E31 850i power steering pump drain plug

[bdiefAZ]

You will need a drain plug and a crush washer only way to stop the leak

[LappingLuke]

Yes this is the ideal. Now if anyone actually made an M14 1.0 thread pitch bolt, this would be quite simple.

- - - Updated - - -

My debate today is basically JB weld vs drill and tap it to 3/8 NPT...

[Hyper]

...1.0 thread pitch...

Seems strange, worthy of audit/review.
There are available solutions at 1.25, as per Cartoonz.

[LappingLuke]

20230321_184110.jpg

- - - Updated - - -

Bought a 1.25 drain bolt and it didn't thread in.

[Hyper]

...Bought a 1.25 drain bolt...

Good, those look available, have a flange that comes down onto a crush washer.
Assuming that the method is viable, crushing a washer down to the case, then the threading could be (?) changed/standardized via M14-1.25 helicoil.
There is risk of the crush washer method not being viable, or helicoil boring damaging essential features at the site, or wall thickness does not support the heilicoil.
Given this "line down" situation, and availability of Plan B (buy another pump), my adventurous alter ego would first inspect the area, triangulate the risk, then proceed.

{ed: The last step in helicoil installation is snapping off the cross wire on the embedded end. Obviously we don't want that left in the pump. Hmm, how to extract or flush?}

[ctuls]

Has anyone found a source for a M14 x 1 thread bolt/plug? I took mine out today as it was leaking and the seal was not great.

[LappingLuke]

It doesn't exist. Period. I removed the pump, disassembled it, drilled and tapped the hole for 3/8 NPT wrapped it in some teflon tape and put it in and haven't had to worry about it since. I used an inexpensive aluminum NPT plug from amazon. The pump case is aluminum so the plug and the case will grow together when they warm up. A brass plug will grow faster and potentially damage the aluminum case. A steel plug will grow slower and it might leak when it warms up. If you put the plug back in and fill it up and it starts dribbling, you get to drain your expensive fluid again into a clean bucket, drill/tap/install NPT and dump it all back in.

For future readers the moral of the story here is basically cartoonz comment in post #20. It's not really a drain plug, DO NOT REMOVE IT unless you have to (e.g. its already leaking on its own). Sorry to ctuls that you might be in for a frustrating job you didn't forsee, but you reminded me to update my end of the thread here which I hope is constructive.

[ctuls]

@Lapping Luke - Thanks for sharing your experience. The comment on dis-similar metals is insightful! I found the plug below, but you are right, the dis-similar metal will likely cause issues
https://www.harfington.com/products/...43411544572153

Sometimes I learn the hard way. I do wish sometime I had a lathe so I could machine my own aluminum M14 plug or bolt

And yes - really dont remove that plug

[LappingLuke]

I toyed with the idea of having a plug made but the car had already sat on the lift for 5 weeks getting a bunch of new parts and I was ready to fix it and drive it! Anyway let us know what you do and how it goes.

[cartoonz]

That plug will work just fine... IF - you get rid of the oring and use a crush washer.

[ctuls]

I might try and order the plug and see then. The only other idea I have is to use a square profile o ring in place of the original seal (as mine is torn off now)

https://www.mcmaster.com/1171N103/

[ctuls]

To close the loop here:

1. Replacing the nylon band with an o-ring (x-profile) did not work out. Even with copious amount of thread sealant as I was threading it in, it was stripping the tread on the plug and the threads on the housing itself

2. I decided to go with as suggested drilling the hole for a 3/8 NPT tap, and using an Aluminium plug with lots of thread sealant.

