1963 Mercedes Benz 190DC Fintail. New fuel tank and leaks.

[jim89]

8 hours ago, lisbon_road said:

Many years ago, I fitted a new tank to a Sierra. I did not realise that the inside was bare steel. It rusted horribly. If I did it again, I would use a tank sealant on it. Kind of counter intuitive to use on a new tank, but the steel is so clean tgag it should stick.

Your experience might be different but I have to share mine.

Is it necessarily going to be "that clean" though?

I'm wondering if there could be traces of lubricant from the pressing of the shaped "halves" that have also been (presumably) welded together?

Hopefully it's flushed with something at the factory to remove "bits" & the worst but whether that could be classed clean enough to paint straight onto ? I dunno...

[Dyslexic Viking]

9 hours ago, lisbon_road said:

Many years ago, I fitted a new tank to a Sierra. I did not realise that the inside was bare steel. It rusted horribly. If I did it again, I would use a tank sealant on it. Kind of counter intuitive to use on a new tank, but the steel is so clean tgag it should stick.

Your experience might be different but I have to share mine.

I've been thinking about painting the outside and rust-proofing it well, but I hadn't thought about the inside, so a massive thank you for that.

That's something that needs to be investigated when the fuel tank arrives.

[Dyslexic Viking]

1 hour ago, jim89 said:

Is it necessarily going to be "that clean" though?

I'm wondering if there could be traces of lubricant from the pressing of the shaped "halves" that have also been (presumably) welded together?

Hopefully it's flushed with something at the factory to remove "bits" & the worst but whether that could be classed clean enough to paint straight onto ? I dunno...

Maybe flush the tank with petrol? That should remove any kind of lubricants if there is any I would think?

[Dyslexic Viking]

9 hours ago, hairnet said:

what later mercs does the tank fit

thats why they have them

Only fits Fintails as far as I know.

[jim89]

7 minutes ago, Dyslexic Viking said:

Maybe flush the tank with petrol? That should remove any kind of lubricants if there is any I would think?

I guess so yes.

Assuming yours has a leak on the horizontal seam, could it be corrosion has got at it from the outside in, rather than the inside out ?

Edit:- just read your post re painting & treating exterior! 😆

[Scruffy Bodger]

18 hours ago, Dyslexic Viking said:

New fuel tank was sent yesterday, can't get over that a regular car part site has a fuel tank for this one that's incredible. 

And looked more under the car and it's not leaking now that it's about half a tank so that's good, what's not good is that the entire rear underside of the car is covered in diesel and this has loosened the underseal and made a mess. I haven't quite figured out how to clean it yet, but I think it will be a lot of work. 

 

Diesel is a great rust preventer so I wouldn't worry about it too much. When I was a kid my old man ran end of life Mk2 Escort vans. He was given one as spares for another but as there was still MOT and tax on it he ran it for a bit. The passenger seat I was sat on was sat on blocks of wood and barely attached to the floor, I remember seeing the tarmac going by underneath where I was sat. The thing stank of diesel and had obviously had plenty of it spilt in the back over time, the rear bed was absolutely fine!

See also oily rag tractors or ones that have had diesel spilt and never cleaned off by the filler neck, the metal near there will be fine even if the mud guards have evaporated.

[Dyslexic Viking]

Used the car a little today and looked under it and there's still no diesel leaking now that the tank is low. But the axle seal on the right rear wheel has started to leak and oil is now dripping out of the brake drum. The leak in front on the differential also seems to have gotten worse.

And I've now got a big oil leak in the engine that has created this mess.

 

So with all these new leaks and the fuel tank gone bad the decision has now been made that I will stop driving this for a while.

[lisbon_road]

1 hour ago, Dyslexic Viking said:

Used the car a little today and looked under it and there's still no diesel leaking now that the tank is low. But the axle seal on the right rear wheel has started to leak and oil is now dripping out of the brake drum. The leak in front on the differential also seems to have gotten worse.

And I've now got a big oil leak in the engine that has created this mess.

 

So with all these new leaks and the fuel tank gone bad the decision has now been made that I will stop driving this for a while.

Sad but we know you will fix it. Interesting from @Scruffy Bodgerabout diesel and lack of corrosion. Ok unless you leave it empty but perhaps it is never really empty.

[Dyslexic Viking]

1 hour ago, lisbon_road said:

Sad but we know you will fix it. Interesting from @Scruffy Bodgerabout diesel and lack of corrosion. Ok unless you leave it empty but perhaps it is never really empty.

