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Old 01-25-2015, 07:42 PM   #1
Thorazine OP
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Replacing crankshaft and camshaft seals

So I've been getting some pretty good leakage from the front cover of my '74 R90/6. After pulling off the cover, I saw quite a bit of new oil near the bottom, also on the bottom of the points well. It looks to be coming from the crank seal.

Can I remove and replace both seals w/o having to remove the timing chain cover, and maybe even do the tach seal while I'm at it? I know how to get the alternator off--just don't wanna mess with the timing chain cover again.

Thanks
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Old 01-26-2015, 01:44 AM   #2
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Maybe, maybe not...

The Crankshaft seal is easy-- enough room to remove it and it taps in easily.

The Camshaft seal is tricky-- the seal is small, no room to work and the cam points quill is still in the way. Not impossible. Do the drill-a-small-hole and screw-in-a-sheet-metal-screw to lever the old seal out. Use a deep-well socket to tap the new one in.

BE CAREFUL-- there is no stop at the bottom of the seal bore with either the cam or the crank seals, so nothing will bottom out. Tap them in even with the outside, be careful.

The tach drive seal-- never have replaced it with the timing cover installed-- I always do that when the cover is removed. IIRC, it would be a bear to do with the cover installed. But if it ain't broke, don't break it...

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Old 01-26-2015, 11:54 AM   #3
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Thanks, Bill. All signs point to the crank seal being the culprit, and I can picture that one being the easiest. I'll be sure to use a socket slightly larger then the hole, then when I get nearly flush, maybe use a large coin to finish it off if I have to.

Funny thing is I did both seals maybe a year and a half ago. I'd really like to see how I screwed it up this time. Maybe with the timing chain cover on this time, it'll go better--we'll see.

Thanks
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Old 01-26-2015, 01:26 PM   #4
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I understand maybe but I personally wouldn't hesitate to pull the cover just to do the seals if I needed to. Just need a new gasket and two donuts in addition to the seals.

The advantage of pulling the cover is that it needs to be positioned carefully when new seals are installed. If the cover is not pulled then any off centerness would remain with the new seals. (hope I said that right)
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Old 01-26-2015, 01:59 PM   #5
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Sometimes seals just decide to start leaking. Replacement is not a big deal.

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Old 01-27-2015, 08:46 AM   #6
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Can be done either way, but last time I was in the same boat, I pulled the cover. Good time to check the timing chain and a few less headaches changing the seal. Just heat the cover up to pull it off the bearing. My friend was borrowing my heat gun so I used a hairdryer and it worked fine. It is also a great time to clean all your charging connections and reapply dielectric grease.

But this is just an opinion. Lots of ways to skin the cat.
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Old 01-27-2015, 01:38 PM   #7
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OK, I guess I'll pull the cover like I did last year. Here's what I did then: I put a thin coat of oil on the edges of the seals and tapped them in flush with the front using a socket slightly larger than the hole.

What I didn't do is the 'centering' that Disston talked about. What exactly needs to be centered? And what is it centered on/over?

Also, what are the donuts you're talking about, Disston? Are they #6 or 9 on this diagram?
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Old 01-27-2015, 02:23 PM   #8
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Quote:
Originally Posted by Thorazine
Also, what are the donuts you're talking about, Disston? Are they #6 or 9 on this diagram?
That would be #9 as I understand it. The two donut-gaskets have the appearance of 3-hole paper gaskets or doublers for use when a hole tears-out.

I think the centering would be controlled by the crank nose bearing and isn't there a dowel in the lower right-side corner of the engine housing.
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Old 01-27-2015, 03:52 PM   #9
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It can be done without removing the cover. It's another of those shortcuts that I don't think always work so well. I've done it this way so many years ago I forget how well it worked.

#9. Always have thought this a funny way to sell gaskets. The two O-ring paper gaskets are needed anytime the main cover gasket is replaced but they are sold separately and by individual piece. Order two.
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Old 01-27-2015, 04:09 PM   #10
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Will do, thanks Disston.

Quote:
Originally Posted by disston View Post
. . . If the cover is not pulled then any off centerness would remain with the new seals. (hope I said that right)
Can you explain what you mean here? What can become off-centered, the seal in relation to the crank?

No hurry--I'm ordering the parts right now, and won't have time to do this for a few weeks. Thanks.
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Old 01-27-2015, 04:17 PM   #11
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When new seals are installed I have been told to pay attention to centering them when replacing covers of any type. I think it was in reference to the timing cover specifically. When I put the cover back on it can sort of wiggles around a little till the bolts are tightened. Hold the cover so the seal is centered. It may work just fine to not pay any attention to do this but I was told to do it this way.

On large V8 cars with much more work involved I don't take the cover off unless I'm doing a timing chain.
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Old 01-27-2015, 04:29 PM   #12
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Quote:
What I didn't do is the 'centering' that Disston talked about. What exactly needs to be centered? And what is it centered on/over?
The crankshaft is automatically centered by nose bearing. On the earlier models I don't recall a locating dowel at the bottom-- I install the camshaft seal and let the cover center itself with the seal over the ignition quill. The bore inside the timing case cover where the nose bearing will fit needs to be heated to a good spit-sizzle (no need to heat the entire cover) being careful to not crispy the new crank seal.

Haynes, et al talk about using a "centering bush" tool on the cam quill and installing the cam seal afterwards with the timing cover installed. This is the "factory assembly method", which can be different from practical field methods. I've always installed the cover with the seals in. YMMV.

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Old 02-09-2015, 05:43 PM   #13
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All the parts are in, including the donuts. All set to go this weekend. Now, the answer to my question may be obvious once everything's torn apart, but just in case:

1. Using the link above, in which holes do the donut gaskets go, the two top ones?

2. Do the donuts go on between the timing cover and the gasket, or between the gasket and the engine?
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Old 02-09-2015, 05:54 PM   #14
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The two donuts go in the top bolts of the timing case cover, above the main timing case gasket. Look at them as a discontinuous extension of the main gasket (been waiting for years to use that word).

Just like in the parts drawing:



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Old 02-09-2015, 06:01 PM   #15
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It should be obvious when you have this apart and there should also be the old donuts in place to give it away.

The donuts don't go between the large gasket and anything. They are above the main gasket between the timing cover and the engine block.

Stck the donuts on with some grease so they stay in place when positioning the cover. Don't forget to heat the cover so it goes over the bearing easily.
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