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Coolant Recirc system


M3S2k

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Hi all,

Was reading about how to drain and refill the coolant system on my car and stumbled onto the part about the car having a recirculation system to cool the coolant after the engine is shut down when it is hot. I never knew our cars had a system like this. My question is how do we test it. I have never noticed my radiator fans coming on after shutting the engine down hot. Wondering if my system has a fault somewhere and if there is a way of testing the system. Thanks

Steve

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Does your heater work ? I only ask as mine completely clogged with crap after the cylinder liners went. After the heater rad was replaced, everything else started working. It only happens under extreme heatsoak however. ie Drive at 70mph for an hour then sit in traffic for twenty minutes then park in a garage in August on a sunny day in Enland (ambient temp say 28 degrees) if you do this it might come on for a few minutes and you can hear it all working. This all may be a red herring and maybe your temperature sensor is faulty. There are two: one for the guage and one for the ECU. I have been through three of the guage ones but never changed the ECU one. :)

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The ECM controls when to turn on the recirc pump, solenoid and rad fans. The relay for the recirc pump is located in the relay station in the rear by the battery. Top one closest towards the front (Relay A), if you ground pin 86 (insert jumper wire to battery - terminal into relay socket and insert relay, carefully ***before grounding make sure there is 12vdc on pin 85, if not check pin 86 for power. Ground the one without power***) it should run the circ pump. Which is behind the passenger seat (RHD), should be able to hear it easily when running.

For the radiator relay just turn on the A/C and they should be running. They are controlled by the ECM as well for other running conditions. If they don't work start at the relay for replacing parts. An easy test would be to jump pin 85 or 86 which ever has 12vdc to pin 87 without the relay in place. This bypasses the relay and directly powers the fans. This relay is located in the front luggage compartment, on RHD cars its the most forward relay closes to the front of the brake master cylinder, on LHD cars its at the front closest to the windshield washer tank.

Edited by 97-Esprit V8
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:):) Nicely put man!

Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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I'd like to know as well. I've been out for drives with other V8's and their fans kept running after shutoff, while mine shuts off with the car.

Same here, happened two weekends ago while out driving with another V8 his came on after ever stop mine didnt but didnt really think much of it :)

Just trying to get my head around what Paul said. May have to raise my IQ by 5 to find its way to the storage centre :)

350.gifNo.23
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Paul is talking about the common number points on relays.. 86, 87, 85 and I can't remember the 4th point.. but basically... he's getting you to hot-wire the electric coolant pump to ensure that it works.. and he's also making you check the relay to ensure the relay isn't shot. I guess... if you wanted.. you could make a "rest" feature for the v8.. where it keeps the cabin warm for up to 30 minutes using the coolant pump and the climate control system... The Touareg does that... but the Touareg is meant for cold weather... I'm not thinking that keeping the cabin warm in an Esprit is a big issue...

Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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Thanks Mark, its been noted and will take car over to Techies in next few weeks to have a look. :welcome:

Kylie,

You should tackle this yourself, very simple to check, and you begin to learn something about your car that will come in handy on a stretch of highway some day. Electrical seems to scare people, which I don't understand. 12vdc systems on vehicles are very straight forward once you understand some basic concepts. Most everything in the car is controlled by relays, which are simply switches. Look at them like a light switch and a light bulb. If you turn on the switch the light turns on, with the car the ECM decides if it wants the recirc pump to operate. It does so by closing a switch inside that allows current to travel through the relay (standard terminals 86 and 85 on relays). This energizes the relay and pulls in the contacts to flow much higher currents to motors and lights. These contacts are relay terminals 30 and 87 (again standard relay terminals) sometimes a relay has terminal 87a (which is just a second wiring point the same as 87). Eventually these relays contacts wear out from the electrical arc created when they are just about to close (take of a light switch cover and watch inside as you turn it on, you'll see the arc) and need to be replaced. Which is why I suggest starting with relays.

If the pump doesnt work after you check out the relay then likely the pump is shot, or you have a bad ground. You can check the pump directly by running a jumper wire from the battery + and - to the terminals on the pump (doesn't matter where the + and - go as it will just change the direction the pump rotates)

I've seen some of the projects you've done on your car, this should be easy for you(maybe not at first, but afterwards you'll be glad you learned instead of paying someone else). If you have a multi-meter (min voltage/current/resistance) you can do most anything on the car. Anything electric on the car must have a + and - supply, first start by checking your ground from the battery to the steel chassis(find a bolt, not the painted tubes), there should be very little resistance, anything above 0.1 ohms isn't good) A poor chassis ground is a typical electrical gremlin creator. If the path for the current isn't clean (low resistance) then it can get lost. Clean battery terminals and clean corrosion free ground points should be basic maintenance on every car.

If you have a factory manual, in which the electrical section is very well done and quite easy to follow though. Start by finding the recirc motor and trace it back to ground and power supply fuse. You will find the relay I am talking about and it's numbered terminal connections. Then find the relay locations and pull them out to have a look, you'll again see the numbered terminals. Find the fuse supplying the load side of the relay and check it to make sure it's the correct size and not blown (hold it up to the light and look between the connectors, just under the rating number. It's blown when you can see the little metal connector inside the plastic is broken. If you have any questions PM me or ask in this thread.

The recirc pump and radiator fans won't typically come on during a normal shutdown, perhaps their radiators are plugging off and the cars are running too hot compared to yours.

