Marginal Cooling to Xflows

[terryp]

I have a very original 1985 Supersprint which believe it or not has only done 9500 miles

Current set up is 74 degree thermostat , rad fan switch set to come on at 85 and off at 76

Pacet suck type fan squeezed in between the rad and the steering rack and the original yellow blow type fan on the front (which will be switched manually in due course)

The question is that if the air temperature is above 28 degrees even with the more efficient fan the car struggles to keep its temperature less than 95degrees. If I put the heater , you can actually see the gauge reduce significantly, this leads me to believe it may be the radiator stuffed full of old gunk

With an infra red temp gauge it was 92degrees top of rad, 72degrees bottom of rad

Any ideas? Or is this normal?

Would there be any improvement if I put sponge on the top of the rad (like my Elan)

 

Thanks

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

 

Edited by - terryp on 26 Aug 2010 15:39:07

[Piers Rendell]

Until recently, I also had a 1985 Super Sprint that I had from new. I replaced it with an R300 a few months ago. My original car came I think, with a Hillman Hunter radiator and was marginal cooling wise in traffic, even when new. In 1988, I changed the rad to the Cosworth Caterham type, which was of much larger capacity. That did the trick of keeping it cool, plus the use of the override switch when in traffic. The fan had to be moved from the front of the rad to the rear.

 

 

[terryp]

Piers

Was your the lovely blue car I saw for sale just after I bought mine?

Anyway thanks for the reply, I think I'll have to do the same if I want to take it out in the hot weather, perhaps a Radtec unit?

 

Cheers

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[andy couchman]

The cure was to convert the system from the total loss (is that the rtight phrase?) to sealed.

 

That meant changing the thermostat housing and adding a sealed overflow tank (from a Metro/Rover). The old system (especially if you tuned the engine) seemed to result in the car getting hot, dumping some water into the overflow, then refusing to suck it back in when cool. That meant less water in the system, which meant it got hotter quicker, which meant - you get the picture.

 

The sealed system cures all that.

 

Try someone like James Whiting for a kit.

 

Andy

[Piers Rendell]

Yes, Terry, C225RPM was sold on Blatchat to the first caller. I should have asked for more money, as I had callers from Aust/France/Belgium/UK all wanting the car.

 

 

[terryp]

Piers

I paid more for mine! Then saw yours, I saw it again shortly after advertised in Belgium I think.

Due to registration problems the early cars are very sort after here.

 

Cheers

Terry

 

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[terryp]

Andy

I've just bought a new thermostat housing!

 

I suppose I'd only need a blank radiator cap and then reroute the old overflow (now pressurised) to an expansion vessle with a radiator cap

 

Thanks

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[Pezky]

Car builder solutions sell a nifty little kit to convert it to a sealed system linky

 

I would recommend a overide switch for the fan or an adjustable electronic fan controller

 

Jonathan

 

penn7's pesky xflow

 

Edited by - Q102 on 26 Aug 2010 19:46:47

[Clousta]

TerryP,

I have been having similar problems.

 

I have a 'big' radiator far forward with a 'suck' electric fan between the radiator and the front roll bar.

 

Bringing the Seven back to Belgium (on purchase) last summer on a hot night after a stop the gauge rose up to 120-140C. I pulled over and stopped. No indication of over heating. I waited for 3/4 hr and carried on cautiously. I got home OK.

 

I overhauled the cooling system. Flushed the radiator, block and heater. Replaced the thermostat with a 74C one. Fitted a new temperature sender for smiths gauge. Reworked the expansion tank and fitted a fresh expansion tank hose and jubilee clip. Filled with fresh coolant.

 

Local blats in Belgium all seemed OK. I was anticipating temperature rise when stuck in traffic. I survived 1 3/4Hr stuck on the Brussels Ring in air temp of 28C.

 

Once I had overhauled the cooling system. It has remained full to the top of the radiator cap. No losses. Expansion tank receives coolant expansion and allows it back into the system when the cooling system cools down.

 

I had a suspect alternator (took a long time for the charging light to go out ) - subsequently diagnosed as a failed rectifier.

 

On a trip to UK. Back on the E40 at 3500 to 4000 revs and the temperature gauge starts to rise to 110C and the 120C even after just a short distance. Maybe my car is allergic to the E40. Proceed cautiously. Get to UK. Redline Components check over the cooling system. The system is full of coolant. Cooling system functions fine. Thermostat and radiator fan switch (which is mounted in the Ford thermostat housing (tower) is working correctly as measured by IR thermometer. Diagnosis is a faulty gauge. Drive back to Belgium with black tape over the gauge. Occasionally sneak a look at the temperature gauge - its playing up again.

