Timing chain link-o-mystery!!!

chrisf · 10-05-2006, 04:09 AM

First, just a little back ground. I got a 76 911s back in June. Original, non-rebuilt 2.7 (tensioner updates). Car has been running great, but recently developed an exhaust leak at the header manifold. I decided this would be the right time to adjust the valves, change filters, etc…..Tear down has been going wonderfully. The most troubling part (until now) was looking at the extremely rusted exhaust nuts, but they came off well, only pulling (4) studs, which will be replaced. I’ve never worked on a 911 myself, and I am amazed at how quickly I was able to strip this thing down!! The only thing left that I would be comfortable removing with the engine in the car would be the fan, intake, and the timing covers, which brings me to the purpose of this post.

Yesterday evening, I finally got around to pulling the strainer from the bottom of the cases. Now, the way this happened is still tripping me out. I stuck my hand inside the case and pulled out……..what I now know to be the small clip for the timing chain master link! It was just laying in the bottom of the case! The tensioner update was done back in March of 2005, perhaps the mechanic shot this clip from his pliers, couldn’t find it and said f’it and reach for another? Maybe not.

I’ll be pulling one or both of the timing chain covers to search for this missing clip on the chain. Typically, is the master link inserted from the back of the timing chain, meaning that I would be able to see that the master link clip is missing? And are the any special considerations before I remove the timing covers, which side would be easier, etc?

Thanks for reading my post and any advice is much appreciated.

Chris

mb911 · mb911's Garage

I would assume the same thing as you but would check it out to verify everything is good to go

Thomas Owen · 10-05-2006, 05:01 AM

Well you may have found this just in time and be extremely lucky. If you find you need another chain (with master link) let me know. I bought one a few years ago and never used it - still in original box. You can have it for the shipping.
Good luck -

2.7RACER · 10-05-2006, 05:51 AM

Chris,
Remember, the clip is oriented closed end in the direction of chain travel.
If it is sprung at all don't use it.
Good luck,

chrisf · 10-05-2006, 06:29 AM

thanks so much for the replies. Thomas, I may contact you about your chain, but will check the condition of mine first, as I believe it was replaced when the tensioners were installed.

I will note the oreintation of the clip, 2.7racer. Clip was in good condition, flat & closed, so I believe I will reuse it.

I'm hoping that I will be able to find the master link, and it will be all there, i.e...this little clip was just dropped in the case.

Which side cover would be better to open, left or right? Is there a reason to open both sides? And any special considerations when dis-assembling or re-assembling the timing covers?

Grady Clay · 10-05-2006, 06:42 AM

Chris,

I agree, it probably is an “extra part” but I wouldn’t take any chances.

Yes, I would open both sides just to look and have new gaskets.

Were the six (5 of one kind and one of another) plastic chain ramps changed with the tensioners? Were the idler carriers up-dated?

Some things to be careful of:
When in your chain covers, wire or zip-tie the chain idler sprocket so the chain can never get any slack. It is possible for the chain to jump a tooth with a slack chain. The cam is then out of time, valves can hit pistons and worse things can happen from there. A little care goes a long way.

This might be a good opportunity for you to just measure your cam timing. Easy to do and a good learning experience with it semi-apart as you have.

If you need to replace the chain, it is necessary to turn the engine by hand. You must not let the valves touch the pistons. The best way is to remove all the rocker shafts. Some only back off the valve adjusting screws. After replacing a chain(s) it is necessary to re-time the cam(s).

Before you get too carried away in this project, I recommend you check the cylinder head nut torque. This is a weak point with the 2.7 engine (it pulls the head stud threads in the crankcase). Use a calibrated torque wrench. Check them at 60% torque spec and then at 80%. There isn’t any need to torque them to spec and risk one pulling. If any move at 60% or 80% - stop and let sleeping dogs lie.

When you are searching for the master link, remember to turn the engine only CW at the crankshaft (cams turn CCW).

If/when you take off the intake, be very careful to not have something drop in an intake port. The fiberglass fan shroud acts like a funnel and the open port like a magnet.

Best,
Grady

dtw · 10-05-2006, 06:57 AM

Quote:

Originally posted by chrisf
Which side cover would be better to open, left or right? Is there a reason to open both sides?

Just to clarify - the 911 engine uses separate duplex chains for the left cam and right cam. So if you opened the left cover and found a master link, you'd still need to check the right side and look for another master link on that chain.

Welcome to the board!

chrisf · 10-05-2006, 07:03 AM

Grady:

Gaskets & hardware ordered.

Not sure about the ramps & idlers. I wasn't planning on going this far, but will note the condition of these parts.

I was planning on checking head nuts once I completed the valve adjustment. What size allen wrench is used for the head nuts?

I am hoping that the studs are still sound. The engine ran fine and smooth before I started. All cylinders & heads were dry, except 6, the one by the oil cooler (which leaks a little). I definetly won't go over 80% of final value.

thanks,

Chris

chrisf · 10-05-2006, 07:05 AM

dtw:

noted. I will check both sides.

kühn tune · 10-05-2006, 08:39 AM

I ordered a set of chains that sat around for months before I got to them. When I went to put them in, one set was missing the entire master link. I purchased a master for a Mercedes or BMW (I can't remember) that used two circlips, one on each prong rather than the long clip that covers both. Someday, someone may be going mad trying to find that lost clip in their engine.

chrisf · 10-07-2006, 07:20 AM

Well, turns out that the master link did indeed pop the clip!! I removed the driver's side cover, spun the crank until I found the master. No clip on it, and the cover link was pretty loose! It was almost off. snugged it up from the front & back and installed the clip, closed end in direction on travel. It went on with a very satisfying snap. I can't understand how it could have popped off. So I checked the passenger's side, and the clip is installed with the open end in the direction of travel. Could this perhaps be the cause of this near disaster? I will take this clip off & reinstall. Gaskets won't be hear until next week, so I can go back and re-oreintate if necessary.

Every thing else looks wonderful in there. Chains are very tight & clean as are the ramps. Every thing looks very new.

This is really exciting. The only tear down left to do is to remove the oil tank & clean it. After that, it's re-assembly time!! This minor tune up has turned out to be quite a task & a great way to break into building first hand experience in working on the 911.

Thanks for the support ya'll. I think I'll go change into some rags & start turning a wrench. later.

Thomas Owen · 10-07-2006, 08:08 AM

In the past I have seen master link installation instructions with the clip ends specifically away from the direction of travel. If it was me, I would not put this clip back on and button everything up. You have to assume the clip was already installed once and came off once. The second time could be true disaster!
Either research the installation procedure and reverse the clip if necessary, or put a whole new clip in there.
Good luck