Major S2 overhaul, requesting advice and moral support

[robdimond]

So, after 4000 miles of blissful S2 ownership I'm contemplating doing some major servicing this summer.

The main reason for doing anything is an intermittent 'rattle' from the top-end, which I'm almost certain is the timing chain. I replaced both pads and the J-tube last year, but it looks like the tensioner is near the end of it's travel. Also, for an unknown period the chain was running on the metal tensioner... so I probably should have changed it then and there...

Some background:
- Well run in (184k miles)
- Original waterpump
- Original cam chain
- Belts last done by PO (at a non-specialist) Sept 09
- Clutch done approx 90k miles ago (and seems fine)

My general plan is to do a compression test (to make sure nothing else is amiss) and then proceed to replace the cam chain. Seeing as the timing belt needs to be disturbed, I also plan to change the water pump, belts, idlers and change the seals on the front.

The reason for DIY is firstly, the car is meant to be a hobby and I want to learn how to do it (I've done similar scale stuff, e.g. head gaskets on lesser cars) and secondly, to allow painting cam covers etc. while they're off and generally doing a leisurely job.

The main question is... what else should I be doing? While the cams are out, why not remove the head, replace the gasket and get it rebuilt by an engineering shop who knows what they're doing?

Any recommendations, especially from others in the high mileage club?

Also... a very specific question... has anyone changed a camshaft seal without special tools 9233 and 9234 (it's a special sleeve and a drift for tapping the seal in).

Thanks anyone who read this far... any comments/support appreciated (even if it's just to say get on and do it... stop asking silly questions)!!

 

[eddieedmo]

I would definitely consider head off , skimming it and lapping valves in , new h/gasket obviously.High mileage S2 's are known to have h/gasket deterioraton which results in damage to the alloy head.
Have fun !

Nick []

 

[robwright]

I wouldn't advise a skim unless there is any evidence of overheating but hey that's just me. Would defo advise lapping the valves though. I am just about to do a top and bottom end rebuild on my Turbo after unsatisfactory compression testing. If I come across any surprises I will let you know.

 

[JamesO]

Also... a very specific question... has anyone changed a camshaft seal without special tools 9233 and 9234 (it's a special sleeve and a drift for tapping the seal in).

Thanks anyone who read this far... any comments/support appreciated (even if it's just to say get on and do it... stop asking silly questions)!!

I just put the seals in place then bolted the bridges down. If the cams are coming out then there is no need to drive the seal in. Be aware the cam carrier bolts round out very easily, not helped if you don't have the tool to clamp the cams in place.

Oh and don't forget to lock the cam pulley with 3 longer bolts IIRC. You'll prob want to check the timing with a pair of dial cages but better to start from what worked before

 

[robdimond]

Thanks for the responses... expect pictures of exposed pistons and lacy head gasket at some point in the future, and you can all say... there I told you so!

James: Interesting point about the camshaft seal. I was worried it might get pinched, but if you managed without problems that is reassuring! I think we talked already about avoiding the special tool for removing the cams (I've been mulling this over for a while...). Regarding chewing up the bearing cap bolts, I saw on a 928 forum a suggestion to use a hand impact driver to crack these loose, which sounded like a good idea.

Rob: good luck with your in-car rebuild... I hope you will post all the gory details.

 

[colin944]

Hi Rob. I am doing pretty much the same thing on my engine at the mo.If you buy a top end gasket set from Porsche you get all the seals etc as weel as valve stem oil seals.I would do that and replace every seal in the top end.If compression is ok then you don't have to worry about rings,so a top end job would be a good start.Also nif you are going to pull the engine out to do the work then take the sump off and clean all the crap out of the sump and the oil pick up,oil ways water ways etc.Then water pump,belts and rollers etc and you will have another few thousand happy miles.

 

[bmnelsc]

ORIGINAL: JamesO

Also... a very specific question... has anyone changed a camshaft seal without special tools 9233 and 9234 (it's a special sleeve and a drift for tapping the seal in).

Thanks anyone who read this far... any comments/support appreciated (even if it's just to say get on and do it... stop asking silly questions)!!