Paul

Edited by 97-Esprit V8
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Thanks for all the info. Gonna try hot-wiring the system tomorrow. No, I have never had cabin heating issues with my car. Don't usually need heat in the car, but the few times I have used it, it always comes out nice and hot by the feet and windshield. Just gotta make sure to close all the dash vents as they always blow cold :welcome:

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This is probably a silly question, but what temperature is a V8 TT supposed to operate at during a combination of highway/city driving? I am a new owner living in Texas so I am a little concerned about overheating. I was driving my car yesterday and if I turned on the AC (it was 87 F outside) my temp jumped over 100 C, but if I turned of the AC then it dropped to about 90 C as long as I was moving. If I had to sit in traffic for a few minutes then the temp went up close to 100 C but would drop again as soon as I started moving. This morning I checked the coolant level near the engine and it was fine. I read the comments concerning the front fans, and I know they were not running after I shut the car off. I guess I am asking if your cars run around 105 C is that okay? :welcome:

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Hi, Nick. Welcome to the forum and Esprit ownership.

I have owned my Esprit for just under one year now, and live in Texas as well. The temperature figures you cite are pretty much what I see in driving around Austin, and our daily highs (unusually warm at the moment for this time of year) are in line with the 87F you quote. Next week it's supposed to drop back into the 60's for daytime highs.

I just went out to the garage to refresh myself on the temp guage indices to be sure I'm giving you accurate information. Since this is the only Esprit I've ever driven, the numbers I see may or may not be representative of "normal," but I suspect that they are.

If the car is moving (and fully warmed up) I generally see a reading of 80 to 85 degrees (the guage, of course, reads in degrees Centigrade) during most of the year. During hot summer days (and in summer in Texas they are all hot, as you well know!), with the AC on, the reading tends to sit around 90+. If stopped, the temp creeps up fairly quickly to 100+, and if stopped for any significant length of time it will go to 105 exactly, at which time the fans will come on, regardless of whether or not the AC compressor is engaged (the fans come on anytime the compressor is engaged, unless above 30 mph), and the temperature will gradually decrease towards about 90 or so, at which time the fans cut out. Trivia item: the AC is disabled (temporarily) by use of full throttle--with the understanding that you're looking for maximum power by this action.

The owner's manual makes mention that it is not of concern that the temp can reach 105C (which is, after all, above the boiling point of water), as the cooling system (like all other cars) is pressurized, which effectively raises the coolant's boiling point.

I hope this helps.

Cheers,

John

Being second is to be the first of the ones who lose.

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John,

Thanks for the response concerning the running temps. It seems my numbers might be a little bit higher than what you are stating, but not by much. I am just a little concerned about what happens when you drive on the 100 degree days. I have not had the car for very long and the driver side window is messed up (regulator or rod in the door) so until I fix it the only air inside I have is from the passenger side window and or the vents. This is not my daily driver, but I do enjoy driving it. If you happen to be in FW sometime give me a heads up and maybe we can get together. Thanks again for your comments.

Nick

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Paul makes a good point, Nick, with his suggestion to follow the factory recommended "clean out" of the radiator. IIRC this is an annual recommendation, and I believe he is referring to the use of a high presssure air hose to blow away (from the back side of the radiator, from underneath the car--mind the fans if you do this) accumulated debris (leaves, etc.) from the radiator's front fins. Space restrictions necessitated a highly angled installation, which makes for a great "lint trap." :D

I forgot to mention in my original response that my car has had a "three core" (some owners have even opted for four!) radiator installed by a PO, and that may account for my slightly lower temp readings--though one could make a case that the "stable, moving" figure ought to be determined (modulated) solely by the thermostat's fixed value, unless a full open thermostat just can't handle really hot days.

Edited by Iconic Ride

Being second is to be the first of the ones who lose.

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Ok, so tested everything today. Jumped the relay for the recirc pump and that started pumping right away, so no problem there. After that proceeded to jump the fan relay which worked as I was sure it would as I've never had overheating issues before. Once I had tested both of those units I started the car and let it run for awhile until the operating temp got up to 100C. At that point the fans came on. I then proceeded to turn off the car, but the recirc system never took over. I waited for about a minute or two, then started the car up again to cool the engine down further by simply running the A/C which forces the fans to stay on and which always brings my coolant temp down to like 85-87C. So my question is at what point does the ECM tell the recirc system to switch on?

On a side note, just finished putting the transmission back in and drove the car last night and drove it around the yard to test if everything was working properly and all I can say is, I wish the clutch burnt out sooner! I don't know what is different, but the clutch pedal feels less than half as heavy as it had since purchase (felt like moving a ton of bricks) and this in turn has made shifting transmission soo much more smoother. Seems to me that the old clutch plates were always dragging and thus making it harder to move the clutch and also never fully disengaging. Its like driving a whole new car!!! Can't wait til the snow is gone to start seriously driving this car!!!

Steve

Edited by M3S2k
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Steve,

For ~20 mins following engine shutdown, if the coolant temperature reaches 105 deg C the ECM will switch on the fans and the recirc pump to facilitate engine cooling. This is very unlikely to happen, I have seen it on my car after running it hard on the race track. Pretty brilliant really to ensure the temperatures don't skyrocket. I would wager everything is fine on your car, the ECM is simply watching the coolant temp after shutdown and closes the contract energizing the relay. Not much could go wrong there, and since you have tested all the components there should be nothing to worry about.

Paul

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I had a vauxhall that did it - after switching off it was possible for the rad fan to cut back in with the ignition off. There were warning stickers in the engine bay.

I guess in the Lotus with the engine being in the middle it needed a bit more of a technical solution to achieve the same thing.

Dave - 2000 Sport 350
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yeah, I've seen lots of cars where the radiator fans switch on after the engine is shut off and run for up to 15 mins after. Just never seen one that actually pumped the coolant in reverse in conjunction with the radiator fans being on. Very cool system.

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