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Front Crank shaft seal on the timing chain cover leaking

J

jclays

Regular Contributor
Front seal around the crank shaft on the timing chain cover leaking. 350 Crusaders. When I first posted this a few months back I thought I would need to pull the timing chain cover. Since then a guy at my marina and the parts guy at the marina chandlery told me this is not necessary. Remove the harmonic balancer carefully pry out the old seal then put some oil on the rubber seal or the crank shaft slide it on and evenly tap it in till it seats. Its been a long time for me since I built my last small block Chevy. Is this correct??
Thanks
Jim
Early small block 1969-70 vintage.
 
I hope so! On outboards, we pull the top seal by driving a few sheet metal screws into it and prying on it.

Jeff

PS: If the crank is grooved where the seal ran, the new one will soon leak as well. The way around this is Fastjeff Seal Repair Trick Number One: Shim the seal out about 1/16 of an inch. Cut a piece of plastic the shape of the seal and put in on first. It will space the seal out enough so the lip will ride on 'good' metal.
 
Ditto Jeff.
Run a self tapping sheet metal screw into the perimeter of the seal metal housing.
Gently hook behind the screw head, and pry the seal out.

NOTE: oil can find it's way out via the crankshaft keyway slot.
Use a sealant when re-installing the harmonic balancer.

NOTE: DO NOT use the crankshaft bolt to pull the balancer onto the crankshaft. Instead, use the correct tool for this.
It still uses the female threads, but only once fully threaded in. The pull is actually created by an additional and larger threaded shaft.
 
The economical seal pulling tools should be adequate once the balancer is removed.

use a light grease on the seal lips before reinstalling it...it won't run like the oil will.

Definitely inspect the sealing surface on the crank before putting it all back together.
 
My mistake, that seal does mate with the balancer. to be complete:

inspect the sealing surface on the balancer's hub. If any grooving is detected, Jeff's relocate the seal method should work fine. If the grooving is extensive, you'll need a salvage sleeve for the balancer or a new balancer.
 
OHHH no... Replaced the seal (also circulating water pump) no drama, went well. I still have a leak. Put a pan under the harmonic balancer and went fishing about 20 miles out and back. Collected about 3-4 oz of oil in the pan.
 
The keyway in the crankshaft and within the balancer must also be sealed, or oil can wick it's way through.
I seal this, and then I'll additionally seal the pulley to the balancer, and the center bolt washer to the pulley.
Usually, sealing the keyway does the trick.

.
 
jclays said:
DO I NEED TO PULL THE BALANCER TO SEAL THIS? iF I DO THEN I'LL NEED A NEW SEAL CORRECT?
Click to expand...
You'll want to remove the balancer so that you can clean the key, the keyway, and to apply the sealant to non-oily surfaces.

No.... the seal will not become damaged. You can re-install the balancer once you seal the keyway.

Be sure to use the correct tool for pulling the balancer back onto the crankshaft.

.
 
I recall sealing only the inside flat surface of the thick flat washer under the balancer bolt, no? When the spinning device leaks, it will throw oil in a circle. If the pan gasket leaks or the fixed seal leaks, it usually drips straight down. Did the balancer seal area look near perfect?
 
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I've seen a straight line pattern indicative of oil being thrown. I've changed the seal and haven't seen that pattern however I have a pan under the balancer to catch any leeks and measure the leakage. If I remove the bolt and washer and it is clean/dry inside the balancer where the bolt goes in as well as the washer being clean/dry. Would it be safe to say that this is not the source of the leak?
 
If the new seal is running in the groove made by the old seal, it will leak the same way. I shim new seals out to make the lip run on fresh, ungrooved metal.

Jeff
 
Took everything apart last night. Starting over again. New seal fit ALOT tighter when tapping it into the timing cover. Took a while to get it in straight. The seal saver that was on the balancer wasnt groved much.It did have a slight wrinkle however it was that way before the leak started.My friend will press on a new one at his shop today and I'll reassemble everything tomorrow.
 
Everything reassembled went on a few harbor cruises with the wife no leaks at about 800 rpm or 5 knots. Went on a 20 mile run this morning to test at higher rpm. Ran the rpms to 2500 at 19-20 knots. Checked the drip pan I had set up and found aprox 3 to 4 oz of oil in the pan. Where else but the front crank seal can this come from? Timing chain cover to oil pan gasket??? Have the old style yoke front engine mounts. Cant see or feel between the pan and cover to check for leak. Dang..
 
That's why I keep away from seal savers: Unless that sealing surface is perfectly round (no bumps on dimples) it will PUMP oil out. For that reason I recommended what I did: relocating the seal a 1/16 " or so further forward (with a shim installed before the seal) to allow it to run on a undamaged shaft surface.

