Oil temp sensor?
 

I have oil temp gauges but they have never worked since i owned the boat. i think the guy i bought it from said they werent wired. poking around my gauges i do see there is wiring connected to them. would this be where a temp sensor would be located? if so the sensor looks like it is wired too. i'll have to test the wiring some other weekend.

http://i534.photobucket.com/albums/e...00531-1410.jpg

I'm having same issue. Just switched from a 496HO to a 500efi and now my oil temp gauges don't work...Actually can't recall if they worked on the 496's either. Any advice? The gauges are wired as I put new gauges in 2yrs ago. I'm guessing it's the sensor wire or the senders aren't in the right location to read correctly. My boat runs 155 degrees on water temp so oil should be within 10-20 degrees I would imagine. It doesn't even move on the gauge.

with the ign key on ground the power wire from the sender to the block with a good ground, gauge should peg at max temp, if it does you have sender problem or ground issue, if does not trace back to gauge....

On my cousin's TG, its a dark brown wire, goes to a sending unit down by the oil filter block adapter. It's a single wire sender tho. You sure that isn't the Hobbes switch for the electric fuel pumps (if you have them)?

Anyhoo - my cousin's boat, HP500's, this is where the oil temp sender is, down in this mess.

I never did get this figured out last summer. This is a priority before it goes in the water this year.

I know the remote filter location is different from the HP500 and 500efi.

My question is where's the best location to read oil temp on a 500efi to get the most accurate oil temp?

That looks like an oil pressure switch. Senders will only have 1 wire going to them.

The best place to read oil temp in a Gen VI block is the 3/8" NPT port just above the oil filter pad (where the oil filter would be in a car). The pressure sender will be there, so you will have to move it. You can put it in the port just above the bell housing, the filter housing, or in the 1/4" npt port on the side of the block just above the oil pan rail near the front. You want the oil temp sender in the flow of oil, not a dead end passage that has stagnate oil. The port I mentioned is the absolute best place. The pressure sender can go anywhere, even if it is in a dead end passage. Pressure is pressure. You want to know the temp of the oil that is going in the engine. Good luck. Give me a shout if I can help.
Eddie

My oil temp senders are located in the pan. This is where the oil is being picked up from to pump into the engine and shouldn't be influenced by block heat. Bottom line is if you take 20 readings of temp with a digital temp gun from 20 different places on your engines, guess how many different readings you will get? I want to know how hot the oil is that I'm sending back into the engine, period. IMO

Thanks Eddie! You always are glad to help out..

Where can I get the correct sender for oil temp other than Mercury?

Livorsi sells all the various senders

I think it's actually the choke switch.. If it's a carbed motor. My carbed HP500 has a switch exactly like that on the remote filter pad, and it's the switch for the choke.

It's actually an oil pressure switch... for the choke circuit. It doesn't allow voltage to the choke coil unless the engine is running. That way if the key is left on without the engine running, the choke coil is not inadvertently warming up and opening the choke without the engine running.

In a factory Merc harness, the wire for the oil temp sender is dark brown, or dark brown with a white tracer. As Eddie stated, 3/8 NPT in the block, just above the filter pad, is the best placement for the sender.

I was wondering if it was a standard GM part? I'll just get Mercury ones I guess from BAM

Oil Temp Sender
 

Bring this old tread up to determine if my oil temps are inline. Does any anyone know if the location Eddie mention above the filter pad is reading before the oil cooler or after? As this is where I'm taking may reading from for my oil temp gauge.

Thanks

Oil temperature in a high performance boat could easily be 100+ degrees higher than the coolant.

My oil temp sending units were mounted in the rear port side of the engine block just above the oil pan. Single wire sender.

After the cooler. This is the temp that the oil is before the oil goes to your bearings, the important temp. If you want to have one in the pan or before the cooler to see how hot your oil gets, do this as a secondary sender and just use a toggle switch to toggle between senders. This will tell you how well your cooling system is working.

My 87 Gun has them in the pans, I prefer to read after cooler but in this case I still don't see more then 180 IN PAN! (hot side) at them temps I am not worried, so I have not moved them yet, new gauges and senders and verified with temp laser, so look down by your pans especially if Hawk powered with GIL pans, very common place, wire is single Brown.