Technical Sump drain plug leaking

[earthman]

Anyone experienced their drain plug leaking? There's a slight weep of oil coming from mine, despite it being tight/torqued up correctly, it's an aftermarket sump but the design is the same, using a washer less drain plug basically.
Apart from using some PTFE tape on the threads, any other ideas, what did you use to seal such a leak?

 

[koalar]

Use to be common on the puntos with third part plugs fitted at a service

I'd start by buying a OEM first, unless you still have your old one to try

 

[jrkitching]

Anyone experienced their drain plug leaking

Leaking as in coming out round the threads, or leaking as in the boss in the sump has failed?

We've seen a few that have failed because the boss has come loose, usually after overtightening, and there have also been problems reported with aftermarket plugs - some have the wrong taper and can be screwed right through and into the sump! There have been more than a few that have failed due to the sump rusting through; a common but avoidable problem.

I'd agree with the earlier post about using an OEM plug if you can get one. And don't overtighten it.

 

[earthman]

Use to be common on the puntos with third part plugs fitted at a service

I'd start by buying a OEM first, unless you still have your old one to try

Leaking as in coming out round the threads, or leaking as in the boss in the sump has failed?

We've seen a few that have failed because the boss has come loose, usually after overtightening, and there have also been problems reported with aftermarket plugs - some have the wrong taper and can be screwed right through and into the sump! There have been more than a few that have failed due to the sump rusting through; a common but avoidable problem.

I'd agree with the earlier post about using an OEM plug if you can get one. And don't overtighten it.

Why would a third party plug be fitted at a service for a start I'm wondering, why not refit the one they remove?
I did save the OEM plug off the old sump before that went to the tip but that's got a different thread to this aftermarket sump pan.

Hopefully it's not leaking from the boss, this sump pan is only a few month old, the OEM sump pan rusted out, this is an aftermarket one due to Fiat parts department wanting like £250 just for that part alone, the jokers.
It's been fine for months, only noticed a tiny park on the drive due to the car not moving for a week, quick inspection, pretty sure that it's coming from the thread,....I always like to torque everything up if I can so it's not been overtightened.

 

[koalar]

Why would a third party plug be fitted at a service for a start I'm wondering, why not refit the one they remove?
I did save the OEM plug off the old sump before that went to the tip but that's got a different thread to this aftermarket sump pan.

Hopefully it's not leaking from the boss, this sump pan is only a few month old, the OEM sump pan rusted out, this is an aftermarket one due to Fiat parts department wanting like £250 just for that part alone, the jokers.
It's been fine for months, only noticed a tiny park on the drive due to the car not moving for a week, quick inspection, pretty sure that it's coming from the thread,....I always like to torque everything up if I can so it's not been overtightened

A few will be genuine as it's not uncommon for the hex to get mullered by improper tool

Most will just be upselling in my opinion

 

[jrkitching]

Why would a third party plug be fitted at a service for a start I'm wondering, why not refit the one they remove?

I'd have refitted the one that I took out. You know that one fits.

I did save the OEM plug off the old sump before that went to the tip but that's got a different thread to this aftermarket sump pan.

In which case, it may not even have the same thread as an OEM sump. There's no guarantee an OEM one would fit an aftermarket sump, not is there any guarantee that an aftermarket plug not bought with the sump is going to fit, either.

 

[jrkitching]

this is an aftermarket one due to Fiat parts department wanting like £250 just for that part alone

Many OEM parts are crazy expensive, but generally they fit well.

Many aftermarket parts don't fit well at all, but they are at least affordable.

The problem is that if we only used OEM parts, repairing these cars once they get >10 yrs old would no longer be cost effective.

Tapered threads have to be quite accurately machined as they need to give a leakproof seal without a washer. With conventional sump plugs, a soft copper washer can make up for relatively crude manufacturing.

If you are sure it's leaking round the threads, a non-hardening sealing compound, used sparingly, is one possibility.

 

[Mike1alike]

A picture of the plug would tell us more.

 

[Mike1alike]

Can you tighten it a little bit more, by hand?
Being all oiled up, the torque differs from when it's dry. And the plug is usually a conical shape, little wider on the base. You can carefully tighten those by hand just enough to not leak. Isn't yours like that?

 

[The Panda Nut]

I use ptfe tape. I have always done it. It seems ro work and stops it being difficult to remove. Dont over do it. two turns and at the external end leaving the engine end uncovered. Make sure you remove the whole lot after each drain though!!!

 

[Pugglt Auld Jock]

Surprisingly perhaps, I've never had a problem with any of the Pandas we've owned or my boy's Punto leaking at the sump plug. Replaced the sump on 3 of them too with pattern parts bought from the local factor. One, for our old Mk1 panda, was poorly dimensioned and needed lots of sealant but it's plug was fine. I have however come across several which have been overtightened to such an extent that they needed a power bar to slacken - luckily never had the boss loosen in the sump either. So I'm not really the best person to answer this. However I am surprised to hear your plug is differently threaded to original equipment? I've heard of internet bought replacement plugs which are not taper formed and screw right through without sealing but never one with a different thread altogether. That would make a nonsense if later you needed to buy another plug for it. I don't doubt you're correct in what you say, just very puzzled by it. After my experience with the replacement I bought for our old Felicity, and the problems I had getting it to seal, I now avoid going for the cheapest option. If I needed one tomorrow, I'd be very tempted to buy from Shop4parts whom I trust to supply quality parts.

