Any MOT inspectors here?

[Adam_W]

Seems to be a fairly common issue with cracks appearing near the rear subframe mounts on E46 BMW's

I have recently acquired an M3 and have found this:


IMG_5120 by Adam Woodford, on Flickr

IMG_5123 by Adam Woodford, on Flickr

Which I believe to be a crack in the floor pan near the left rear (rear) subframe mount.

My question is, is that an MOT fail?

[jagracer]

If it is a fracture, Yes.

[richie barry]

its an easy enough weld tho...

[Adam_W]

You can just weld that up?

BMW seem to replace sections of the floor when they repair it!

[richie barry]

its worth a try...

[McSam]

Adam_W said:

You can just weld that up?

BMW seem to replace sections of the floor when they repair it!

Well yeah, they would, wouldn't they! Welding is far too quick and easy and removes parts markup. It also requires skill, rather than a spanner monkey.

[disco!!!!]

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

[richie barry]

disco!!!! said:

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

why not just run a weld over it and not bother with the drilling?

[Billy_rfc]

A spray can of underseal will sort that right out

[Mr Happy]

richie barry said:

disco!!!! said:

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

why not just run a weld over it and not bother with the drilling?

The crack will continue to spread, if you drill the end, then you stop the crack progressing.

[E30M3SE]

If the M3 is less than 10 years old BMW should rectify this FOC.

[richie barry]

Mr Happy said:

richie barry said:

disco!!!! said:

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

why not just run a weld over it and not bother with the drilling?

The crack will continue to spread, if you drill the end, then you stop the crack progressing.

or you could weld a thin metal plate over it?

[carl_w]

What are the holes? Has someone already drilled a hole to stop the crack spreading?

[anonymous-user]

carl_w said:

What are the holes? Has someone already drilled a hole to stop the crack spreading?

They are bloody lousy shot with a drill bit if they have!

[Babu 01]

disco!!!! said:

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

It's actually a common failing and is often repaired free by BMW assuming the car is <10 years old and on OEM suspension etc.

And yes, that should be a fail as it is a "fractured rear subframe".

[Adam_W]

Yeah I was aware of the BMW free fix (if you are lucky) within 10 years, the car is an 02 with 120k but doesnt have OEM suspension, just bought it with a fresh MOT, taken it back to the dealer now for them to resolve this issue.

Edited by Adam_W on Saturday 17th December 17:27

[Mr Happy]

richie barry said:

Mr Happy said:

richie barry said:

disco!!!! said:

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

why not just run a weld over it and not bother with the drilling?

The crack will continue to spread, if you drill the end, then you stop the crack progressing.

or you could weld a thin metal plate over it?

That's more work, it's easier to drill a small hole at the end and then just weld along the length of the crack.

Also, tacking a plate over it and lashing it full of seam sealer is a bit of a bodge, all things considered. You should really fix the crack first.

[richie barry]

Mr Happy said:

richie barry said:

Mr Happy said:

richie barry said:

disco!!!! said:

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

why not just run a weld over it and not bother with the drilling?

The crack will continue to spread, if you drill the end, then you stop the crack progressing.

or you could weld a thin metal plate over it?

That's more work, it's easier to drill a small hole at the end and then just weld along the length of the crack.

Also, tacking a plate over it and lashing it full of seam sealer is a bit of a bodge, all things considered. You should really fix the crack first.

thats a good point..

[disco!!!!]

Babu 01 said:

disco!!!! said:

never head of this happening on the M3 has it lead a hard life
the easiest way to repair it would be to drill a hole at the end of the crack and run a weld over the course of the crack finishing at the drilled hole
so long as the weld is good then it will hold
you could always make a strengthening plate and weld it on top after the crack has been repaired but the M3 should have strengthening plates fitted

It's actually a common failing and is often repaired free by BMW assuming the car is <10 years old and on OEM suspension etc.

And yes, that should be a fail as it is a "fractured rear subframe".

i knew it was a problem on the early E46s and can be seen on thrashed E36s but its the first time ive seen it on an M3
bmw never issued a recall so it was down to the owner to fight with bmw to get it fixed
ones that hadnt cracked were filled with expanding foam to help strengthen the area

[Babu 01]

Adam_W said:

Yeah I was aware of the BMW free fix (if you are lucky) within 10 years, the car is an 02 with 120k but doesnt have OEM suspension, just bought it with a fresh MOT, taken it back to the dealer now for them to resolve this issue.

Edited by Adam_W on Saturday 17th December 17:27

Just seen your thread on Cutters. I think the advice about cracks continuing around any patches is sound. In your situation I would be after the expanding foam fix at the very least, if I chose to deal with this myself.

Personally I think a refund is in order given you asked the selling dealer specifically about this and was told that the car had no such problems.

If the dealer gets arsey then, was the MOT conducted recently and at a garage local to the seller? If so then a useful tool in your refund bargaining would be to mention that calls to VOSA for an inverted appeal (process to investigate a car which passed but should have failed) and to Trading Standards will have to be made.