chain tensioner failure poll:

[sammyg2]

The recent debates about tensioner upgades has me curious, how many folks here have actually had a tensioner fail on their 911? (no brother's best friend's cousin stories please)

[Jim Harlan`]

Three times (at least)

1967 911
1977 911S
1984 Carrera

I think the 1984 went twice. It failed at 96,000 miles got replaced and then I got a very bad mechanical noise at 122,000. My wrench may have told me what it was but I don't remember, but reading here I think the 'guides' went, but I'm not sure.

I remember clearly on the 1977 and on the 1984 the wrench saying the new tensioners were the same as on the turbo and 'nothing could go wrong'!

Next time, knock on wood, I'll fix 'em myself! (Of course with everyone's help here!)

Jim Harlan
in Utah

'84 Carrera

[Wayne 962]

Define "fail"

-Wayne

[Jim Harlan`]

Hi Wayne!

Failed for me is when I had to pay, what, $1500 or $2000 to have it fixed! I can't remember the symptoms, I was dependent on my wrench. I have been stranded on the road many times. That's probably what started it. Of course my wrench may have needed some funds for his kid's orthodotist!

Thanks for a great site!

Jim Harlan
in Utah

[3.2 CAB]

Very interesting, it seems the carrera tensioners have had the most failures. I know that I am still in the process of replacing mine due to the right side failing, no engine damage, just the chain dragging in the case.

[Siena911]

on my 84 motor the rhs went and it did the chain dragging through a dustbin sound.

They were both replaced.

As it is an upgraded motor from the standard 3.0 which the PO had done, I am not sure what mileage the 3.2 had in it.

Cheers Jakes

[mb911]

My 3.0 liter when purchased had 2 collapsed stock tensioners . Went to pressure fed no problem since

[jabb]

I had a pressure fed tensioner fail. The liitle valve on the top
of the tensioner popped off. When ever the motor was hot
the oil would seep out and the chain would knock.

[Danskman]

I think due to the age of the cars, we are getting quite a distorted picture of the tensioner failures. I recall in the early/mid-eighties when I was a parts mgr at a Porsche dealership, we had numerous cars in the service department due to tensioner failure. I recall having over dozen loose tensioners in stock (with overnight replenishment) and five or six of the complete update kits on hand at all times. This was at a time when these cars were numerous, and being driven a lot - maybe similar to a Boxster of today. Take this same snapshot twenty years ago, and I think it would be similar to today's Boxster owners complaining about rear main seals. Twenty years from now, this Boxster RMS issue will still be one to deal with, but not like it is today.

[asphaltgambler]

Bought my '85 Targa, 2 months ago, 1 month ago (on a road trip) started making noise from the right side, got worse as we drove it. Was in the middle of nowhereville and no cell reception and it really started to sound bad.

Decided to drive it (I know) slowly until we could at least find post-deliverance society. then .........BAM!! engine kept running, nothing kicked outside the case but lost oil pressure immediately. coasted over to the shoulder.

I was pissed at the car, then myself and then thought this was just a good reason to hot-rod the engine and fix the trans while I'm in there!!

[911pcars]

Not sure what these final numbers will reveal.

The bar graph only reflects a relative number of failures and not failure frequency compared to their use. For example, the number of late 911 owners actually using early tensioners is practically zero (0).

... and from the poll results shown as of this date, one might incorrectly assume the oil-fed Carrera tensioners have a higher failure rate than the other types.

One might also assume mechanical tensioners are preferred due to their low failure rate, yet many (but not all) engine "experts" do not recommend using them.

Perhaps more poll choices and the ability to choose more than statement would reveal more useful information; e.g.:

I used early tensioners that have failed
I use/used early tensioners that have NOT failed

I used Carrera tensioners that have failed
I use/used Carrera tensioners that have NOT failed

I used oil-fed tensioners that have failed
I use/used oil-fed tensioners that have NOT failed

Sorry, I must have felt a little too anal this morning.
Sherwood

[sammyg2]

my definition of failure as it pertains to this poll is, any time a tensioner fails to perform as designed and has to be either replaced or rebuilt.

