Upper chain tensioner replacement

[Cefalu]

I bought 3 new chain tensioners for my 1999 Cabriolet. The two that are accessible from beneath the car I replaced. I did not replace the upper one because it is under the AC compressor.

 

I understand the AC compressor needs to be moved to access the tensioner and this is accomplished by removing the 3 compressor bolts. But Bentley says you need to remove the power steering pump reservoir too, which looks messy. I suspect you need to remove the reservoir if you are removing the compressor, which I am not. I just need to shift it over.

 

Can anyone speak from been there done that?

[Ahsai]

No need to remove any of those. Just undo the 3 bolts holding the a/c compressor. You need to remove the engine temp sensor on the right intake manifold to drop an extension with a socket to get to the bolt at the back of the compressor. That bolt cannot be removed but it can slide up enough for you to slide out the compressor. 

[Cefalu]

That's great, thanks!

[Cefalu]

Mission accomplished. The good news is replacing the upper tensioner did the trick. No more noisy morning starts.

 

The bad news is the upper tensioner is a ***** to get at. I had to pull the AC compressor all the way out to get access to the tensioner. Then down near the tensioner there are some hoses you need to unbolt and relocate to get the 24mm(?) socket on the old tensioner. The new tensioner uses a 14mm hex head which is much easier, but I didn't have, so trip to NAPA. 

 

By far the hardest part is the AC compressor. Its front two bolts are easy, but the back bolt you can't see. I used a mirror to locate it, and it must have taken a half hour to find it. Next time, 5 mins. putting the compressor back in is tricky because you need make sure the back bolt does not slide down and hang up on the engine while you are sliding it back in. I rigged up a piece of wire to hold the bolt up that I could pull out once the compressor was in place.

 

At the same time I replaced the water pump/coolant, replaced the OEM thermostat with a Raby thermostat and installed a new coolant reservoir tank, so I had the motor dropped a couple of inches which helps. 

[Ahsai]

Glad to hear you fixed your issue. Agree that a/c bolt is so easy after you removed it once.

[996_Driver]

What version of tensioner did you buy? I am a little hesitant to do this, but it sounds like something I am capable of. 

[Cefalu]

I don't recall the version, except that it uses the 14mm hex drive which is characteristic of the newest version. Call Suncoast Porsche for the latest part. 

[Beau911]

When you replaced the upper chain tensioner, did you lock the cams before removing??

[IslaTurbine]

On 5/6/2018 at 10:08 PM, Beau911 said:

When you replaced the upper chain tensioner, did you lock the cams before removing??

 

My understanding is that only 3-chain engines must have the cams locked. Locking the crank at TDC will suffice for a 5-chain engine. Hopefully someone more knowledgeable than I will jump in to confirm. 

[JFP in PA]

55 minutes ago, IslaTurbine said:

 

My understanding is that only 3-chain engines must have the cams locked. Locking the crank at TDC will suffice for a 5-chain engine. Hopefully someone more knowledgeable than I will jump in to confirm. 

Bad idea.  ALL M96/97 engine variants should be at TDC with the cams locked before pulling any of the tensioners.  Some get away not doing it, but that is more a matter of luck the correct procedures.

You are also replying to a two year old posting.😉

[IslaTurbine]

1 hour ago, JFP in PA said:

Bad idea.  ALL M96/97 engine variants should be at TDC with the cams locked before pulling any of the tensioners.  Some get away not doing it, but that is more a matter of luck the correct procedures.

You are also replying to a two year old posting.😉

Fair enough. I’ve been on and off RennTech over the years and know you’re very well versed and respected on these types of things. But out of sheer curiosity, how can a five chain motor have a cam skip if only one actuator is changed at a time? The cams are interlinked so I don’t understand how there’s any risk. 
 

Zombie thread bumps can be head scratchers, but I also hate having a solid question go unanswered. 🍻

[JFP in PA]

Much like the the dual row IMS bearing don't fail as often as the single rows, but still do fail; removing the tensioners, even one at a time, can induce quite a bit of slack in the long chains running from the cams to the IMS shaft.  If they are already stretched from normal wear, it can be just enough to create a situation you really don't want to be in, namely an otherwise unnecessary cam reallocation exercise, for which most people do not have ready access to the required fixtures.  Better safe than sorry.