Esprit S1, how’s my radiator fan setup?

[tristan reidford]

Are those the original fans and motors?

my cooling situation is anxiety inducing.  I knew going in that S1s had an issue with getting hot in traffic, but I think I can do better.  Temp will climb 1/8 of an inch before the red on the gauge if I’m stuck in traffic.  I don’t even know if the fans are working or not.  I{be read through a couple of threads here about aluminum vs copper radiators and the various fan replacements.  As for coolant filling, is it supposed to be an inch below filler cap in the vertical tank?  And, is there a knack to getting the cap off?

cheers!
 

[drdoom]

Don't chase off down the cooling rabbit hole too quickly Tristan, as much of what gets echoed in the Web is looping falsehoods. I've known of 2 early Esprit run routinely here in Vancouver, both tracked on HPDE days and one of which toured from here to Northern California returning in part via Napa Valley ( 102 deg heat that day ) without overheating concerns. Both cars running the OEM early rad. There has been plenty of mystery concerning Lotus over the ages and regrettably many cars were not as well maintained as would have been proper. In summary, do check through as many aspects of your car as you can but do so with the fair and reasonable presumption that it was built to run reliably when in as new condition.

Cheers

[ChrisJ]

I'd first just start it up on the drive and leave it with the engine running until the temp rises enough for the fans to come on. That's what I do with my S3 Esprit.

[tristan reidford]

13 hours ago, drdoom said:

Don't chase off down the cooling rabbit hole too quickly Tristan, as much of what gets echoed in the Web is looping falsehoods. I've known of 2 early Esprit run routinely here in Vancouver, both tracked on HPDE days and one of which toured from here to Northern California returning in part via Napa Valley ( 102 deg heat that day ) without overheating concerns. Both cars running the OEM early rad. There has been plenty of mystery concerning Lotus over the ages and regrettably many cars were not as well maintained as would have been proper. In summary, do check through as many aspects of your car as you can but do so with the fair and reasonable presumption that it was built to run reliably when in as new condition.

Cheers

It’s good to hear these cars will run just fine stock, the car is pretty OEM it would be cool to keep it that way.  And thanks Chris, that makes a lot of sense, I think I’ve been avoiding looking too closely in case I find it’s all bad news.  I opened the expansion tank cap and it looked like a nearly empty thermos of old tea in there.   

I will give it a flushing and check all the fans. 
 

 

thanks!
 

[ramjet]

The fans are easy to check. As Chris said, start it up your driveway and let it idle. When the fans turn on, you'll hear them.

Good flush is at least easy to do. The last time I did mine in my S4, I used distilled water with Redline Water Wetter. I'm in Australia and it can get hot here. Car never gave me any concern, in stop/start traffic or on a highway. Fans and radiator were the originals as well.

Ok. Not an S1, but still an Esprit.

[GavinT]

Yes, those are the original fans.

The fans on an S1 are triggered by a thermo switch located in the aluminum coolant pipe by the alternator.  It’s a two wire switch. Bridge these two wires with a small length of wire and the fans should run. If they do not then check the fuse. The wiring connector that pushes onto the thermo switch has been known to become unseated during driving resulting in a bad contact. Get some wire and wrap it around the connector and the aluminum coolant pipe. Effectively clamping the connector onto the thermo switch.

The wiring for the coolant fans is not not very good on an S1. All the current for the three fans is drawn through one wire and a single fuse with no relays.  An upgrade to consider is a three relay re-wire that uses the original Lotus wiring to trigger the relays. You basically separator the fans into three separate circuits. I did this on my S1. I think I have a post somewhere from years ago giving details.  You can also add a manual override switch.  I have this too. Pretty much every time I sit at a light for any extended period I just throw the switch and run the fans. Upgrading the fans will improve things. I just got some modern fans off eBay and made some brackets to mount them to the radiator.

I also have an aluminum radiator. In my experience, the aluminum radiator is way more efficient than the original. 

