Running Very Cool

[alanrichey]

OK. I thought I had made it clear in the thread that I had already replaced the existing 82C thermostat with a new 88C one hoping that would cure the problem. It didn't, and the car kept running cold. My logic (probably incorrect as it has been in the past) was that although the thermostat is rated at 88C, that is the 'fully open' temperature, and apparently it actually starts to open around 76C. And in my case even such a small flow through the radiator was enough to keep the engine running at a temperature in the high 70s. So I needed to reduce the efficiency of the radiator and the grill blanking seemed the obvious solution.

 

I guess I could blank off even more of the grill and then use the fan to keep the temperature down, but not sure there is much point in that if I already have the temperature close to ideal ?.

 

Does that make any sense ?

Edited March 31, 2016 by alanrichey

[Guest mower man]

Card board and tank tape on the rad when?summer come take it off ,have fun , see you in May mick

[speedtripledan]

Are you sure that water isn't somehow bypassing the stat. When I sorted my zetec it ran at about 65deg before I put an 82deg stat in giving approx 90 degree running temp

[alanrichey]

Pretty certain not. With no thermostat in the engine stabilised at 62C. With an 82C one in she stabilised at 73C. With an 88C in she stabilised at 76C. Now, with my partially blocked grid and the 88C thermostat I just got back from an hour-long drive and she stabiiised absolutely bang on 88C.

 

Happy bunny

[Guest 2b cruising]

Sorry Alan, I read your post but somehow missed you saying you had changed the stat.

It's good that all is solved and running correctly now.

[fry61]

If the thermostat is working correctly & your temperature gauge is measuring block water temperature then there must be too much cooling air reaching the block, is your rad ducted so engine bay air has to pass through the rad? Might be the solution to duct the air or I may be totally adrift on understanding your problem in the first place.

[alanrichey]

The long term story is that I suffered overheating problems for 2 years and tried everything, including, as you say, trying to force the air through the radiator (which on the Superspec is absolutely HUGE), and running without a thermostat, but at the same time found the coolant was also leaking under pressure from somewhere, One of the modifications I tried was to change the pressure cap from 13psi to 20psi and that resulted in a rather dramatic breakdown on the way back from last years end-of-season bash when one of the rubber cooling pipes blew off a stainless pipe. In hindsight I suspect that was where the coolant was leaking, as since I fixed that the leakage has been minimal. That was when the car started running very cool, mainly because it was full of coolant and with no thermostat, so I started playing with thermostats. So at long last I think I may be there and I will now remake the grill blank so it is a bit more adjustable for various conditions.

[Big Jim]

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Edited April 2, 2016 by Big Jim

[alanrichey]

Sorry Jim but I don't think you can compare the Superspec with a 'normal' 2B. Although the pipes are routed differently to the Rover 420 (because the engine, radiator and expansion bottle are mounted in different places) looking at my Haynes manual it is still fundamentally the same system. And I haven't made any modifications to the cooling system.

 

And as I said before, our radiator is almost twice the size of any normal one (including the 420), but angled back almost 70 degs to compensate. The Superspec doesn't have a heater fitted so that is not a player in the equation.

 

The only major difference is that Richard Stewart fitted an extra pipe from the top of the radiator across the top of the engine (with a bleed valve brazed on) into the expansion bottle, as the bottle is almost level with the top of the radiator. I suppose you could get reverse flow through that pipe from the expansion bottle to the top of the radiator, but it is a very narrow bore.

 

Anyway, bottom line is that for the first time in 3 years I seem to have a perfectly working cooling system so I don't really care how it is working, I'm just enjoying driving around without having to continually watch the temperature gauge

[Big Jim]

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Edited April 2, 2016 by Big Jim

[Kerry]

Hi Alan,

I have to agree with above, you have water bypassing the thermostat,

[Guest Gargoil]

I do.

I drilled a small hole in my stat (often recommended on here and other sites) and Betty never gets up to full working temperature over the winter months.

Steady as a rock in the summer but now that my temps are fine, I'm wondering if fitting a new stat without a hole, might be the best thing for winter running.

[alanrichey]

Have to admit my 88C thermostat, bought from Rimmer Bros, does have the 'jiggle' hole in the stat. So maybe I should try another thermostat without the hole ?

 

I didn't realise this subject would cause such a heavy reaction, but in my defence can I reiterate that I have made NO modifications to the basic plumbing, it is exactly as it left the Robin Hood factory in 2001 .

[fry61]

Solving the problem is more important than who was right or wrong Alan, & given enough monkeys, I mean members; a solution will come -- maybe -- eventually.

[Big Jim]

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Edited April 2, 2016 by Big Jim