W126 Proud new owner, found and oil leak..

[Classic_car]

Hi,

1st post, so I hope I've started this thread in the right place?

I have recently bought a very smart 300se with the m103 6cyl engine and I am delighted with the car, it drives very well and seems like a good example.

My only problem is i've started to notice the car is leaving a puddle of oil about the size of my palm after each journey. After checking the oil level I did a 70 mile journey yesterday, this morning I noticed the puddle and checked the dipstick again, it had lost about half a litre of oil.

I've been reading this forum and learn't that these engines do seem to sweat a bit and a common leak is at the front by the dizzy, mine had a slight leak there but not much. As far as I can see there is no head gasket leak at back, but the oil seems to drip from the rear of the engine. I cannot tell which side, but it seems to drip on to a cross-member under the car, about where the auto bell housing meets the engine, then on to the floor.

Any ideas what could be causing this? I am very worried it might be a rear engine seal and require removing the gearbox etc? Are my fears un-founded, or is this the most likely?

 

[Classic_car]

Update. Oil leak around Starter motor

Ok, I have had the car in the air today and given the engine a good clean underneath, it was covered in black oil.

There is a slight leak from the front, but the main oil leak, where it is actually dripping on to the floor appears to be coming from above where the Earth cable bolts to the engine, near what looks like the starter motor. Having cleaned the underside as much as I can, then gone for a 10 mile drive, it looks to me as if the oil is leaking from the gasket/join where the starter motor mates with the engine. Does this sound possible/plausible explanation for my engine leaving a palm sized oil stain on the garage floor each night?

If someone with knowledge of the M103 engine could advise me, I would be very grateful and I hope to contribute to the forum as I fix other things on the car.

Many thanks, Jack

 

[219]

My biggest worry , based on what you say , is that it might be the rear crankshaft oil seal ! If oil is leaking there , it would spray around inside the bellhousing and could well come out via the opening where the starter engages against the ring gear on the flywheel .

Sadly , this is quite a big job to fix , and may well be why an otherwise smart looking car came up for sale .

 

[iscaboy]

Yeah, almost definite rear crank seal.

Dead easy and quite cheap job, if the engine is sitting on a bench....

Back in 1986 I had to quote a guy the equivalent of £3,000 to change a 50p core plug.

The core plug was behind the injection pump, to remove the injection pump you had to remove the timing cover, and the front pulley.

To remove the front pulley you had to remove the engine.

To remove the engine you had to lift off the cockpit and steering gear.

He sold the boat in preference... to someone who hadn't identified and costed the problem. So some things never change.

 

[Classic_car]

Hmm, thanks for the replies. The real crank seal is my worst fear! I do most work on my cars myself, partly because I have no garage I 100% trust near me and partly because I enjoy working on old cars. But, removing the engine and gearbox is beyond what KI can do at home, so would be a garage job and big ££££ :-(

May be that was why it was for sale, makes sense.

Does the starter motor gasket not sound worth doing? Could it be that, before I spend £££? The leak does seem to be from there as far as I can tell? I would thing if it was the rear seal it would leak at the very bottom of the bell housing, rather than over halfway up?

Cheer for the help, just need to know what i'm in for before I visit the garage, I guess :-(

Jack

 

[219]

The starter motor just bolts into a hole in the flange of the bellhousing - there is / should not be any oil on the other side (unless something is wrong) as it just pokes through to where the flywheel/clutch or torque converter should be - in either case what 'should' be a perfectly dry area - so , no the gasket ( I have never seen one here ) would not make any difference .

 

[johnsco]

I agree.
I've never seen a gasket between a starter motor mounting flange and the bell-housing.
I'm sorry to say that crank-shaft rear oil seal sounds likely.

BUT

Have a look a bit farther up.
If the rear of the valve cover gasket is leaking, the oil would drip down in more-or-less the same place.
These gaskets do harden and crack with time, and this is a possibility.

Oil leaking from the top of the engine can still only run downwards.

 

[Classic_car]

Thanks Johnsco, I will check the valve cover gasket tomorrow. I've got some "Forte Leak Conditioner" to go in, hoping that might sort the rear seal temporarily, whilst I find a suitable garage to check it over.

I did a quick oil change on the car today and the oil pressure is now up too almost 2 at hot idle, which seems pretty good. I used Mobil S SemiSyn 10-40 and the car is even smoother and quieter now. The m103 seems a nice engine to work on, the oil filter was very easy to access. Noticed there was a very slight petrol leak, where the fuel lines join the rubber hose near the oil filter, at the false bulkhead. Just tightened the union and it's stopped now, but would suggest anyone reading this have a look at there's also.

Next job is clearing all the leaves + debris that seems to have collected beneath the battery tray and replacing the old looking leads and dizzy cap/rotor.

Jack

 

[johnsco]

The W126 is a nice car to work on in so many ways.
I loved ours and was really sad to let it go.
The build quality on these cars was magnificent.

If you are going to replace parts like rotor arms, buy the genuine MB parts.
I bought some from Euro Car Parts and they were very poor.
It's worth paying the extra.

