freeman1

HI everyone had a quick question. When I start up my boat my temp guage jumps all the way to the right side (After about 1/2 of running it drops back down to 160 Degrees). I have a VDO guage and 2 senders (One on the T-stat housing and one on the intake manafold)....How do I tell if it is a bad guage or a bad sensor?? I'm assuming since the guage jumps to the hottest setting when the motor is Ice cold that there is a problem somewhere.....



Thanks

Chris

Vinny P

I have never heard of having 2 senders for 1 guage. I would think that there may be a feedback problem here. Try eliminating 1 sender and see what happens to the guage.

blue thunder

I had that same thing happen when I installed VDO senders with gaffrig (merc campatible) gages. The voltage reference was backwards so the readings started high and then dropped off. The second sender is probably a temperature switch for an alarm.

BT

ursus

The sensor on the intake manifold is for the audio warning system. The one on the Tstat is for the guage.

Standard VDO guages use senders which operate backwards 10-180 ohms versus US standard (merc) 240 -33 ohms. To confuse things more VDO also makes guages which are backwards and work on US sensors.

You need to match the sensor to the guage. Here is a list of VDO senders. Pick the base size, probably 3/8 or 1/2 NPT and the terminal type, probably spade. I am not vouching for the online vendor either way, have never used them but they have a good list of vdo part #'s

Sender Listing Link