 

Back in Belgium I fitted a new temperature gauge - all seems OK. Hurrah.

 

During a summer holiday in UK (without the Seven) I took the suspect alternator to my local man in Cornwall. Had it tested and an excellent replacement unit supplied. This is fitted now.

 

Had a trip up the E40 to see Elie Boone. On both legs the temperature gauge was playing up again!! I saw 140C - Full gauge at one stage!

 

Did some more research and checked out the earth paths to the temperature and fuel gauge. No separate earth path to the gauges apart form the dashboard itself. 1.5 to 2 Ohms from clean bolt on bulkhead. Which doesn't seem too bad.

 

I have read up about the Smiths Voltage stabiliser and have purchased a solid state alternative. I am just waiting for this to arrive and will fit it - fingers crossed.

 

Solid state voltage stabiliser from Ebay I bought the 'MGB' one.

 

Or you can purchase from his website directly (a bit cheaper too)

Classic stabilisers

 

You can make your own solid state device that fits in the original case if you want authenticity. I not that bothered under the dashboard! DIY solid state voltage stabiliser

 

I found this text of interest on the DIY site:

 

By modern standards, thermal Voltage Stabilizers are inaccurate and inconsistent. Their output varies a lot between summertime and wintertime because their accuracy is affected by ambient temperature. Heat under the dashboard (e.g. when your windscreen defrosters are turned "on") can cause a significant shift in gauge readings. Output may also vary over the life of the Voltage Stabilizer as the bimetallic element fatigues, as internal contacts grow dirty, etc. If the resistance wire breaks, the Voltage Stabilizer will simply pass-through electrical current at continuous and unregulated voltage, so the old-fashioned thermal gauges will read high.

 

This sounds like my problem. After all the bi-metallic voltage stabiliser is at least 22 years old.

If your Voltage Stabilizer is old or broken, or if you just want to improve the accuracy and consistancy of your fuel level and coolant temperature gauges, you may want to consider converting to a modern solid-state electronic voltage regulator.

 

IMPORTANT NOTE: if you replace your original MGB gauges with aftermarket gauges, you should probably remove and NOT replace your old-fashioned thermal Voltage Stablizer. (Jumper across the Voltage Stabilizer connections.) Modern dual-coil gauges provides accurate information regardless of supply voltage, but they may not be adequately damped to accomodate the abrupt on/off cycling of a thermal Voltage Stabilizer.

---

 

Note MGB had Smith's gauges and the same voltage stabiliser (I remember them well).

 

So in summary my cooling systems works even in hot ambient temperatures. However, temperature indication is my problem. The next step is to fit a solid state voltage stabiliser to supply a stable 10V to the temperature and fuel gauge. When at speed, alternator voltage or engine heat seems to affect the voltage being supplied to the gauges (or possibly affects the stray resistance) in the mounting of the instruments in the dashboard. The final step will be to run dedicated earth to each instrument if that is not successful - I may do so even if it is successful as a precaution.

 

Further info. I have no sponge or any other ducting around the radiator.

 

I bought the Seven with 9,000 miles on the clock. I now have 10,800 miles with no coolant loss or overheating.

 

I have most of the parts to convert to a closed cooling system but have fitted it yet. Other more pressing jobs to do.

 

I hope this little history gives to something to think about.

 

Gavin

1988 1700 Supersprint (LA, long cockpit)

 

Edited by - Clousta on 26 Aug 2010 20:14:07

[terryp]

Jonathan

Nice kit, the problem is that I wanted to keep everything looking as original as possible. I know thats a bit unusual for a Seven owner! It is really nice though.........

 

Gavin

Very interesting story, and food for thought and very similar to my car

(I had a similar story to yours on my journey from the UK to France (450 miles), I did on that occasion wire the fan on)

I did purchase a solid state replacement voltage stabiliser to look like the original from a fellow poster from lotuselan.net , I've tested it and it puts out a steady 10.2v. My gauge seems to be OK now, but I do think its over reading by about 5-10 degrees.

I too overhauled the recipricating arrangement and all seems to be working fine with no water loss.

 

The thing that I can't understand is my Lotus Elan +2 also a car with marginal cooling. It has the original type radiator, a kenlowe modern blow fan , thermostat at 71 degrees and fan set to go on at 78degrees .....it works fab, why the difference to the Caterham.

 

The only thing I can think of is that when the fan comes on at 85 its really too late to do anything if the ambient temperature is very high

 

I'm going to flush the system , just in case , then wire the original fan to work manually in front and the fan behind to work of the switch and see what happens. Surely 2 fans on the original radiator must work?

 

We just took the car out for a blat and my wife noticed that the gauge suddenly rose?

