Cooling Problem

[phil9000]

Hi all,

Slight overheating problem. The car is a MY2002 with 26,000 miles.

Since acquiring the car some six months ago, I never heard the cooling fans start up after the engine was shut down. In fact, if the fans would be running, they would stop as soon as the engine was shut down. The car always kept a steady reading of 85-90 degrees while on the highway and would rise to about 105 in traffic at which point the fans would start and the temperature would fall back down to 85-90.

Yesterday, when I shut off the engine following a very leisurely drive, the fans started and kept running after 2 minutes. I then restarted and shut down the engine which caused the fans to stop. The coolant temperature during the drive was a steady at 85-90.

Today, I took a short drive on the highway with the heater and AC off. While at highway speed (70 MPH) with an ambient temperature of 20 C (about 68 F), the coolant temperature raised to 105 degrees at which point the fans switched on but the temperature kept rising up to +110 and stayed there. I pulled over and allowed the coolant temperature to settle down. While returning home, the temperature raised again to about +110 where it remained. When I shut off the engine, the fans stopped.

Coolant level is OK and radiator looks clean of debris.

Suggestions?

Regards,

Phil

[mike_sekinger]

The cooling system behaviour that you describe prior to the problem is perfectly normal for a system that is controlling the coolant temperature properly.

I would suggest changing the thermostat.

Cheers,

Mike S

[phil9000]

Is it a do it yourself job? What is the difficulty level?

Do I need to take the car to a dealership to change thermostat?

Regards,

Phil

[mike_sekinger]

It should be fairly straigh-forward provided you can remove the water pump housing, without having to remove the inlet plenums. Clearance is a little tight, and having not performed the operation I do not know how long the bolts are and what vertical clearance is required. If you have to remove the plenums, it is just more work - but again, not difficult.

It will also involve opening up the cooling system. You may want to drain down the system, so you

[glynherron]

On my 52V8 the radiator looked clear from the front, but when I dropped the radiator stack the debris had gone throught the condensor of the aircon and was seriously clogging the radiator (smaller clearance between the fins)

I know its a pain, I would drop the stack and clean out the fins

Expect bolts to shear and it to be a pain in the A**

Glyn

[Winter]

On my 52V8 the radiator looked clear from the front, but when I dropped the radiator stack the debris had gone throught the condensor of the aircon and was seriously clogging the radiator (smaller clearance between the fins)

I know its a pain, I would drop the stack and clean out the fins

Expect bolts to shear and it to be a pain in the A**

Glyn

Sorry, hit the post button before I added my reply.

Regrettably, it sounds more like the radiator than the thermostat. The former is a service item in that the fins should be blown-through with air at service intervals (6,000 miles). I had exactly the same problem and several fraught journeys before having the rad replaced with an improved cooling version.

If it is the thermostat, although I doubt that it is, replacement is fiddly but no great job. You have to perch inelegantly over the engine to see the housing and remove the three bolts. No need to remove the plenum. It can be done from the side but visibility is not as good - I've done it a couple of times thinking the stat was the problem when in fact it was the rad.

I chickened out at that stage and had the work done at my local Lotus agent. It is a swine of a job. Access is awkward and to add insult to injury, corrosion of just about every fastener is likely to await.

[phil9000]

On my 52V8 the radiator looked clear from the front, but when I dropped the radiator stack the debris had gone throught the condensor of the aircon and was seriously clogging the radiator (smaller clearance between the fins)

I know its a pain, I would drop the stack and clean out the fins

Expect bolts to shear and it to be a pain in the A**

Glyn

Hi Glyn,

Logically, I do not expect that this problem is radiator related since the increased temperature is not a problem which gradually worsened, it happened very suddenly. That is the reason why I suspect it is a broken part.

Regards,

Phil

Sorry, hit the post button before I added my reply.

Regrettably, it sounds more like the radiator than the thermostat. The former is a service item in that the fins should be blown-through with air at service intervals (6,000 miles). I had exactly the same problem and several fraught journeys before having the rad replaced with an improved cooling version.

If it is the thermostat, although I doubt that it is, replacement is fiddly but no great job. You have to perch inelegantly over the engine to see the housing and remove the three bolts. No need to remove the plenum. It can be done from the side but visibility is not as good - I've done it a couple of times thinking the stat was the problem when in fact it was the rad.

I chickened out at that stage and had the work done at my local Lotus agent. It is a swine of a job. Access is awkward and to add insult to injury, corrosion of just about every fastener is likely to await.

Hello Edward,

Thx for your reply.

Did your car exhibit the same symptoms as I described above? Did the problem occur suddenly or was it gradual?

In my case, the heating issue is quite sudden.

Regards,

Phil

[glynherron]

Hi Phil

Yep I would agree with you due to its sudden nature.

I guess that my intention of the post was to say not to assume that because the radiator looks clear from the front that is actually is.

On the subject of thermostats, I thought that they were designed to fail safe ie 'open' ?

