Very Slow Warmup

[Candles]

Fellow Elaners,

I recently pulled my Elan out of storage where it had resided for 4 years. I drained and flushed the cooling system and replaced the thermostat with one of these:

QH-Benelux QTH102K Coolant Thermostat

Now I have an issue; the car is really slow to warm up. It can take an age (~5 miles) for warm air to flow from the vents and normal operating temp is rarely reached on a steady drive - it is as if the thermostat is either too low a value or stuck open. It wasn't stuck open when I fitted it, so is 88degC too low?

Thanks, Candles.

[lotusflasherman]

Fellow Elaners,

I recently pulled my Elan out of storage where it had resided for 4 years. I drained and flushed the cooling system and replaced the thermostat with one of these:

QH-Benelux QTH102K Coolant Thermostat

Now I have an issue; the car is really slow to warm up. It can take an age (~5 miles) for warm air to flow from the vents and normal operating temp is rarely reached on a steady drive - it is as if the thermostat is either too low a value or stuck open. It wasn't stuck open when I fitted it, so is 88degC too low?

Thanks, Candles.

Lot of discussion about engine temp and temp gauge here -- forum.lotuselancentral.com/viewtopic.php?f=44&t=23199&start=20#p308470

88C is higher than Elan standard thermostat so cannot be too low. I've fitted a 89C stat, the highest I could find, - www.ebay.co.uk/itm/VAUXHALL-ASTRA-1-7-DTI-16V-1-7-CDTI-16V-00-10-Replacement-Thermostat-/400593866420?hash=item5d45414eb4 to run the engine slightly hotter.

There is a bypass hose running across the front of the engine and through the heater that allows water to circulate when the thermostat is still closed. This means the heater is not dependent on the stat opening and should warm up as the block warms up. If it isn't I would suspect that in the 'draining and flushing' you have got an 'air-lock' somewhere in the heater system..

[Nickydee]

I had similar issue with mine with a couple of non OEM thermostats, both bought using part numbers on the Wilki. The issue appears that same dont have a jiggle pin in one of holes which obviously restricts the flow- Think there is thread from Britnut re this somewhere.

Replaced mine with a proper Lotus item - about £15 so twice the price of the non OEM but solved the problem. My exhaust pops less now so think before car was overfueling which is not ideal.

Cheers

Nick

[lotusflasherman]

I had similar issue with mine with a couple of non OEM thermostats, both bought using part numbers on the Wilki. The issue appears that same dont have a jiggle pin in one of holes which obviously restricts the flow- Think there is thread from Britnut re this somewhere.

Replaced mine with a proper Lotus item - about £15 so twice the price of the non OEM but solved the problem. My exhaust pops less now so think before car was overfueling which is not ideal.

Cheers

Nick

Fueling has nothing to do with the thermostat or the temperature at which it opens. Information for fueling is sent by the Coolant Temperature Sensor - which is hidden away down the back of the engine and not to be confused with the Temperature Gauge Sender which sticks out the top of the Thermostat Housing and only drives the gauge.

As far as I know Lotus have never made thermostats so I consider there is no such thing as 'a proper Lotus item'. As long as you buy the right design it will work. The one I've fitted was physically identical to the one that came out and works fine.

[Simon_P]

The CTS is next to the gauge sender and upstream from the thermostat. The fan switch is next to and downstream from the thermostat.

The correct thermostat is eccentric and has a jiggle pin. Ask yourself why Isuzu/Lotus went to the trouble and expense?.. Perhaps to prevent airlocks and improve flow?

Candles,
If the temp gauge reads ok the thermostat is not stuck open. You most likely have an air lock. Have you bled the radiator?

[Rambo]

Sounds like an air lock to me too although it isn't unknown for the cheaper thermostats to be problematic

[Nickydee]

I had similar issue with mine with a couple of non OEM thermostats, both bought using part numbers on the Wilki. The issue appears that same dont have a jiggle pin in one of holes which obviously restricts the flow- Think there is thread from Britnut re this somewhere.

Replaced mine with a proper Lotus item - about £15 so twice the price of the non OEM but solved the problem. My exhaust pops less now so think before car was overfueling which is not ideal.

Cheers

Nick

Fueling has nothing to do with the thermostat or the temperature at which it opens. Information for fueling is sent by the Coolant Temperature Sensor - which is hidden away down the back of the engine and not to be confused with the Temperature Gauge Sender which sticks out the top of the Thermostat Housing and only drives the gauge.

As far as I know Lotus have never made thermostats so I consider there is no such thing as 'a proper Lotus item'. As long as you buy the right design it will work. The one I've fitted was physically identical to the one that came out and works fine.

Phil

Wasn't suggesting that the thermostat was hand crafted in Norfolk by carrot munching artisans but simply that the one sourced via a lotus dealer is the correct item.

I brought two using the wilki part nos which were incorrect. I don't doubt the correct item is available elsewhere and others have successfully sourced the right item outside lotus. However there are a few who have has the same experience as me.

I would agree its usually silly to pay extra for the correct part wrapped in a Lotus box but in this particular instance for the sake of a fiver it might be preferential to get the OEM part - as this will either solve the problem or leave no doubt that this not the cause.


Re overfueling then if the engine is running cold due to an incorrect thermostat then would be detected by CTS, which may lead to the engine running richer than it would if the coolant was at "normal" temperature.

Wouldn't airlock lead to overheating due lack of circulation rather than running cold.

[Simon_P]

Nick,
You have your would and mays mixed up.

An incorrect thermostat may lead to poor circulation which may lead to the CTS under reading which would lead to over fuelling if you don't have an O2 sensor.

I'm guessing that the described symptoms refer to the heater rather than the engine.

