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Bang after 102 days

infrasilver said:
Bank 1 you can fit them first then drop the conrod/piston unit into the bore but bank 2 it's not even possible to see the clip when fitting it so you have to do it blind through a 1 inch hole on the outside of the crankcase then you have a look afterwards with a tiny inspection mirror to see if you got it in.

Never having stripped a 996/boxer engine, why can't the complete piston/Conrod assembly be fitted in one go? Surely there is a way to insert them without having to assemble the piston/rod in situ? :what:
 
You have to fit the con-rods to the crank 1st and then the cases are fitted together. You must use the special installation tool and must be used correctly, otherwise the circlips do not get installed correctly and this PROBLEM occurs.
 
No time to read all posts so hope this is useful.

When around 12 or more years ago now - we first were asked to repair a Boxster with IMS failure - we could not obtain gaskets, seals etc (let alone the assembly tool) so had to supply an engine from a crashed car to help the customer (and this is why we know we were definitely one of the first to rebuild them from the Independent sector).

You can fit the first three rods in a conventional way but then if you fit the second half casing you cannot get access to fit the rod ends from the other side - so a new method was needed.

When eventually spares supply enabled us to rebuild an engine we heard on the grapevine that some main agents had experienced trouble with the official circlip assembly tool and some of their rebuilt engines didn't last very long before a similar failure - which frightened me that the tool was not reliable - so being a bit of a belt and braces man - we invented a way to assemble the engine differently by fitting long 6mm studding to each corner (with a wing nut and washer) for the second half case to sit on - so we could gradually lower the second half crankcase while fitting a purpose made ring clamp from underneath between the cases using an angled piston ring fitting clamping tool. This way we knew the circlips were already in place.

We had to rotate the crankshaft while doing so in a sequence with angles and piston heights following a pattern until the last piston being the centre one and all the ring sets were in the bores and the last ring clamp tool (spring steel) was withdrawn by pulling it out as it twisted - leaving space to seal the faces before closing them.

This worked perfectly but was time consuming and awkward and as numbers increased it put pressure on throughput - so eventually we obtained the official tool but made sure we used a camera to inspect the final positioning fit of each circlip.

We have since found that tool 100% reliable and easy to use - but perhaps in the early days a few mistakes were made elsewhere and we still insist that every one is checked with the camera (although this has never revealed one fitted incorrectly or having fallen out (which I agree is the most likely problem that could occur).

Other non standard pistons without the recessed larger diameter next to the circlip groove for the tool to fit in could also be a problem. When using some development pistons for various tests we have re-machined that area of the piston ourselves to allow the tool to fit although they really benefit from some extra material for the increased diameter location.

So - YES - there is a way to fit with circlips in place and without risking a fitting tool but the fitting tool can be perfectly reliable but always worth checking afterwards.

Our time-lapse video (available on our web site www.hartech.org) might help those doing it themselves as it shows the complete strip and rebuild speeded up. I have read that someone managed to slow it down - but you can always pause it, rewind etc to follow some sequences. This might also help when refitting all the auxiliaries as it is easy until you are used to it to get something out of sequence and find you have to take things off again to make it all fit.

I am not bothered if this helps someone who cannot afford a specialist like us to do the job for them although I do recommend that if they can save the cost of the full strip and rebuild by doing some themselves - they still consider sending us the cases to have the best type of cylinder replacement carried out and a few other important mods at the same time.

The cylinder blocks are the same height to the head face from the centreline of the crankcases in all models from the 2.5 Boxster to the 3.8 997. In this time the stroke has been increased twice so later engines have the gudgeon pin reaching a lower point in the cylinder at BDC than earlier examples and can therefore be more risky if the circlips are no reliably in place.

Good luck.

Baz
 
I've been hoping to hear from OP that the dealer or rebuilder are doing the right thing...
 
CFo said:
I've been hoping to hear from OP that the dealer or rebuilder are doing the right thing...

+ 1 :x
 
bazhart said:
No time to read all posts so hope this is useful.

When around 12 or more years ago now - we first were asked to repair a Boxster with IMS failure - we could not obtain gaskets, seals etc (let alone the assembly tool) so had to supply an engine from a crashed car to help the customer (and this is why we know we were definitely one of the first to rebuild them from the Independent sector).

You can fit the first three rods in a conventional way but then if you fit the second half casing you cannot get access to fit the rod ends from the other side - so a new method was needed.

When eventually spares supply enabled us to rebuild an engine we heard on the grapevine that some main agents had experienced trouble with the official circlip assembly tool and some of their rebuilt engines didn't last very long before a similar failure - which frightened me that the tool was not reliable - so being a bit of a belt and braces man - we invented a way to assemble the engine differently by fitting long 6mm studding to each corner (with a wing nut and washer) for the second half case to sit on - so we could gradually lower the second half crankcase while fitting a purpose made ring clamp from underneath between the cases using an angled piston ring fitting clamping tool. This way we knew the circlips were already in place.

We had to rotate the crankshaft while doing so in a sequence with angles and piston heights following a pattern until the last piston being the centre one and all the ring sets were in the bores and the last ring clamp tool (spring steel) was withdrawn by pulling it out as it twisted - leaving space to seal the faces before closing them.

This worked perfectly but was time consuming and awkward and as numbers increased it put pressure on throughput - so eventually we obtained the official tool but made sure we used a camera to inspect the final positioning fit of each circlip.

