'65 Differential Cover cracked?

[Oliver S.]

Hello,

I had my differential resealed this spring - it was out for this purpose. After experiencing posi noise an additional bottle of posi fluid was added. Some diff. oil had to be removed. So far so good.
Now I discovered that it is leaking - where the spring bolts are. I brought the car to the shop and they'll have a closer look tomorrow - removing the spare tire and its mounting for bettr view. Asked if they know about the problem of cover crack they said no. Having had a short look they said that the oil could come from the top, but the air vent doesn't show a trace of oil.
Suppose that they won't find an obvious leak - what is a suitable and easy methode to check if the bolts cracked the cover. Remove/Reinstall one by one to see if oil is dripping and the bolt thread is oily?
I may be in need for some arguments.

Regards
Oliver

[Jim D.]

Re: '65 Differential Cover cracked?

Were the 4 spring bolts tightened with the weight of the car on the spring? If they were tightened with the ends of the spring hanging free, that can and will crack the housing.

[Wayne M.]

Re: '65 Differential Cover cracked?

Oliver -- fair amount of info in previous threads; here's one to check original bolt lengths:

https://www.forums.ncrs.org/showthread.php?t=29771&uid=5200[IMG]http:

Here's a pic of originals; note small number of threads, to ensure not screwed in too far on the forward two bolts

[Oliver S.]

Re: '65 Differential Cover cracked?

@Jim, I'm not sure on this since it was done by the shop.

[Oliver S.]

Re: '65 Differential Cover cracked?

@Wayne, thr previous owner installed a mono leaf spring. I assume that special bolts came with it. Crawled under my car in my garage on Sunday here are two pics of the bolts. The oily one is from the back the other one from the front.

I hope its not the cover - but...

Coming back to my initial question - how can it be checked if the cover is cracked without removing the diff. or spring.

Oliver

[Gary R.]

Re: '65 Differential Cover cracked?

Hi Oliver,
Differential oil leaks only can come from a couple of places:

1- Pinion Seal
2- Side Yoke seals
3-Cover gasket
4-Cracked cover holes
5-Overfill- comes out the vent
6-Cracked Carrier(housing)

#1-2 are the usual leak areas, however #4 sounds more like what you have since you have a question on the length of the spring bolts used. I've seen wrong size bolts come with 'glass springs before.

Here is a cover with a broken inside hole casting. I've seen guys plug the holes with a set screw and RTV but I would replace the cover if it's cracked. If you remove the bolt and it comes out you found the problem.

The covers also crack from heavy impact like a huge pothole or not installing the spring correctly,snapping the ears.

[Russ S.]

Re: '65 Differential Cover cracked?

If you think the oil is coming thru the threads on the bolt, the first thing I would do providing you don't see a crack anywhere is remove the bolt, (with the weight of the car on it's wheels) clean the bolt threads and the cover threads with brake clean, and then put pipe dope on the bolt threads and reinstall. If it fixes the leak ,it is much quicker and less painful than replacing the cover.

[Oliver S.]

Re: '65 Differential Cover cracked?

OK, cars is back.
Good news:
According to the shop the problem was the red Posi plastic, which was deformed. I've added some pics. The oil was channeled behind the plastic to the rear, which could be seen after removing the plug. Maybe this explains why the bolts in the rear were oily not the ones in the front. Since the problem occured only after adding posi additive in July hopefully this was the actual cause.
But: when they reinstalled the spring in May during differential resealing they tightened the bolts without load on it.
Now the car is stored for the winter. I'll have to see what happens.

Oliver