water temp. rising at high speed

[niels]

Hi S-fanatics!

I've got a slight temperature problem with my S1, hope someone can give me a hint.

When I drive the S on a normal road, the temp. just rises till about 90 deg. and remains there (the fan kicks in prettry quickly). Even when I drive it hard for a while, the temp. never exceeds 90. So no problems here...everything works fine.

When I drive the car on the highway at approx. 3500-4000 rpm the temperature rises above 90 into the red. Now when I get off the throttle and do a 3000 rpm, the temperature seems to bee allright. (but I'd like to drive it a little faster than 3000 rpm occasionally)

Now I've heard from a former S1-owner that this is a common problem, and that the housing of the radiator fan causes to little fresh air flowing into the engine bay. He adviced me to get rid of the housing and mount the fan directly on the radiator. I didn't want to remove the housing just yet so I made 3 large holes in the housing yesterday. I drove it afterwards and it doesn't seem to have any effect, because the temperature rises just as same.

Does anyone an idea how to solve this problem. I've looked in the S-forum (I always look, regardless of any problems, because it' great), but I can't find any previous posting that looks like my problem.

Thanks & Cheers

Niels S
Holland

[greenv8s]

Do not put holes in the radiator fan cowling. They make no difference significent at high speed but reduce the effectiveness of the fans when you are stationary.

From your symptoms I suspect either the water pump is cavitating or you have an air lock in the radiator. Have you bled the radiator recently? Is the water level OK and is it using any water?

[niels]

hi GreenV8S

Last time I checked the fluid it was ok. Do you mean there's an air-bubble in the cooling -system ? Is there any way to check this or should I just bleed the thing ??

Thanks & regards

[WildfireS3]

When I had water problems, I bled the system and replaced the pressure cap + seal.

[dern]

If the fan kicks in when you're driving at speed then it's worth a quick check to make sure that it's pulling air through the rad in the same direction the as airflow caused by the car moving. It's unlikely but possible that the fan is wired up wrongly so that the fan is blowing against the normal airflow which would affect the cooling capability of the rad.

Mark

>> Edited by dern on Thursday 29th July 15:05

[pies]

When you say you checked the fluid level was this at the swirl pot or the rad

[niels]

thanks guys

I checked the fluid level at the reservoir. I'll go and check it again this evening just to make sure.

The fan seems to be working the right direction, since it cools ok when I'm in traffic or standing still.

[pies]

[quote=niels]thanks guys

I checked the fluid level at the reservoir. quote]

You need to bleed the radiator to get any air out,there should be a plug on the top of the radiator normally on the nearside.

Then check the level in the swirl tank

If you have air in the rad it points to a leak in the system,i.e holed rad, leaky hose, gasket leak,pressure cap not sealing etc

[dern]

niels said:

The fan seems to be working the right direction, since it cools ok when I'm in traffic or standing still.

It'll work at a stand still or when you're crawling regardless because it'll push all air out of the front drawing air from under the car so you'll get a good airflow through the rad cooling the engine. If you're running at speed and the fan kicks in it'll blow air forward (if connected/installed wrongly) which will meet air coming in the nose resulting in a much reduced flow of air through the rad than you'd get if the fan was off and you were moving at speed or if you were stationary and the fan was running. Therefore your assumption that it must be ok because it cools when stationary or in traffic is wrong.

Run the car up to temp and wait for the fan to come on then lift the bonnet and check which way the air is being blown (mind your fingers/hair/tie/etc).

Mark

[dern]

pies said:

When you say you checked the fluid level was this at the swirl pot or the rad

...and not in the plastic overflow tank.

Mark

[niels]

thanks Mark,

There's a fan-override switch installed so it should be easy to check.

Cheers!

[niels]

Morning

The fan works in the right direction. I 've checked the fluid levels again and the "swan neck" wasn't completely full. There also was hardly any fluid in the overflow tank. Filled the swan neck up.

Now I've looked in the manual (yes the original S-manual!) and if I understand correctly, the swan neck must be completely filled and the overflow tank should be about 1/2 full.

Can anyone confirm this? This evening I'll testdrive it again and see if there's any improvement.

Cheers!

[pstruck]

Anyone else get this happening?....

My water temperature gauge jumps up by a few degress when I switch on the lights, or fan. Switch them off again and it goes back to normal. This had me worried at first, as I glaced down and saw the needle nudging the red, but now I know it is a false reading.

When running without extra electrical items on the temperature is rock steady, only climbing to the line in traffic and the fan controls it perfectly.

I assume this is just another one of those 'TVR electrics' peculiarities.

[z_chromozone]

It may also be worth checking your thermostat incase it is not opening fully.

Z

[dern]

niels said:

The fan works in the right direction.

Cool

niels said:

I 've checked the fluid levels again and the "swan neck" wasn't completely full. There also was hardly any fluid in the overflow tank. Filled the swan neck up. Now I've looked in the manual (yes the original S-manual!) and if I understand correctly, the swan neck must be completely filled and the overflow tank should be about 1/2 full.

This is the subject of much debate...