Cheap to replace so lets hope its this

Good luck

Glyn

[Winter]

The symptoms appeared suddenly. It was on a motorway journey on a warm day in March last year. I got caught in a jam and even with the aircon on - I rarely switch it off - and hence with the cooling fans operating, the temperature rose to 110 C.

It stayed at this and for the following few weeks, 110 C was common and on one occasion, it rose to an indicated 115 C. My blood pressure was rising in parallel. What struck me was the obstinacy to return to the usual 85 C or so. Once 110 C had been reached, moving traffic saw a reduction to only 100 C.

Changing the thermostat didn't improve matters and besides, the old one worked. Controlled tests with thermometer-checked temperatures showed that it was opening at 82 C. Besides, it looked as good as the new one I put in.

I had the left hand turbo coolant feed pipe replaced because there was a hint of corrosion/constriction in one of the elbow bends and a forum poster from Scotland suggested that replacement of these on both sides rectified overheating in his V8. No change in mine.

Last July, I had the radiator replaced with a recored version and have had no problems since. Curiously, the old rad didn't seem to be too clogged. In due course, I will get that one recored so as to have a spare at the ready.

All-in-all, there wasn't one clear-cut reason why the apparent overheating was occurring. I say apparent because I understand that the system is designed to withstand up to 120 C and that overheating is recognised as a possibility hence, it has a coping strategy designed in.

What puzzled me was the suddeness of the appearance and then the near-mysterious disappearance.

As a postscript, at present I am not running aircon because I have a major fluid leak that seems to be condensate. The carpets are soaking wet and the stuck-to-the-floor sound proofing sponge is saturated. I have peeled the carpets back and removed the sound proofing to let things dry out. Then I will re-run the air con to try and identify the source of the leak.

In traffic earlier this week, the temperature rose to 105 C, the fans cut in and 85 C was back in minutes. All working correctly.

[ibandre]

The same thing will happen in my car when driving in heavy traffic. I happened to read in the manual book in my car (the green one behind the drivers seat) that the temp will rise to around 100 in heavy traffic (this is normal for the V8), and go back down to between 70-85 when picking up speed again. I don`t see this as a problem, and I also registered that my fans will turn on when turning the car off and the engine is very hot. Am I totally wrong here??

[andyblackman777]

Phil,

It is possible its the gauge, mine moves around alot but the temp on my odb scanner is solid at 89. Also try changing the expansion bottle cap it could be that its not holding the correct pressure and allowing the coolant to boil which would could cause overheating. That and changing the thermostat. Its cheep and u can diy.

good luck Andy

[atgnat]

the rad is junk brand new. get it re-cored. quick...

[phil9000]

UPDATE

Got the car back from the Lotus shop.

Changed the following parts:

Sensor

Thermostat

Gauge was tested and runs within 10% error, i.e. it reads about 10 degrees higher than the reading from the Tech1.

Also took laser temp readings off coolant intakes and outakes of the radiator and it seems to be within the normal operating limits.

In summary, the car runs a little hot but within Lotus parameters. I will plan on getting the radiator replaced if the car starts to run hotter.

How much time to take out and reinstall radiator?

What is the cost of getting a new radiator (not Lotus OEM) or having the original re-cored?

Regards,

Phil

Edited May 11, 2007 by phil9000

[atgnat]

the new one is a grand. re-coring one is @$300. look at @12 hours to do the job.

[actwon]

On my 52V8 the radiator looked clear from the front, but when I dropped the radiator stack the debris had gone throught the condensor of the aircon and was seriously clogging the radiator (smaller clearance between the fins)

I know its a pain, I would drop the stack and clean out the fins

Expect bolts to shear and it to be a pain in the A**

Glyn

Glyn,

HOw do you drop the radiator cluster? I need to get to the radiator to check it and my aircon condensor. I can't seem to find any instructions or picture how-to's.

[glynherron]

As far as I remember:

1. Loosen front wheels and jack front end as high as possible and support on stands on the chassis adjacent to the lower wishbones, remove wheels

2. remove oil cooler platforms and rear exit grilles

3. Drain radiator (release clip on where the bottom hose connects forks to the heater and the return

4. Disconnect the top hose

5. Disconnect fan(s) wiring loom

6. Remove the oil cooler ducts

7. Support the cowl that holds the radiator stack and disconnect the 6 nuts and bolts that hold it to the front boot floor (4 are vertical and 2 are hotizontal)

8. Lower the cowl to the floor

[rockstar1958]

I've been having the same problem and was suggested replace the thermostat. I've been trying to find what thermostat lotus uses for a 2000 turbo esprit. Anyone know?

Is it a do it yourself job? What is the difficulty level?

Do I need to take the car to a dealership to change thermostat?

Regards,

Phil

[phil9000]

I've been having the same problem and was suggested replace the thermostat. I've been trying to find what thermostat lotus uses for a 2000 turbo esprit. Anyone know?

John,

I've read that you should get a Lotus thermostat to avoid problems.