So... Is there such a reducer? From what I've read the stock coolant temp sensor under the oil filter stand is a M8x.75 thread pitch. Pretty rare from what I'm finding out... I'm wanting to use that for my coolant temp gauge, so I've been looking for a 1/8 NPT female to M8x.75 male reducer/adapter. Does this exist? Anybody know where to find one? Or am I just going to drill and tap my own hole?

 

I am sure that the thread is BSPT not NPT..not metric.
something to do with 28 threads per inch/27 threads per inch kind of thing.
YOu can put the NPT into the BSPT hole but it will not be the "exact fit"..but it will work.
This is in some threads already posted in the Sec Gen Specific Section.

Clokker or RE know more about this subject.Maybe they will chime in.

 

Have you pulled your sensor to confirm it's the straight thread/crush washer style?
If not, as Styx said, you can weasle your sending unit in...damn the 1 thread per inch discrepancy.

If it is though, put the old sending unit back in and use the blind plug in the lower front iron.
It's 16mm, IIRC and you can get adaptors for that.

 

Yeah, I have the older sensor with the crush washer. The thread pitch on the OE sensor is m8x.75. My aftermarket coolant gauge/sensor is 1/8 NPT. Figured I'd see if there were a reducer/adapter available first since I lost the OE sensor durring rebuild and they are $30ish bucks new.

 

the issue you are presented with is the sensor is larger than the metric hole, you would need 2 adapters likely to make this happen which would be a 1/8 NPT to metric adapter, which would probably be a 10mm thread and then from the 10mm thread step down to 8mm.

no adapter exists that i have seen or know of, even if it did it would be so wacky looking and perform so poorly that i don't even recommend it.

your best bet is to use an NPT to 12mm metric adapter for the front iron or the back of the water pump.

you could possibly just get a brass NPT fitting and thread it to make your own adapter but the coolant flow to the sensor is gonna suck, as will the accuracy and responsiveness. since there is no way of physically putting the sensor inside the engine the coolant will not actively flow across it with such an adapter. think of it like a cove in a lake, the main body is choppy but the cove is calm and has lots of stagnant water in it.

 

https://www.amazon.com/GlowShift-NPT...dp/B00CA91AIK/

Best 15 bucks i ever spent.

 

I'm using the 12mm hole on the back of the water pump housing for my fan switch. But you say there is another 12mm location on the front iron?

 

Towards the bottom of the front iron, on the driver side, is an allen plug. Cold climate cars can use this for a block heater, I've used it for fan triggers and gauge senders.
It is 16mm, not 12.

 

OK cool, I'll check that out do you know the thread pitch? M16x1.50 ect? Thanks!

 

About 18 bucks.

https://www.mscdirect.com/product/details/01221019

 

Why not just tap the front of the water pump housing?

 

you can also use the thermostat neck, which sometimes houses the auxiliary fan switch which already has a boss there ready for a sensor to be drilled and tapped. downside to this spot though is that if you ever have air in the system it will lose all temp reading when a air pocket passes.

 

Just wanted to do a little update for future users to search. The bung on the front plate driver side is a M16x1.50. So I decided to use it for my coolant temp gauge, and it also turns out GM LSx engines also have a M16x1.50 bung that leads into an oil passage. So was able to find a different few adapters, and this one in particular I really like. Because it's really thin and I feel will probably put the probe into the iron for proper readings.

http://www.ebay.com/itm/141962755212?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

that lower port is for coolant, the oil passages have brass drifts in them.

 

I was really tired when I posted that, and thought to myself after I went to bed that I accidentally said oil psi gauge instead of coolant temp gauge hahaha.

 

I dunno, i heard the ideal spot for coolant temp is as close to the outlet of the thermostat as possible.

 

actually it'd be in the coolant flow on the exhaust side of the engine.