3.2 Chain Case oil weep minor issue I hope

[steely]

Would anyone know of the proper stud I should use for the passenger side chain case-to-crankcase at the top behind the oil temp sender (see pic)? (M8? And length?)
Or, can I get away with just tightening the shouldered bolt (and do I need a washer to take up the remaining gap left by the bracket I removed)?

Background
I have a small oil leak that I may have caused.
I removed the A/C Compressor bracket a few years ago, but I did not replace one of the (shouldered?) bracket bolts out of ignorance. This is /was (apparently) a dual purpose bolt that supported a compressor bracket brace, and it served as a fastener for the Chain case to crankcase. I thought it only was used to support the compressor bracket.
I became suspicious when I started having a weeping leak at the bottom of the chain case / crankcase interface that comes down the ‘back’ of the chain case. I was afraid it could be the Cam O-ring or worse, something to do with the #4 Cylinder gasket.
Only while investigating this did I realize this nut was only finger tight and what it’s other job was.
The torque is supposed to be 18ft-lbs according to Bentley.
I cannot find the info in the PET for this particular stud – probably M8.

If you removed your A/C what did you do?
Many thanks,
Dan

[steely]

Here's a shot from under the passenger side chain case showing the leak before I cleaned it up, and after a few miles of driving, the gasket gets wet. It is the low point, but I don't think it is coming from the cam (I hope anyway).

It's not the end of the world, but I'd like to fix it.

[proporsche]

Hi Dan..if you have removed the bracket replace this special nut with regular alu washer and nylon nut.

if it is leaking after, it is most likely your chain housing vertical housing gasket

Ivan

[steely]

Thanks Ivan, I appreciate your help very much, but that circled item is actually a bolt (with what I call a shoulder). In the pic, it is fully seated even tho' there is a gap showing.
I was looking for a proper stud to put in there so I could use a nyloc.
I can remove it and take a picture if you'd like.

[proporsche]

hi..it should be a nut ..yours is stuck on he stud....look here behind the oil pres sending unit
Ivan

[proporsche]

the nut number is 964 126 125 2o

[Flat6pac]

Pull the shoulder nut and install a nyloc.
What you have there is already tight and it’s not your leak.
Bruce

[steely]

Originally Posted by proporsche

hi..it should be a nut ..yours is stuck on he stud....look here behind the oil pres sending unit
Ivan

You are right - major mistake on my side - it is a nut and there is a stud
I will just get a washer and nut.

[steely]

Originally Posted by Flat6pac

Pull the shoulder nut and install a nyloc.
What you have there is already tight and it’s not your leak.
Bruce

Will do Bruce thanks - I'm hoping you're wrong b/c the nut is only finger tight for now, but I'll torque a nyloc on there and keep an eye on it.

[KTL]

I don't want to be a Debbie Downer but that leak does look a lot like the drip you'll see when the camshaft thrust plate gasket needs replacement.

If you do have to replace that gasket, I strongly suggest you flatten the thrust plate by sanding it on a true/flat surface. You'd be surprised how uneven that plate's gasket surface is, even though it's a finely machined surface. It's also a VERY good idea to flatten the gasket surface around the bore of the cam housing. But that's not easy to do with it installed on the engine!

[steely]

LOL Debbie Downer - But honestly that was my initial concern.
Is there Any way to put eyes on this w/o tear down or determine from drip path?
I don't think dye will help b/c I can't see the source anyway.
Am not sure if the leak is using the lower tin baffle plate to travel along the chain case rear and throw me off. (ignorant hope)
Can't see squat looking down with front shroud removed.
How long can I live with it?
If I do one side, I suppose the side is other warranted?
Thanks for the tip Kevin re: thrust plate flattening.