[GavinT]

 

[tristan reidford]

Thanks for the info Gavin, super useful, I think I located the thermo switch (otter switch?) and it looks like it has been strapped onto the pipe like you described.  Those two terminals don’t look like the otter switches I see when I look up the part, and the wiring doesn’t look super reliable.   So if I bridge between those two terminals the fans will come on?  (Assuming fuse is ok).  I like the idea of adding the relays like you suggest.  
out of interest, if you are stuck in traffic for a while how far does your temp needle climb with the fans on?

Also our cars are twins,  is your factory yellow? My car was repainted and I’m not sure it whether it was a factory color or not but looks very similar to yours.

Thanks!

[GavinT]

Hi Tristan, yes - that’s your thermo / otter switch. And the black/yellow is disconnected from its pin. Your fans have probably not been running. Connect the black and the black/yellow together and the fans should run. Being black wires, I think the otter switch completes the ground circuit and the fans are wired constantly hot. I’m away from my car and circuit diagrams so I’m doing this from memory and I can’t believe I did the wiring mod in 2010. Time flies!

at-least they have a good clamp holding the otter switch in the pipe but those connectors are messy. Test the otter switch when the car is hot and see if you get continuity across the pins. 

I’ve never had my temp gauge go over 1/2 in traffic.  As soon as I hit traffic I switch on the fans. I don’t wait for the temperature to climb. Going done the highway the temp will be at a 1/5 above cold.

Not sure of the code but Lotus called the paint color Lemon Yellow.  My car was repainted in the 90’s. My vin is 165H.

[tristan reidford]

Thanks again Gavin, it’s still a bit confusing as my car seems to have an unexpected third spade connector that the black and yellow is connected too, leaving the blunt prong terminal unconnected.  Unless they lost the correct terminal for that prong, and so wired in that spade connector instead.
 I  can at least connect the two wires together like you suggest and see if the fans are running. Does the engine have to be running when I do this?  

When you say test the continuity, do you mean with a multimeter or something? Sorry I am very green when it comes to electrics (and everything else).

[GavinT]

That third spade connector has been modified to fit over the left prong/pin on the otter switch.  If the spade being disconnected from the prong is how you found it, then your cooling fans have not been working.

Turning the ignition on, not starting the engine, will send power to the fans. Connecting the black/yellow and black wires together will complete the ground/earth circuit for the fans and energize them. Connect them together before turning on the ignition.

If you have established the fans are working the next step is to test the otter switch. Re connect the third spade to the left prong of the otter switch. Then start the engine and allow things to warm up. Keep an eye on the temp gauge. The fans should come on as the temperature gets up between 1/2 and 3/4 on the gauge. Hopefully everything works and you are good to go. At this point I would replace the black/yellow connectors for one that fits the prong nice and tight.

If the fans don’t work then the otter switch is faulty. It’s a cheap part. Call JAE and have them send you a new one.

[drdoom]

Great advice from Gavin, as usual. I'll attach a screenshot of the wiring diagram FWIW, from what I read it looks like the fans are hot with key in "Accessory" position, on the white/blue wire to fuse block then onward via yellow/green.

 

[GavinT]

You beat me to it Steve. Was looking around the web for an S1 wiring diagram to post.

I made a mistake….I referred to a black yellow wire but is actually black orange.

[tristan reidford]

Ah I see now, for some reason I thought the spade clip had been soldered to the base of the prong to somehow bypass it, but now I see what you mean that it has simply been stretched to fit over the prong and has fallen off because that’s a terrible solution.

I found a fuse box in the glove box, is where the I will find the fan fuse, in case that’s an issue?

I will run the tests you suggest when I get a chance. Thank you for bearing with me!

[GavinT]

Do you have a work shop manual?

[drdoom]

If the diagram I posted is correct for the car and there's been no fiddling otherwise then, yes, the feed for the fans will be fused in the glovebox. It may be possible to get a peek at the wiring to the 2 blocks so as to narrow down which fuse is the one. Agree with Gavin absolutely on the wisdom of adding relays for significant loads in the electrical system.

_Manual - S1 and S2 Workshop Manual.pdf