You have the metal swirl tank and the plastic overflow tank. On the swirl tank should be the pressure cap (some disagree but tvr say that's where it should be) and the plastic tank has the flat cap (no spring assembly). So first of all check that they are the correct way around. The next thing to check is that when you put the pressure cap (the sprung one) on the swirl cap is if the bottom of the sprung bit reaches the seat. You'll know this happens because you'll have to push the cap down a bit (or I guess you can measure it). If the end of the sprung bit is not pressed down in the seat in the neck of the swirl tank the cap cannot act as a pressure cap because water will be able to force it's way out of the system and up into the overflow tank. Given that the overflow tank has itself an overflow pipe which exits to the floor the system cannot be pressurised if the pressure cap is too short or broken, which is a bad thing. The next thing the check is that the pressure cap (assuming it's long enough) is still working correctly. I don't know how you do that so if it looks really scabby and old I'd probably replace it. Once you've got that far then refill the swirl tank (don't bother putting any water in the overflow tank *) and recheck the system. Replacing the thermostat is always a good idea if you don't know how old it is and while you're in there have a good look around the pipes and the pump to look for leaks. You could go bananas and flush the system but as it's working at a standstill it does sound like you're getting air in the system presumably introduced while your water leaks out of the system.

My system was broken because the cap was broken which allowed hot water out of the filler neck and up into the overflow tank whereupon it boiled because it was no longer under pressure and shot out of the overflow tank overflow pipe as steam. Replacing the pressure (the one on the swirl tank) cap did the trick. During the time I had the car I also replaced the water pump and the rad but neither caused cooling problems as you described as they merely evacuated the entire contents of the system for me.

* The reason I say don't bother putting water in the overflow tank is that I can't see how it could possibly get back into the system. The only route between the swirl tank and the overflow tank is the pipe from the swirl tank neck and the overflow tank. The only way this path can be open from the overflow tank to the swirl tank contents is when the pressure cap is open (assuming it fits and is working) and if that cap is open it must mean that the pressure in the swirl tank is high enough to open the pressure cap so muct be at a significantly higher pressure than the overflow tank which is at one atmosphere as it's open to the atmosphere through the small plastic overflow pipe. If the pressure cap does open thus opening the path between the swirl tank and the overflow tank then the pressure difference between the two will be so great that water/steam will only flow one way and that is into the oveflow tank. I can't see any circumstance where the swirl tank can possibly suck water back from the overflow tank.

Now, just to confuse the matter, some people put the pressure cap on the plastic tank and the blank on the swirl tank which seems to go against the advice of tvr and the bible. You pays your money, you takes your choice.

All the best and good luck,

Mark

[kentishS2]

pstruck said:

Anyone else get this happening?.... My water temperature gauge jumps up by a few degress when I switch on the lights, or fan. Switch them off again and it goes back to normal. This had me worried at first, as I glaced down and saw the needle nudging the red, but now I know it is a false reading. When running without extra electrical items on the temperature is rock steady, only climbing to the line in traffic and the fan controls it perfectly. I assume this is just another one of those 'TVR electrics' peculiarities.

Yep, seems to be a TVR quirk, mine is similar.
You may also notice that with headlights and blower fan on full the speedo flicks a little, turn them all off and it's fine.

[kentishS2]

Mark is right and gives a very good explanation. I still have the original owners books and it says the same about the caps.

There is another common cause of air being introduced into the system and that is via the water pump. This sounds strange I know but they can wear and suck air in (like a venturi) prior to you noticing any water leaking out. Pop into your local garage and ask them to pressure test the cooling system for you as this will show any areas of weakness, including the rad, pipework and water pump etc. Cost around £20 for a test and is money well spent.

[dern]

kentishS2 said:

There is another common cause of air being introduced into the system and that is via the water pump. This sounds strange I know but they can wear and suck air in (like a venturi) prior to you noticing any water leaking out. Pop into your local garage and ask them to pressure test the cooling system for you as this will show any areas of weakness, including the rad, pipework and water pump etc. Cost around £20 for a test and is money well spent.

Good point, forgot about that and that would give the cavitation that was mentioned earlier. Basically the system works fine when in good fettle and is pretty cheap and easy to get in good order. The pump is only 30 quid from memory and the rad was only 100 quid to recon. A stat is only a couple of quid and caps are a few quid as are hoses if you shop clever. Sort all this out in advance of any problems and you never need worry about your cooling system again

Mark

[kentishS2]

dern said:

kentishS2 said: There is another common cause of air being introduced into the system and that is via the water pump. This sounds strange I know but they can wear and suck air in (like a venturi) prior to you noticing any water leaking out. Pop into your local garage and ask them to pressure test the cooling system for you as this will show any areas of weakness, including the rad, pipework and water pump etc. Cost around £20 for a test and is money well spent. Good point, forgot about that and that would give the cavitation that was mentioned earlier. Basically the system works fine when in good fettle and is pretty cheap and easy to get in good order. The pump is only 30 quid from memory and the rad was only 100 quid to recon. A stat is only a couple of quid and caps are a few quid as are hoses if you shop clever. Sort all this out in advance of any problems and you never need worry about your cooling system again Mark

It's worth mentioning that it's best not to go to cheap on a new water pump. AP Lockheed are very good and around £58 from a motor factors.

[dern]

kentishS2 said:

It's worth mentioning that it's best not to go to cheap on a new water pump. AP Lockheed are very good and around £58 from a motor factors.

That's entirely up to you but I've never held with the idea of spending twice a much on an item when the standard one works just as well. The pump I bought at a factors worked fine for a couple of years (until I sold the car) and was 30 quid. Personal choice though, the only reason I replied was that this personal choice rapidly turns into the general belief that the standard pumps are cr*p when they aren't. The one in my car worked fine for over 10 years until it gave up.

It's the same with magnecor leads and braided brake hoses. Both are better than the sh*gged ones you're replacing but the advantage over new standard stuff is marginal at best unless you're racing. Imo obviously.

Mark

>> Edited by dern on Friday 30th July 11:16