I just put the seals in place then bolted the bridges down. If the cams are coming out then there is no need to drive the seal in. Be aware the cam carrier bolts round out very easily, not helped if you don't have the tool to clamp the cams in place.

Oh and don't forget to lock the cam pulley with 3 longer bolts IIRC. You'll prob want to check the timing with a pair of dial cages but better to start from what worked before

Regarding seals - even the 928 training video posted here a few days ago shows the tech using the seal driver to place the seals AFTER re-installing the cam shafts but IIR the WSM describes a procedure for replacing the seals during assembly and tightening the bridges down as James describes - particularly helpful for replacing the rear seals (which was not discussed in the video) when you are doing this with the engine in the car.

Also 0 interesting comment about using an impact to loosen the cam bearing bolts when you don't have the hold down fixtures...I didn't realize that could be a problem. Good to know.

 

[robdimond]

Regarding seals - even the 928 training video posted here a few days ago shows the tech using the seal driver to place the seals AFTER re-installing the cam shafts but IIR the WSM describes a procedure for replacing the seals during assembly and tightening the bridges down as James describes - particularly helpful for replacing the rear seals (which was not discussed in the video) when you are doing this with the engine in the car.

The workshop manual uses the procedure for replacing the seals during assembly only for the non-driven end of the camshafts, for the driven end it specifies the special tool. It was me who posted the 928 videos

Sounds like everyone can get by without the special tools... but clearly they make sense if you do a few of these a week.

 

[colin944]

You can get by using standard tools.Special Tools are usually made by a manufacturer to make workshop procedures easier and quicker for the mechanics.

 

[zcacogp]

I've done the belts and waterpump on my S2 and it's not hard. If you have taken the head off another car then the job won't be beyond you. A crankshaft lock is helpful, as is the correct pin spanner to get the pulleys off the end of the balance shafts, but neither are essential.

I attempted to change the cam chain but failed; I couldn't get the bolt out of the cam pulley. It's a cheesehead/triple-square thing, and I snapped one tool and bent another one trying to get it out. I measured the old chain as closely as I could, decided it was OK after all (only around 40k miles old at that point) and settled for just changing the tensioner pads.

I didn't bother taking the head off. I had no problems with overheating and (despite the horror stories from Baz Hartech and others on here) decided the gasket was OK. A purist would say I should have taken it off and re-ground the valves, but it does make a one-day DIY job into something quite a lot bigger and more expensive. I don't regret not having done so.


Oli.

 

[robdimond]

I attempted to change the cam chain but failed; I couldn't get the bolt out of the cam pulley. It's a cheesehead/triple-square thing, and I snapped one tool and bent another one trying to get it out. I measured the old chain as closely as I could, decided it was OK after all (only around 40k miles old at that point) and settled for just changing the tensioner pads.

I've heard it's not uncommon to have to grind off or drill out the bolt head, as in the post below:

http://forums.rennlist.com/rennforums/968-forum/409911-diy-camshaft-chain-tensioner-pads.html

In fact this guy ended up drilling out more bolts than unscrewing them! I bought a good quality german triple square tool, so hopefully that will do the job.

 

[JamesO]

I've heard it's not uncommon to have to grind off or drill out the bolt head, as in the post below:

http://forums.rennlist.com/rennforums/968-forum/409911-diy-camshaft-chain-tensioner-pads.html

In fact this guy ended up drilling out more bolts than unscrewing them! I bought a good quality german triple square tool, so hopefully that will do the job.

Blimey, would have thought he would have changed his plan of attack after the first few gave way.

Think I tapped a socket onto one I damaged.

 

[robdimond]

One more question... how likely is it that the bolts/studs will break when I remove the old water pump. Bear in mind it's an original 23 year old pump (hence I really can't leave it alone when I do the belts). Any tricks to minimise the chances? Heat?

There is quite a big oil leak down there as well []... some oil on the cambelt and on the metal guide rail that bolts to the water pump.

Also, for all those wanting water pumps, I ordered one from the French website rosepassion.com, was only 181 euros. I'm not sure if it's a Laso... will see when it arrives.