3. I removed the pump from the vehicle, I got the thread tapped at a machine shop (as my tap was not going straight), installed the plug, replaced all the seals and installed the pump back in.

items used:

1. Drill America - POU3/8NPTW/DRILL 3/8" Carbon Steel NPT Pipe Tap and 37/64" High Speed Steel Drill Bit Set, POU Series
2. AC PERFORMANCE Plain Aluminum 3/8" NPT Male Socket Allen Head Plugs, Silver, Pack of 2
3. Permatex 59214 High Temperature Thread Sealant
4. 2 M16x22x1.5mm washers and 2 M14x20x1.5mm Copper Sealing Washers Flat Washers (for the hoses)



Seems pretty leak free for now

[LappingLuke]

Nice! I'm glad it worked out. Yes, it's a pain to fix but what you have done is really an improvement over the factory's crackpot idea. It's serviceable and will last forever.

[Hyper]

...crush washer...

...crush washer...

...crush washer...

...crush washer.

Looks like the Harfington investigation will have to wait for the next victim.

[LappingLuke]

There is nowhere to put a crush washer with the factory plug and no replacement flanged plug with suitable threads.

- - - Updated - - -

It should be noted I would be more than happy to be proven wrong about my above statement. However, I searched high and low for weeks myself, had several other religious car enthusiasts, engineers, hardware nerds at work, etc all searching to help me as well and we turned up absolutely nothing.

[Hyper]

... M14 1.0...

...https://www.harfington.com/products/p-1302621?variant=43411544572153...

wth? ctuls provided a flanged plug with threading you asked for, something to follow up on.

[LappingLuke]

I found several plugs out there that were listed at M14x1 but on further inspection, downloading spec sheets, drawings etc were actually 1.5 or 1.25 thread pitch. The photo they have on the listing could be a stock photo of another part, but just eyeballing the thread major diameter compared to the thread pitch, its not 1.0 as the 1.0 threads are TINY.
In my interest to provide useful information on this topic, I ordered one of these plugs for under $8 shipped and will report back with photos in "9-14 days"

[ctuls]

There were two reasons I ditched the harfington idea:

1. When I tried the o-ring idea, it damaged some of the threads on the housing thus reducing the chances it will seal well
2. They communicated back "....We are sorry that this item has run out of stock, but the replenishment is on the way. In this case, would you mind waiting for a week?...."

This was already after waiting for 10 days I just wanted to get the car started after sitting for 6 months and this plug being the last piece

[LappingLuke]

I'm pleased to be able to confirm that after 25 days the "Harfington Plug" has arrived and is indeed the fabled 1.0 metric pitch with 14mm major diameter. The integrated rubber o-ring is pretty nice and I think this would be a very suitable direct replacement/upgrade for the factory plug should it start leaking on you. It also makes servicing the fluid a snap if that's something you like to do or need to do often. It's very cheap to buy but does take a while to get to the USA.

Photos:
https://drive.google.com/file/d/1Pc4...ew?usp=sharing
https://drive.google.com/file/d/1CZP...ew?usp=sharing

[cartoonz]

use an aluminum crush washer too.... the o-ring will not do the job for long, if at all. The outside edge of the plug cap will seal the crush washer.

[JurgenBMW318i]

clean all threads with isopropyl. Dry.
Use Thread SEALER (not loctite) liberally on the plug.
Install, let dry overnight.
Fill system.

This is the only reliable way to keep that plug from leaking after it is removed.

What brand and type of thread sealer did you use please? I have removed mine as I was refurbishing the pump and now I’m trying to figure out what to use to make this thing leak free! Hopefully 🙏

[cartoonz]

What brand and type of thread sealer did you use please? I have removed mine as I was refurbishing the pump and now I’m trying to figure out what to use to make this thing leak free! Hopefully 🙏

Loctite actually makes a good thread sealer... but make sure it is a SEALER, it is different from the locking compound.

[JurgenBMW318i]

Is it ok if I use a thread sealer with the oem grabscrew (if i can call it like that), or better use a bolt and washer? I managed to find a M14X1 bolt from a peugeot.

[cartoonz]

use the bolt and a crush washer... you must use the crush washer with a bolt

[JurgenBMW318i]

Great thanks 😊