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engine side valances or mechanical fan?


lincolnsix
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GT6 mk3.  My cooling system has had a recent uprated rad, 82c thermostat and temperature sender,

 

and 13lb rad cap. The block has been flushed,  all hoses o.k.  the heater works fine.  The problem is:

 

on the open road the temp gauge stays 1/2 way on the dial,  but when I'm around 30/35 mph the

 

needle starts to creep up and the electric fan cuts in.

 

I don't have side valances or a mechanical fan --- they were not with the car when I bought it, 

 

would fitting either or both of these cure this low speed issue, I have a feeling that I would be

 

wasting my money.  I was driving recently in below freezing conditions but it was just the same.

 

                                  Any opinions please,   thanks     John. 

 

 

p.s.   I have a proper cowl in front of the rad.

 

 

 

 

 

 

 ,

                 

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The side panels keep road muck off the engine AND channel hot air under the car. If they weren't there hot air would sit under the bonnet. However, I don't think this makes a great deal of difference with a standard set up, but if you've got a tweeked engine the cooling could be on the edge.

 

The wiring failed on my modern and I installed a toggle switch to turn the fans on when needed. Surprisingly I could cruise down the motorway for hours or drive locally at 30mph, stopping for lights etc and only needed the fans on when stationary for 5/10 minutes or crawling in very slow traffic. I'm surprised your fan is turning on at 30/35. 

 

Silly question buts is your number plate obstructing the grill? That would decrease the flow.

 

My GT6 has a mechanical fan and only overheated when stuck in a 30 minute traffic jam.  I'm considering adding an electric fan on the front of the radiator for this eventuality.

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Air flow is the key.

Number plate as doug says.

Make sure that the fan is turning the right way - reverse electrical connection will make it a pusher not a puller.

Hang on - which side of the radiator is it?

 

BUT, what's the problem?

At speed, velocity provides your airflow.

Slow down and you need the fan to give airflow - that's what it is supposed to do!

 

John

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When the Herald was first introduced, 1959, it did not have ant side valances. The motoring press slated the fact that dirt easily entered the engine bay. As a result the Herald was given side valances,1960. This has been carried over to all subsequent Triumph models based on the Herald.

 

I am not convinced they help the cooling especially when stuck in traffic. They appear to trap the heat in around the engine and if anything when on the move push it against the bulkhead with nowhere to go. I have tried a GT6 with and without the side valances in temperatures 28 -30 degs, Summer of 1996, and found it ran cooler without them. This is not a very scientific finding and only my view.

 

Dave       

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Thanks for all your comments.       The number plate is mounted  below on the valance, the fan is in front of the rad.

 

I know that popular opinion says it's best behind the rad, but in slow moving traffic is that going to make any difference?

 

After Dave's comments I shall not bother with valances, the fan is turning the right way.

 

The fan has a manual overide & is not wired through the ignition,  when I switch the engine off the fan runs on for some time to cool the engine.

 

John

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Rich mixture problems with hot conditions is seriously aggrevated by hot static air under the bonnet

In traffic a engjne fan is shifting the air all the time , this really helps , if the electric comes on when its

realy too late , expect it to run rich and resist starts when its coughed into a stalled

 

I guess whats needed is a speed signal switch to start the electric fan at 10mph

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Clive, yes you're right, but whatever the accuracy of the gauge, it shouldn't start rising when the speed drops to 30mph! I would more expect this when you've come to a halt in a traffic jam, after 10 minutes.  

 

then the fan comes on, and then ... and then ...

What, John?

 

John

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At what temp is the fan coming on? if it was set using a gauge that is not reading accurately it isn't reliable. I have seen a similar issue where the fan was set to come on at the same temp as the thermostat opened with predictable consequences..... (fan running almost continuously, but not actually needed, owner thinking there was an overheating issue)

 

Fan wants to come on at 6-10 degrees above thermostat opening (approx) assuming sensor in top of rad. 

 

BTW it is normal for a fan to run on after engine off. Heat soak from the engine, and the water should continue to slowly circulate by convection.

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I have been trying the fan at different temp settings as to when it comes on.

