature gauge needle a couple of mm above where it was previously.  It seems that the gauge is reading correctly because the electric fan cuts in at about the same point.  I have checked the timing and that is spot on, as is the mixture.

I  did find that when I re-filled the cooling system after replacing the head and radiator that it wouldn't accept the full 8 litres specified in the WSM and I initially put that down to the heater not having been drained but now I wonder if it was because of an airlock.  When I check the coolant level, there is no apparent loss and thus far no evidence of bubbles which might indicate head gasket issues.

For the moment all I am going to do is keep on using it but any suggestions would be gratefully received.

Rgds Ian

 

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Me and my TR agree there is no air locked anywhere.

This is why after a engine repair I always refill the rad and engine without any care and just drive her without any problem or complaint.

 

Edited by Z320
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If you assume air locked in the engine,

meens areas where no water flows to because of air,

why does this make the water constantly hotter while you can drive the car without any other problems?

Edited by Z320
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Don't know so much about 4 pot TRs but the 6 pot motors airlock quite easily when refilling with coolant.

Raising the front of the car as high as possible while filling the rad helps. Also try squeezing the main radiator hoses to 'burp' the air out.

Usually any remaining air works its way out over several cycles of heating up and cooling down.

Nigel

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Hi Ian

If your concerned re air lock then you could raise the front of the car as high as possible and run her up to temp with the rad cap off any trapped air should rise to the highest point. Squeeze the bottom and top hoses it might help. 

Don't suppose you have changed the temp sender?

Andy 

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3 minutes ago, Nigel Triumph said:

Don't know so much about 4 pot TRs but the 6 pot motors airlock quite easily when refilling with coolant.

Raising the front of the car as high as possible while filling the rad helps. Also try squeezing the main radiator hoses to 'burp' the air out.

Usually any remaining air works its way out over several cycles of heating up and cooling down.

Nigel

Beat me to it!

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1 hour ago, Z320 said:

If you assume air locked in the engine,

meens areas where no water flows to because of air,

why does this make the water constantly hotter while you can drive the car without any other problems?

I am only assuming an air lock because I can’t think of any other reason why the car should appear to be running hotter. 
 

Rgds Ian

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Just now, iain said:

Is the engine now running lean? That would increase temp. I can’t remember how much you pulled apart.
Iain

Thks for the suggestion Iain but I have checked the mixture with two Gunson colourtunes and after a fifty mile run when I pulled the plugs they were the correct colour. 
 

Rgds Ian

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2 hours ago, Z320 said:

why does this make the water constantly hotter while you can drive the car without any other problems?

By restricting the flow of coolant to the radiator.

Pete

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Ian,

If you suspect an airlock, start the car up without the radiator cap fitted and run for a while (say 20 mins or so) as this will bleed any air in the system. Switch off, let it cool down, check the water level, top up if necessary, restart and run up to temp (185) then check whether the top and bottom hoses are the same temp, if not repeat.

What thermostat do you have fitted, modern wax type or the bellows? 

Regards, Andrew

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10 hours ago, stillp said:

By restricting the flow of coolant to the radiator.

Pete

No air "trapped" anywhere can reduce the massiv coolant flow from the water pump.

The story of air trapped in the engine in my opinion is credulous hearsay since ages.

 

Edited by Z320
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Interesting, but it doesn't take much air in a home central heating system to make a radiator run cold, it's like turning a tap off, so a similar airlock in a car could easily stop the flow. The very small about 1cm bore hand pump for the suspension on my bike easily pumps 180 psi and that pressure will take a 75 kg rider!

Chris

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12 hours ago, Z320 said:

 

The story of air trapped in the engine in my opinion is credulous hearsay since ages.

 

No, it's the result of many years of observation by many people. Perhaps you've just been lucky.

You might notice that the air visible in your video doesn't go away, but returns when the engine stops, and will remove heat from the block less efficiently than water would.

Pete.

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The truth is bended until it fits to the rumor,

if you know there is no air trapped - and have a different look on your problem - you will find another reason for your problem.

 

 

Edited by Z320
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Perhaps Marco, but if that's true, why have so many overheating problems, on so many different cars, been cured by bleeding the cooling system?

How much air do you think can be in the system before it causes overheating? 10%? 50%?

Pete

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There MUST be about 1 liter of air in the cooling system to be compressed by the expanding coolant.

With the water pump below coolant level (when you start the engine) the water pump ( a monster) keeps the air in the flow. 

The coolant is then mixed with air and lovely turbulent.

Edited by Z320
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The TR4A (and most moderns) has an expansion bottle to take care of expanding coolant. Do you think Triumph could have saved the cost of that by advising owners to put less water in the radiator?

Pete

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Pete,

are you angry with me because I have a different view on that?

If you want I can explain you my view on that bottle, you will be surprised!

So, are you really prepared for a different opinion?

Ciao, Marco

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