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Felling Hot Hot Hot - Thermostat

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Well after a breif hiatus and not having used the car for quite some time it was time to take it to Donny for the Lotus Festival; great day out and fun had by all.

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On the way up there i noticed my Temp guage getting very high...and quite quickly too... I promptly got on the M1 and the temp cooled around the standard 90 odd. Upon queing to get into Dony the temp was really climbing, 110, 120, 130. switch it off and left it!

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i discussed this with Henry, Dave and Martin and upon examining the expansion tank there was very little in it! (hadnt been checked in ages!) So we topped up with around 3 litres to get it back to the mark.

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I then set off from dony back down the M1, temp getting quite hight quite quickly then settling around 90 or so on the move.

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I pulled into Cherwell valley services on the M40 to check the temp and let the car cool for a while and as i was leaving after a short stop the temp shot up, 110, 120, 130 and as i bombed down the sliproad white steam started to pour from my louvres.... oops..... pull over to find the expansion tank has had a hot steamy pee everywhere.

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let the car cool, topped up with water and off we go again. within 3 miles or so the temp is back up to 110, 120.... pull over as i dont want to cause any lasting damage. call to the AA

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Texts to sparky and a quick chat, couple of check too;

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fans not comming on over 95, check otter switch short it and theyr on... strange.

open the bleed on the top of the rad to ensure no air in system and no all fine just a steady stream of coolant.

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After recovery to Oxford services then waiting for the AA man we did a couple of tests,

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system pressure test and some other colour test confirm that water pump is fine and Head gaskett is thankfully fine too.... Phew!

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so attention comes to the thermostat,

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it is removed and looks to be stuck. jammed shut (i think) so no water is going to the rad/fans.. problem solved (i think) i boiled the thing in a pan at home and no change in the opening appatures so must be stuck right?

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003-2_zps6eccdbdf.jpg

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Now this is the kit which im now told is obsolete....

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this is a sealed unit on the dry sump turbo which is not next to the block its down by the earth/chassis behind the drivers seat anyone know where i can get one? or an equivalent? is this the root of my issues?

 

Many thanks in advance

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Can you use the later B082K6043F thermostat? SWLC have it at a good price at the moment.

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The 6043 thermostat is the one used with the cooling system modification kit. One of the pipes coming from it is of smaller diameter than the original, it's the one coming out at an angle by the main inlet pipe. Otherwise it's the same unit; you'd need to deal with stepping down the original pipework to fit. Or, of course, you could simply knock the whole innards out of the broken thermostat and run without one...as had been done to mine by a previous owner (or garage.....!) that should stop the overheating but your feet will get cold in winter! I had fitted the 6043 type thermostat by stepping down the pipework...but then I got the cooling system mod kit in one of the "proper" cheap parts sales, and fitted that. It came with a new thermostat of the 6043 type, and changes the cooling system flow, incorporates a seperate nylon overflow tank and moves the pressure cap to this new plastic tank that fits to the RH rear wheelarch. It's a very good modification, you get loads of aluminium pipework and a new metal header tank, too.

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Very interested to hear what you say about the engine normally operating at 90°C. Mine runs bang on 60 when driving normally. If i stop and leave the engine running , the temp will climb to 90, or just above, at which point the fans kick in.
 
I realise now that it should be operating at 90... in which case my heater might actually produce some heat. As mine is also a dry sump Ill be interested to hear what fix you decide on.

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Scary temps!

I had to buy one of those thermostats last year - I got it from Esprit Engineering. I don't know if he has any now, but it's worth a try - 01725 514449. It was about 100 quid I think. The other thing I remember is it was a pig to get out and back in!!

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Maybe a Land Rover PEL500110 thermostat is a viable alternative (82 deg C) ? Any one know what the inside of the stock thermostat looks like?

Edited by sailorbob

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Inside the thing that looks like an artificial human heart there is a perfectly normal thermostat; problem is that it fits into where the ridge is around the casing. I think the whole thing is swaged up as a unit.... might be possible to cut it open and fit a new thermostat inside, but you'd have to be a decent welder ... and not overheat the wax capsule in the new thermostat....! On the whole, I'd replace it....or knock the whole thing out and do without. Just means the engine takes longer to warm up, no other deleterious effects that I noticed in the several years I ran it like that.

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My question about what the insides look like was really about which way the coolant flows are going.

Not having a thermostat is a bad idea, the extended warm up period results in greater engine wear.

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Extended warm up...theoretically yes; practically it didn't make a huge difference and I don't think it resulted in any signficant additional wear. I'd rather risk that than have a 910 overheat....

 

As for coolant flows...the inlet is the one that is co-axial with the unit; the bypass is the one coming off at an angle next to the inlet and the outlet to the radiator is the solo one on the other end. With the original unit, the diameters of the inlet and outlet and bypass are all the same...the modified version has a smaller diameter bypass.

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Thanks for all the assistance folks.. i have been digging around specialists and talking to anyone ane everyone who knows about esprits!

 

As John correctly states mine is an early remote thermostat (not sure when they changed) and the inards are just a bog standard thermo i belive which opens at 82. Sj's dont do em, the later sealed type has a smaller pipe of the side and Steve at Sj's has informed me in the condesending way that he does that this would not be suitable for my car due to the differing temps and plumbing.

 

despite the part being obselete, ive found one for the sum of £122.00 crazy when the later ones are about a fiver! the car was attended and diagnosed with assistance from the AA and i have aa breakdown repair cover so i can get it fixed at a local garage with the right parts, i then pay the bill then they reimburse me minus an excess of £35 or so.. Well theoretically. i will keep you posted!

 

Malcolm as above i will be replacing like for like as the car is original as possible (although im not anal on these things!) it will be interesting to see what temp it now runs!

 

will keep you posted

 

Rob i was pretty alarmed at the temps! hopefully i have done no lasting damage.. any ways of checking?

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How about getting an aftermarket inline thermostat housing and just knock the innards out of the original?

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If you've done the colour test to detect any products of combustion in the coolant...the one that sort of "sniffs" the air above the level in the header tank....and that was OK, then it's unlikely that you've done any damage...as long as it didn't seize a piston! If it did, it will become apparent later on. My 82 turbo ran for years on the later type of thermostat...I just wasn't going to pay stupid money for the original, so the later one was fitted with a reduction in the pipe diameter and no adverse effects. Then I fitted the cooling system modification kit later on. I think I still have the later type thermostat spare, having replaced it with the one that came in the mod kit. 

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I had a sniff test done on my car twice and it passed both times!

Becasue of other syptoms I had, I was sure the head gasket had gone and sure enough a few hundred miles down the road it became apparent without a shadow of a doubt!

 

Hopo - where did you manage to get the thermostat from in the end?

I hope it get's sorted ok.

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Sniff tests can fail if done at idle, you need to give the engine some revs to build the pressure up.

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I thought pressure was built up by the expansion of the water as it heats up. Revving the engine would not change the coolant pressure in any way.

 

In my Excel the thermostat is stuck but in the open position but the car heats up fairly quickly and the temperature sits around the 70 degree mark until I slow down when it can move up to the 85 mark before the fans kick in.

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An increase in pressure is normally attributable to the temperature rise in the coolant. If the coolant was pure water then a rise from 15 deg C to 82 deg C in a typical 18l system would result in an increase in volume of 0.25l.

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It is normally roger but a busted head gasket leaking pressurised air into the coolant will increase the pressure further. At idle the passing of air from the combustion chamber to the coolant may not be any where near as high as when the engine was revving.

I've not thought about it before but the above seems like a pretty likely reason to not do it at idle.

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