Engine overheating when idling.

[GreenGoddess]

7 hours ago, LotuStuart said:

How hard is fitting a new water pump? If it’s easy and it hasn’t been done for a while I’d be tempted to do that. 
is it possible to fit a sensor in the engine area where the water rises to 106? To at least have a fan turn in at the right time.-id certainly fit an override switch until it’s resolved. 
 

I feel your pain…

I think fitting a new water pump is beyond my capability. Turning the fans on using an override switch will make no difference because the coolant doesn’t seem to be flowing through the radiator at a rate fast enough to cool it. 
 

It looks as though I’m going to have to change the thermostat. Apart from the water pump, it’s the only thing I can think of that could be restricting coolant flow. 😞

[drdoom]

It's been mentioned here by others earlier but if the car has been worked on during prior ownership there's a number of ways things might have been botched in terms of engine cooling, not solely the pump. Of course you must make maximum effort at eliminating all the more readily resolved possibilities, removing and possibly tearing down the engine will be the last resort. Anyone here have experience with collapsing rad hoses? I know these are internally reinforced by coiled wire in some cases, in order to prevent collapse on the suction side prior to the pump.

[910Esprit]

Wonder if it would be worth temporarily bypassing the rad, just to rule out a blockage there?   

[LOTUSMAN33]

I’d get the pump out for an inspection as I’ve found some horrendous ones on engines over the years with unbelievable corrosion and impellers incorrectly gapped. It’s a shame you’re so far away as doing the pump isn’t that bad (certainly not fun mind) especially if the cap screw has been installed in way of the Aux pulley.

As Steve says you could bypass the rad with a length of hose, the fans would still kick in if flow to the Otto switch is achieved. 
Time to get this sorted as it’s been going on a good while now and you don’t want to get caught in a traffic jam situation and do your headgasket.😬

I had collapsing fuel hoses on a MG metro turbo years ago right up behind the tank, it was fine cold then kept dying as the cars temp went up, took me months to fix that and endless talks to people. An old boy from stock car racing pointed me to it in the end so don’t rule Steve’s thinking out 👍🏻

[GreenGoddess]

2 hours ago, drdoom said:

It's been mentioned here by others earlier but if the car has been worked on during prior ownership there's a number of ways things might have been botched in terms of engine cooling, not solely the pump. Of course you must make maximum effort at eliminating all the more readily resolved possibilities, removing and possibly tearing down the engine will be the last resort. Anyone here have experience with collapsing rad hoses? I know these are internally reinforced by coiled wire in some cases, in order to prevent collapse on the suction side prior to the pump.

Most of the coolant hoses look new. Many still have the labels on. The engine rebuild invoice from last Feb shows that lots of hoses were replaced. I don’t think it’s a collapsed hose but thanks. 

2 hours ago, 910Esprit said:

Wonder if it would be worth temporarily bypassing the rad, just to rule out a blockage there?   

The rad is virtually brand new so I think that’s unlikely. It’s the rad for the V8. It’s definitely an idea I hadn’t considered though, thanks. 

33 minutes ago, LOTUSMAN33 said:

I’d get the pump out for an inspection as I’ve found some horrendous ones on engines over the years with unbelievable corrosion and impellers incorrectly gapped. It’s a shame you’re so far away as doing the pump isn’t that bad (certainly not fun mind) especially if the cap screw has been installed in way of the Aux pulley.

As Steve says you could bypass the rad with a length of hose, the fans would still kick in if flow to the Otto switch is achieved. 
Time to get this sorted as it’s been going on a good while now and you don’t want to get caught in a traffic jam situation and do your headgasket.😬

I had collapsing fuel hoses on a MG metro turbo years ago right up behind the tank, it was fine cold then kept dying as the cars temp went up, took me months to fix that and endless talks to people. An old boy from stock car racing pointed me to it in the end so don’t rule Steve’s thinking out 👍🏻

I am going to call the garage that did the engine rebuild. It was only done in Feb last year and it wasn’t a Lotus specialist that did it so I’m hoping someone there will remember the car. Hopefully they can remember why it needed rebuilt and also if they looked at the water pump. 

[LotuStuart]

Add an electric water pump. Like the after run pumps. Aid circulation. 

if the fans come in and drop the radiator temperature then the system will cool down-even if the radiator isnt really hot. 

