As promised here is my tech article on this subject.

Very easy, step by step instructions with a parts list including part #'s

why keep the factory oil pressure gauge?

I did it that way so that my factory gauge on my dash would still function. If this is not important to you than you can just use the 1/8 BSPT/1/8NPT adapter and then run your tubing. It’s just one way, not the only way.

9!'clipseDOHC you should replace the male to male 1/8" adapter with a short piece of hydraulic hose and attach the "T" fitting and the sender to chasis. With the current setup the sender will oscillate due to engine vibrations and will probably lead to fatigue failure of the aluminum fitting, a large mess on the ground and possibly a large hole in your wallet. Good luck.

That is a good idea. However I had this same setup for the last 5 years except with all cheap brass fittings and nylon tubing and never had a problem. This was just a little upgrade for me to the performance fittings and copper tubing. I do like your idea though, it does sound more stable.

Sorry to start antoher old thread but mechanical gauges are more acurate I would think. Im getting one because my stock one is shit and NO after reading what a guy said 3 years ago am I replacing the stock gauge.

This guy is right. A good friend with a 95 GST used to have an aluminum T with a thread adaptor hanging off the oil filter housing to add an aftermarket oil pressure gauge, and the aluminum T cracked after less than a year, causing him to dump oil EVERYWHERE and he ended up using that as an excuse to dump his 7-bolt motor for a 6-bolt with 1G head.

Another way (which somebody already described) is taking out the stock 3/8-NPT hex plugs in the oil filter housing (there are at least 2 in the 2G oil filter housing) and using a 3/8NPT->1/8NPT bushing to install aftermarket pressure/temperature senders. This is how I installed my aftermarket senders.

MIdsm said:

9!'clipseDOHC you should replace the male to male 1/8" adapter with a short piece of hydraulic hose and attach the "T" fitting and the sender to chasis. With the current setup the sender will oscillate due to engine vibrations and will probably lead to fatigue failure of the aluminum fitting, a large mess on the ground and possibly a large hole in your wallet. Good luck.

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there is no pipe thread on these cars that come as npt. they are bspt!

ramsack said:

there is no pipe thread on these cars that come as npt. they are bspt!

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BPT and NPT are extremely similar. You can run a 1/8" NPT tap through a 1/8" BPT threaded hole to "clean up" the threads and pull the TPI (threads per inch) and the angle of the thread to match NPT threads. I did it on my oil filter housing a couple years ago.

extremely similar isn't the same, and i think people should just be informed of what is correct in case they actually search and find this thread, and they end up getting a npt adaptor and putting it in a bspt hole. 3/8" will be a bigger difference in thread pitch than a 1/8" too. you might get away with it at 1/8" but i wouldn't want to do it with 3/8".

Hmm, interesting info. Is it possible that 2G and 1G oil filter housings have different threads on those 3/8" ports?

I used a 3/8NPT->1/8NPT bushing, put a bit of grey RTV on the threads, and installed my aftermarket oil pressure sender and it literally didn't leak a drop for 9 years/80K miles until I swapped out the oil pressure sender. The bushing threaded in just fine too--didn't feel any unusual resistance or looseness.

FYI, I can confirm that the stock 1/8" oil pressure sender is 1/8 BSP, and a 1/8 NPT will NOT thread in at all. In fact, for some reason, even the 1/8BSP male->1/8NPT female adapter I bought from Summit Racing couldn't thread into the damned 1/8 port (the stock 1/8BSP looks tapered while the Summit 1/8BSP looks straight). I ended up installing an oil temperature sender into a sandwich adapter--not ideal, but I didn't want to mess with tapping new threads into an existing port.

ramsack said:

extremely similar isn't the same, and i think people should just be informed of what is correct in case they actually search and find this thread, and they end up getting a npt adaptor and putting it in a bspt hole. 3/8" will be a bigger difference in thread pitch than a 1/8" too. you might get away with it at 1/8" but i wouldn't want to do it with 3/8".

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i may be wrong about it then, but i wouldn't see why they would use bspt on one hole and npt on another on the same piece.

EDIT: i am positive now. i just measured that 6 threads on one of these oil filter housing plugs is 8 mm in length. this converts to 19 TPI which is 3/8"-19 BSPT. if it was NPT, 6 threads would measure about 8.5 mm, as there is 18 TPI. also BSPT is 55 degree threads, and NPT is 60 degree.

Well what is the cheapest easiest way to put in a after market oil pressure gauge.

ramsack said:

extremely similar isn't the same, and i think people should just be informed of what is correct in case they actually search and find this thread, and they end up getting a npt adaptor and putting it in a bspt hole. 3/8" will be a bigger difference in thread pitch than a 1/8" too. you might get away with it at 1/8" but i wouldn't want to do it with 3/8".

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It's common knowledge that DSMs have BPT ports. I just also want it to be known that it's a waste of time and money to source out BPT adapters/bushings when commonly used NPT fittings will work just fine.

I have a 3/8" NPT fitting in the front of my oil filter housing for one of my turbo's oil feed, and an 1/8" NPT fitting in the rear for my pressure gauge. Been that way for years and I've never had a leak. I'm not guessing that it will work - I've already proven it.

99gst_racer said:

It's common knowledge that DSMs have BPT ports. I just also want it to be known that it's a waste of time and money to source out BPT adapters/bushings when commonly used NPT fittings will work just fine.

I have a 3/8" NPT fitting in the front of my oil filter housing for one of my turbo's oil feed, and an 1/8" NPT fitting in the rear for my pressure gauge. Been that way for years and I've never had a leak. I'm not guessing that it will work - I've already proven it.

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Maybe 1g and 2g oil filter housings are threaded differently because I couldn't get an 1/8 NPT fitting to go in more than 1 or 2 threads for my 1g pressure sensor. I got a 1/8 BSPT to NPT adapter and and went in perfectly, all the way.

McMaster-Carr is a good place to get these fittings and it isn't exactly foreign or anything. they are cheap, and most of the good fittings are stainless!

here are some part numbers on mcmaster-carr, all are stainless steel:

1/8" BSPT male to NPT female adaptor ~$8: 4092k11
3/8" BSPT male to NPT female adaptor ~$16: 4092k13
3/8" NPT to 1/8" reducer bushing ~$4: 4443k751

4092k13 and 4443k751 would be used together to put a sensor on one of the big plugs on the housing. 4443k751 is probably something you could find at a hardware store though, seeing as how both threads are NPT.

hope this helps. stainless steel is a better alternative to brass or aluminum which would crack over time, especially aluminum.

Has anyone tried mounting the oil pressure sender unit off the turbo oil feed line?

1gDSM4g63 said:

Has anyone tried mounting the oil pressure sender unit off the turbo oil feed line?

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How Do You Pressure Test the Feed Line?

So can I install my mechanical oi pressure gauge, with out using a "t"?
Is the only reason every one uses a "t", is so they still have function out of the OEM gauge?
I'm not worried about the OEM gauge functioning at all.
Am I correct?

^^ Yup, correct.

Cool, thanks.

Well I decided not to use the mechanical oil pressure gauge I have.
For fear of the line breaking and getting oil in the cab.
So now I'm trying to connect the stock gauge back up, it hasn't worked since I bought the car.
When I looked to see what was going on, I see a light blue wire and a yellow wire spliced together?
From what I understand the blue is supposed to go to the sending unit.
(the bell shaped bowl, by the oil filter)
The yellow is supposed to go to the "idiot" light.
Now I don't see the plug for the idiot light???
And I'm missing the plug that goes the the "nail head' on the sending unit.
Does any body have a way to hook it back up, with out ordering the OEM plug?
Also did it hurt anything, having those wire crimped together?
Here is a picture of my oil filter housing, it seems to be different from the pictures I've found online.

NeMiZiS said:

Well I decided not to use the mechanical oil pressure gauge I have.
For fear of the line breaking and getting oil in the cab.
So now I'm trying to connect the stock gauge back up, it hasn't worked since I bought the car.
When I looked to see what was going on, I see a light blue wire and a yellow wire spliced together?
From what I understand the blue is supposed to go to the sending unit.
(the bell shaped bowl, by the oil filter)
The yellow is supposed to go to the "idiot" light.
Now I don't see the plug for the idiot light???
And I'm missing the plug that goes the the "nail head' on the sending unit.
Does any body have a way to hook it back up, with out ordering the OEM plug?
Also did it hurt anything, having those wire crimped together?
Here is a picture of my oil filter housing, it seems to be different from the pictures I've found online.

You must be logged in to view this image or video.

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Your OFH looks almost exacly like my 1g 6 bolt OFH. Where you have the pressure sensor is where the dash light goes on mine. Also you are correct about the wires, yellow goes to the dash light and blue goes to the pressure sensor. Here is a picture of mine (you can ignore the "T"). Hope this helps!

This is on my 1990 Tsi.. I didn't put that originally.

Oh I see, I guess the previous owner thought it would be a good idea to move the pressure sensor and completely remove the idiot light?
Goddamn the owner of this car has messed up so much crap, it is ridiculous!!!
I just noticed today my power steering pump wasn't bolted down and was about to fall out!

I have a friend with a almost complete 1991 4g63 N/A, can I pull the idiot light and pressure plug out of it?

NeMiZiS said:

This is on my 1990 Tsi.. I didn't put that originally.

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I thought that looked like mine.

NeMiZiS said:

I have a friend with a almost complete 1991 4g63 N/A, can I pull the idiot light and pressure plug out of it?

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Yes, they are exactly the same.