Updated chain tensioner

[Cefalu]

When my 1999 996 sits for a week or so and isn't driven, I get a brief moment, maybe 1 sec where I can hear what I think is the cam chain at a cold start. I know tappet sounds and I don't think that's the issue.

So I ordered two new tensioners, 1-3, and IMS (not 4-6 too hard to get to for now) to see if that fixes the issue.

I was expecting to receive the updated style which had the exterior spring. These ones don't have the exterior spring.

Did I get the old type? Or has it changed again?

The attached pic shows I received parts 996-105-186-01 and 996-105-180-57. Correct part number but old part sent?

Thanks,

Doug

[Loren]

Have a look at TSB 10/00 1551 New Drive Chain and Seal for Intermediate Shaft - dated 11-10-00

[logray]

Search is your friend!

[Cefalu]

I must be missing something here! I read the TSB and that thread before I posted my question. The TSB seems to talk about the overall change to a tooth type chain, and an improved IMS seal. I can't change my chain type, so the TSB does not seem to apply to me. And I installed the ceramic IMS bearing so I have the modified IMS seal already. As far as the TSB goes, I think I have done as much as I can without tearing the motor totally apart and replacing the chain type.

The thread was confusing to me, and to the posters who participated in it as well. I knew I had the most recent part numbers, according to that thread, but the TSB and the thread referred to an updated tensioner that had an exterior spring. JFP noted in that thread the exterior spring was the new design. And mine did not come with a spring. That's the issue. Is mine an update of the updated design?

[JFP in PA]

Not to my knowledge, as far as I know, the last time I checked, these were the old and new numbers:

996-105-180-54-OEM Old style IMS tensioner

996-105-180-56-OEM New style IMS tensioner

996-105-051-58-OEM Old style 1-3 tensioner

996-105-186-01-OEM New style 1-3 tensioner

996-105-053-58-OEM Old style 4-6 tensioner

996-105-188-01-OEM New style 4-6 tensioner

That said, I think Logray went through this dance and found out that some parts had been superseded yet again so God (and Stuttgart) only knows what the latest parts are. Suggest giving Jeff at Sunset Porsche (board sponsor) a call, he is usually up on the latest changes

[Cefalu]

From what I can tell, the latest greatest IMS tensioner is updated from 996-105-180-56 TO: 996-105-180-57. That's what Logray concluded last June in the thread referenced above.

But, the big question I have is, I thought the newest design(s) were supposed to have a supplemental exterior spring to increase the chain tension when there is no oil pressure present, such as a cold start.

[logray]

Do not use -55 or -56 (one with external spring). They are designed only for the non-roller (hyvo) type chains. The reason why Porsche moved to the hyvo chains was apparently to reduce chain noise. There's nothing wrong with the old roller chains (in fact I tend to believe they are stronger, even if they make more noise).

You should ONLY use the -54 (supersceded to -57) tensioner. Unless you have torn your engine apart and replaced all of the components per the TSB referenced above then you can use -55 or -56.

There have been reports of people trying the -55 or -56 tensioner with the roller style chains and having problems with that combination. You should not attempt that combintation since other people have already tried it without success.

If you read the TSB it clearly spells out the -55 (supersceded by -56) is only applicable to the updated hyvo chain.

The -54 (supersceded by -57) is only applicable to the roller chain in your engine.

I have the -57 in my 100% rebuilt roller chain engine and it makes absolutley no startup noise whatsoever.

You will see that -56 is NOT superceded by -57. 996-105-180-56 is still orderable today (and not replaced by a different part).

In fact, -54 was still orderable up until a few months back when I ordered mine (the confusion in that thread was because I managed to order it before it was inserted into PET, it was a very new part number when I ordered it).

Edited April 4, 2012 by logray

[Cefalu]

OK, got it. I have the original roller type chain, so the 996-105-180-57 is the newest tensioner for my car. The exterior spring style tensioner is only for the later tooth type chain. I thought maybe the dealer had sent me an old part since it lacked the spring, and I didn't want to miss out on all that bonus spring goodness! I plan to install this weekend while I change my oil.

Thanks!!

Edited April 4, 2012 by Cefalu

[Steve Tinker]

Cefalu....

