thermostatic fan switch

[addict]

hi lotus want £50+ pounts for a thermo fanswitch
but after a bit of research i found a cheeper option.
intermotor part no 50399 barcode 5012225 464111 (£18 from ebay)
my old one is marked up as 110 deg
my new one is marked up as 107 deg
the top connections are the same.
pictures to follow

[GeoffSmith]

Good find and now on the Wiki. Guess you didn't find this one for £6.

[addict]

awww shoot

old new and box


the fan now kicks in at 2/3rds of the way up or halfway between half and 3/4 on the temp gauge
and brings the temp back to just under half..
no nerve wracking wait for the fans to kick in 4 me

[nitroman]

With the Rodney Dickman low-temp thermo fan switch (200/210) my thermoswitch completely ceases to engage every 18-months or so. It ceases to function consistently enough that I've ordered two switches the last couple of times I've placed an order. I grounded the electrical feed tonight and sure enoungh, both fans came on full-speed. Due to my "safe" ordering practice I have a spare on hand waiting to be screwed in, as well as a couple original temp switches plus one of Rodney's 195/185 switches, however, does anyone else experiece such a rapid failure rate?

I know DocFizzix received two non-functioning switches in a row via post, but besides him I don't know the experience of others.

The OE thermoswitch rarely fails, but it engages at an unacceptably high temperature. Does anyone order the truly low-temp switches from a source other than Rodney Dickman? (IE, comes on at 1/2, goes off at 1/4)

[dunnlor]

In my case, the inconsistently working fans was due to a bad ground connection of the housing that the fan switch screws into. The housing is insulated from the block by a gasket and is grounded only by the two mounting bolts. With locktite or other materials on the bolts, the housing was not always a good ground.

I added a supplemental ground from the housing up to the intake plenum. Haven't had a problem since.

Tom

ThermostatSwitch1.jpg

ThermostatSwitch2.jpg

[nitroman]

I replaced the thermoswitch and the fans are working normally again. However your grounding idea makes me wonder if a marginal ground-connection is causing high-resistance to electical flow thus burning out the switches prematurally. Tomorrow I'll attach a ground wire from the thermostat-housing to a threaded-tap that's directly in the block two inches behind it. I'd ground the thermoswitch directly to the block, except I can't figure-out a way to affix a wire directly to the thermoswitch, because it has teflon-tape wrapped oround its threads.

In my case, the inconsistently working fans was due to a bad ground connection of the housing that the fan switch screws into. The housing is insulated from the block by a gasket and is grounded only by the two mounting bolts. With locktite or other materials on the bolts, the housing was not always a good ground.

I added a supplemental ground from the housing up to the intake plenum. Haven't had a problem since.

Tom

ThermostatSwitch1.jpg

ThermostatSwitch2.jpg

[Brit-Car-Nut]

I replaced the thermoswitch and the fans are working normally again. However your grounding idea makes me wonder if a marginal ground-connection is causing high-resistance to electical flow thus burning out the switches prematurally. Tomorrow I'll attach a ground wire from the thermostat-housing to a threaded-tap that's directly in the block two inches behind it. I'd ground the thermoswitch directly to the block, except I can't figure-out a way to affix a wire directly to the thermoswitch, because it has teflon-tape wrapped oround its threads.

You should NEVER use teflon tape on the threads of sensors as they get their ground through those threads. That is why most threads are tapered or those that are not have a crush washer of some sort.

[nitroman]

So is it best to use dielectric grease then? Something will be required to keep it from seizing. That just applies to ANY threaded fixture in contact with coolant.

I replaced the thermoswitch and the fans are working normally again. However your grounding idea makes me wonder if a marginal ground-connection is causing high-resistance to electical flow thus burning out the switches prematurally. Tomorrow I'll attach a ground wire from the thermostat-housing to a threaded-tap that's directly in the block two inches behind it. I'd ground the thermoswitch directly to the block, except I can't figure-out a way to affix a wire directly to the thermoswitch, because it has teflon-tape wrapped oround its threads.

You should NEVER use teflon tape on the threads of sensors as they get their ground through those threads. That is why most threads are tapered or those that are not have a crush washer of some sort.

[Brit-Car-Nut]

Honestly, that is why the sensors use a brass thread. They are most likely to seal when tightened correctly and least likely to seize with dissimilar materials. I have never had a temp sender I couldn't remove after many years of use. That doesn't mean it can't happen, but if you are using a decent coolant additive, the sender should not need any grease or sealant on installation.

[nitroman]

I used Kopr-Shield both for the thermo-switch and for the bolts. I also made a grounding-wire connected to the engine block. It all works fine and the fans run right on queue.

I took pictures but for some reason my computer isn't recognizing when my SD-card is plugged-in, so I can't transfer them onto the computer. Its been figity like that for a long time, but this is the first time its completely refused to aqknowlwedge its plugged in.