Yes I will fix it and I have to so it will be done. It's just a bit of a bad time that all this is happening now when I've already stretched myself a bit financially with that fuel tank and there's a lot going on that has higher priority so it will be a while before I get everything fixed. It's also Mot time this fall and this needs to be fixed before that or the car put on sorn so I already feel a little pressure from that and this last doesn't help.

[lisbon_road]

1 hour ago, Dyslexic Viking said:

Yes I will fix it and I have to so it will be done. It's just a bit of a bad time that all this is happening now when I've already stretched myself a bit financially with that fuel tank and there's a lot going on that has higher priority so it will be a while before I get everything fixed. It's also Mot time this fall and this needs to be fixed before that or the car put on sorn so I already feel a little pressure from that and this last doesn't help.

You have a good attitude I think. Sometimes the old cars are put in the garage when there is more important things to do, but when you are clear of them, it will still be there.

Appreciate your updates. 

[bigstraight6]

Keep the faith Viking, these old cars can test us but the joy of driving them outweighs this.

[bigstraight6]

It’s always worth the effort as it was for me last weekend to wake up the old car after the winter layup👍

[hairnet]

is there a schaefft in your part of norge?

winnah

[Scruffy Bodger]

6 hours ago, Dyslexic Viking said:

Used the car a little today and looked under it and there's still no diesel leaking now that the tank is low. But the axle seal on the right rear wheel has started to leak and oil is now dripping out of the brake drum. The leak in front on the differential also seems to have gotten worse.

And I've now got a big oil leak in the engine that has created this mess.

 

So with all these new leaks and the fuel tank gone bad the decision has now been made that I will stop driving this for a while.

Just keep it topped up and enjoy it? How much is that if you poured it onto it?

[Dyslexic Viking]

7 hours ago, Scruffy Bodger said:

Just keep it topped up and enjoy it? How much is that if you poured it onto it?

I can until mot time  except for the axle seal I don't want to have oil leaking into the brakes and the brake shoes on these are specialist items so expensive and there is a good set at the back of this one now and I don't want to ruin them.

So the fuel tank and that axle seal are what are preventing the car from being driven now.

[Dyslexic Viking]

Had a look on the car and in the books I have for it. And changing the axle seal is a pain in the backside since Mercedes, it involves disassembling the brakes completely, special pullers and tools and there are different threads some left and some right depending on the side and more and this is too much for me I also want to get the wheel bearings done at the same time. Wish this was a little more agricultural and simpler made at times. But a little interesting the rear wheel bearings do not go in oil but are lubricated with grease.

Large oil leak in front is located and it is the steering box, most of the steering components are wet with oil and dripping. New steering boxes are no longer available, so the one on the car must be taken off and new seals be installed.

[Surface Rust]

6 hours ago, Dyslexic Viking said:

 

Large oil leak in front is located and it is the steering box, most of the steering components are wet with oil and dripping. New steering boxes are no longer available, so the one on the car must be taken off and new seals be installed.

Rover P4 steering boxes also develop leaks like this and mine was no exception. The P4 drivers club recommended this stuff as a replacement for the oil:

https://www.classic-spares.com/product/penrite-steering-box-lube-500ml/?gQT=1

It's a non-setting semi fluid grease that won't leak. As it was a lot easier than a box rebuild I bunged it in and never had any more problems. That was 12 years ago. I took the fill plug off a few years ago and the grease was still semi fluid so it seems to work long term.

[Dyslexic Viking]

1 hour ago, Surface Rust said:

Rover P4 steering boxes also develop leaks like this and mine was no exception. The P4 drivers club recommended this stuff as a replacement for the oil:

https://www.classic-spares.com/product/penrite-steering-box-lube-500ml/?gQT=1

It's a non-setting semi fluid grease that won't leak. As it was a lot easier than a box rebuild I bunged it in and never had any more problems. That was 12 years ago. I took the fill plug off a few years ago and the grease was still semi fluid so it seems to work long term.

Thanks, I will definitely try that.

[bigstraight6]

9 hours ago, Dyslexic Viking said:

Had a look on the car and in the books I have for it. And changing the axle seal is a pain in the backside since Mercedes, it involves disassembling the brakes completely, special pullers and tools and there are different threads some left and some right depending on the side and more and this is too much for me I also want to get the wheel bearings done at the same time. Wish this was a little more agricultural and simpler made at times. But a little interesting the rear wheel bearings do not go in oil but are lubricated with grease.

