3.8 Sump Plug

[Series 1]

I've owned this car for nearly 20 years and it's always had a small leak around the sump plug. It occurred to me after an oil change today that perhaps this one isn't standard. Can anyone confirm if this is original or from a plumber's merchant? Many thanks.

Angus

[Philk]

Definitely different to that on my 3.8.... Also, if you zoom in on your photo, you can see the screw thread on the inside of the hole (which is what my design screws into)

[tinworm]

That looks like a taper BSP plumbing fitting Angus. The correct plug has a washer to seal on the external face as pictured.

Barrie

[Series 1]

Phil, thank you so much for the photo and Barrie, I agree with your plumbing assessment. I’m rather embarrassed that it’s taken me so many years to spot, especially after the amount of work I’ve done on the car (which might not be a good sign!). On the plus side, no more oil on the garage floor.

Thanks again

Angus

[mtnjag]

If it's a BSPT use some liquid Permatex Thread Sealant with Teflon or some Teflon tape (high Temp variety) and it should stop the leak if the plug is a decent fit and you don't want to start tapping out to a proper size.

You can also get a BSPT plug with a hex head that will look better if that matters to you.

You may be able to tap it back to a BSPP, not sure but I think the thread count is close but the thread angle is off. Use some grease on the tap and flood back with oil from the top. Shavings.

Of course best is to pull the pan and use a nice insert.

[abowie]

https://www.sngbarratt.com/English/#/UK ... %20plug%60

The thread is UNF so not tapered.

There should be a copper or fibre washer under the head.

[mtnjag]

OK, agree it started life as UNF but that looks like a tapered pipe plug.
Easy to tell, if it has a shoulder and washer a straight thread probably still UNF. If no shoulder-pipe.
Can't see it quite good enough but those lugs are usually pipe plugs and I was thinking he will have to correct that if he wishes to get back to go. Or dope it and stay with the plug.

[Series 1]

Thank you for the input. I don’t think it is tapered but will have to now check. I was going for the SNG brass replacement but saw the magnetic sump plugs by ‘Gold Plug’. These are stainless so I’m not sure if any galvanic corrosion would be likely. Alternatively I see that Speedograph do brass bodied plugs with a magnetic insert. They don’t list 5/8 UNF but say they can manufacture any size.
Or perhaps I’m getting a bit unnecessarily bogged down with this and should just go the Teflon tape route!
Thanks again guys.

Angus

[mtnjag]

If it’s still a good UNF thread and not previously stripped out, which happens, and buggered up by someone cramming a pipe plug in there then get the right sized proper plug with copper washer that fits well. No dope required.

It will take an oil drain to easily check the size and condition but you can do a quick switch with oil in the sump once you know the size without loosing much oil at all. (Oil cold of course)

If it is a pipe thread it becomes a little more complicated but may be NBD, depending on how you want to correct the condition.

I’d check it out. Gotta pull it anyway to dope it up.

BTW-if it is a Tapered Pipe plug be careful and don’t tighten it too much. The tapered thread gets larger as it is threaded in and can expand and crack the pan.You might clean the area well to make sure that has not happened.

[dlgis]

As stated it may have been fitted to replace the original where the sump thread was stripped out. I only know this because yesterday when doing a simple oil change for the first time since buying my car, we found the sump plug was only holding with some silicon assistance. We had to fit a larger plug having cut a new thread and a 2 min job took nearly 2 hours

[Series 1]

Just to finish up on this thread, I removed the plug and quickly found it was ½” BSPP (ie not tapered). An easy fix from Jewsons for £1.38 plus a copper washer and now a clean garage floor.
Many thanks to you all for taking the time to reply.

Angus

[mtnjag]

So the problem was what-Wrong sized plug, no copper washer?

[Series 1]

It was the correct sized ‘plug’ but BSP, ie non-standard. As it was a plug with not a bolt it simply screwed in until it was pushed against the baffle inside the sump and with no washer it leaked slightly. It bizarrely never occurred to me to question this. Now with a ½” BSP bolt I have a copper washer and no leak. I’m still feeling smug that I now have an oil free garage floor under a 58 year old car.

[Series1 Stu]

Half inch BSP is similar in dimensions to 7/8" UNF so you've probably got away with using the slightly smaller thread. Although I would change it for the correct item, but that's me.

No harm, no foul.

Regards

[mtnjag]

Whoa, wait a moment, oil free floor. something’s wrong.
Better check.
Harleys and Jags, if it ain’t leaking it’s out!

[Series 1]

It’s definitely got oil in it!

Series1 Stu, I’m with you regarding fitting the correct item and ½” BSP being close to 7/8” UNF is good info but I thought the correct size was originally 5/8” UNF? If you are correct perhaps my sump has not been messed with.

[mgcjag]

Hi....whats your name...please try to out it in the signature area with your car model...Sump plug 5/8 UNF....Steve

[Series1 Stu]

Maybe your plug is 3/8" BSP then, which, at 16.7mm, is a little bigger than 5/8" UNF at 15.9mm. It also has 19 tpi vs 18 tpi for 5/8 UNF.

1/2" BSP plug would be around 21mm outside diameter.

The picture you posted doesn't suggest to me there has been any modification to the casting to fit a bigger thread. I can't tell from the photo whether or not there is a threaded insert fitted.

Regards

[Series 1]

Hi Stuart, thank you that’s just the information I’ve been looking for. I’m most grateful.

Steve, apologies for the lack of details in my signature box. My name is however on posts #1, 4, 8 and 11 above and my photo has always shown my car.

Without trying too hard I have managed to out my name and car as requested. Apologies again for the omission.

Kind regards

Angus

[Allrand]

Wow yours is near the end of the 3.8 run, what was the production date?