Sump Plug

[Steve Marshall]

Looks like I need to tap out my sump drain plug to 20mm. Previous careful owners have taken it out to 18mm and then managed to strip the thread again!

I have drained the oil.

I would like to do it in situ, then run the old old through the engine to flush out (nearly) all of the swarf.

Does the oil pump suck oil up from the sump through the rubber hose and filter? If so I feel a little more relaxed about this idea.

Steve Marshall

[Mich7920]

Hi Steve,
If you look at the books, you'll see that the pump suck the oil directly into the engine oil sump.
The oil in pressure goes through the rubber hose and at last by the filter before going into the engine.
Mich

[mgcjag]

Steve.....the rubber hose under the filter housing is from the pressure relief valve and dumps oil back into the sump if pressure is too high......the pump draws oil directly from the sump....then through the filter......so in effect it pumps the un filteted oil...so you dont want swarf in the sump.....Steve

[Mich7920]

Oupsss
My answer was stupid!

[Mich7920]

Of course As Steve said the oil come to the pump directly from the Sump.
After the pump puts the oil under pressure it goes to the filter AND into the engine.
The hose is for the over pressure.
After the yesterday's party, my ideas are more clear now

[Steve Marshall]

Thanks guys
I thought the main oil pickup was from the inclined tube which goes through the P clip.
The careful previous owner put the P clip upside down so that the pickup was too steep, then bolted the sump up, which fractured the oil pump body.
Then they seized the engine big time.
Unanswerable question for the forum: Why is stripping sump drain filler plugs such a popular hobby?
They only need removing maybe 12 times in the life of an average car. eBay is full of kits to re-tap them oversize for modern cars. My E has done 56,000 miles, had the 5/8th hole stripped, was then retapped to 18mm, then stripped again.

Are these people hanging off the end of a strong bar or what?

[johnetype]

On E types the problem of easily stripping the sump plug thread comes from Jaguar using an aluminium sump and a UNF thread. Plus of course the inevitable mechanics "one last push" to ensure it doesn't come undone and spill oil on the road as I've been too cheapskate to replace the copper washer.

I suspect that Jaguar moved to an aluminium sump for the E type as a cheap compromise over not fitting an external oil cooler for normal road use but they retained the 5/8" UNF threaded sump plug because that was what was already in use for the rest of their current XK engined models but they had steel sumps so could live with a UNF thread - Mr. Whitaker at work again no doubt but also just sensible parts commonality across the range for servicing.

Contemporary Mini's have an aluminium sump - it's actually the gearbox housing but that comes with a UNC threaded plug so is much stronger and harder to strip.

[Steve Marshall]

UNC looks like a better choice. But it's not only Jaguar who are so fond of fine threads. 1.5mm pitch looks pretty standard for 13mm, 15mm 17mm and 20mm plugs.

I just bought a 20mm magnetic one intended for a Porsche for my 'E'.

Steve