Large oil leak in front is located and it is the steering box, most of the steering components are wet with oil and dripping. New steering boxes are no longer available, so the one on the car must be taken off and new seals be installed.

Are the rear axle seals on the Mercedes similar to my Zodiac, where you need a special puller tool to attach them from inside the axle tube with the diff removed? I overcame the problem with a sealant on the end of the halfshafts instead of just the paper gaskets which stopped the leakage of diff oil, worth a try….

[lesapandre]

I'd also check the weight of the diff- oil. Something heavier might stem this. See what the service book says and what's available. Modern oils don't sometimes suit.

[Dyslexic Viking]

38 minutes ago, bigstraight6 said:

Are the rear axle seals on the Mercedes similar to my Zodiac, where you need a special puller tool to attach them from inside the axle tube with the diff removed? I overcame the problem with a sealant on the end of the halfshafts instead of just the paper gaskets which stopped the leakage of diff oil, worth a try….

Fortunately it's not that bad. The axle seals and there are 3 are accessible from the outside towards the brake.

Here are some drawings from a book I have.

 

Description of this and drawing of the Mercedes original extractor and this continues for one or two more pages.

[Dyslexic Viking]

3 minutes ago, lesapandre said:

I'd also check the weight of the diff- oil. Something heavier might stem this. See what the service book says and what's available. Modern oils don't sometimes suit.

There is 90 weight gear oil in it now as the cars manual states.

[lesapandre]

4 minutes ago, Dyslexic Viking said:

There is pure 90 weight gear oil in it now as the cars manual states.

That sounds right - you could go up to a 110 or 140 - but I'm no oil technologist.

Some of these modern EP's have additives like sulphur that can play havoc with old components. See what's on offer.

I use non-EP in the gearbox of my 1980 Landcruiser  - EP additives are bad for it's bronze parts. 

[Dyslexic Viking]

3 minutes ago, lesapandre said:

That sounds right - you could go up to a 110 or 140 - but I'm no oil technologist.

Some of these modern EP's have additives like sulphur that can play havoc with old components. See what's on offer.

I use non-EP in the gearbox of my 1980 Landcruiser  - EP additives are bad for it's bronze parts. 

I'm not sure if I dare use anything thicker than what the manual says because this oil is already quite thick.

And this is what is in the Mercedes now. 

[rusty_vw_man]

Saw this out today and thought of this thread 

don’t know my mercy so no idea how similar it is to yours! They’d done a lot of work on it, not sure the stanced look suits it, but I’d drive it!! 

[Dyslexic Viking]

15 minutes ago, rusty_vw_man said:

don’t know my mercy so no idea how similar it is to yours! They’d done a lot of work on it, not sure the stanced look suits it, but I’d drive it!! 

This is a W111 so it is almost the same car as my W110 only the W111 has a longer front end to fit the 6 cylinder engine and different headlights.

But can't say I like the modifications they've done to it would have been much nicer if kept original.

[hairnet]

On 01/05/2025 at 18:24, Dyslexic Viking said:

Thanks, I will definitely try that.

@PhilA is this the corn head grease i asked you about that time

viking sounds like the same stuff described up there

[High Jetter]

2 hours ago, rusty_vw_man said:

Saw this out today and thought of this thread 

don’t know my mercy so no idea how similar it is to yours! They’d done a lot of work on it, not sure the stanced look suits it, but I’d drive it!! 

I'm not much into Mercs, but like big old 600's. Whoever dropped that should be shot.

[Dyslexic Viking]

The new fuel tank will arrive on Thursday so that's good, another good thing is that Mercedes thought when they made these cars so the tank level sender is accessible through the floor.

 

So since it can be replaced without removing the fuel tank, I can reuse the old one and save about 300 euros plus VAT and shipping on a new one. But that's as long as the old one doesn't look like it came off the Titanic.

So I have started removing the old fuel tank and it's something that could have taken about half an hour, it's that simple, but the trailer hitch uses the same rear bolts as the fuel tank so that has to come off before the fuel tank can. And of course, the trailer hitch has a bolt that is impossible to get to as a weld is in the way and needs to be sanded down, which will the  project in the next few days.

[PhilA]

19 hours ago, hairnet said:

@PhilA is this the corn head grease i asked you about that time

viking sounds like the same stuff described up there

Same concept, different manufacturer.