90mphRAGE

Does anyone know where I can install a oil temp sender on a 500efi? I noticed there's a 1/4" hex plug in the bottom of the remote housing & in the block adapter. Could one of these be drilled & tapped or is there somewhere already prepped? There's already a wire in the harness (brown/white) to the gauges, but engine side is not hooked to anything, so I assume it's not a required part of the engine electronic system, or am I missing something? Mercruiserparts.com shows a sender for this motor, but no location on the drawings.

nedpoole

On my 502 Mpi, I put my oil temp sender in the port right above the relocator. (where the stock pressure sender is) I relocated the pressure gauge sender to a t that I added on the bellhousing port right behind the intake manifold (where the pressure alarm sender is) Eddie young said to do it that way cause the port above the relocator will give the most accurate temp reading for the oil re entering the motor after the cooler

DesertRage

Randy,
On some of the newer boats that did not come with Oil Temp gauges, the brown/white wire is used for the drive trim gauge. If it is not hooked up on your boat, I am guessing it came with a mechanical trim indicator and the wire would be great to use for your new gauge.

90mphRAGE

I think the previous owner removed the oil temp gauge for a depth finder. I added a hole, the wire is right there with connectors & all already on it. The wire is just hanging behind the ecu. I ordered a 1/4" sender & gauge from Gaffrig, but the sender looks more like 3/8" or 1/2" threads & about 3/4" deep. Now I need to find a spot for it.
Ya, boat has mech trim. The Merc manual has wiring diagram & shows the wire as oil temp, not trim.

90mphRAGE

So added the oil temp gauge & sender (spare port just in front of adapter on the block) & oil looks in line @ 160~180 degrees 40~45 psi. It takes some time warm up but stays consistent once there. My water temp is 100~110 & 20~ish psi. I'm running no thermostat (per Whipple direction). My thought is the water too cold causing a little condensation in the valve covers. Should I add some more breather or put a thermostat back in the water? breather on stb side now, pcv on port. I'm scared to add thermostat against Whipple direction, they say steam pockets form & poof goes the head gasket.

sport

Keith Eicket and Hardin Marine both have some very nice billet oil thermostat's that would do the job up here in Utah's colder waters, they come in ethier 180 deg. or 210 deg.

I used the 180 deg. on my old 28 heat that had a blown 509 with know thermostat, my water temp also would never go above 110 but the oil would run between 170 and 190 at 3000 and 200 at 3500 to 4000 rpm's and 210-220 at full throttle and never had any milk under the valve covers. I got my oil temp reading on the return side of the oil thermostat because I wanted to see the oil temp that was going back to the bearings.
John

nedpoole

is this the one your ran?

http://www.keitheickert.com/detail.aspx?ID=1036

if so, how did you plumb it?

sport

That's the one, I made an aluminum mount and bolted it to the back of head but it can be mounted on the transom with the two bolt holes, I plumbed it like the instructions said, all it does is bypass the oil cooler until the oil gets hot enough. My engine was a MKIV block and it had a Merc. oil filter adapter on it but the MKV and MKVI blocks have the the ports on the block. I used #12 AN fitting and hose.

Some will say that 180 is to cold and it might be but that motor made 865 HP on the dyno and is 13 years old has 390 hours on it and is still going strong today.

The 180 and the 210 are the same unit just a different thermostat inside but the 210 is what they recommend for engine oil temp.
John

90mphRAGE

The HP500 has a thermostat in the stock filter adapter, I believe it's 165*. Did your Heat have a stock thermostat & if so did you just remove? Did your water temp go up as well & did you run a thermostat on the water? The more I read, the more this sounds like the anwer, but I don't want to spend too much $$$ to get 30* if I can just change the thermostat on the stock adapter.

sport

I used a cross over system with no water thermostat because that is what Paul Paff and Teauges Marine both recommended for a blown motor to help keep the heads cooler and to keep steam pockets from forming in the combustion chamber cooling passages. My oil cooler did not have a thermostat, I did not know that the HP500 already had an oil thermostat, I know my 600sci has one but not sure what temp it is. Have you called merc. racing to see if they have a higher temp themostat?