Eharrison

When doing the IMS retrofit I spoke with LN Engineering regarding chain noise on start up and he recommeded replacing the chain tensioners while I'm in there.

Chain tensioners are running $1000 a piece. Was it really the tensioner cylinder or the chain tensioner adjuster? I hope it's not the cylinder....

wow $938

"as chain tensioner" but the part is also named adjuster $81.21

Thanks in advance.

Shark Attack

Im confused, I have never been in there. But that looks like the vario cam solinoid. When I spoke with them about tensioners they said to just do the pads

ivangene

Pads are a wear item - and much cheaper

ivangene

here is a pic of the cam tensioner assy - you only have to change the guide (rub strip)

there are several of these in our motors and the cam ones are supposed to be fairly simple to do compared to the others - It does require special tooling to hold the cams in place and a threaded rod to compress the tensioner so it can be removed. Also the valve cover off which is not trivial, but .... if you are in there for IMS job, its not THAT much more (so I hear)

you can see there is also one on the top of the assy... they just "pop" on and off

2 per side (total of 4)

Eharrison

It's these

https://rennlist.com/forums/7295275-post101.html

Dharn55

the first link you show is for the VarioCam solinoid/adjuster, also the picture that Ivangene has posted. This is not what LN is referring to. LN is referring to the three tensioners that go on the chains from the IMS to the heads (2) and the IMS to the crank (1). These are the tensioners that are supposed to be removed prior to removing the IMS flange and bearing as they put pressure on the IMS. Particularly on the ones for the IMS to cams on head 1-3 and the IMS to crank., both of which are on the flywheel end of the engine. The tensioner for the IMS to cams on head 4-6 is on the pulley end of the engine, harder to get at (you have to remove the AC compressor and loosen a bracket), and exerts less pressure on the IMS, at least the end that has the bearing you are replacing. The pads for these chains cannot be replaced without taking off the cam covers and cams, and even them the IMS to crank pad cannot be accessed. Please note that there are three different tensioners here. The part number according to my PET are as follows:

IMS to cam 1-3 996.105.179.58 superceded to 996.105.186.01 $91.78 list
IMS to crank 996.105.180.54 (can't find a superceded number) $67.54
IMS to cam 4-6 996.105.176.51 superceded number 996.105.188.01 $111.34.

Please check/verify these numbers before you order any, but they are the ones on my PET for a 99. These tensioners are sometimes scoured/worn and as you see Porsche has come up with a superceded part/design.

As for the pad on the VarioCam adjusters, Ivangene shows how they can be worn quite a bit. This was the case on my engine (whereas the pads on the IMS chains were in good condition). But to replace these pad you have to remove the cam covers and the cams, which is not part of the IMS bearing procedure.

Eharrison

Those are what I'm talking about. My second link on the first post is the new version of 996.105.180.54

I was using this PDF for parts info.->Part Catalogue

Thanks for the info. I need to verify that these are what need to be replaced.

ivangene

Yes, sorry I was off - based on the original post, the tensioner makes more sense since they (2 of 3) are removed for the IMS retrofit.

I inspected one at my indy and he was not planning to change it, I pointed out the marring on the edge. The metal parts slide in and out of each other and gawl causing them to them stick. Its easy to see if you are used to seeing parts gawl, but if you are not, its a little tough to tell. Replacing them would be a great idea - however, they are a snap to remove (the 2) so if you do it at a later date I think that is fine. Inspect them and then make the call. I am almost certain mine will need replaced with 115k miles

dan_996

I'm doing the IMS replacement also, and I looked into using the revised tensioners. The information I've gotten from the Porsche dealer is that the revised tensioner was implemented with the change in the the timing chain from the two piece roller type chain (motorcycle type chain) to the new one-piece tooth type chain which also included the change in the crankshaft and IMS shaft (introduced into production on August 2000, as of engine number M96.04 66 1 00501). According to the Porsche Service bulletin the new tensioner is not compatible with the old chain. Hence the old style tensioner (996.105.180.54) is still available and is the the only one that should be used with the earlier type chain.
If anyone has different information please let me know.

Eharrison

Interesting, I thought the chain tensioner did not come directly in contact with the chain, rather is was connected to the slide. Parts 24 34, 35

We are going to need more professionals in on this one issue.

Dharn55

The tensioners push on the chain support brackets (items 18 and 30 on the diagram), which have wear pads on them. I don't know why you could not use the newer tensioners as they do not come into contact with the chains and according to my PET the brackets themselves have not been updated.

ivangene

that is your engine

rb101

I replaced all three adjusters when I did the IMS bearing replacement. Two of the 3 were scored. The crank to IMS adjuster popped out fully as I pulled it out of the bore.

Rick
99 996C4
87 944S

dan_996

The service bulletin doesn't mention whether the tensioner pads are a new part, however the pictures show that they are different, with the tensioner contact point further away from the chain. The tensioners themselves are very different. And the bulletin specifically states that you should not use the new tensioners with the earlier roller chain.
I've decided to keep the original tensioners since they are in good working condition. I think that's the key point if the tensioner is binding then the chain can be either too tight or too loose. In either case causing noisy operation or shortening the life of the chain.

rb101

What service bulletin number is this?

Thanks

Rick
99 996C4
87 944S