We have since found that tool 100% reliable and easy to use - but perhaps in the early days a few mistakes were made elsewhere and we still insist that every one is checked with the camera (although this has never revealed one fitted incorrectly or having fallen out (which I agree is the most likely problem that could occur).

Other non standard pistons without the recessed larger diameter next to the circlip groove for the tool to fit in could also be a problem. When using some development pistons for various tests we have re-machined that area of the piston ourselves to allow the tool to fit although they really benefit from some extra material for the increased diameter location.

So - YES - there is a way to fit with circlips in place and without risking a fitting tool but the fitting tool can be perfectly reliable but always worth checking afterwards.

Our time-lapse video (available on our web site www.hartech.org) might help those doing it themselves as it shows the complete strip and rebuild speeded up. I have read that someone managed to slow it down - but you can always pause it, rewind etc to follow some sequences. This might also help when refitting all the auxiliaries as it is easy until you are used to it to get something out of sequence and find you have to take things off again to make it all fit.

I am not bothered if this helps someone who cannot afford a specialist like us to do the job for them although I do recommend that if they can save the cost of the full strip and rebuild by doing some themselves - they still consider sending us the cases to have the best type of cylinder replacement carried out and a few other important mods at the same time.

The cylinder blocks are the same height to the head face from the centreline of the crankcases in all models from the 2.5 Boxster to the 3.8 997. In this time the stroke has been increased twice so later engines have the gudgeon pin reaching a lower point in the cylinder at BDC than earlier examples and can therefore be more risky if the circlips are no reliably in place.

Good luck.

Baz

Thanks for the video Baz, as they say a picture paints 1000 words! Much as I love working on cars & engines, it has to be said the 911/boxster/Cayman are a complete ball ache to work on enginewise for the home enthusiast, and somewhat of a different proposition to the old Cosworth YB & Vauxhall XE engines that I cut my teeth on :grin:... without a ramp you are fighting a loosing battle already, & watching that video there is a hell of a lot of work that goes into a 911 engine!

One last simpleton question, sorry, what's stopping the piston/ring compressors on bank 2 from being drawn through the bores, so you could fit the barrels as one item, if that makes sense?

Merry xmas to all :thumb:
 
Sorry RWD either I am still hungover or I really didn't understand your question about assembly - you do realise the cylinders are part of the cylinder block?

If I understand your proposition correctly - the only way you could assemble as you suggest would be with long tubes made from steel a couple of thousands of an inch thick fitted over the top of the pistons and withdrawn from the top?

Anyway I'm off to watch Bolton Wanderers now - probably will need a drink after that again!

Happy New Year,


Baz
 
bazhart said:
Sorry RWD either I am still hungover or I really didn't understand your question about assembly - you do realise the cylinders are part of the cylinder block?

If I understand your proposition correctly - the only way you could assemble as you suggest would be with long tubes made from steel a couple of thousands of an inch thick fitted over the top of the pistons and withdrawn from the top?

Anyway I'm off to watch Bolton Wanderers now - probably will need a drink after that again!

Happy New Year,


Baz

From the video, what I I have seen are the crank cases, then the cylinder block, then the heads going on.... Just wondering why you can't have extended ring compressors to allow bank 2 cylinder block to be fitted to the assembled conrods/pistons? Trying to assemble pistons to rods in the block looks to be a real pain in the arse lol!
 
The crankshaft is held in a carrier of square section alloy.

The crankcases incorporate the cylinders.

Imagine a conventional cylinder block that you assemble normally except there are spare crankshaft journals unused.

Now imagine that instead of fitting the sump there is another identical block that you have to fit to the other side where a conventional sump would fit.

You cannot lower the pistons complete with rods into that half because you cannot get inside the half you have already assembled to fit and tighten the rod caps - so you have to either already fit the pistons and find a way to compress the rings while you lower the second block half (and then find a way to remove the clamp - which is what we did initially) or you have to lower the block onto the roads and find a way to fit the gudgeon pins and circlips afterwards (which is what the Porsche method is through holes in the side of the block and an assembly tool).

I did once consider if we could freeze the rings in a compressed state and quickly lower the block before they melted the ice (probably a mad idea) but in actual fact - with the right tool and the proviso of checking with a camera - the Porsche method is trouble free, quick and easy - when you are used to it.

Baz
 
We're getting way off-topic here.

Scarletboarder, have you had any joy from the dealer?
 
Hi chaps, been having some Christmas time without thinking about this too much!
Had to have a letter served on the dealers due to no contact/action. They have since contacted the re-builder asking what has happened and whether I've been screwing the car! They have still not contacted me in any way. The re-builder has told the dealer that there were no signs of issues during the service at 2000 miles after the build and that the car had done 'a fair bit of mileage' since the rebuild. Going to call in to the dealer in the New Year to try and get some answers prior to the next step with solicitors.
 
Keep at it, scarletboarder, because 'quite a bit of mileage' has to be the lamest excuse in Christendom; sounds like desperation, to me.

Everyone (including they) knows they're liable, the only way they'll get off the hook is if they can give you the run-around long enough for you to give up, or maybe your rights to run out.

Keep pushing this - hard. It's big money they're costing you.

Good luck and I hope a happier New Year.
 
Cheers EGTE. Going to be on it every day in the New Year!! Phil
 
scarletboarder said:
Cheers EGTE. Going to be on it every day in the New Year!! Phil

Best of luck :)
 
Question: am I right in thinking that an engine from a manual car (mine's a tiptronic) just needs the original wiring harness fitted to the replacement engine? Seen a 25k 3.6 one!!
 

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