This is only for informational purposes and I'm not trying to make a point, like I said i'm just curious.
I intentionally did not include anything about severity of failure or what the failure did as far as damage to the engine.
My very limited understanding of the results of a typical failure is that on an oil-fed tensioner a failure makes noise and requires replacement but probably doesn't cause severe damage the the engine, while a failure of an earlier non-oil fed tensioner has the potential to cause valves to hit pistons IF it doesn't have the safety collars. The earlier tensioners also have the potential to fail due to galling or breaking at the bracket.
Is that generally correct?

[dd74]

When I had my 2.7, TRE prescribed Carrera chain tensioners after a hard, clattering mechanical sound came off the right side of the engine after a nice brisk drive in the canyons, or when the engine got hot.

At the time, they gave me a second option, which was a 3.0 replacement, given all the other maladies that could plague a sketchily documented 2.7, so I pulled the trigger on a 3.0.

At the time I bought the engine from Supertec, Henry Schmidt strongly advised against placing Carrera chain tensioners on the motor, with the fact that they were no better than what came on the engine from the factory. Granted, he could have taken the $1,400 I offered him to install the tensioners, but he said I might as well go with mechanical tensioners IF I were racing the engine on a full-time basis.

Where has this left me? Without a failure so far, and on stock tensioners. This is after three years, and a couple of strong sessions at Willow Springs.

YMMV of course.

[911pcars]

IMO, a tensioner failure of any type has the potential to destroy the engine. Without adequate tension on the chain, it will flop around and, if not attended to, will beat up the chain box; worst yet the plastic chain ramps, until they break. When that happens there's a strong likelihood of a piece of ramp falling between the sprocket and the chain which will result in the instant retiming of the cams followed by a crash between valve(s) and piston(s).

If you hear a clattering sound from the engine that is louder at lower rpms, it's probably a chain tensioner that has gotten soft.

For a street prepped car, I would recommend any of the hydraulic tensioners (self-contained or externally-pressurized).

Sherwood

[Ray B]

I've been thinking about this one as well. My street/track car has the original tensioners. I think it is safe to say that both the pressure-fed and the original type hydraulic tensioners will fail eventually- moving parts, rubber gaskets-it's only a matter of time. The question is: What happens when they fail? Obviously if you drive around with chain clatter from a failed tensioner of either type, you are asking for trouble. Given the fact that either can fail,why not rebuild the originals and install (with loctite) collars?? That way seems as bulletproof as the pressure-feds and less costly.

[Kraftwerk]

Ray,
I have wondered about this myself as an option, since I am riding all original gear on a 105,000 mile car. Also, don't particularly like the looks of all those banjo fittings and extra oil lines associated with the oil-fed tensioners, thin argument , I know but still...
Mike on the other hand, has a very good point about actual useage....
jt

[asphaltgambler]

As a Technician I see are lots of other types of engines that utilize hyd chain tensioners. Believe me they fail on occasion too. The real advantage about the hyd tensioner is that it ALWAYS has the proper amount of tension on the chain drive for that particular application.

Like anything mechanical, there is the chance of the original design or manufacture not being up to par. I think the real question is; if that is the only weak link, then Porsche must make a really good engine!

[beamonk]

Why do you guys have to bring this up just as I have track weekend a comin' ?

[al lkosmal]

Rebuilt my 2.7 75K ago or so.No failures w/standard tensioners w/hydra-stop collars. Add a no failures selection. The hydraulic tensioners just looked like adding more potential failure points.

[911pcars]

As opposed to self-contained tensioners, the oil-fed tensioners do not use rubber or silicone seals or O-rings to work; they are designed to leak a measured amount of oil (clean oil helps) under normal operation. The only O-ring is the fitting seal at the chain box cover.

Sherwood