Lotus Elan

Running hot

PostPost by: gino1 » Mon Jun 19, 2017 3:14 pm

Hi ..Just wanted to share some thoughts on a possible overheating problem I may have on my Elan S2.
Yesterday the temperature was 35°C (very hot and stale) and during a run up the motorway cruising at around 5000 rpm I noticed the temperature creep up around 100°C and stayed constant all the way even if I ran higher revs.... although it never went past this figure i was constantly looking to see if it moved either way...
I have a TT radiator and fan fitted which are working well but to reduce the temperature to a constant 90° C if possible, i'm thinking of fitting a smaller pulley on the water pump to make it run faster.
Anyone any comments on this ? Has anyone tried this ?
Appreciate your feedback and experiences on this..

Thanks
Gino
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PostPost by: Maulden7 » Mon Jun 19, 2017 4:13 pm

Gino - with my S2 I have found that the problem running in hot weather conditions is actually getting the heat out of the engine compartment (later Elans had an opening / vent on the exhaust side of the inner wing into the wheel arch area)

I created an exit route in the inner wings on both sides of the engine compartment & have not had an issue ever since (I too have a TTR aluminium rad & electric fan)

I would have thought that making the water pump run faster introduces other risks, but then I never saw anything over 85degC when on the move - & even that was on track in hot weather (the higher temperature readings only occurred when stuck in traffic for long periods)

Dave M.
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PostPost by: William2 » Mon Jun 19, 2017 4:44 pm

Hi Gino, I also think it is a good idea to try and get more heat out of the engine bay. Have you done all the obvious standard things such as blanking off all the areas around the rad to help direct the airflow through the core. I have always thought that there is a lot of hardware that impedes the airflow in front of the rad, brake servo and air filter case being the main offenders. You could also check the temp gauge to see how accurate it is. Having said all that, 35 degrees is fairly warm air!! It's even 31 in the UK at the moment! Regards, William.
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PostPost by: RichardHawkins » Mon Jun 19, 2017 6:55 pm

Gino,

A friend had a similar problem with his Elan and was able to work out that air flow out of the engine compartment was the problem. His method was simple, he opened the bonnet whist driving, and the engine temperature reduced.

Richard Hawkins
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PostPost by: knockoffnut » Mon Jun 19, 2017 8:44 pm

Getting the heat out of the engine compartment has always been an issue on these cars. I have seen Elans with the rear of the bonnet raised a bit on hold-down pins. Many Elan racers would cut vent holes from the engine compartment, out to the wheel wells above the suspension, and I did cut oval holes there on my S3, back when it was just a used sportscar. I also installed a custom quadruple core oversized radiator leaning forward towards the bumper. I have never had a heat issue since,
img-20161127-01416.jpg and
but now when I look at it I keep thinking it looks too heavy...
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PostPost by: gino1 » Tue Jun 20, 2017 6:59 am

Thank you all for these very good comments; although I've seen cars with round slots cut out over the wheel arches I completely forgot about this. :roll:
I've fitted the square sponge over the radiator to close off an air passage but not along the sides...I'll fit some ally ones in this weekend and get the drill out and cut out some ventilation ways.
Travelling in that high heat on Sunday I also noticed the temperature of the gearbox tunnel ...it resembled an oven and was very unconfortable....
Especially during the journey back in the hottest period of the day I was thinking of how I could get some fresh air into the car and not how to get it out of the engine compartment !

Thanks for your help.
Ciao
Gino
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PostPost by: rgh0 » Tue Jun 20, 2017 10:17 am

Hi Gino

Cruising at high motorway speeds should not overload a TTR radiator if everything else is OK. it also may not be really overloading as 100C is not excessive and the thermostat may not be fully open until around that temperature. depending on its first opening temperature.

My race Elan has a 3 row wide radiator ( modified spitfire that was standard on the later S2 and S3) and has no trouble on the track at 40C+ and 180hp / 8000rpm and similar average speeds to what your doing on the motorway at 5000 rpm. Higher ambient temperatures, much more heat load and similar air flow in a less capable radiator than the TTR alloy version and it works for me but the engine does get to around 100C on the track on hot days.