[910Esprit]

7 hours ago, GreenGoddess said:

The rad is virtually brand new so I think that’s unlikely

I reckon if you built a 'new' car entirely from brand new replacement/pattern parts it would be the biggest crock of s**t ever!!  🙃

Like you, the non-standard thermostat is worrying, but odd why the car then runs OK on the road.

Maybe you need to interrogate the previous owner - There are 2 possibilities:   Either one of the new parts have introduced the problem, or someone has spent a lot of money chasing this problem but has still not resolved it....  

NB - Find another LC owner, leave the 2 cars idling while comparing temperatures at all points of the system

 

 

[JimmytheTurbo]

I know you got a new rad but sounds like you got a blockage there.

Id drain coolant and see If you can blow through it.

[Rambo]

4 hours ago, 910Esprit said:

Maybe you need to interrogate the previous owner - There are 2 possibilities:   Either one of the new parts have introduced the problem, or someone has spent a lot of money chasing this problem but has still not resolved it....  

I suspect the latter which is why they moved it on. As mentioned early on I still suspect you might find a sludge buuld up somewhere at the bottom of the system 

 

On 08/05/2023 at 20:01, Rambo said:

So, nothing about a replacement water pump in the rebuild invoices?

What if someone had accidentally mixed EG with OAT antifreeze? There'd be a helluva sludge build up which would impair circulation and thermal efficiency

Just a thought.

 

[GreenGoddess]

5 hours ago, 910Esprit said:

Maybe you need to interrogate the previous owner - There are 2 possibilities:   Either one of the new parts have introduced the problem, or someone has spent a lot of money chasing this problem but has still not resolved it....  

 

Can't get hold of the previous owner, I've tried. 😒

 

3 hours ago, JimmytheTurbo said:

I know you got a new rad but sounds like you got a blockage there.

Id drain coolant and see If you can blow through it.

Trouble is, some water is passing through the rad because the outlet hose gets hot. I've never blown through a radiator before so I don't know how much, if any, resistance there should be when blowing through it.

22 minutes ago, Rambo said:

I suspect the latter which is why they moved it on. 

 

 

I am beginning to think that too.

[Rambo]

31 minutes ago, GreenGoddess said:

Can't get hold of the previous owner, I've tried. 😒

Now there's a surprise. What's the betting the garage are hard to get hold of too 🤔

[GreenGoddess]

18 minutes ago, Rambo said:

Now there's a surprise. What's the betting the garage are hard to get hold of too 🤔

Technically the guy I bought off off is the previous owner but I think he was a bit of a dealer on the side and he only had it a few months. He had other cars for sale at the same time. The “real” previous owner was the guy who had the engine rebuilt. He owned it for years. There is no phone number for him, he’s not on social media so I wrote him a letter last year. Sadly I didn’t get a response. 

[Escape]

Sludge build-up can be hard to diagnose. I've had a Range Rover overheat and despite repeated flushing of the radiator it turned out there was still a lot of sludge left. Flow was seemingly normal, but part of it was blocked internally so it hard a hard time getting rid of the heat when the engine was under load. What finally gave it away was the fact that capacity when refilling seemed considerably lower then expected and the empty weight was much heavier. Not easy to test... If you have access to a lift or ramps, you could check if the heat distribution is even when idling. You want hot at the intake and gradually lower by 10-20° towards the exit, with no obvious cold spots (indicating no flow) or hot spots (poor heat dissipation, possibly clogged airflow).

[GreenGoddess]

I've just got off the phone to the garage that did the engine rebuild. He was actually really helpful. Apparently the car came in because it was smoking and burning oil (nothing about overheating). The guy doesn't specialise in Lotus cars and he tended to agree with me that the water pump or thermostat were the most likely culprits. He also suggested I take off the hose that feeds back to the header tank to see if there is a good flow coming out of it. That would suggest that the water pump was OK. He also advised blowing the radiator through with an airline. 

Lots of ideas to try. 

