jax

My girl has 170k on her, some of it borrowed time as I have the records since 90k and there is no variocam (or any head work for that matter) to be found. Perhaps part of the reason it has survived this long is the specialist doing the waterpump, belts, and seals 40k miles ago put the lower BS Gear upside down preventing the PO from comfortably driving her past 4k rpms.

ANYWAY... I have highlighted in yellow all the stuff I am buying and I was hoping some of you could do a quick scan for any pieces you see I missed or anything else I should do while in there.

Unfortunately, a full rebuilt variocam assembly was $1,860 so I am hoping I can just replace the stuff on the DIY that Raj and Arash made and not double the cost of this maintenance. If my engine makes it through this, next will be rod bearings, oil pick up and probably a bunch of other stuff that I dont know yet.

Since it is almost halloween I will tell you what scares me most, seeing what my cam sprockets look like when I open her up (re-timing cams is a close second).

Thanks for everyone's help.


----------------------------------------------------------------------------


----------------------------------------------------------------------------


----------------------------------------------------------------------------


----------------------------------------------------------------------------


----------------------------------------------------------------------------


----------------------------------------------------------------------------


----------------------------------------------------------------------------

tamathumper

With that many miles, if you're putting in a new tensioner, I might recommend a new tensioner bolt as they've been known to shear off with catastrophic results. It's just a prophylactic measure, but then again so is maintaining the rest of the timing belt/roller system.

RajDatta

There is no lower roller on 968's (#7) even though the manual shows it. Also, use blue lock tight on the bolts for the roller and #15 nuts. I know someone who had one pull out on them and cause severe damage.

docmirror

Number 15 on 103-15. For the lower balance shaft, it gets a lot of heat from the exhaust and fails all the time. I don't think you need to replace the tensioner per-se. It's a non-movement item, and failure rates are non-existent. Inspect the upper cam pulley carefully and replace as necessary. Cam chain, and tensioner pads are a must.

dougs968

Might not be a bad idea to replace the disc valve, PN/ 928 574 573 03, POS 25, illustration 105-05.

Doug

jax

Thanks!

What specifically should I look for on the upper Cam pully? Wear? Fatigue?

I am use to having extra parts after I put something back together, so I appreciate your advice Raj, and also for saving me $40.

Doug, did you ever make CAD for the Cam removal tool you machined? I think I might make a set out of wood.

docmirror

Pulley wear. Put a small straight-edge across the tooth and check for a gap underneath. The 928 guys are looking into re casting them or metal coating. Not sure what's avail right now.

tamathumper

I'd be very interested in the dimensions of the camshaft bridges. I have a CNC machine and a wooden copy from a fellow member, but I can't verify the actual dimensions.

Rob in Oz

Sorry to semi-hijack this thread - but it is relevant. I'm in the middle of doing the belts on my 968 and am stuck at the point of removing the tensioner arm (#10 in 03-10 kindly posted by the OP). I've removed the retaining circlip and washer and released the tension on the cambelt, but the tensioner arm doesn't want to slide off the pivot, although it pivots quite freely. Am I missing something here, or is there perhaps a slight wear ridge on the pivot bolt preventing removal, or???

Edit: A bit of judicious levering and wiggling got it to move along the pivot, to the next impediment - about 1mm overlap with the crankshaft pulley prevents further movement. I was hoping to not have to remove the pulley, but it looks like I'll have to borrow a crankshaft lock tool and remove the pulley...
Thanks
Rob

dougs968

Jax, I'm sorry but I never did get a CAD print made. I would be more than happy to send any of you guys a copy of my hand drawn prints. Just PM me your info. What I can tell you right now is the center to center dimension of the camshafts is 4.310 inch. The camshaft diameter under the caps is 28mm or 1.102 inch. These are probably the most important to get you going.

On your belt gears, check for chipped teeth. The small crankshaft gear ( #15 ) had a chipped tooth on mine. May have been OK to use, but I replaced it with a new one.

Doug

kwikt

If you can send me that Doug. that would be great. I may have a friend try fabricating a set.

dougs968

Give me a day or two so I can clean up my prints. I need to add some stuff so that you get the whole picture. If one of you guys want to PM me your number, I can send pics from my iPhone, if somebody wants to post them up here. I don't have that skill yet. I have a spare stripped head that would work as a good subject with the tools.

Doug

jax

I just edited the original post because I forgot diagram 103-05.

$1500 doesn't get you much these days!

kwikt

Don't tell me you're looking for the infamous "pot metal" distributor housing.

jax

I already got one of those...



That is why it is not highlighted on 103-05!