[KTL]

Hey Dan,

I think you can take off the valve covers and that'll give you a look at the back of the chain box where the thrust plate mates with the bore in the cam housing.

https://forums.pelicanparts.com/911-engine-rebuilding-forum/738419-specific-question-arp-head-studs-2-7-magnesium-case-insane-6.html#post7456800

[steely]

Originally Posted by KTL

Hey Dan,

I think you can take off the valve covers and that'll give you a look at the back of the chain box where the thrust plate mates with the bore in the cam housing.

https://forums.pelicanparts.com/911-engine-rebuilding-forum/738419-specific-question-arp-head-studs-2-7-magnesium-case-insane-6.html#post7456800

Thanks Kevin. I will prepare to do that in the next couple of days. I appreciate the link.

I am collecting some other threads so I can scope the job and see if I want to tackle it myself (with help as opposed to taking her in).

Drove it on some errand runs and she showed a drip on the crankcase side of the chain box vertical, but I need to cool her off before I get under and look. One of the errands was to pick up some M8 nylocs, probably a fools run, but I will replace the AC nut when she's cool.

So do I understand that this will involve a valve adjustment, engine drop, sprocket removal, gasket/o-ring, and inspection of the tensioners, guides, chain and sprocket teeth? I need to figure out if an amateur like me can tackle the timing and parallelism requirements not to mention getting the special tool(s). Maybe a winter job.

[KTL]

Well I recall DRACO A5OG Jim mentioned awhile back that he was able to remove the cam housing and retain the timing by marking the sprocket. Basically if you index the sprocket on the cam and on the chain in the same location, your timing should end up being the same.

https://forums.pelicanparts.com/911-engine-rebuilding-forum/948857-part-trois-3-4l-build-journey-4.html#post9570894

Also you shouldn't have to re-shim the sprocket if the parallelism is already OK. Honestly I found on my former '87 engine during a top end job that the right side sprocket was previously installed backwards by someone prior to me owning it. So the parallelism was apparently way off. I didn't check it to see how far off it was. I just noticed the sprocket wasn't flipped with the dish facing inward. Didn't seem to cause any major issues in terms of side wear on the cam sprocket, idler sprocket or the chain.

https://forums.pelicanparts.com/911-engine-rebuilding-forum/334465-rocker-arms-shafts-wear-condition.html#post3152085

So my point is that you should be able to put the same shim count back in place and call it good. That is, as long as your sprocket is oriented properly!

Timing is actually really easy and we all seem to over-think it. There's only a few special tools like the Z-block and the dial indicator for the timing. Oh and there's the sprocket holding tool. I also have the parallelism tool with the straight edge and the mounting block if you wanted to borrow it.

[steely]

Can't thank you enough for getting off on the right foot, you just gave my confidence a real boost. I'll read that material, study the projects, and brace for slippery slopes. And thanks for that anecdote about the flipped sprocket (I guess there's some margin) and your very kind offer. I will try to source it around here and will let you know.

10 years and I've never browsed the rebuilding forum - this could be a new addiction.

[steely]

UPDATE - I replaced the shoulder nut with a nyloc and washer, wiped down the bottom and rear of the chain case and block (either side of the interface) and have yet to see a leak. I've only put a 100 miles on it since then, so I will continue to monitor. It had been getting wet within a day, so I am hoping this was the cause.

I could not torque the nut to spec b/c the oil line is in the way, but it is tighter than I had it before. Eventually I will remove the oil line so I can get a socket wrench in there - I just used an open end wrench b/c it was all that would fit. I've been a bit side tracked with another (broken rear sway bar mount) issue.

I was going to wait to see if I still had the leak before I removed the top rocker arm cover to inspect the cam gasket, but nothing is migrating down the vertical. This may take a while if it is weeping slowly, so I have some time and will keep an eye on it.

From looking at a picture of the chain case gasket, it looks as though there's no hardware along the 'rear' case seam between the bottom and the top, unlike the 'front', so I am optimistic the single loose top nut was the cause (fingers crossed).

Thanks for the input Ivan, Bruce and Kevin.

[KTL]

Great news!