I also have no ventilation holes next to the alternator. I don't believe these holes were added to aid cooling air flow through the radiator but to help remove excess heat locally from around the dynamo / alternator when the tubular exhaust was introduced as these modifications happened around the same time. There is I personally believe plenty of space for the air that comes through the radiator to vent out the bottom around the engine and gear box, the 2 small holes in the wheel arch add only a small amount of extra flow area.

Water pump speed should not be an issue either as race engines typically run a smaller crank pulley to slow down the alternator and water pump to normal speeds when running at 8000 rpm to minimise losses witohut problems

Things I would check if worried about engine temperature at high engine loads and speeds

1. Sealing around the radiator so no air bypasses it ( most critical IMHO)
2. Ensuring the radiator is clean externally and the coolant is clean and full and its also clean internally
3. Ensuring the thermostat is fully open at or before the desired operating temperature
4. Ensuring carb fuel air ratio and timing is correct at high load and engine speeds as if either are off the engine is less efficient and rejects more heat to the radiator.
5. Checking to ensure no small loss of coolant that may indicate a head gasket leak. A small head gasket leak due to a cracked fire ring can cause an engine to run hotter even without coolant loss, been there done that.
6. Checking the pump suction hose to ensure it is not collapsing at high suction by the pump
7. Ensuring what ever fan setup you have is not obstructing natural air flow though the radiator, at motorway speeds you should not need the fan
8. Ensuring the drive belt is sufficiently tight when the engine is hot to not slip at high revs. When cold this is quite slack otherwise it overloads the water pump bearing when hot so it is a delicate balance
9. Maybe a few other items I have forgotten if you get this far through the list without finding any solution
10. Beyond the above you then get into the internal assembly and details of the pump and block and head and gasket which are much harder to check.

if all the above checks out OK and your still concerned about the operating temperature then try some Redline Water Wetter in the coolant it does work !

cheers
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PostPost by: gino1 » Tue Jun 20, 2017 12:39 pm

Hi Rohan,
Thanks for your comments.
Obviously before cutting out holes in the engine compartment I will try to close off the side passages of the radiator to ensure it all goes through the radiator.
No thermostat fitted
Everything else is new , hoses, radiator clean , new coolant etc... and tight.

I will also try this Redline coolant .
Thanks
Best regards
Gino
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PostPost by: denicholls2 » Tue Jun 20, 2017 5:58 pm

gino1 wrote:No thermostat fitted


It is a peculiarity of the Twincam engine (in my reading) that this is likely your problem (and not a great idea anyway because it causes the engine to run too cool to be efficient when it isn't hot out). There are many posts here and elsewhere that the thermostat's restriction on flow is necessary to prevent cavitation around the water pump in a Twink.

Not sure I buy the whole argument, but it's well-established lore (and a real cheap fix.)

In large American cars, the only downside of no thermostat is no heat and poor efficiency. But maybe not so in all engines.
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PostPost by: RichardHawkins » Tue Jun 20, 2017 8:04 pm

Gino,

When blanking the gaps above and beside the radiator, dont forget the gap under the radiator by the steering rack. I think there was a piece of moulded board in this area when the cars were new. Many cars are now missing this piece.

Richard Hawkins
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PostPost by: gino1 » Wed Jun 21, 2017 7:09 am

Good point on the cavitation ...I'll study that one...

Re the lower blanking plate ; I can't fit that as I have an oil cooler that sits directly under the path of the radiator making sure I didn't exclude air flow to the water radiator.

This weekend I'll try adding the side plates and then share the results with you...

One for Rohan; I tried looking up the Redline water wetter liquid and found that its produced in Cheshire UK and sold on Amazon in US for $9,99 a bottle while the same bottle on Amazon Italy it is sold for approx 24 Euros :shock: :shock:

Thanks
Gino
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PostPost by: knockoffnut » Mon Jun 26, 2017 5:14 pm

I certainly agree that running no thermostat can be a source of problems. I have seen this on a number of cars. If you want to test the theory it is easy to put in a thermostat, take it out and run without, and swap in a lower temperature stat to see the differences. I remember doing this on my S3 years ago with a few different thermostats, and with none. Running without a stat is not a good plan.
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