 

I will make sure that it does not start until past the thermostat opening temp., the sensor is in the top hose.

 

If I manage to drive home without the fan on ---- very rare as I live in Lincoln, traffic light nightmare!  by the time I've parked in front

 

of the garage door and opened it (with the engine running) on comes the fan.

 

John.

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Colin, In theory the two thirds gauge reading should be around 90 deg C. But, as we all know it all depends on the state of the gauge, sensor and Voltage stabiliser.

 

As for the side valances, the vents slots around the exhaust manifold point to the fact they trap some heat in. The competitive people back in the 1960's took them off.  Trying to be diplomatic!

 

Dave     

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I am not convinced they help the cooling especially when stuck in traffic. They appear to trap the heat in around the engine and if anything when on the move push it against the bulkhead with nowhere to go. I have tried a GT6 with and without the side valances in temperatures 28 -30 degs, Summer of 1996, and found it ran cooler without them. This is not a very scientific finding and only my view.

 

Dave       

 

It's bound to run cooler without them due to less blockage of airflow but as other posters have said, the main reason for valences is to keep dirt off the engine and components, so you're striking a balance between heat causing problems and dirt also causing trouble, probably electrical. The valences don't help the cooling at all (especially when stuck in traffic); this is the job of the thermostat, radiator and fan. Keeping the system in tip-top condition should mean that when sitting stationary or in hotter weather the engine can cope; radiator cowlings will force more air through the radiator to draw off excess heat. An improved uprated radiator core is a big improvement; I only ever saw an electric fan as helping the engine when NOT working i.e. freeing up a bit of power rather than rotating all the time, but it's no more of an improvement to air flow than the original mechanical fan and if poorly fitted can actually block airflow.

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Slight thread drift (ish)

Modern cars run electric fans in well-designed cowls. They are far better at cooling than the GT6 mechanical fan could ever be. 

MAin reason is the mechanical fan is too fan from the rad, and much of its effort just stirs air behind the rad, where as an electric fan in a proper cowl will move the vast majority of air through the rad. Add that to the fact the electric fan can work flat out when the car is stationary when the mechanical fan is running at its slowest (but when it is needed most)

Nothing clever at all, just a big improvement on technology that was pretty old even in the 1960's

 

I am a fan (!) of electric cooling fans.The mechanical ones are often ok, and aftermarket electric fans poorly fitted. A decent cowl on a mechanical fan would be a very good idea if somebody wanted improved cooling but didn't want an electric fan.

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I find myself agreeing with everything that's been said, swayed back and forth by each additional post!   :wacko: 

 

I DO think the valences channel the hot air, against the bulkhead yes, but also under the gearbox. But of course only at speed, sitting in traffic they're no use at all!

 

Last year my GT6 had it's first overheating incident and blown head gasket in 40 years. I sat helpless in a traffic jam for 45 minutes watching the gauge climb. Had I had an electric fan it would have cut in and probably saved me. However, had the disaster not happened I wouldn't have taken the head off and found the blocked water pump, almost certainly the root cause of the problem. I would still be driving around in blissful ignorance,

 

That's the issue with electric fans, they can very effectively cover up the inadequacies of the cooling system. The mechanical fan should be able to cope. So what to do? I'm gonna fit an electric fan! :lol:  This will be additional to the mechanical fan and on a switch, to be used only in emergency. In this way I will know if the mechanical fan is becoming less effective and remedial action is required.

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  • 7 months later...

Forgive me for resurrecting an old thread, but I have just made a pair of engine valances out of aluminium. Not fitted them yet but then I found this thread. Now the question, is it worth fitting them or should I use the aluminium for something else? Would they be more efficient (or efficient at all for that matter), with some holes/slots drilled in them towards the back or down the sides?

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The club shop sell them and they have louvers on the sides, picture in the club shop section. Despite what others say I still think they have a benefit to heat reduction at speed and the louvers allow heat to escape when stationary. Andy Cook did a piece on returning his GT6 to mechanical fan in a recent Courier article. He decided it was a great improvement, his normal running temperature went from 3/4 to 1/2.

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