944S/S2, 968 camshaft chain with master link

[944s2cab]

Could this be the answer to replacing the timing chain without having to take the cams out and redo all the timing???????
Here's how I came up with a possible answer
first noticed this http://www.ebay.com.au/itm/Timing-Chain-944-968-Carlton-Senator-94410550101-09424/371709406722?_trksid=p5713.c100043.m2062&_trkparms=aid%3D999002%26algo%3DURGENT.LUI%26ao%3D1%26asc%3D20140502134130%26meid%3D57ef86ab929d48508900b3f525e82301%26pid%3D100043%26rk%3D1%26rkt%3D1%26so%3Dlastwatched%26sd%3D262873972457 that we share the same cam chain with a series of Opel engines,
Then, post 8 in an Opel forum mentions that they use Mercedes master links as an easy way of replacing their chains,http://www.opelgt.com/forums/6a-engine-mechanical/72778-how-install-master-link-timing-chain-w-o-removing-head-timing-cover.html

Led me to this http://www.ebay.com/itm/152119243285?ss
IWIS is an OEM supplier to Porsche, it has enough links (have to remove a few,
Thoughts please

[Rob]

Just be aware, if your chain needs replacing, the tensioner pads will be stuffed, so you'll need to do the full Monty to get to those anyway.

[Plugger2]

Just be aware, if your chain needs replacing, the tensioner pads will be stuffed, so you'll need to do the full Monty to get to those anyway.

Not sure what you mean by "the full monty" in this context, but I recall the procedure for replacing the tensioner pads was not that big of a deal. This was a few years ago, so I was a bit hazy on the details, but this write-up on rennlist rang all the bells (I now remember the J-tube, etc.):

http://rennlist.com/forums/diy-submission-forum/600465-diy-chain-tensioner-pad-replacement-944s2.html

Does this entail "the full monty" you were referring to?

[Rob]

Hey Plugger - yes - that's what I was referring to.  That has to be one of the most thorough write-ups I've seen for a twin cam 944, so a good find.  Some good secondary advice in there re the potential stripping of the tensioner securing bolts.  I believe the S2s had some history of failing tensioners, probably related to these bolts.

[brian in buddina]

 I believe the (S &) S2s had some history of failing tensioners, probably related to these bolts.

My understanding is that the original tension pads were not specified, to be replaced,  as originally noted in the P maintenaince documents. I stand to be corrected by a higher authority.

Is anyone aware of any differences between the original twin cam in the S, other than the displacement, bore & stroke, to the later S2?

[Buchanan Automotive]

All timing chain "Nylon " / Plastic chain slipper guides wear & more to the point they deteriorate due to heat cycles , after all they are just plastic type material , and they ( like they all do after 20+ years in hot oil ) = deteriorate 

Now how to accelerate the destruction of the top end on a 944S , 944S2, 968 ??? ( YES I mean Accelerate )

Easy , first of all run a engine oil viscosity that when the oil temp gets to 80 deg cel to 100 deg cel " normal operating temp " ( or above ) that the engine drops in oil pressure at idle to a point where the timing chain tensioner ( hydraulically operated by pressure ) has insufficient pressure & the timing chain starts to rattle ( we call it death rattle ) or put another way} the MONEY Pit rattle 

So for Australian ambient temp conditions that oil that does the most destruction / damage is a oil viscosity which is less than a 15W-50 , so that means oil viscosities that are 10W-40 , 5W-40 & the ultimate in destruction is a 0W-40 & a 0w-30 is madness in the extreme in these deep last century Porsche's

How do we eliminate the above issue and only that issue ( to start with ) , is to consult the owners manual that came with these last century Porsche's & the answer is a 20w-50 engine oil & better still most 20w-50 engine oils have higher ZDDP levels , which gives higher oil film strength ( added bonus)

So there is that out of the way , I know it sounds too simple , and humans like to overthink things , buts its that simple & remember I am talking about ambient temp ranges as specified by the owners manual from Minus 10 deg cel to UNLIMITED high ambient temp ( very much Australian conditions )
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Now onto life span of moving parts in an engine & in field observations over the DECADES , yes I said decades not weeks 

First of all , what did I hear about & read about around the early 2000's ( 17 years ago ) apart from the beginning of camshaft lobe wear ( pitting ) and pitting of the hydraulic lifter faces we also ( at the same time ) learned / heard about the timing chain sprocket teeth wear , be very afraid of this because these chain sprockets are part of the camshaft , meaning that are cast with the camshaft & machined to form a sprocket ( very trick , but very expensive if they wear ) , now when we/I first heard of this we started to take a much closer look at our own customer's 944S , 944S2, 968  cam lobes & sprocket wear & we just could not find any at all ( no wear at all ) , at first ( 17 years ago ) I was a bit mystified , but soon realised the ones we were hearing about were the ones that ( unfortunately for the owners ) were running on a so called synthetic engine oil of either a 5w-40 or a 10w-40 & these engines on these oil viscosities suffered ( owners pockets ) suffered greatly , but the ones that has 200,000 Kms + that had been on a 15w-50 or better still a 20w-50 had no cam lobe wear & no cam chain sprocket wear } 20W- 50  = high oil film strength & decent oil pressure at operating oil temp ( hot ) at idle  