Keep us informed of the outcome of the upgrade - theres quite a few of us that have the (initial) startup noise and I for one would appreciate your findings.

As a matter of interest, whats the price of the new tensioners - they are probably about $1,2 million here in Australia, so it would be cheaper for me to fly to Sunset Porsche and pick up the things if your mods are successful !!!

Edited April 5, 2012 by Steve Tinker

[logray]

The tensioners in the USA are between $65 and $100 USD each, there are three of them.

[Steve Tinker]

Thanks for the info logray - yep, that sounds about right, $US100 will be the equivalent to just over a $million in Australia.......???? Well, at least 2-3 times what you guys pay.

But if spending $US300 helps Cefalu startup rattle and wear on the tensioner pads, its cheap.

[logray]

LOL, last I checked the AUD was doing better than the USD...

[Cefalu]

OK, changed the oil, and filter and the 1-3 and IMS tensioner yesterday. I did not change 4-6 since it is a hassle to get to. At initial start up there was no noise!

That's encouraging since those conditions replicate a cold start after the car has been sitting for a couple of weeks, almost.....Almost because I had driven the car one week ago. Usually it has to sit for a couple of weeks to hear the noise. And if the 4-6 tensioner is the bad one then it may have still had enough residual pressure left in it to suppress any noise.

My old tensioners looked perfect, no scoring. However...the new IMS tensioner is about 1/4" longer than the old one I removed from the engine. I don't know if the new tensioner is designed to be longer, or the old tensioner was stuck in a partially closed position.

I also noticed the internal spring in the old 1-3 tensioner seemed slightly stronger than the new one. It might have been residual internal oil giving some resistance though.

My advice? Try changing the IMS tensioner as a first step when you do an oil change. The filter and tensioner are right next to each other. It might save you the cost of the 1-3. But the 1-3 tensioner is located on the bottom of the motor so you will need to do it during an oil change since oil will come gushing out. I bought the parts from Pelican out of convenience as it was online. But as others have noted some Porsche dealers are cheaper since Pelican has to buy the parts from the dealer too.

All in all it adds about 15 mins to an oil change.

***EDIT*** next day...I have driven the car for a day now and the motor is noticeably quieter. It wasn't bad before but the new chain tensioners have defeinitely made a difference. The IMS tensioner that was a little short must have been the culprit

Edited April 7, 2012 by Cefalu

[Steve Tinker]

Cefalu...

Can you remind us of the miles / history of your car......

Is a worn IMS tensioner a typical "weak" point of the valve tensioning system ??

[logray]

A worn IMS tensioner is not necesarilly considered a "weak" point of the design.

They can get dirty if the oil is not kept fresh and clean. If you are religious about maintenance, many have lasted 200k plus and could last even longer.

Like most cars, once they reach 100k or so and you are unsure of the service history, there are things you might want to consider doing if you plan to keep the engine for a long time, for example timing chains (and their related tensioners/etc.). There are different schools of thought on that however.

Although there have been a few documented failures, there have been very few failures of the tensoiner itself. If it is dirty it will cause some more startup noise and perhaps additional paddle/chain slap, and perhaps accelerated wear of the paddle button or other parts, but I don't think it will cause a problem immediately or even in the near future.

I believe failure of the paddle is more common, which in itself is not very common.

[xmac]

Forgive my igonorance, but can the tensioners be replaced one-at-a-time without having to lock the cams, etc...? I have the same 1-2second noise if my car sits for a few days also that makes me cringe. 29,025 miles on the car.

[Cefalu]

I have a '99 with 63K miles. It has been well maintained. I locked the accessory pulley with a dowell that came with my IMS replacement kit. I did not lock the cams. I don't know if the pulley needs to be locked or not but I did it anyway.

The only real issue I observed is the IMS chain tensioner that I removed from my motor was 1/4" shorter than the new replacement tensioner. I don't know if my old one was failed and stuck or if the new ones are a little longer.

But the car is quieter for sure.

[xmac]

Cefalu, thanks for this post. I tackled the IMS tensioner today with a 5/16" dowel in the crank pulley. It is amazing how much smoother the startups are and overall the reduction in engine noise (the bad kind).