Gearbox Oil Leak - 'Suspected Flywheel Bolts'

[Oli3000]

Hi All,

At recent dealer service for my Mk 3.5 Leon 1.4tsi ACT @ 75000 they commented that there was a gearbox oil leak, and commented they suspected it was 'leaking flywheel bolts'.

I did not action it for the £1100 they were asking at that time and chose to investigate it a bit first as I had to do some brake work, anyway.

Looking underneath there is what I would call a 'smear' of oil between the gearbox and engine. (N.B. ignore the bigger patch in the background which was me making a mess of the brake fluid). Picture below.

My plan is to monitor and see, and hope that it can limp through to needing a new clutch (albeit that could be in a while).

Has anyone any experience or comments about this? I did have a quick look online and saw that a revised flywheel bolt part number is now sold, so presume that this is relatively common...

Any help appreciated.

 

[Guyelle]

Interesting, sounds plausible but it's not something I've heard before. Have you noticed excess loss of engine oil at any point? I'm assuming £1100 includes the clutch replacement while they're in there, otherwise that's very steep for just replacing flywheel bolts!

The oil is likely to be contaminating the clutch currently, so it'll likely wear the clutch out faster.

 

[Big Vinny]

It sounds more like a defective flywheel oil seal. I had it on a manual Renault Scenic it leaked engine oil from the engine/gearbox union and drove like an automatic with rising and falling revs as there was oil on the clutch plates.

 

[Oli3000]

Thanks both.
Follow-on questions that you’ve made me think of:

If the gearbox is losing oil, is there a way to check gearbox oil level and/or top-it-up?

I suppose if the oil is wearing out the clutch faster is a moot point - it may as well be replaced if the gearbox has to come off anyway?

Have not noticed any drop in oil between services at oil - but I will monitor closely.

I assumed £1100 included a new clutch - as they always quote for the most expensive thing and then if it’s less charge that. But I didn’t question it closely as I was in a hurry at that time.

Attached picture from the report to confirm their wording!

 

[Big Vinny]

The gearbox oil level is checked on the level by removing the fill bolt then filling with oil until it overflows through the same bolt hole. Gearbox oil typically is 80/90 viscosity which is much thicker (viscous) than engine oil and can be easily identified. I have never found the fill bolt on any VW Group car easy to access and usually requires a home made funnel and filler tube arrangement pushed into the bolt hole.

 

[bahyr]

Flywheel bolts, yes sure . Oil leak hire at 99% of the cases came from the crank shaft seal. This leak can not wear faster the clutch but at some later point can cause it to slip. To see exactly from where is the leak (and fixing) the gear box must be separate it from the engine.

 

[Guyelle]

If oil is leaking from the flywheel, rear main seal or whatever it'll be engine oil, not gearbox oil. It is unlikely to be gearbox oil leaking in that location. And yeah, always replace clutch whilst gearbox is removed, might as well...

 

[SuperV8]

Hi All,

At recent dealer service for my Mk 3.5 Leon 1.4tsi ACT @ 75000 they commented that there was a gearbox oil leak, and commented they suspected it was 'leaking flywheel bolts'.

I did not action it for the £1100 they were asking at that time and chose to investigate it a bit first as I had to do some brake work, anyway.

Looking underneath there is what I would call a 'smear' of oil between the gearbox and engine. (N.B. ignore the bigger patch in the background which was me making a mess of the brake fluid). Picture below.

My plan is to monitor and see, and hope that it can limp through to needing a new clutch (albeit that could be in a while).

Has anyone any experience or comments about this? I did have a quick look online and saw that a revised flywheel bolt part number is now sold, so presume that this is relatively common...

Any help appreciated.

View attachment 38063

I think its possible.
The crank main bearing caps are fed with pressurised engine oil. There is a main cap directly next to the flywheel mounting flange (on the right) - and unusually - VAG use a large crank seal which seal's on the outside face of this flywheel mounting flange, meaning the back of these flywheel bolt holes can 'potentially' see some engine oil.
I can also see the flywheel bolt supersession & later bolts have much more thread lock/seal.

The later bolts do have much more thread lock

vs

 

[Seriously?]

This issue also known on VAG 2L diesels as fitted to T5/6 Transporters. I guess the fact that the crank flange has through holes and not blind ones doesn't help.

 

[Walone]

I think its possible.
The crank main bearing caps are fed with pressurised engine oil. There is a main cap directly next to the flywheel mounting flange (on the right) - and unusually - VAG use a large crank seal which seal's on the outside face of this flywheel mounting flange, meaning the back of these flywheel bolt holes can 'potentially' see some engine oil.
I can also see the flywheel bolt supersession & later bolts have much more thread lock/seal.

Usually the crank seal would seal on the small diameter meaning the flywheel mounting flange is 'outside' of the engine oil area and impossible for oil to leak out of bolts.

View attachment 38073

View attachment 38071

The later bolts do have much more thread lock
View attachment 38074
vs
View attachment 38075

Thanks for posting that, I had that in mind but didn't want to seem foolish if that wasn't the case! I looked at the workshop manuals and couldn't see the end of the crankshaft. One thing I did see was mention of never removing the crankshaft from the block, at least on the 1.4 engine, can't remember the reason for this, also lots of special tool mentioned for renewing the oil seal. Engines are too complicated these days!!

 

[SuperV8]

Thanks for posting that, I had that in mind but didn't want to seem foolish if that wasn't the case! I looked at the workshop manuals and couldn't see the end of the crankshaft. One thing I did see was mention of never removing the crankshaft from the block, at least on the 1.4 engine, can't remember the reason for this, also lots of special tool mentioned for renewing the oil seal. Engines are too complicated these days!!

Much easier when they used to use rope rear main oil seals
The 1.4 (and guessing all EA211 variants) doesn't list a part number for the crank - so any issues there and its a new engine! Gone are they days of polishing and re-grinding cranks!

 

[Walone]

Much easier when they used to use rope rear main oil seals
The 1.4 (and guessing all EA211 variants) doesn't list a part number for the crank - so any issues there and its a new engine! Gone are they days of polishing and re-grinding cranks!

I remember on my Mk1 Lotus Cortina the crankshaft oil seal (rope type), oil would seep out, especially if parked facing up a steep hill.
I eventually fiitted a Mk2 cylinder block which had a 'conventional' circular oil seal, no problems after that

 

[LeylandVCDS]

I remember on my Mk1 Lotus Cortina the crankshaft oil seal (rope type), oil would seep out, especially if parked facing up a steep hill.
I eventually fiitted a Mk2 cylinder block which had a 'conventional' circular oil seal, no problems after that

The way the prices have gone, I bet you wish you still had that Lotus Cortina now

 

[Walone]

The way the prices have gone, I bet you wish you still had that Lotus Cortina now

Too true!! Amazingly it's still around! Here it is pictured in a forest somewhere in Poland around 1970, with my ex brother-in-law.