Classic cars forum & vehicle restoration.

shell27 · Joined: 30 Nov 2007 Posts: 26

I have had problems with overheating for years now, I have a 4 litre side valve engine with the water pump at the back of the engine and it works fine all water pipes ok radiator new aluminium normal fan working ok. This engine gets hot a soon as it is in traffic jams of any kind, traffic lights roundabout zebra crossing anything once up to temp, on a journey stays great around 75c any help would be greatly received.

Rick · Site Admin Joined: 27 Apr 2005 Posts: 22446 Location: UK

Hi

Ignition timing out?

Impeller vanes on the pump corroded away, reducing its effectiveness?

Is the pump belt-driven? if so is it slipping at all?

Obstructions within the water jackets/passageways in the engine itself - ie clogged up internally?

Is the (new) radiator to original spec, with the same number of tubes etc?

I assume there are no obstructions to the air flow - eg spotlamps, extra badges, number plate etc?

Would it originally have had a shroud behind the rad, to help draw the air through the core? and if so, is it still in place?

What car is it?

RJ
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shell27 · Joined: 30 Nov 2007 Posts: 26

Thanks for the quick response.
This is a 1939 Sunbeam Talbot 4 litre and there are not many of them I Think mine is the only saloon left certainly in this country there are a couple of sport saloons with the smaller engine 3 litre and 4 litre, I have had conversations with them and they say they have a small problem but not like mine. The new radiator is of the same spec as is but is as is the right one not sure, there are no obstructions in the way of the airflow, no idea if it had a shroud or not. The pump is driven by the dynamo and the dynamo is driven by the distributor so no belt, the pump has been completely refurbished to its original design, I am pretty sure the timing is on the button but worth checking. I have had this problem what seems like forever, the engine was rebuilt 4 years ago and I had some fusion welding done by a company in Leicestershire but my engineer who rebuilt it said it was the best bit of welding he had every seen and at the same time all the engine areas where cleaned out.
I was just looking for somebody out there that had a similar problem as I so here`s hoping.

peter scott · Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh

If the radiator is good then my money would pick clogged water passages from Rick's list as the prime suspect. You really need to take all the core plugs out and scratch around with what ever implements you can get around the bores and other obstructions. It is much more effective if you have the block out of the car and can turn it upside down, lay it on end or one side or the other. It's also better with the head off so you can access as many passages as possible and you are not displacing mud from one area only to let it fall into another.

Peter
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1939 SS Jaguar 2 1/2 litre saloon

goneps · Posted: Sun Dec 27, 2015 11:55 pm Post subject:

An interesting query cropped up recently on the Morris Register forum, when a Cowley owner found that his fan blades were set the wrong way, ie. instead of pulling air backwards through the radiator they were trying to push it forward. Have you checked that your new fan is correct?

Just a thought.

Richard

shell27 · Joined: 30 Nov 2007 Posts: 26

Thank you for your replies, I too thought it might be a fan problem. When I became the owner of the car back in 2007 it had a 4 blade fan and a friend of mine said perhaps a change would be good so I got hold of a MK2 Jaguar fan which I am told sucks and it had 12 blades on but it had no effect on the temp of the car. The other point about slugged in the water chambers throughout the engine I could believe if the the engine had not been out in recent years, I had the engine out and completely rebuilt in 2012 and since then done around 5k so I think a build up of rubbish is very unlikely but I am open to suggestion.

Peter_L · Posted: Mon Dec 28, 2015 3:28 pm Post subject:

Hello.

Do you know if the new radiator has the same capacity as the original ?

Do you loose water when it idles ? and the fan is pulling air through the radiator and over the engine ?

Do you have photos of the car and the engine. ?