 

Very frustrating stuff

 

Terry

 

 

 

 

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[Piers Rendell]

Terry - yes I sold C225 RPM to a Belgian guy, who emailed me last week and seems very pleased with the car. He was 6ft 4" tall and I said he would be a tight fit. He also has other Lotus cars. Parting with a car after 25 years was quite tough, as it was sad to see it go. However, the replacement: R300 KWK is just RAW in comparision and huge fun.

 

 

[Graham Perry]

To keep cool on mine;

 

Sealed system with header tank

Modern bigger fan that covers the whole radiator core - not the horrible original one from the 80's

Heater

High capacity Ali radiatior

Fan overide switch

Good head gasket

Electric water pump.

 

Okay you don't need the last one but the others all help along with a suitable thermostat

 

Edited by - Graham Perry on 26 Aug 2010 23:27:28

[terryp]

Graham

Thats a lot of modifications! yours must run at 60 degrees!

 

Do you keep the heater on , even in summer, my legs were getting very very hot the other day!

 

I'm begining to wonder whether its worth having a thermostat at all, perhaps a fan that comes on at say 80 degrees would act as a theromostat?

 

Thanks

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[Graham Perry]

Yes, Mine does run cool quite cool, but on track days in the summer it can still reach into the 90's. I don't use the heater all the time, but its there as a back-up to assist a little if required.

 

The EWP is useful as when coming straight off track with a hot engine you can keep it circulating the water round the radiator for a few minutes after shutting down. Not a simple thing to fit though.

[Graham Sewell]

I notice that nobody has mentioned the couling around the fan - this is essential for the fan to actually suck air through the radiator as against just pushing air around behind the radiator.

 

Cheers,

 

Graham

------

Low tech luddite - xflow and proud!

[terryp]

Does anyone think that sponge on the top would help, otherwise the air will just go over the top of the rad (easiest route)

 

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[Graham Sewell]

I would think that anything that can push more air through the rad rather than let it slide past would help - as does removing any dead flies/wasps/etc from the matrix.

 

Cheers,

 

Graham

------

Low tech luddite - xflow and proud!

[terryp]

Thanks to everyone for their replys

One final question:-

 

Is anyone running cool/OK on the original standard set up?

 

Thanks

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[Graham Sewell]

I have a standard 1995 setup - but that does include a fan mopunted on the engine side and a couling around it.

 

I don't know what was standard in 1985.

 

Cheers,

 

Graham

------

Low tech luddite - xflow and proud!

[CageyH]

Are you sure your temperature sender is ok? Is the gauge accurate?

 

A bigger fan may help.

However I would try flushing the rad out, and would look at the cooling fins to see if they are damaged/blocked. If air can't flow through, then it is not going to cool. This would be my first action.

 

You could also get a rad fan switch that turns on/off slightly lower. What temp is the engine supposed to run at?

 

 

 

Only dead fish go with the flow....!

[terryp]

Graham

Standard in 1985 was small rad with tiny yellow fan set 6 inches in front of the rad at the top RH corner .......not really enough!

 

CageyH

I'd like the engine to run at less than 85 degrees all the time, with a 74 degree thermostat it should be possible.

I'll try and get another switch and I think a good flushing is on the cards.

 

Thanks again

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[CageyH]

So, you are looking at a bigger rad, bigger high capacity fan, a sealed cooling system and a lower temp fan switch?

 

I have a K series and can't get that to run at 85 degrees, with all of the above. As soon as you come to a rest after a spirited blat, the upgraded fan on my Radtec will run continously as the coolant temp slowly rises (but stays in a sensible range). However, when moving, everything is fine, even when it is 39 degrees ambient.

 

If your heater makes a big difference, it sounds like you are not getting enough air flow through the rad, so it is either blocked internally, or the cooling fins are full of dead insects dating back to 1985 😳

 

If you want to try one of the Caterham ali rads (I believe they fit crossflows and Rovers?) and are passing by Toulouse, I have my spare sat in the garage with an uprated Pacet Pro fan that you can try.

 

Only dead fish go with the flow....!

[terryp]

Thanks so much for the offer CageyH. I'll try the flushing and clearing first and see if it makes a difference and if not will come back to you.

Redline do a new radiator (normal type) for £65 I wonder what this is like?

 

i could just drive it and stop worrying after all it hasn't overheated yet!

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[terryp]

Well, flushed the system and found some sand(?) and also a leak to the radiator!

So new radiator it is!

 

Thanks all for your help

Terry

 

Lotus Elan +2 S130/4 1973

Caterham Seven Supersprint 1985

For a Gite Holiday in France - Click here

[CageyH]

Question is, which one?

 

Only dead fish go with the flow....!