[GeoffSmith]

I'd go for airlock in the heater matrix and/or pipes or crap in the heater valve maybe caused by laying idle for so long and/or changing the coolant. Did you ever fit the ScanTech one you bought in 2009?

[Candles]

Thanks for all the helpful replies.

I had discounted the 'airlock in heater' theory, as the heater will blow very hot eventually and yes Geoff-of-big-data-fame, I did put in the all-plastic heater valve! I can't remember if I bled the radiator - I think I probably did, but who knows! I'll check that.

I am running a Autometer Phantom (Ebay Link) water gauge, so aside from the F/C conversion, I am fairly confident of the actual temp of the gauge sender - it is a few miles before it hits the 150 mark, which is only about 65C.



Candles.

[lotusflasherman]

Phil

Wasn't suggesting that the thermostat was hand crafted in Norfolk by carrot munching artisans but simply that the one sourced via a lotus dealer is the correct item.

I brought two using the wilki part nos which were incorrect. I don't doubt the correct item is available elsewhere and others have successfully sourced the right item outside lotus. However there are a few who have has the same experience as me.

I would agree its usually silly to pay extra for the correct part wrapped in a Lotus box but in this particular instance for the sake of a fiver it might be preferential to get the OEM part - as this will either solve the problem or leave no doubt that this not the cause.


Re overfueling then if the engine is running cold due to an incorrect thermostat then would be detected by CTS, which may lead to the engine running richer than it would if the coolant was at "normal" temperature.

Wouldn't airlock lead to overheating due lack of circulation rather than running cold.

No point in wasting money on a cheap one if it doesn't do the job so I can see your point of view but WikiLEC has rather 'led you up the garden path'....

Thermostats mounted in the vertical position (as Elan) should have a 'jiggle valve' - it's to help clear air from the thermostat housing and should always be installed at the top (12 o'clock). The theory is the 'jiggle pin' will let air through and then close the hole by water pressure behind it. Without a jiggle pin the fixed surround in the vertical position will create a bit of a void that may trap air but there are plenty of thermostats with 'jiggle pins' that aren't at 'Lotus Prices'. Any designed for vertical installation will do but I note the WikiLEC says "Halfords HTK602, Quinton Hazell QTH100K, e.g. Any 1000cc Mini 1969-1992" which I consider BAD advice as I know the Mini uses a horizontal thermostat that hasn't a jiggle pin so not suitable at all. Actually, I think £15 is pretty good for a Lotus 'stat. I paid £6.99 through ebay for an Astra DTI but the ad says it's RPI is £17.99 and ebay has somebody selling a Gates equivalent stat at £30.90, so £15 is pretty cheap!.

The Eclat Parts Manual has a choice of thermostats, with a difference of 8C between Temperate Climate and High Ambient Climate applications and I used to swap them around before going to south of France. Lotus/Isuzu only seem to have selected one from the GM parts bin for the Elan so of course it’s the High Ambient Climate option which means we run cooler than ideal in UK. I wanted a higher set thermostat for UK use, particularly through the winter and Lotus don't offer that. (I won’t bore you with a lecture on the Laws of Thermodynamics but more power and efficiency is obtained from cooler air going into a hotter engine according to Messrs Carnot and Otto.) My Elan 'Lotus' thermostat appeared to be running the engine at 72C to 74C according to a digital thermometer with thermocouple so I've changed to a nominal '89C' and it's now running at 87C to 89C and the heater clears the windscreen much more effectively. I'll go back to 'High Ambient' before I go to France in the summer where ambient can be 35C or more.

On your other points - if the engine is running cooler than it should, the CTS will provide information for the fuel metering to run a rich mixture but that would be the correct mixture for that engine temperature. Your mpg will be crap but I would not use the term 'overfueling' as that implies to me, anyway, 'richer than it should be'.

Having had various road and competition cars with complicated plumbing I always refill the system with one of the highest hoses off and only put it on when coolant is coming out of it and whatever it goes onto, with the engine running if necessary. For road cars often the heater hose is the highest and the heater valve should be open too. Makes a bit of a mess but good way to ensure system is air-free. If you start with no air in the system it should continue like that.

[Candles]

So I bled the radiator and also pulled off one of the thermostat hoses. I can't see how air would get trapped in there as the expansion hose to the header tank comes off the top of the thermostat - but it got a bleeding anyway!

I've actually taken the plunge and bought the 89C Astra DTI version (which includes a jiggle-pin) which I'll fit when Bristol isn't returning to the ocean one raindrop at a time.

[Candles]

The old thermostat was in backwards! I've now installed the 89C version in the correct orientation and all is well!

[lotusflasherman]

That's good. Now you should have a heater that does something and you'll be able to drive with the hood down in winter. I usually do, keep side windows up, heater on full blast on face vents and side vents aimed at side windows and it's quite cosy - apart from the top of my left ear gets cold on a long run if I don't put up the wind deflector. Gave a neighbour a lift and he said he'd always thought I 'was made of strong stuff' but was surprised how warm it was in there.

[FunElan]

Reviving an older thread, as I have a similar issue.
I have a brand new thermostat in my Elan (82C), and it takes a few miles for the car to get to "operating temperature," a quarter way up the coolant temp dial. It seems this tracks with oil pressure as well. I have new 10w30 oil in the motor, and new filter as of today. The other day I drove almost 20 miles and it didn't get to that mark on the dial, although it was cool outside (55F and overcast).

Eventually, every time I drive, the car warms up and acts as normal. Fans come on when they should. Heat is HOT, really lovely at night time to have it blowing in the footwell with the roof down.

Is it normal for these engines to take a little while to warm up? My BMWs warm up very quickly. Perhaps I shouldn't even compare.