Re: 405 Mi16/1989 temperature unit sending problems

Robert K Cullemore (robertkc@storm.ca)
Tue, 16 Sep 1997 17:19:06 -0400

> This sounds like a classic case of coolant from a leaky thermostat
> housing fouling the plug attached to the temp sender. You may have
> already replaced the t-stat gaskets(If you have not, than do it now), but
> I bet the pins in your plug are still fouled with coolant (wet or
> dried)...which would cause the symptoms you describe.

Actually, the thermostat housing on this engine has been updated as per
the TSB.

> I bought replacement pins and a new plug (the latter was unnecessary)
> from the dealer and that cured my problem.

Are you talking about the thing that plugs into the temp-sending unit or
the plug that is below the housing where the fluid leaks onto? I don't
recall what that switch is called and how much it costs.

> It is standard bosch plug, so
> a good auto parts shop should be able to find replacement pins.

Good

> If you can remove the plug and the fans come on high, then it rules out a
> problem with your ECU, fan relay, or fan motors.
>
If you're talking about the temp seding unit that screws into the
thermostat housing, then yes, when it is unplugged both the fans come
on; this is how I have things at the moment, because when the
temp-sending unit is plugged in, the fans don't activate at all.

Many thanks,

Robert Cullemore
89 405 Mi16