[Gis]

You can sort this out. Go at it systematically and step by step. If I were you, I would drain the coolant next, blow through the radiator as advised by the folks. If that doesn’t yield more insight, I’d remove the thermostat blow through the pipes toward the front to make sure they are clear and then straight connect the system, without the thermostat. Then test it without the thermostat. Draining and refilling the coolant isn’t difficult. It needs to be done when changing cambelt etc so it’s a good learning exercise. Lift up the rear on ramps or stands and drain it. Refill it from the back through the coolant tank with the bleed screw on the rad open. Look at it as a blessing in disguise. You’ll learn the car. My car doesn’t even have a thermostat by the way, but mind you, I live in a climate with the coolest possible temp is at 23 degrees at night and an average of 32 at day so the the engine never truly gets ‘cold’. The coolant warms to 70 degree within less than 5 mins after engine start and stays on 90-95 degrees rock solid in any traffic with the fans kicking in at 72-75 degrees. (Otter switch for warmer climates). Test, narrow it down and you’ll get this thing worked out mate. 

[GreenGoddess]

*** SOLVED ***
Today I have finally confirmed the problem. Take a look at the attached photo. 
New thermostat on the left. The thermostat I’ve just removed from the car is on the right. Both thermostats are IDENTICAL and both are WORKING PERFECTLY. 

However, notice the difference in the way I have laid them on the desk? Turns out the garage that did the engine rebuild 18 months ago fitted a new thermostat but hooked it up in the wrong orientation (as seen on the right). They even went so far as to install a reducing hose in order to get it to connect. That should have sounded alarm bells!

So, for the last 18 months, the thermostat has been getting to temperature and opening but it was only letting a tiny amount of coolant through to the radiator. That explains why the fans never came on (because the water entering the radiator wasn’t hot enough to trigger the otter switch). Most of the coolant was simply recirculating around the engine. Weirdly, the temperature would stay bang on 90c when driving but as soon as I stopped and let it idle, the temperature would quickly rise to 120c and even up to 140c occasionally before I noticed. The cool British weather probably helped. 
 

So I’m now waiting for a piece of standard 30mm hose to arrive so that I can install the thermostat properly. 
 

I remember another forum member suggesting to me that the thermostat may be the wrong way around in another thread. I did check it at the time but the new thermostat design is different to the original and I was sure it was installed correctly. Only when I bought a new thermostat in a desperate attempt to solve the problem did I realise which way the coolant flowed through it. That’s when I checked it again and saw the error. 
 

I’d just like to thank all of you for your help in this long running saga. I have learnt a huge amount about the Esprit when trying to solve this. It will stand me in good stead for the future. 
 

I am sorry this dragged on for so long. 🥹

Edited June 17 by GreenGoddess

[Sparky]

Jaysus.  I remember saying to @Chillidoggythe other day that there's no way they could have connected it incorrectly due to differing hose sizes.  A good kicking deserved.

[GreenGoddess]

I think they may have also butchered some of the other coolant hoses to get it to fit. I’m having a nightmare trying to install the thermostat the correct way 🤬

[LotuStuart]

Strewth. And well done for checking before simply putting it back the way it was-which would have been standard practice. A good reminder (to me at least) to not take anything for granted. 

[Escape]

So good to hear you've found a smoking gun! And one that's easily corrected, too bad you've already bought a new thermostat but it never hurts to have some spares.

And yes, it just goes to show you need to trust but verify everything. Which is why I am so weary of cars supposedly restored, as I'm sure there are plenty of things wrong waiting to be discovered. And to be fair, I do double check my own work as well when things don't seem to work as they should or have a mate go over it when in doubt, just to make sure.

[GreenGoddess]

Thanks guys. I’ve been out in the car for a couple of decent drives since getting it all put back together. No more overheating. 😊

I will NEVER replace the thermostat on one of these cars again. It was a total nightmare of a job 😂

[Sparky]

So you'll let some other 'specialist' do it?  You know how that may end...

[Rambo]

I'm glad you have solved the problem eventually. But at what cost? Those garage mechanic butchers may have caused long term damage to your engine 🤔

[GreenGoddess]

29 minutes ago, Sparky said:

So you'll let some other 'specialist' do it?  You know how that may end...

Yes. But I’ll be watching them like a hawk 😂

3 minutes ago, Rambo said:

I'm glad you have solved the problem eventually. But at what cost? Those garage mechanic butchers may have caused long term damage to your engine 🤔

I’m reasonably confident that the engine is ok. I have always kept a very close eye on the temperature gauge and have turned off the engine when it was getting hot. The coolant has never boiled over. Unfortunately the thermostat was installed as part of the engine rebuild for the previous owner 18 months ago so I have no recourse against the garage. 

[LotuStuart]

Out of interest who was it?