Author Topic: Oil pressue and temp gauges...  (Read 2819 times)

Offline Ross

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Oil pressue and temp gauges...
« on: June 06, 2006, 06:13:03 AM »
I'm thinking I want to have some accurate gauges on the dash so I'm thinking of running some brand new wires from the engine bay up inside the bus in my overhead wire track to the front of the bus.  My original gauges don't work very well.  The temp is about 50 degrees off, which means it's just coming off the peg when the bus is at operating temp.  The oil pressure registers, but it's way off as well.  Gauges in the engine bay funcion perfectly, so I know it's the gauges, not the engine.  What would be the best wire to use for connecting the sending units to the gauges? 

My other thought was to point a small camera at the engine room gauges and wire it into the backup monitor, but I'd rather have some accurate guages, if that's possible with a 50 foot wire run.  I'm really nervous about heading south this summer without a very accurate temp gauge.  As we all know, all it takes is one overheat to scrap an engine.

Offline Len Silva

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Re: Oil pressue and temp gauges...
« Reply #1 on: June 06, 2006, 09:16:34 AM »
I really doubt that it's the wiring causing you problems.  I would replace the gauges and senders with new good quality units (VDO, Stewart-Warner, Isspro etc.)

The wiring is usually only one lead from the sender to the gauge.  Verify it's condition by disconnecting both ends and grounding the sender end. Measure from the gauge end to ground with a good ohmmeter and it should be very low, less that 1 ohm.
Remove the ground and measure again on the highest scale (100 meg or higher) to ground to be sure there is no leakage. The needle (or display) should not move, measuring infinity.

Be sure that whatever the sender is mounted in (engine block, water manifold etc.) is well grounded.

Read the directions carefully when installing the senders and do not use teflon tape.  Most of them have a tapered thread and require no sealant at all.


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Offline TomC

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Re: Oil pressue and temp gauges...
« Reply #2 on: June 06, 2006, 01:35:17 PM »
Actually, in commercial boats, many times they will have a camera pointed at the mechanical gauges right on the engine as you said.  So it is done!  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.


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Re: Oil pressue and temp gauges...
« Reply #3 on: June 06, 2006, 03:16:42 PM »
Do your absolute best to make sure the sending unit and the guage are 'matched'..mostly being from the same manufacturer.  A VDO dash guage won't necessarily work properly with a Stewart-Warner sending unit.
Always buy in matched pairs from a supplier you trust.