Radiator Re-coring - any recommendations in the NE

[85S3NA]

Had a fantastic weekend in the sun - Saturday night out in the Esprit, and Sunday out in the Elise (although was with a Kawasaki ZX9 & Honda CBR so spend most of the time playing catch up over a 300 mile trip around Northumberland & Scotland) - but that's another story.

The Esprit ran beautifully except it gradually got hotter and hotter - so on the hottest day of the year I had my heater on full - felt like I was driving a sauna - a separate point is that my fans didn't appear to come on (it's an S3 normally aspirated, so it has two orange fans) - so next on my Esprit 'to do' list is to overhaul the cooling system - as a start point, I'd like to triple core the radiator, but was wondering if anyone could recommend a specialist to do this in the Northeast i.e. around Newcastle / Tyne Valley areas ??

Supplementary questions are does anyone know where the thermostat is, and where the fuses for the fans are ?

Thanks in advance - even with the heater on, aren't Lotus cars fantastic to drive

Jonathan 85S3NA

[rob.e]

I had the rad recored on my v8-gt by Serck Intertruck. They have branches all over the country.. cost about 180 quid i think.

[Esprit2]

85S3NA said:

The Esprit ran beautifully except it gradually got hotter and hotter (Snip)... a separate point is that my fans didn't appear to come on (it's an S3 normally aspirated, so it has two orange fans) (Snip)... I'd like to triple core the radiator (Snip)... Supplementary questions are does anyone know where the thermostat is, and where the fuses for the fans are ?

It's fairly common for dirt and mud to pack in around the radiator, blocking air flow. My US-Federal S2 had started running warmer and I was contemplating a re-core. But a leak forced removal before I had really gotten around to the big job. When the radiator came out it was packed with mud like a cement mason had trowelled it on. It had to be manually cleaned off. A blast of water squirted in from the front was not going to do the job.

The core was in pretty good shape. With the mud removed, airflow re-established and the leak fixed, the matter of a re-core became purely optional.


If the fans aren't coming on, it may be the fuses or the thermo-switch (Otter switch), but don't overlook the relays. I've had more trouble with the relays than anything else. Use heavy duty relays rated at 40 Amps or more.

If the fuse has blown, the real question is "why". If you don't address the root cause, a new fuse will just blow again. Fuses don't usually get tired and crap out for no reason... something pushes them over the edge.

The fan motors are pretty cheap and don't last forever. Do the motors spin freely? Also, the fan shroud is just vacuum formed ABS and the metal insert that mounts the motor is not very substantial. It's common for one or both to break and allow the fan blade to contact the shroud, stalling the motor.

Anything that prevents the motor from spinning freely will cause a high current draw that will blow the fuse.

I'm in the US, and the naturally aspirated S3 was never imported here so I'm not familiar with all the details of component location.

On US models, the fan Otter switch is mounted in a vertical coolant tube in the right front corner of the engine bay. In early DOM G-Turbos, the Otter switch was installed in a short coolant pipe near the radiator... top right hose I believe. Perhaps your S3 is more like that.

Relays are near the left headlight pod.


There seems to be a bit of a disagreement between the temp gauge and the fans. The gauge says the engine is getting hot, but the fans don't come on. It may be that the gauge is wrong. If the voltage stabilizer (mounted to the back of the speedometer) goes bad or if it's ground connection looses continuity, the temp gauge reading will read high.

Do the fans ever come on? If you park the car and let the engine run, will the fans eventually come on? If yes, then they at least work. Now the question is whether it's the temp gauge/ voltage stabilizer or the Otter switch that is reacting to the coolant temp incorrectly.

If the fans don't come on by themselves, find the Otter switch and short across the two wires while the ignition switch is on. If the fans don't come on when the wires are shunted, then there's something wrong in the fan circuit. Blown fuse, bad relays, bad wiring, bad motors.

If the fans come on when the wires are shunted but never when the engine is genuinely running hot, then suspect the Otter switch.

To test the Otter switch, remove it, connect a multi-meter or test light across the terminals and immerse it in hot water with a thermometer. Heat it until it the meter indicates continuity or the test light turns on. Compare the thermometer reading with the value stamped on the Otter switch.

If the Otter checks out, and if the fans come on both when the Otter wires are shunted and when the engine is allowed to get hot (running while parked), then suspect the temp gauge... or more likely, the voltage stabilizer. The engine is probably not hot... the gauge is just indicating it is.

If the voltage stabilizer or it's ground are bad, both the temp and fuel gauges will read high. Does the fuel gauge tend to indicate full forever, then seem to dive for empty toward the end. Suspect the voltage stabilizer.

Regards & good luck,

Tim Engel
Lotus Owners Oftha North
Minnesota, USA

[PatHeald]

I took my knackered rad to the Post Office and sent it to SJ Sportscars.

It arrived on my doorstep all nice and spangly in less than a week.

Excellent service.

Cheers

Pat.

[wedg1e]

There's Motorcool Services in Thornaby (near Stockton) who can do uprated cores etc.

Ian

[superdave]

PNM do recoring and they also do uprated cores as well I think. I thought they charge about £80 or so. You just need to double check with them on 0151 630 6101.
Sorry about the shameless plug on PNM yet again.


Dave Walters

[hilly]

I have replaced the dual core in my S3's radiator for a triple core and have no cooling problems.

I just took it to a local radiator shop and they offered me the triple core to me as an option.

As i remember it was about £200 all in and only took a couple of days to finish.

I also replaced the OEM orange bladed Ford fans for a pair off of a Peugout 205 diesel. The vaccum formed cowling was also nadgered and the 205 fan came with a nice moulded plastic cowling which fitted a treat.

Have a look at my LEW page for more details www.lotusespritworld.co.uk/EOwners/Hill.html

Andy
1981 S3