Engine slight oil leak through bellhousing 1.2TSI 16V

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RUM4MO
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Engine slight oil leak through bellhousing 1.2TSI 16V

Post by RUM4MO »

Has anyone heard anything about the possibility of the flywheel securing bolts slackening off leading to a slight engine oil leak between engine and gearbox, this so far seems only to be a 1.2TSI 16V engine issue, which VW have been taking care of under warranty?

This tale comes not from a fellow Polo owner, but someone on the Skoda Fabia forum, as he was just happily topping up the engine oil as he thought it was slight and acceptable oil usage - until an alert Skoda Tech spotted oil leaking out from between the engine and gearbox, so reported it and removed the gearbox and replaced all the flywheel to crank shaft bolts and told him it had been recorded happening on mainly Polos with that engine!

Edit:- I wonder if this is to blame for some of the clunking that some people have reported with increasing miles/age?
veteran
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Re: Engine slight oil leak through bellhousing 1.2TSI 16V

Post by veteran »

Hmm, interesting, particularly as I've hitherto mentioned in a PM, RUM4MO, that when I changed the engine oil on my 1.2 TSI Match Edition in July I noticed a few droplets of what could have been engine oil around the frontside gasketing of engine and gearbox. I assumed that this had happened because, at handover, the engine had been overfilled with its oil by some idiot, with consequently a high possibility that the excess would blow past the primary seal and contaminate the clutch. Certainly, that's what the dipstick had indicated. Any oil of reasonable quantity finding its way past that seal would therefore probably end up pooling on the bottom of the bell housing and in time leaking past the engine-to-gearbox gasketing (probably more of a partial plate than a gasket). Oil contamination of the clutch could account for a 'clunck' I regularly hear when changing gear at low revs, and also for a forward jolting of the vehicle when first firing the engine up. I've not, however, noticed any oil drips under or around the car since first spotting the minimal leakage of presumed engine oil, and also after having fixed a different and most definite leak coming from the gearbox drainplug, ie. leaking on the ground/floor when the car's been parked or garaged, nor have I noticed any diminution in the level of oil in the sump. Mind you, I probably don't cover sufficient miles per unit time for that to become obvious. I've heard nothing from the VW dealer, so as far as I'm aware there's been no official recall on Polo 6C 1.2 16v's in respect of this. Perhaps this has only affected certain production runs?

Somewhere in these forums I read recently of a VW website where you can type in your VIN no. and it'll list all recalls for that specific vehicle since the vehicle's release into the marketplace. Perhaps I need to search for that site and give it a whirl?
RUM4MO
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Re: Engine slight oil leak through bellhousing 1.2TSI 16V

Post by RUM4MO »

I thought that it would be better to throw this out into the open as a opening posting to a new thread as that way everyone had a chance to see it - rather than just PM’ng you.
Now, this Fabia owner said that, at least in his case, there was no contamination of any part of the clutch assembly, so I’d guess it was refitted after replacing all the flywheel to crank shaft bolts, this would have been a recognised workshop “recovery action” for this exact warranty issue, so entirely dictated by VW UK.
You mention “recalls” listings, these recall listings will never include this sort of thing I’m guessing - they would only cover safety recalls and recalls that if ignored would cost VW Group lots of money later on during warranty.
I’d think that this problem, will only “show up during warranty period” on a few cars, the rest will either never suffer this problem or will only suffer it outside warranty when VW Group can either raise 2 fingers or charge a good chunk of money for repairing that car.
I’d think that if we did manage to have access to all the possible potential failures being discovered during warranty and shortly afterwards, all car manufacturers would have very busy workshops and we would not have to pay for these design/build errors!
Edit:- now if this is flywheel fixing bolts or the small screws/bolts for the crankshaft rear seal retainer, I don’t know, but it does sound more probably the oil seal retainer plate retaining bolts in my eyes, which would tie in with the answer to my question to that Fabia owner, which was “did this cause any other clunking issues?” the answer was “no other issues at all - any clunking that was apparent has come back again”!
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Re: Engine slight oil leak through bellhousing 1.2TSI 16V

Post by veteran »

I think you'll agree that flywheel bolts are normally torqued very tightly and that their threads are often also coated with a hard-setting sealant to prevent them from easily becoming undone. Thus, if the flywheel bolts on that Fabia (and possibly also on some VWs) really had loosened then surely it would have pointed to a rare assembly issue, affecting just a relative handful of the vehicles?

I see what you mean by VW dealerships not considering this being serious enough - if indeed it's found to be at all widespread - to warrant recalls. So, it might well be 'an issue', one that causes annoyance and possibly problems to some owners, but for which dealerships will not voluntarily recall these vehicles. If the leakage were to become worse, then I guess it would be up to the owner to complain about it to the dealership and request it be investigated and rectified.

As I've stated, in my case, the amount of oil found weeping from the engine-to-gearbox joint has, thus far, been very minimal. Most workshop personnel would, I'm sure, have missed it, and it was only because I'd previously had to remedy a true gearbox leakage and therefore now always check the gearbox casing and its interface with the engine whenever I'm under the car that I myself was eagle-eyed enough to spot it. Another possibility of course is that, during factory fitting of the gearbox into the vehicle, some clutch fluid escaped from the slave cylinder (mounted on the end-top of the bellhousing) and ended up on the primary shaft and then got flung around the interior of the housing, finally pooling at the bottom. As you'll know, on the 6C Polo it's not easy to distinguish between gearbox oil, brake/clutch fluid, and engine oil when sampled in very small amounts (because all three have the same yellowy appearance).

I guess this is just yet another situation with this car where all I can, or should, reasonably do is to keep an eye on the matter, looking for further signs of this particular leakage whenever I get under the car and need to take off the front undertray. I think that if there is a genuine 'flywheel bolts' or 'seal-cover bolts' issue with mine it might not become obvious until the car's covered many more miles.

I do think, though, that the two external observations I made - namely, hearing the clunk and experiencing the momentary jolting forward of the car when firing up the engine (with of course the clutch depressed) - are indications that oil of some sort has contaminated one or more of the clutch components. Whether that's likely to get better in due course is perhaps a matter of conjecture.
RUM4MO
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Re: Engine slight oil leak through bellhousing 1.2TSI 16V

Post by RUM4MO »

I've still not checked for any forward short jolt when the engine is started on my wife's Polo, I'll try to remember to check for that today!

Of course, if I remember correctly there will never ever be any question about if you pressed the clutch before starting the engine, as I'm sure that modern cars can not be started without the clutch fully pressed down to the floor - so no one can suggest that is causing this issue - although it might have been helpful if it was possible to start with the pedal up - to compare behaviour!
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VictorAzzopardi
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Re: Engine slight oil leak through bellhousing 1.2TSI 16V

Post by VictorAzzopardi »

I had the same problem it looked like oil leak between the engine and gearbox bell housing but it came out that it was a camshaft oil seal. Oil was dripping over just between the engine and gearbox make it look like the gasket is leaking. there was a replacement of the oil seal and a small belt.
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