Crankcase thread - union, oil feed pipe (engine end)

[56G80S]

Solved my first problem but on inspection, although functioning, the threads into the crankcase for the steel union are shabby.

For the sake of £3 plus P&P for a 2nd tap 1/4 BSP - 19TPI from Tracy Tools (only carbon steel, no need for HSS) I thought to clean them up.

Or leave well alone? Dad always said I fiddled about with things too much.

Waits for Mick D to advise!!!

Johnny B

[clive]

Was it leaking? If not leave it alone. And now the proper advice from Mick!

[uas526]

Wouldn't you be better off with a plug tap, rather than a 2nd? There's not a lot of depth to get the thread going. To clean the thread I would start with a new steel 1/4 bsp union, and some light cutting/tapping oil. Taps can be overly aggressive in alloy, if only a thread clean-up is required.

[Mick D]

Hi

I'd leave well alone, use PTFE plumber's tape on assembly to bulk up the joint a little if necessary.

Any damage is likely to be at the end outer end of the thread so a second tap would suffice though a plug or bottoming one is correct when finishing blind threads.

Egg sucking time: Always restrain the union with a spanner when torqueing the oil pipe gland nuts

Regards Mick

[56G80S]

Thanks for reining me in.

Clive - not that I'd noticed.

uas526 - I think that's good too, I'd thought plug but 2nd easier to get started as Mick said the damage is the early threads.

Mick D - I've plenty of that stuff, quite like doing plumbing. Even have PTFE cord, not appropriate here of course.

On the egg sucking front, I don't recall ever removing this before, as removal not necessary to get the copper pipe out, and wish I hadn't! I have used two spanners, a bit like tappet adjustment (and using plumbing compression fittings). The irony is that the other thread, which I've had in and out several times, is perfect.

I'll go down the leave it alone and put it back in with a turn or two of PTFE tape route, thanks. I'm still wondering why that additional collar, which I lost on the floor but is in stock for about £1.50 at AMOC as "High grade aluminium, steel n/a" is for. Did someone just make the threaded part too long and that was the fix. Apparently the sealing for the union to crankcase is on the face of the crankcase.

Thanks

Johnny B

[Mick D]

Hi

I think the collar in question is visible in this snag:

Oil Lines.png

I'd fit one rather than risk damaging the case by trying to thread the union into an area of partially formed thread.

Regards Mick

[56G80S]

I gave the wrong impression, I was always going to, it just seemed strange to have it there from the factory.

Johnny B

[raffles]

John
if the spacer was not there you would not be able to get a spanner on the flange nut
Tony

[56G80S]

I think it was a factory bodge to correct a measurement / manufacturing error when the found that they couldn't get a spanner on the flange nut!

Johnny B

[Duncan]

Probably not a bodge as the parts could have been easily modified over time but to protect the face of the crankcase from the steel adaptor cutting in/dragging and overtightening by having a bit of give and it would act a bit like a fat crush washer to seal oil leaks