bearings

[carcar]

rebuilding 997 engine after cylinder liner failure at 19000 miles
having already found a number of things to change I have taken down the bottom end to replace the conrods from the cracked cap design.
can anyone explain this misalignment in 4 of the big end bearings??

[Pumaracing]

Well it's not exactly the puzzle of the century. Either the tang is in the wrong place on some of the bearings or the cutout is in the wrong place on some of the rods. You have the bits in front of you. Do some measuring!

[stevieturbo]

Why are you replacing the rods ? At least with a cracked cap, they are almost idiot proof in terms of mixing parts up.

[carcar]

didnt expect this level of engineering
this is the first time its been stripped from new

[stevieturbo]

carcar said:

didnt expect this level of engineering
this is the first time its been stripped from new

So that picture IS the cracked cap and installed correctly ? Weird.

[RKDE]

Doesn't look like the right cap on it, but then the photo is not that clear. The crack should almost be invisible when together

[carcar]

oh god
what do you think i did ,took em off and mixed them up ?
look at the wear line in the centre
they are as they came off,orientation everything,you cant mix up crack caps.
3 of them look like this and one isnt as bad
the reason for the post is to get an opinion why a car at this level or any car for that matter would be like this
remember this is stripped from new at 19000 miles

[crossle]

Pumaracing said:

Well it's not exactly the puzzle of the century. Either the tang is in the wrong place on some of the bearings or the cutout is in the wrong place on some of the rods. You have the bits in front of you. Do some measuring!

I'd be very interested to hear your views on stem seals and shimming David, so perhaps you could get in touch?

You have my contact details.

Many thanks

Paul

[stevieturbo]

carcar said:

oh god
what do you think i did ,took em off and mixed them up ?
look at the wear line in the centre
they are as they came off,orientation everything,you cant mix up crack caps.
3 of them look like this and one isnt as bad
the reason for the post is to get an opinion why a car at this level or any car for that matter would be like this
remember this is stripped from new at 19000 miles

Only answer is...havent a clue !

I know it's a longshot. But have you tried emailing Porsche ? It certainly isnt anything Ive ever seen in an engine before.
Or some Porsche rebuild places ? Even RUF etc ? You never know, you may get a response.

[carcar]

stevieturbo said:

Only answer is...havent a clue !

I know it's a longshot. But have you tried emailing Porsche ? It certainly isnt anything Ive ever seen in an engine before.
Or some Porsche rebuild places ? Even RUF etc ? You never know, you may get a response.

ok
porsche have had seven chances to step up to the plate over the cylinder liners
there response was that its not a problem that they recognise as only a very few engines have had a failures !!!
this finding however is another point which i would like to take up with them and my reason for putting these pics up on the forum is to get some input and maybe technical
explanations before i go down that route

[Mr2Mike]

I'd start within doing as Pumaracing suggested, get the verniers out and find out which bits have been made inaccurately.

[stevieturbo]

Are there any other Porsche resources you can contact who may have stripped similar engines ?
If yours is like this, surely others must be too ? As odd as it seems, maybe there is a reason ?

[virgil]

Is there anything to prevent the wrong cap being put on the wrong rod in the factory? Nothing is infallible...unlikelybyes, but not impossible...

[DrDeAtH]

i think you will find, that crack caps will not be able to be assembled to a rod other than the original, this is due to the unique way the joint faces separate. they will only match each other.

the pic does look like it could be a tang out of position.

[chormy]

Anyupdate !!