Overheating at speed

[GDPR]

I have read in an old thread while looking at water pump stuff that a spoiler will help with overheating at speed.

My car is fine at 55-60 but bring the speed up to 75 or more, then the gauge rises quite rapidly - it will come down again after a few minutes at 55-60 though.

I have flushed the block and rad (got just clean water out) and have re-antifreezed at 35%. I have a 6 vane pump, what appears tobe aquite new3 row core rad, a 16" electric fan as well as the viscous (which seems OK but how can you tell how well it works at speed) and would have thought that would be enough to keep the temp under control.

How does the spoiler make the difference, and if it really does, where would I find one? I have seen a couple with what looked like Dolomite Sprint spoilers........

[Stagdad]

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TR6 spoilers are used alot.

[dogsnadgers]

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Hello mate, it shouldn't get hot at 75mph, of course you did this on a private road!!

My temp gauge only rises above half on the hottest of days, 30 degrees plus, driving it very hard, high speed doesn't seem to make any difference to the gauge, I think you have a bigger problem than a spoiler will cure, look to the actual problem rather than an expensive modification. The standard system, whilst marginal will keep the car cool if all is working properly.

Dave

[Stagdad]

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Dave's right

If it's all working as it should you'll have no problems .I came back from a mates house yesterday doing 80mph along the dual carageway when i got to the end noticed i was in third overdrive:shock: whoops,but temp gauge was fine.



Steve

[redstag]

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Is it definitely a 3 row rad? I think the 3 row wasoriginally fittedwith the 12 vane pump anda 4 row rad with the 6 vane pump. Not sure how much difference a mismatch would make but it could restrict coolant flowat speed. Also check you don't have a 12 vane cover fitted.

First off I would make sure the engine is correctly tuned, especially timing and fuel mixture.

Pete

[GDPR]

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The previous owner tells me that he fitted a new 6 vane pump 500 miles before I bought it - I've just checked and it has the correct housing to go with it - there is virtually no coolant loss - just a slight dampness between the banks, which appears to be coming from the inlet manifold - this I can live with for the moment.

I have no problems in traffic, no problems at lower speeds and keeping the heater on hot with the blower on keeps the temp markedly lower.

It would appear to an old thickie like me that I have either a lack of airflow across the rad at high speed, or a lack of heat transfer capacity from the rad due to silt blockage or bad internal soldering/design. I haven't physically removed the rad yet, but that's high on the list of things to do - I have just flushed with it in situ. It doesn't seem to have any real cold(er) areas with the engine running,but the electric fan covers a good proportion of the rad front face making checking quite difficult.

Can the Torqatrol unit make that much difference to air movement at high speed, or should I just bite the bullet and get a Rimmer 5 row core rad? Is there an easy way to "lock" the Torqatrol unit just to prove the point?

Sorry to be a pain, but whatever way I turn I have to spend money on this and would rather get it right first time

[marty64]

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hi, this might seem stupid but i was told to just remove the bonet insulation, just for a test.

the air can circulate around the engine a lot betteralso letsthe hot air escape. my gauge has stayed well under half since i done this.

give it a go, nothing to lose.

marty

[GDPR]

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I suppose I have nothing to lose by it - Cheers Marty!

[Stagdad]

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Or try popping the bonnet as a testso you get a gap to let the air out of the top this should give more airflow through the engine bay.I tried this just as an experiment and it did nothing for mine but then again mine doesn't overheat,It's worth a try.

Steve

[marty64]

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but hasnt your stag just been rebuilt?

[dogsnadgers]

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"just a slight dampness between the banks, which appears to be coming from the inlet manifold - this I can live with for the moment."

You might find this dries out, the gaskets can get waterlogged if the car stands for a while with coolant in, they dry out with the heat and seal again, mine did anyway. Or perhaps the bolts need torqueing up a bit, but be careful not to strip the threads in the head



"I have no problems in traffic, no problems at lower speeds and keeping the heater on hot with the blower on keeps the temp markedly lower."

So does mine, by about 1/6 of the gauge



"or should I just bite the bullet and get a Rimmer 5 row core rad?"

Or one of the new alloy ones, available from two suppliers I believe, you need to ascertain the cause or you could spend lots of money and time before you cure it, any friendly stag specialists near you, it may be worth a visit?!

Dave

[seaside bill]

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The TR6 spoiler increases the air ram effect so, in theory at least, should help to cool things down. However, if you've got this problem and your radiator is of unknown vintage, I reckongetting a newa 4 row Supergill is a sound investment (about £200?). At the very least, take the existing 3 core radiator out and give it a thorough flushing by filling it with water, blocking the hose outlets and shaking the hell out of it (repeat several times) to clear any crud from the core. The effect of themechanical fan is irrelevant at high speeds as the purpose of the viscous coupling is to limit the fan speed irrespective of revs. If you've got an auto, I think they're more prone to higher temperatures at speed as the revs aregreater than the equivalent manual with overdrive - you could fit a different ratio dif if you don't mind losing a bit of acceleration. In my experience it's normal for (an auto) the temp to rise above normal at 65mph+, but not beyond the 3/4 position, and only then on a hot day (25 degrees+) and/or going up a hill. Peveresly, I think the 16" fan might actually add to the problem at higher speeds, because it does obstruct the air flow, but like many things in life, it's a trade off. I wouldn't be without my Kenloweon a hot day in a traffic jam - at least if I'm doing 75mph and it's getting hot, I've always got the option of going slower (or turning the heater on)

[022Dave]

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Hi,

It definitely sounds as though you have an area of poor circulation within the system, if it's only running hot at speed. I had a similar problem some years ago. When you flushed the block, did you remove the two block drain plugs which live under the exhaust manifolds on each side of the block? Most people forget these, and there is a water gallery in behind them which fills up with silt, preventing good flow. You need to get under the car to find them. When you remove the plugs, (3/4"AF) you may need to give the gallery a good rodding with an old wire coat hanger or similar. You'll find the water then comes gushing out - not a clean job when you're lying on your back! When both sides are clear, then flush out the block as normal. Make sure you fit new fibre sealing washers to the plugs before putting them back. If that doesn't cure the problem, then have the radiator flow checked by a rad specialist, such as Serk. Generally, radiators have a limited life, as they silt up over time, which means fitting a new core. Regular flushing can extend this life.

Dave

[TimShoubridge]

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Stagdad wrote:

Dave's right

If it's all working as it should you'll have no problems .I came back from a mates house yesterday doing 80mph along the dual carageway when i got to the end noticed i was in third overdrive:shock: whoops,but temp gauge was fine.



Steve

That was naughty !!

Must put something other than sugar in your tea next time.

[GDPR]

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I did remove the block plugs, both sides and the water poured out with gusto - got my head very wet in the process!

The more I think about this, the more I'm convinced the rad is the problem so I'm going to take the thing out for a more thorough de-clagging - a mate of mine is a heating engineer and he says he has some pukka stuff for de-scaling etc so I'll scrounge some......

If that fails it's the 4 core Supergill I suppose..........