We had the same problem with leaves and other debris under the battery tray.
It turned out to be pretty-corroded when I removed it to clean there.

Good Luck with your new car.
I hope you get your little problems sorted without too much heart-ache (or wallet-ache)

 

[Scott_F]

If you do remove the battery to clear debris from the tray area don't leave your keys in the ignition like I did. The central locking kicked in and locked all the doors and I didn't have a spare set. A replacement key took nearly a week to arrive from Germany !

It can be surprising how much rubbish you find in that area and it's a job worth doing regularly.

 

[126-valeter]

i have the same problem with a oil leak not as much a your slef classic car as the oil level never realy seems to go down much been told it coud be head gasket theres no water mixing with the oil but i have see that in the header tank a bit of gunk ive alls been told this coud be the antifreze sweating coud this be true

 

[Classic_car]

Problem Solved - Thanks to the forum!

Thanks to Johnsco the problem of my oil leak was the rear of the valve cover gasket was leaking. I had to get the engine really clean to prove it, but I am delighted it was a simple fix that I was able to do myself. Glad I joined the forum!

I got the battery tray out and there was quite a lot of crispy dry leaves underneath. The same underneath the brake booster, although that was hard to get to and removed a good bit of skin from my knuckles! Glad I did this before disaster struck though.

 

[Classic_car]

i have the same problem with a oil leak not as much a your slef classic car as the oil level never realy seems to go down much been told it coud be head gasket theres no water mixing with the oil but i have see that in the header tank a bit of gunk ive alls been told this coud be the antifreze sweating coud this be true

Hi 126-Valeter. To be honest I have not heard of anti-freeze sweating, that is new to me. If you put a finger in the header tank, when cold and the anti-freeze feels slippy, then it is probably mixing with the oil and you have a headgasket failure. Hope that helps, Jack

 

[corned]

That's quite a result, given the way this seemed to be shaping up! I bet you are hugely relieved.

Well done, and I hope your W126 motoring days continue in an uneventful way.

Thanks for the update.

 

[Classic_car]

That's quite a result, given the way this seemed to be shaping up! I bet you are hugely relieved.

Well done, and I hope your W126 motoring days continue in an uneventful way.

Thanks for the update.

Hi Corned,

Thanks, I am, as you said, Uber relieved! It's not nice to have to spend big ££££ when you have just bought a car, unless, you were aware before purchase, that such major work needed doing. I am very pleased, I joined the forum here, it seems very friendly and as someone who in in-experienced in fourms, that means a lot.

As a novice home mechanic, I certainly would have had the engine out to do the rear seal if I had not had the advice I got here.

For what it's worth.. I've had quite a few motors over the years and I am really coming round to respect the W126 more each day. It's may be a bit of a slow burner emotionly, but the more I do long trips in it, the more I notice how much better it accomplishes them, in comparison to previous cars I have had.

Jack

 

[126-valeter]

ok i know this is goign to sound very daft but if the oil is ever so slighty mixing with the water ie a very tiny seep woud radweld sort ito ut or woud the head have to be taken of if so what sort of cost woud that be

 

[Classic_car]

ok i know this is goign to sound very daft but if the oil is ever so slighty mixing with the water ie a very tiny seep woud radweld sort ito ut or woud the head have to be taken of if so what sort of cost woud that be

Radweld is certainly not the answer if you have oil and water mixing, it is designed as a cheap, temporary "fix" for a leaking radiator, not headgasket issues. The headgasket replacement I would imagine is likely to be £400+, but really depends where you go, best to phone round a few people.

 

[126-valeter]

i knew it was a stupid question to ask any way but heard it from the guy down the road to get some radweld. if it is the head gasket then its been the same for mounths and mounths and mounths and nohting has changed temp is fine nothing at all in the oil but will ask where i work to see what it woud cost woud it be a good idea to drain the tank and radiator re fill and see what rate it is if it has a very slight leak or if its just gunk travling round the tank

 

[Classic_car]

i knew it was a stupid question to ask any way but heard it from the guy down the road to get some radweld. if it is the head gasket then its been the same for mounths and mounths and mounths and nohting has changed temp is fine nothing at all in the oil but will ask where i work to see what it woud cost woud it be a good idea to drain the tank and radiator re fill and see what rate it is if it has a very slight leak or if its just gunk travling round the tank

I've read on here that sometimes the m103 engines can have a slight headgasket leak around the no6 cylinder at the back and run for ages without any real difficulties. There is a great guide to doing a m103 headgasket on here, in the "how to" section, if you feel like having a go yourself.

It's certainly a very good idea to drain and replace the coolant anyway if it is at all gunky. Just remember not to use the cheaper green coolant in these engines, you need the proper MB stuff or at least the RED coolant that they sell in Halfords.

Jack

 

[219]

It is more usual for water to go into the oil than the other way round ( due to the water being at higher pressure ) . Of course if the leak is from the edge of a cylinder to a water channel then combustion gases and a small amount of oil may be forced into the water , but I'd expect that type of leak to get worse fairly quickly .

Another possibility is that it is residue left behind after a previous repair .