Another chain tensioner question

[golfbuddy]

After looking at many posts, it seems that many feel that upgrading the chain tensioners is a must. Is this because of the amount of miles on the engine? I just got an 82 SC with 80k documented miles on it. Runs great. So with doing the upgrade costing $2k, I am wondering if it is needed at this time.
Also, how many have had their chain tensioners fail and how many miles on it at the time.
Thanks

[Jack Stands]

Back when the update kits were only a few. Hundred bucks and you could do the update yourself, I'd say it was a no-brainer to do it. However, if you have the clamp-on collars on your tensioners (so they can't fail completely and allow the engine to lose the valve timing or other chain problem), you should be safe. I don't hear as much about the sooner failures now when I compare to the late 70s and 80s.

I'd do the update when the engine has to be out for other procedures unless you can do the work yourself as a nice project. It's not that hard of an update if you're handy.

[stormcrow]

I have a 78 SC Targa that I rebuilt and put 80,000 miles on it. I have the existing chain tensioners installed. I took both apart and checked the springs - never had a problem.

[Trackrash]

The collars are a must. The problem with the "old" style tensioners is they only have a limited supply of oil in their built in reservoir.

It is not too hard to rebuild the stock tensioners, and with the collars you will be good for many miles.

[Sunroof]

Changing over to the hydraulic chain tensioners is the best insurance you can have. When considering the damage caused by "valve crash" and the cost of repair its well worth the change over. Anyways, any educated Porsche buyer knows that the two critical upgrades before the 1984 Carerra is the pop-off valve and hydraulic chain tensioner. I would not buy a used 911 unless I knew both upgrades were completed. You might find this out when its time to sell.

My 2-cents

1973.5T 911
1974 911
1979 911SC

[The cap'n]

I disagree. I've been working on 911s for 40+ years and have done only ONE chain tensioner "update". Note I said "update", NOT "upgrade" These fail, too. A properly done late SC update, along with carefully rebuilding the tensioners and installing chain guards is FAR less expensive and lasts for a long time. I just rebuilt a set in an 83 cab, a 30 year old car. I suspect it'll last another 20-30 years.

The Cap'n

[stormcrow]

Gordon

On my tensioners there is an adjusting screw that is backed up with the spring. Once the tensioner is adjusted, there is a lock nut that locks it in place. Between the locknut and the top of the rod that comes in contact with the tensioner arm I installed another nut that takes the place of the collar.

Like I stated previously I have had these tensioners in the car since it was new - did the rebuild after 80 thousand miles - and put another 80 thousand miles on the car and never had a problem.

[The cap'n]

Genuine Porsche chain tensioners have no adjustment. That's the whole point of the design, they maintain tension using a method somewhat like a shock absorber. There have been a number of attempts (notably the temperature compensating Hoeptner Improved Products tensioner) and a number of solid designs. While I haven't seen the type you have, I suspect it's some kind of hybrid. I tried the HIP tensioner when it came to market, and found they didn't really survive as long as the real deal. I would never again put an aftermarket design chain tensioner in a 911. Anectdotal evidence is nice, but a one person/one car argument doesn't mean very much when it's up against dozens or hundreds of examples in the real world.

The Cap'n

[RSTarga]

930 tensioners, when correctly installed, are every bit as good as the newer hydraulics.

[stormcrow]

Well Cap"n I don't disagree with you that the tensioners you have seen have no adjustment but mine does. They were installed as original equipment on my 78 911 SC Targa.

I might have a picture of them when I did the rebuild on my engine - I will see if I can find a pic to post.

[Jack Stands]

There is also a school of thought that part of the tensioner problem was too small of a bearing surface on the idler arm pivot, causing binding. When Porsche went to the oil fed tensioners, they also upgraded the idler arms, so that may have been the 'fix' all along.

There was another design back in the day that had a ratcheting mechanism built into the design to make up for chain stretch over time, but my vintage brain can't remember the fellow's name anymore, and they are no longer being produced.

[RSTarga]

part of the 930 upgrade are newer idler arms and spacer, along with ramps