Auto_Werks 3.6

This is related to a thread that I started over on the 911 board regarding my '89 carrera 3.6l conversion. It looks like I will need to replace the timing chain tensioners and probably the ramps while I'm in there.
I just wanted to see if anyone else has done this as a DIY repair. Also is there a good shop manual available which covers tearing down a 964 engine, as well as valve adjustments, cam timing etc...
Thanks for any help or suggestions you might offer!

Auto_Werks 3.6

OK.. so I did some searching, and it doesn't look like the tensioners themselves are that hard to replace, but I don't see many people replacing the ramps. Is there any trick here? Is there a quick and easy way to make sure the cam doesn't skip out of time while the tension is off?

garrett376

If you leave the rockers installed, the cam is usually held pretty snug. But, you still need to check the timing...

TR6

Completely off topic, but I'd love to see some photos of your TR250. One of my favorite all time cars!

stevepaa

I have some ramps from a Porsche parts supplier that are new but the nipple in the hole does not catch. Some people say it doesn't matter, but I opted to buy a second set from Porsche dealer that were not "discrepant". Make offer if you would like them.

Auto_Werks 3.6

Steve, for now I'm going to pass. I want to make sure that this all goes back together properly if I'm going to take the time to do it. Are OEM porsche the only parts that install properly??

Greg, I will see what I can do about some pictures... The TR250 is kind of a long story. Im in the process of selling my old one that was highly modified, but taken apart. My dad and I became partners in a completly stock car that was restored in the 80's. There is no rust *anywhere* on the car, but the paint and primer had a chemical reaction to each other, and the results aren't pretty.

Auto_Werks 3.6

Out with the old....

chancecasey

The "tensioners" in the 3.6 are "bananna ramps" unlike the sprockets used before. 2 of these and 2 straight ramps, plastic. I wouldn't bother replacing them if you aren't replacing the chains as well. Chain stretch is more detrimental than ramp wear. They say the ramps get brittle over time - not sure if anyone has seen one break, though.

Although not for the faint-hearted, you can replace the chains without cracking the case with master-link chains. It's pretty tricky to feed them through, and, as I think i've posted here before, the little e-clip on the master link will pop off on the 964 ramp "lip", so you'll have to shave the lip down.

Auto_Werks 3.6

Chance, I know exactly what you are talking about..

ala thread "help with timing chain"



What I don't know is how they come apart... and I also am trying to find out where the 5 smaller ramps are (or at least pelican says there are 5 per car), and how they come apart. Maybe the my thread should actually be titled "looking for 964 engine manual".

Auto_Werks 3.6

OK... Now I've got it. The 5 per car was for the early turbo. My mistake!
4 total guide parts for the 964 NA, and the "tensioner rails" are the same for both side. I guess now all I need are torque specs, though common sense would tell me the bolts in this assembly are not very tight.
Just for the archives I'm attaching the parts diagram for one side. I really feel a little simple now, but I'm just a little nervous about tearing into my engine!

chancecasey

See the little brown disc to the lower right of the marker cap? Unless you are extremely skilled or lucky, that sucker will crack/break when you remove/replace it as it gets brittle over time - it holds the ramp onto the vertical piece that bolts in with 4 bolts there.

You can't remove the chains without either breaking them or splitting the case.

FYI this was one of the trickier parts of my rebuild, getting those ramps in just right and then stabbing those long screw-in pins that hold the "crank side" of the ramps in place. Getting the chains fed over the drive and cam sprocket just right (sounds easy) can be a b*tch also - took me a good hour or so and then *pop* it just sets right in and I'm not even sure what it is I did right. You will say some choice words before it's over.

I'm wondering if it's worth it - what's the mileage? Have you taken a dial indicator to check where the valve timing is at TDC now? What's your rebuild plan?

Auto_Werks 3.6

As far as rebuild plans go, I hope not to have to.. The documentation I have for the car is somewhat sketchy, but the engine should be relatively low miles (~60k). It runs great, doesn't smoke, and uses no oil. The only problem I've been having is a cold start chain noise that my mechanic verified as sounding like a "tensioner problem". I think the car did quite a bit of sitting around after the previous owner passed away, so I think the tensioners might have become gummed up from sitting. Or at least thats what I'm hoping for, rather than stretched chains.

Is that little brown disc a separate part, or is it part of the aluminum block (part #17) in the diagram I posted?

stevepaa

See item 24 on 103-05 for that little "bearing".

chancecasey

A little chain rattling noise at cold startup can be *normal* - do a search for that. No leaks and no smoke at 60K - unless it's been abused by oil starvation it's probably good to go.