Mine's a hot one - or is it?

[Robbie693]

On S4 cars it helps to recore the radiator with a three row, add blanking panels on either side if the originals are missing and it"s important to use a thermostat that's the correct temp, 82c. A thermostat that's too cool will actually cause the system to overheat.

Interesting Jeff, especially as mine still runs hotter than I'd wish (albeit quite stable) and I have a 74deg 'stat fitted at the moment. Could you explain why the lower 'stat could cause the overheat? (Bearing in mind I'm no engineer!)

Regards

Robbie

[elansprint71]

At this point may I remind all of us about the previous doubts expressed about the accuracy of the temperature gauge readings where the sender is placed directly over the exhaust manifold/header pipes. I imagine that when all that spare capillary tubing is coiled up in a "hot zone" it can't help either. I'm fairly sure that someone checked out the true temps with a digital thermometer thingy not to long ago. Or did I dream that?

[Robbie693]

You are correct Pete, someone did. I also recall that Jeremy did a thermal imaging shot of his engine too.

The gauge (in a Plus 2 at least) is not much use anyway, only having 3 numbers on it - 50, 85 and 120, mine runs at around the tick mark after 85deg - what temp is that? I assume it is 90deg as the car is constantly cycling the fan which comes on at 92 and goes off at 88deg. In fact it runs with fan on so much that the fan bearings have started to rattle! I thought about wrapping the sender in some heat insulating tape as a test...

I had stopped worrying as it always cools down with the fan but after a recent trip to South Lincs in hot weather the temp stayed fixed at about 94deg whilst on the motorway (assuming my gauge interpretations are correct) and the oil pressure started to drop a bit when slowing down, which made me rather uneasy.

Still interested to read Jeff's explanation of the higher thermostat rating fix.

Cheers

Robbie

[Jeff@Jae]

Hi Robbie
I had been told this before and while I had a cooler thermostat I still encountered edgy temperature situations in my S2 Elan on warm days in traffic. I tried a normal temp thermostat and it seems to keep things from reaching critical. What happens is that a warmer thermostat not only allows the coolant get to proper range initially it also cycle open and closed more often and allows the radiator to exchange heat longer. When the 'stat reopens the engine receives a charge of cooler liquid and drops the heat and repeats the cycle. Hot coolant flowing uninterrupted throw the radiator doesn't have enough time to exchange heat as well. You'll see it on the gauge (at least the capillary gauge on the S2) but the overall average temp will be slightly lower than before. I had ignored this advice for years and I am pleased with both the higher normal temp on cool days and the less worrisome situation on hot days at slower speeds.

[EEED]

Thanks for all the replies. Differing views as usual on this topic! I wonder if some of us are over-sensitive to given that we've got used to modern cars with 40-50 years more development?

In my first post I mentioned my experience with MGs (bear with me Lotus folks). In August 1978 I drove my '72 Midget out to Portugal. There were lots of roadworks going through France because the autoroutes were being constructed; and then in Spain the temperatures were very high, but the car only came close to overheating once in a very long queue approaching Burgos. The air temperature must have been in the mid 30s (I saw 39 degrees in the shade at one filling station I stopped at). It had a belt-driven fan, a small but well ducted radiator and was fitted with an oil cooler. In the next four years I never had any overheating problems. (As an aside it also had a dynamo and I never experienced any battery charging problems either).

In investigating my Elan my local garage checked it out for me and noted that the rad was an even temperature (so no hot/cool spots) but said the sump was very hot (and this was before I fitted the blanking plate below the radiator).They suggested an oil cooler (and weren't too complimentary about an electric fan as a solution to overheating).

Another angle that intrigues me: in an article on tuning the twin cam engine in Car and Car Conversions in 1976, the author stated that these engines lose c5 h.p. between 70 degrees (noting that "this is about the best [temperature] for the horsepower on these engines) and approaching boiling, which they noted happened quite quickly, saying "after 70 degrees you can just sit and watch the power fall off." The car they were testing was a '67 S3, so not an old car at the time. I quite like the idea of gaining around 5 h.p. whilst mitigating any cooling problems.

Alternatively, I found a posting on a Morgan site suggesting a recouperator bottle (plus a multi blade plastic fan) is a solution to their overheating problems, which matches the view expressed in this thread in a previous post. However if I'm not mistaken, early cars didn't have a recouperator, so what did their owners do - perform regular checks presumably?

Nevertheless, I really wonder if an oil cooler would help the Elan. Has anyone had any experience of reduced engine temperature after fitting one?

A plastic multi-blade fan off ebay, plus regular coolant level checks and an oil cooler would be much cheaper than most of the alternatives.

Paul

[elansprint71]

Tony Thompson (who knows one or two things about Elan racing) also reckons that 70 degrees is the magic number.

[Robbie693]

Hi Robbie
I had been told this before and while I had a cooler thermostat I still encountered edgy temperature situations in my S2 Elan on warm days in traffic. I tried a normal temp thermostat and it seems to keep things from reaching critical. What happens is that a warmer thermostat not only allows the coolant get to proper range initially it also cycle open and closed more often and allows the radiator to exchange heat longer. When the 'stat reopens the engine receives a charge of cooler liquid and drops the heat and repeats the cycle. Hot coolant flowing uninterrupted throw the radiator doesn't have enough time to exchange heat as well. You'll see it on the gauge (at least the capillary gauge on the S2) but the overall average temp will be slightly lower than before. I had ignored this advice for years and I am pleased with both the higher normal temp on cool days and the less worrisome situation on hot days at slower speeds.

Thanks Jeff,

Makes sense, I think I'll give it a go.

Also apologies to Paul for the slight hijack

Cheers

Robbie

[richardcox_lotus]

Mine also runs regularly at 95 on the guage - up to about 102-103 in traffic. Car is a Sprint with holes in the wheel arch; foam on the radiator "wings"; deflector under the rad; small 3-core rad; original electric fan - pretty stock really - recently flushed it all with radflush as well - to no avail. Have similar issues when it does get very hot - not pleasant to drive - misfiring, erratic etc. which I also put down to heat soak in carbs & maybe o-rings allowing a bit more air in when v. hot.

The water expands into the overflow bottle correctly & is recuperated correctly - it always looks full to the brim when I check the levels when cold.

So what to do ? I've a sneaking suspicion my guage is not too correct - but I placed the temp sensor in a pan of water alongside a cookery thermometer & they were pretty much even stevens. But I still have my doubts, as the fan just kicks in soooooo late.....(105 on the guage)

Regards
R

[collins_dan]

Richard, The description of your experience is very similar to what I experienced with my S4. The larger aluminum radiator and 2 fans certainly helped. Rebuilding the carbs with new adjustable needles also helped reduce erratic behavior and backfiring when hot. The final fix for me was doing the following test http://www.elanfactory.com.au/pdf/techn ... 20test.pdf and it turned out that my cartridge water pump had been installed incorrectly. I would be curious to hear about your results from testing the water pump effectiveness. I'm sometimes wonder how many people with cars that run hot have water pumps that are just not working at full efficiency and this test is very easy to do. Dan