Hi, I have what appears to be an oil plug in the front of the block just above the timing chain cover. See black square headed plug on the right side of the picture. Can anyone confirm this is an oil plug? I'd like to install an oil temp sensor here. Does anyone know what size this plug is?



Thanks,

John

 

I don't know if it's oil or water - but I'd guess it's a standard 1/4 NPT - same as the similar looking plug on china wall by distributor (which I know is oil). There's also usually a plug just above oil filter (which is also oil) - but this one is a different size.

Could always take it out and see - if nothing comes out, probably oil, or else you'll see collant leaking as you loosen it.

 

Yeah I'll check it out when I have a chance. Its much more fun to speculate though.

I'm looking to order parts but don't really have much wrenching time available the next two weeks.

 

If your oil temp sensor has a different sized fitting on it, and I'm right on the NPT of the block, any hardware store will have NPT-to-whatever adapters in brass in the plumbing section. I use an oil pressure gauge from an older 3rd gen atop my china wall, but had to get plumbing connectors/adapters to come up & out of that area and turn 90* to fit it in there (just like the older cars had them). My new motor had the oil port above the oil filter plugged, and that sucker wasn't coming out (especially after I installed the motor and had no room to get a grip in there), so it was just easier for me to attach to china wall.

Good luck - let us know what you find there so we all know!

 

Will do. The sensors are available in many different sizes. I'd rather not use pipe bushings if possible. Just makes for a cleaner install.

 

It goes into pressurized oil.

It's actually 1/8" pipe; same as the one under the dist.

You won't measure oil temp there. You'll get block casting temp. You have to put an oil temp sensor in the oil, not in the block. You could measure oil pressure though.

 

Hmmm. How would that be any different than a coolant temp sensor screwed into the block? Perhaps coolant temp and block temp are extremely similar?

I would expect oil temps to typically be higher than block temps and the temperature probe sticks pretty far into the passage. I would tend to think it would be fine there. In other words I would not expect the cooler block to significantly change the reading. Typically the temperature sensing portion of the sensor is way out at the tip. But I am no expert.

I'm guessing you would suggest reading the temp in the pan?

 

Yes the block is basically the same temp as the coolant. Not least, because very little heat passes from the cyl to the coolant via the block; the vast majority of the heat goes through the heads, and the coolant may actually WARM the block.

Most "coolant temp" gauges, including the ones in these cars, are really "head casting temp" gauges, for this reason. The head castings are usually a few degrees, maybe 10-15, hotter than the coolant since they're what the coolant is cooling, and by definition, something that cools has to be cooler than the thing it's cooling.

But aside from that, a temp sensor screwed into that tiny hole in the block, with a LARGE area of contact with block casting and a TINY surface exposed to whatever else, stuck into a dead-end passage filled with stale oil that just sits there and never moves, won't be affected much by the temp of the HUGE majority of the oil ... from a foot away.

Yes if you want to measure oil temp, you pretty much have to go where the oil is; which would be, in the pan. Or, if you had an oil cooler that circulates oil, you could measure it in the line right at the exit from the engine.