 

[Yolanda]

I renewed mine after buying the car due to deformation of the hex as mentioned above. I bought mine from ECP for a couple of quid, it may of had some kind of sealant on the thread, can't say for sure as it was about four years ago but it's been in and out three times since. I think the car has its original sump pan, I don't use a Torq wrench when refitting, never have with any car I've owned.

 

[Pugglt Auld Jock]

I renewed mine after buying the car due to deformation of the hex as mentioned above. I bought mine from ECP for a couple of quid, it may of had some kind of sealant on the thread, can't say for sure as it was about four years ago but it's been in and out three times since. I think the car has its original sump pan, I don't use a Torq wrench when refitting, never have with any car I've owned.

I don't use a torque wrench on taper sump plugs or steel sumps generally. However I do tend to use one on Ally sumps as I've seen quite a number with damaged and/or stripped threads. The earlier VAG ones were quite bad for it but I've noticed, for a number of years, that the threaded metal boss and plug itself is now longer - so more threads to engage with - and they are not so susceptible. I do worry though whether all the oil which invariably is impossible to remove from the threads, is detrimental to achieving a correct result. I've seen a number of very late models now with custom plastic drains, some aren't even a screwed fitting. Wonder if they will tend to snap when they get old?

There is one which is like a "flip" device which isn't removed from the sump. Been trying to find a video of it but can't remember what car it's on however here's a couple in use today:



and this one in the VAG stuff:

 

[Mike1alike]

And the plug is usually a conical shape, little wider on the base.

That is as stupid thing I said there. The plug is actually cylindrical, not wider at the base. I was told that misinformation once by a mechanic. I didn't really believed it as for the naked eye the plug looks cylindrical to me and I never put a measuring calipers to it. But as part of the plug remains outside I thought it might be true. It isn't!

What stops the plug for going further inside the pan actually is the boss, it has a blocking 'lip', plug coming in contact with it closes the space and keeps the oil in.
I took the pan down now as the oil pressure was low on idle and paid attention to the plug. This is how it looks like.
I am going to use ptfe tape from now on mostly on the tip of the plug because the rest remains outside. The tape will definitely do a good job in closing the spaces in the thread and there will be no need to extreme tighten the plug.

 

[jrkitching]

What stops the plug for going further inside the pan actually is the boss, it has a blocking 'lip', plug coming in contact with it closes the space and keeps the oil in.

That must be an aftermarket plug.

The OEM sump plug is tapered and has no lip. I know this because I've got two cars so equipped and have changed the oil in them many times.

Straight threaded plugs with a blocking lip seal on the lip; there should be a sump plug washer, usually copper, between the lip and the sump. It's considered good practice to replace the washer if the plug is removed.

Tapered plugs seal on the threads; there is no washer.

What I'm taking from this thread is that aftermarket sumps may use a different type of sump plug; you need to use whatever plug came with the sump you bought. Using an OEM plug in an aftermarket sump might not work.

Interestingly in the factory, the engine must be painted after the sump plug has been fitted, as on both my cars, there is a clear paint line at the point on the threaded part where the plug seals.

 

[Pugglt Auld Jock]

That is as stupid thing I said there. The plug is actually cylindrical, not wider at the base. I was told that misinformation once by a mechanic. I didn't really believed it as for the naked eye the plug looks cylindrical to me and I never put a measuring calipers to it. But as part of the plug remains outside I thought it might be true. It isn't!

What stops the plug for going further inside the pan actually is the boss, it has a blocking 'lip', plug coming in contact with it closes the space and keeps the oil in.
I took the pan down now as the oil pressure was low on idle and paid attention to the plug. This is how it looks like.
I am going to use ptfe tape from now on mostly on the tip of the plug because the rest remains outside. The tape will definitely do a good job in closing the spaces in the thread and there will be no need to extreme tighten the plug.

That's very interesting. I've never looked that closely at one. However I have seen some which screw further into the hole than others. The one on my boy's Punto was pretty much flush with the outside of the sump threads whereas our Panda has about two or maybe three threads proud. Just out of interest I'm going to measure the plug diameter top and bottom next time I have it out.

I remember reading someone's post a while back to the effect that the a replacement plug they'd bought just wound right through into the sump without tightening, whereas the old one did tighten. Which would seem to support the opinion that it's tapered?

Mind you, who cares as long as it keeps the oil in? Be careful what you do with the tape, you don't want any of it getting into the strainer. Others have made this observation too.

 

[Mike1alike]

That must be an aftermarket plug.

The OEM sump plug is tapered and has no lip. I know this because I've got two cars so equipped and have changed the oil in them many times.

Nope, it's the original plug. And the original sump, I just took it down now for the first time. The 'lip' I've mentioned is on the inside of the pan at the end of the thread as it goes from outside - inside. First looking at it I was under impression that there is something that prevents the plug from going more inside. Looking now again, I'm not so sure there is something, still kind of looks there is. I don't know if the plug is tapered, I will definitely put the measuring calipers on it tomorrow and see.
These are some new pictures I just took, as I still have the oil pan not on the car, I've painted it today.
Mine is Punto mk2, so if there are differences that might be the cause.

 

[Mike1alike]

Mind you, who cares as long as it keeps the oil in?

That's true. But I was curious. How is it made, how does it work?!

 

[Mike1alike]

Actually, untill getting to the calipers I tried this other thing as I have the pan here. I tried to put the plug from inside and it goes in. Went in a couple of threads without any problem. It means that yes, the plug is tapered, indeed.

 

[koalar]

Which engine

There's more than one type of sump plug fitted to the panda

A 1.1/1.2 uses a tapper plug

The original poster hasn't been online since Sep 11, 2025