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Now let's take a  944S , 944S2  ,968 thats on a 5w-40 so called synthetic engine oil , summers day in sydney , the said car is in traffic for a hour or two or three & low and behold the oil pressure insufficient oil pressure warning starts to flicker on  ( we see it every summer on Porsche's we have never seen before ) & there oil pressure warning light is on and one can clearly hear the poor twin cam chain tensuooner has little or NO oil pressure to keep tension on the timing chain & what do we hear as this poor thing is idling in the driveway at our workshop ???????????

Answers = The Timing Chain death rattle , meaning the chain is loose & this is actually a double whammy for wear / destruction of the timing chain & the camshafts timing chain sprockets ( which are part of the cam shafts ) because the oil pressure is dangerously low = bad news , but we have an oil that is low on oil film strength as compared to a 20w-50 which means the timing chain is making very aggressive metal to metal contact with there sprockets & easily cutting through the weak oil film strength of the hopeless so called synthetic 5w-40 engine oil & we accelerate the wear on the teeth , this then leads to extra slack in the chain & its becomes a hopeless situation because the timing chain noise is often not noted at all by the owner , its just another noise & yes its a human made disaster , caused by humans not reading the owners manual & costing them dearly 

Now lets add old fragile starting to crack plastic timing chain tensioner guides , with the timing chain starting to whip ( loose ) because of low low low oil pressure hot at idle the plastic timing chain guides fail very quickly & break up , once this happens ( we are now talking seconds before IMPACT ) , the timing chain has nothing left and is caught in a whipping bind and just snaps / falls to bits , in this micro second ( yes we are into a fraction of a second now ) the exhaust cam ( which is run by the cam belt ) continues to run , but the inlet cam has already stopped & the timing chain is piling up under the exhaust cam sprocket & the lower tens pad and just tears the entire hydraulic tensioner from the cylinder head & usually pushes a hole in the twin -cam  cam- cover ( rocker cover if it had rockers but it doesn't ) & naturally we have bent valves and a badly damages head and destroyed cams ( WHAT A MESS ) and completely avoidable 

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So using common sense ( yes I know common sense is not always common ) but sometimes its just that simple , we look at what is happening to others & look at what we are seeing and we add 2 & 2 together & we get a simple answer ( this is not rocket science , its just some mechanics & physics )

First of all , years & years ago , when we were preparing customers 944S , 944S2. 968 etc for club track work , one of the things we implemented is one very simple preventative maintenance schedule & apart from oils , il leaks ( sump gasket ) etc , timing belt etc , we removed the cams & replaced the timing chain and the nylon guides , this actually coincided with Porsche ( out of the blue ) making these tens pads available without having to buy the complete hydraulic tensioner ( excellent )

And being these Porsche's are going to the track( maybe 4 or 5 times a year ) they are NOT going to get anything less that a 20w-50 engine oil with high ZDDP levels 

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Now lets take a normal road use only 944S , 944S2 , 968 , years ago we recommend to customers to replace the timing chain & the tensioner ( plastic ) pads every 120,000Kms , we usually coincide it with a cam belt/ rollers replacement interval ( somewhere in the 120,000Kms range ), so the over-all time spent is reduced ( less labour)

And Yes when they let go its a stupidly expensive exercise & COMPLETELY avoidable 

We have never ever lost a 944S , 944S2 , 968 due this issue & we have quite a few of these cars being belted at the track & interestingly , but not surprising to me one bit is that we see ZERO cam lobe wear , ZERO hydraulic lifter wear & ZERO cam chain sprocket wear when these deep last century Porsche engines run on a deep last century high oil film strength oil viscosity that is recommended in the owners manual by the people who but these engines } 20w-50  

Fancy those humans who made these engines new( last century )knew what was needed & the stupid humans in this century having no clue at all , its all very human

Oh , one last thing & its important , do not use a timing chain on these Porsche twin cam engines with a master link ( removable link), its just introducing something else that can go wrong , always use a endless chain , same as what Porsche did 


Regards

Bruce Buchanan
Buchanan Automotive       40 years & 3 months working on Porsche sports cars 

[brian in buddina]

If you wrote a book Bruce, I would buy it!

[Buchanan Automotive]

Hi Brian , thanks , but my objective here is to try to stop the destruction of these great cars , hence the length and detail of my posts

Regards

Bruce Buchanan
Buchanan Automotive

[brian in buddina]

I am a bit of a tech & gear head. I love reading your expanded versions from your experience. I think a book on "keeping your 924, 944 & 968 alive" would be very well recieved. With the escalation of these cars values increasing over the last couple years I am sure there will be an increased interest in restorations. Not unlike the aircooled cars.

Thanks for all your imput and not letting us, PFA forum, get distracted by incorrect assumptions.

Brian in Buddina