Jeff
 
I had a similar problem with one of my 454s. After replacing the shaft seal and installing a sleeve on the balancer there was still a leak from somewhere. The oil was still running down the front of the cover, onto the oil pan, and finally dripping off the rear of the pan into the bilge. So I replaced the timing chain cover (which meant having the timing marker removed from the old cover and welded onto the new cover) and no more leaks. The new timing cover came with the seal already installed. I don't know why or where the old cover was leaking, but replacing the cover fixed it.
 
The seal savers should have a sealant of some type between them and the original balancer surface.
Likewise when the actual seal is being installed into the timing chain cover.

I agree with Mark, if when the center bolt is removed, and you find it dry in the bore of the balancer, you should be OK here.
 
So you think that the issue is still the seal/seal saver? The seal saver was pressed on straight with no wrinkles liquid selant applied prior to pressing on the seal, sealant applied between seal an timing cover. no oil present in the balancer after removing the bolt. Keyway also had sealant applied along with sealant applied to the thick washer prior to bolting all together.
 
Think about this for a minute.....

if the seal was leaking, the oil would be slung out as the balancer was spinning...the oil in the bilge would NOT be in your drip pan but spread out in a line parallel to the balancer, likely from stringer to stringer (and beyond depending upon its magnitude).

If the oil is in a drip pan, it isn't coming out from anything rotating but from something static. given the possibility that the cover is original, that would make it well over 40 years old....add to that it is made of stamped sheet metal and I'd be looking for a rusted thru spot (or two). The pan is another suspect but they are typically thicker so should have a longer life.

Could also be the fasteners on the cover or pan have worked loose - may wanna check and see. the pan gasket under the timing cover is another possibility - especially if it is original, too.
Just my two cents....
 
makomark said:
Think about this for a minute.....

if the seal was leaking, the oil would be slung out as the balancer was spinning...the oil in the bilge would NOT be in your drip pan but spread out in a line parallel to the balancer, likely from stringer to stringer (and beyond depending upon its magnitude).

If the oil is in a drip pan, it isn't coming out from anything rotating but from something static. given the possibility that the cover is original, that would make it well over 40 years old....add to that it is made of stamped sheet metal and I'd be looking for a rusted thru spot (or two). The pan is another suspect but they are typically thicker so should have a longer life.

Could also be the fasteners on the cover or pan have worked loose - may wanna check and see. the pan gasket under the timing cover is another possibility - especially if it is original, too.
Just my two cents....
Click to expand...

I've got a combination of both. Fine spray pattern (side to side) on the diaper under the engine and pan as well as about 3oz on motor collected in the pan. Hmmmm. Wish I had access to the lower front of the engine. Yoke type motor mount doesn't even allow for a fingers width to prod around and feel for leaks
 
Yeah; that sucker's leaking alright.

Hate to say it, but you need to do the "Fastjeff Repair". The damper pulley has to come off (again!), but you can pull that seal with sheet metal screws driven into it. That repair sleeve then needs to come off, and the shaft below it cleaned thoroughly. Next, cut a "washer" out of plastic about 1/8 " thick and put it in before the seal (to space it out).

Jeff
 
fastjeff said:
Yeah; that sucker's leaking alright.

Hate to say it, but you need to do the "Fastjeff Repair". The damper pulley has to come off (again!), but you can pull that seal with sheet metal screws driven into it. That repair sleeve then needs to come off, and the shaft below it cleaned thoroughly. Next, cut a "washer" out of plastic about 1/8 " thick and put it in before the seal (to space it out).

Jeff
Click to expand...
Are you talking about putting the washer on the harmonic balancer shaft so that it does not seat all the way in?
 
I've got to take a trip in a week and won't have time to change it before then. 26 miles out to the island and 26 miles back. Will bring extra oil an watch the drip pan. I think it will hold.
 
Is it possible that we are exaggerating the negative aspects of small grooves that may be present in the balancer seal surface? A fresh front timing chain cover seal should offer a squeeze that is more than adequate to account for a .001" or .002" or even .003" polished groove.
New seals generally offer a .030" to .035" squeeze on a true surface.

Perhaps forget the seal saver, polish the surface.... or replace the balancer, and take another shot at this.

For a 52 mile round trip, I'd live with it, and repair it when I returned.


.
 
Went on my trip. Ran the boat 2400rpm 15 knots. Loaded heavy choppy confused seas. Leaked 1 quart up and also 1 quart back. Doesnt leak at low rpm say 900rpm. Gotta find this leak.
 
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