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bass gt · Posted: Wed Dec 08, 2004 12:28 am Post subject: Oil Temp and Pressure

Gents,

Can someone enlighten me as to where i can connect the pickups for oil temp and pressure gauges. Whats the best, electrical or mechanical gauges in your opinions. Is the oil pressure switch on the rear of the head just a switch or also the pressure sender for the gauge as i think mine is kaput. I seem to have a short to ground on both terminals. Is this a difficult part to change.
So many questions, so little time!!
PS, the car is an 81 931

Many Thanks,

Steve

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

The big round sender on the back of the block is for the oil pressure gauge. I've only heard of it leaking oil when it goes bad. If your gauge is reading funny then one of the wires might have grounded itself somewhere. Unfortunately, the sender and those wires are a real pain to get at on the 931!

For oil temp, you can buy an electric sender that screws into the oil pan and takes the place of the oil drain plug. There is a vendor who sells them on ebay fairly cheaply. Doesn't get much easier than that!

Mechanical gauges are much more difficult to plumb and you have the possibility of leaks into the cockpit. I think electric gauges work just fine.

nick

bass gt · Posted: Wed Dec 08, 2004 2:28 am Post subject:

Thanks Nick,

the oil pressure unit is not leaking, i just seem to have a short to ground on both wires. Can this unit be removed with the engine in situ? i suspect it is a real pain in the a$$
Any idea the name of the vendor for the drain plug pickup? Seems a simple enough method
I presume that the factory pressure sender unit on the rear of the head can be used to drive a non standard gauge such as SPA/TIM or VDO.

Regards,

Steve

CMXXXI · Joined: 05 Nov 2002 Posts: 1939 Location: Vicksburg, MS

If the wires coming off the sender are hooked up wrong, the gauge will "peg out" as soon as the key goes to the ON position, and the idiot light will constantly glow. I accidently hooked them up backwards once...I made sure I didn't do it again by putting on different connectors on the leads... one a bullet type, the other a spade connector.

I've recently been toying with the idea of getting an oil temp sensor and gauge, and have been checking out eBay. Do a search on "vdo oil" and it will return a couple of pages of hits of oil temp and pressure gauges, as well as the sensors.

I don't know if all the 924/931 oil pans are the same, but there is a second hole above the drain plug that can be used for the oil temp sensor. I understand that some cars have this hole used as the return point for the oil separator canister though. I think it is threaded 14x1.5mm but I can't confirm that off-hand.
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'79 Eurospec 931