SEAC 450 Coolant Temp Sensor

[SIIX TT]

Has anyone got the correct Lucas part number for the coolant temp sensor.
I have taken the old one out and tested the Ohm reading , which seems to be too low for a cold engine. I havent tested it warm yet - and for the cost I may as well replace anyway.

The present one fitted has nothing written on it whatsoever and is all brass with black plastic socket and 19mm head. I think the correct part may be Lucas SNB 802 -but just double checking as the ones now listed under that number seem to have the head and connector covered in black plastic.

Is this the right one?

http://www.ebay.co.uk/itm/lucas-SNB802-temperature...

Thanks
J

[Jack Valiant]

Hi there,

Are you after the water temp sender for the gauge or the temp sensor for the ECU? if the later then the one you are looking at should be fine and is standard for all RV8 engines if you need the send unit then:

Water temp sender UNIPART. GTR138

Hope that helps fella

Chris

[SIIX TT]

Hi

ECU sensor. Car is running very rich and this seems to be the best place to start.

[Jack Valiant]

Fine the Fleabay one should be ok then fella

Cheers

Chris

[SIIX TT]

toook some readings - 5000 ohms cold - 490 ohms at 70 degrees. Might be ok?
Will change it anyway - one less thing to consider.

[honestjohntoo]

SIIX TT said:

took some readings - 5000 ohms cold - 490 ohms at 70 degrees.

Spot on! So if the ECU is not seeing the expected sensor reading then the cause may be in the sensor connector or the local wiring to the ECU multiplug and/or to the earth connections at the rear of the engine block.

[Wedg1e]

SIIX TT said:

Hi

ECU sensor. Car is running very rich and this seems to be the best place to start.

Often caused by the dreaded solder joint issues within the ECU.

Give me a shout if you get stuck.

[adam quantrill]

Agreed with HJ2 and Wedg1e.

You need to re-test the ohms fron the ECU multiplug end, this will reveal any faults in the loom or connectors. The last time this came up about 6 months ago I couldn't get this concept across. Also, when fully hot (90C) you should see it reduce further to around 300 ohms.

If this still doesn't help then the ECU itself could be suspect and it's a fairly simple matter to reflow all the solder joints and tracks on the two circuit boards inside it. Perhaps one day I'll do a photo story with a bit of video showing how to do it.

[SIIX TT]

Noted.

It seems obvious to test at the ECU end now you point it out.


Do I need to be wary about introducing heat (soldering) to anything sensitive inside the ECU?

[adam quantrill]

I've done a couple with no problems. When I'm doing around the IC's (chips) I usually do a quarter of the legs at a time and then go elsewhere for a few mins before coming back. This prevents too much heat buildup in the IC packages. Get some nice quality multicore leaded solder for this job, and maybe a flux pen might help.