Bitumen Boy · Posted: Mon Dec 28, 2015 4:32 pm Post subject:

The symptoms described remind me of experiences with other (admittedly much more recent) cars, where I eventually came to the conclusion that the cooling systems were pretty marginal, even with everything in A1 condition, and worked out a couple of tricks to largely get over it. I wonder if your basic problem is a similarly under-specified cooling system, particularly in view of the rather large engine capacity, although it's entirely possible that a smaller than original rad could be causing the trouble as already mentioned. The problem with something so old and with so few survivors is that there's always likely to be something of a question mark over exactly what was original...

Is there any sort of thermostat in the system? Going on the age of the car I'm guessing not, but could be wrong there.

Peter_L · Posted: Mon Dec 28, 2015 6:02 pm Post subject:

Sometimes proving the basics helps.

The link shows a basic flow system.
http://mototechauto.com/images/coolingSystemWaterPump.jpg

Before modern assembly methods, it was not that difficult to put things together in the wrong position. You mention the pump is at the back of the engine, is it pumping the water the right way ?

As for radiator replacement, back in the 70's, we had a new radiator built for the war surplus works fork lift truck, it looked to be the right size and fitted straight in but the engine would overheat like crazy. There was talk of cracked blocks or cylinder head gasket etc, but all was fine before it was backed into an old fence that punctured the rad. Then the capacity (gallons) was measured and compared with similar size engines, it was far less. New rad built and all was well again.

goneps · Posted: Mon Dec 28, 2015 11:14 pm Post subject:

Does the engine have a thermostat, or some other means of temperature control such as radiator shutters? A thermostat that's only partially opening could unduly restrict the already low flow when idling. If shutters are automatic they'd be operated by a thermostatic device of some kind.

Richard

shell27 · Joined: 30 Nov 2007 Posts: 26

Hi People thank you for your replies. I have today connected the top hose and put a glass tube so I can see the water travelling to the radiator and I can confirm that the water is moving because I am able to see small air bubbles passing the tube in the right direction, this tells me all is ok with the pump. The next thing I was unsure about was the fan, looking at it logicically when the car slows down the wind stops blowing in the grill that I would thought is when the fan comes in to its own, so I have took the fan off and tomorrow morning I shall start the car and see how long it takes to get up to temp. Once again I dont know if this was the right radiator or not when I got the car. The engine did have a thermostat in it but I took it out because I thought that may be the problem, the engine does not have shutters that open and shut you are able to get your fingers in between the grill bars.
I dont actually know if the radiator is right or wrong but it looks similar to one in a book that I have. The shroud is worth looking at so once I have determind that all is ok with the existing fan then I will be trying to get a shroud.
Once again thanks for your input.

Steve

Peter_L · Posted: Tue Dec 29, 2015 7:45 pm Post subject:

Tissue paper, such as Kleenex, or better still smoke, is good for showing air flow. If the air is being pulled into the engine from the front, either should react to the flow. Whether or not the flow is sufficient is another matter.

shell27 · Joined: 30 Nov 2007 Posts: 26

Hi Peter

Yes I tried that earlier stuck a piece of bluetac and a small bit of tissue to it and it did blow it away but it did not look too forceful, it did not look as if it was sucked away more like blown away. There is only 25mm between the fan blade and radiator core. I may try to sort out some sort of smoke so I can see what happens outside the engine bay in front of the grill good test I feel.

Steve

Peter_L · Posted: Tue Dec 29, 2015 9:41 pm Post subject:

Hi Steve. Looking over what you have said, the problem appears to be when there is zero airflow through the rad, or at idle, not enough circulation from the pump.

So now for a totally unscientific idea. A large domestic fans, set up in front of the car.

I presume the system is running at sufficient pressure. Pressure v Boiling Point. Boiling water has gas, which does not conduct heat and the local surface temp will rise. Flow through the pump will also be reduced as the pump will only move a liquid. You mentioned seeing bubbles in the water.

Bubbles of what ?

The other thing, is the engine overheating, or is it only the temp gauge that shows a higher than normal reading ?

peter scott · Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh

If you have removed the thermostat then it's possible that your bypass is not being blocked and a disproportionate amount of your water flow is bypassing the radiator. You could test this by clamping the bypass hose.

Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon