Oil pressure switch and banjo bolt issue

[linkinpark9812]

Ok, So I want to add an oil pressure sender but also keep the stock oil pressure sensor/warning light.

I'm sure some of you know, but in pic 1, you have the crank case, then the banjo bolt that screws into it, and then that banjo bolt has an opening at the top for the stock oil pressure switch. I am pretty sure it is 1/8" NPT

Now I bought a 1/8" NPT T adapter, one end is male and the other 2 are female for the sensors. Both the aftermarket sender and stock oil switch screw into the female ends, which to me confirms that the stock sender is 1/8" NPT.

However, the male end of the T adapter will NOT screw into the banjo bolt. If I try hard enough I can get a thread to catch but it only turns about 1/4 before stopping.

Just doesn't make much sense to me because if the stock unit is going into the female end, why isn't the male end going into the banjo bolt?

The T adapter is tapered, but not sure if that makes a difference. Also the banjo bolt looks a little recessed but I don't think that is an issue because it does grab a little. And again, since the stock sender screws in to the adapter fine, it just doesn't make sense why the adapter won't go into the banjo bolt.

Also directly trying to screw the aftermarket sender into the banjo bolt causes the same thing as the T-adapter, only a 1/4 turn. It also has tapered threads.

Any help appreciated!

[Racer x]

It sounds like the threads are NPT 28 or BSP 27. I will check in the morning.

[Racer x]

The thread size of the oil pressure sender is 1/8 BST 27. NPT 28 will not serew into it. You can go the other way but you can not screw NPT into BST. You can however drill out the BST threads. Not much but just enough to cut the NPT threads. Also don't use plumbers tape to seal the threads. This will leave dangerous strings that could clog. Use a liquid thread sealant from a tube.

[DaBlue1]

Originally Posted by linkinpark9812

Ok, So I want to add an oil pressure sender but also keep the stock oil pressure sensor/warning light.

If you don't mind me asking.... Why the need to add a sending unit?

[linkinpark9812]

Originally Posted by DaBlue1

If you don't mind me asking.... Why the need to add a sending unit?

Adding a sending unit for an oil pressure gauge.

Originally Posted by Racer x

The thread size of the oil pressure sender is 1/8 BST 27. NPT 28 will not serew into it. You can go the other way but you can not screw NPT into BST. You can however drill out the BST threads. Not much but just enough to cut the NPT threads. Also don't use plumbers tape to seal the threads. This will leave dangerous strings that could clog. Use a liquid thread sealant from a tube.

Thanks for the info! I knew there was a 27 and 28, but I was unaware that a BSP would be able to go into an NPT, so I didn't think that was my problem.
Luckily I have a 27 to 28 BSP adapter laying around so I will try that when I get a chance.

Btw, do you know what the maximum oil pressure is in the ninja 250 engine? I would like to know so I know what sender to get. I heard somewhere the pressure relief valve is 65 psi, so I am guessing it is around there.

[DaBlue1]

Originally Posted by linkinpark9812

....Btw, do you know what the maximum oil pressure is in the ninja 250 engine? I would like to know so I know what sender to get. I heard somewhere the pressure relief valve is 65 psi, so I am guessing it is around there.

The Ninja 250 oil pump produces 14-21 psi at 4000rpm. The low oil pressure warning light will light up at pressure under 14 psi.

Should be neat to see. Not many have a oil pressure gauge, mostly temp gauges and a couple of oil coolers.

[DaBlue1]

Instead of trying to fabricate a connection for the sender unit at the banjo bolt and oil pressure switch, why not just tap into the oil plug hole where the measurements are taken (lower right side of engine)?
You'll need an adapter (M18 × 1.5) and of course a gauge and fittings for it.
This way there is no potential pressure loses (due to restriction) to the head.

[linkinpark9812]

Originally Posted by DaBlue1

Instead of trying to fabricate a connection for the sender unit at the banjo bolt and oil pressure switch, why not just tap into the oil plug hole where the measurements are taken (lower right side of engine)?
You'll need an adapter (M18 × 1.5) and of course a gauge and fittings for it.
This way there is no potential pressure loses (due to restriction) to the head.

Not sure if there would be enough room, as it is the bell-type sender unit. I wonder, instead of using an adapter, if it would be ok to buy another banjo bolt that the stock oil pressure unit uses. I could use that one and take out the regular banjo bolt at the top of the head and tap it off there? Would have to make sure the banjo bolt holes for both matched the same length to make sure there isn't a problem. Might be better than Tee fitting.

[DaBlue1]

Originally Posted by linkinpark9812

Not sure if there would be enough room, as it is the bell-type sender unit. I wonder, instead of using an adapter, if it would be ok to buy another banjo bolt that the stock oil pressure unit uses. I could use that one and take out the regular banjo bolt at the top of the head and tap it off there? Would have to make sure the banjo bolt holes for both matched the same length to make sure there isn't a problem. Might be better than Tee fitting.

Just use a small hose in between the engine block (oil plug hole) and sender to allow enough clearance. That way you get a straight reading and don't have to bother with banjo bolts.

[linkinpark9812]

Originally Posted by DaBlue1

Just use a small hose in between the engine block (oil plug hole) and sender to allow enough clearance. That way you get a straight reading and don't have to bother with banjo bolts.

Hmm, I checked today and there is a decent amount of room back there for the oil pressure sender, as long as I had a 90 degree adapter. Hopefully I can just use one adapter, though not sure how hard it would be to find an M18X1.5 to 1/8"X28 BSP 90 degree adapter. Looks like a good spot to tap off of, I might just do that. Thanks for the heads up!