HG42 - installed new rear main seal.... and it still leaks

mr.precision · May 04, 2015, 01:25:25 PM

The rear main seal on my HG42 leaked so bad that it would leave a trail of oil when operated. Finally the clutch stuck to the flywheel, so I pulled the whole thing apart. Installed a new rear main seal, clutch disc and TO bearing. Also replaced the pan gasket. Put everything back together - and it leaks in the same way. Parked in my shop, engine at idle, it will leave a puddle of oil the size of your hand on the floor in 5 minutes.
1XK3 motor runs fine, no blow-by from the oil filler or exhaust. Has good oil pressure and no unusual noises.

Any thoughts on what is wrong? I know the previous owner pulled the head off and re-used the head gasket, but I can't see that causing a massive oil leak at the rear main seal.

Jethrow · May 04, 2015, 01:50:20 PM

Which rear main seal are you using?

mr.precision · May 04, 2015, 05:50:57 PM

Quote from: Jethrow on May 04, 2015, 01:50:20 PM
Which rear main seal are you using?

Provided by Zimmerman's. Timkin package. Identical to the one removed.

Robert Barbour · May 04, 2015, 09:30:41 PM

The rear seal runs on a lip on the back side of the flywheel. Did you check the seal for fit on the flywheel before you installed it. That lip can wear over time and some times they are turned down and an under sized seal used. That is the only thing I can think of that might be your problem.

Jethrow · May 04, 2015, 09:49:51 PM

I removed a National 38220 from my IXB-3 and attempted to replace it with a Timken 455189 seal from Zimmermans. The result is about a .1" gap all around between the seal and the crankshaft journal. I ordered a National 38220 from NAPA to see if that makes a difference.

Jethrow

Robert Barbour · May 05, 2015, 02:14:46 AM

That sound about right. There should be a lip on the back side of the flywheel that goes over the end of the crankshaft. That lip fills that .1" gap.
Does your flywheel have that lip??

Blake Malkamaki · May 05, 2015, 03:07:29 AM

I wonder if there is a difference in that seal diameter between an IXK-3 and IXB-3, and an IXB-5? Just wondering if that seal from Zimmerman's is for an IXB-5 ? I really don't know.

Lowspeedlife · May 05, 2015, 11:51:59 AM

When you had the flywheel off did you notice if there were two pins about 5/8" diameter in the flange that the flywheel bolts thread into. There are six holes in the flywheel/crankshaft, two of them should have these pins, the other four have the bolts that secure the flywheel to the crankshaft. If one of the pins is missing there would be a direct path from the crankcase thru the crank & flywheel to the clutch housing.

Scott R.

Jethrow · May 05, 2015, 02:37:47 PM

Ray, yes the flywheel does have a lip. I greased the seal side of the lip and bolted it back to the crank. Can't tell what the clearance is now. I'll have to wait until it's back together and running. This motor is planned for a test stand so it will be a while. I still need to drill the cap bolts for safety wire.

The flywheel is pretty dinged up. Don't know if I can just knock down the nicks with a flap wheel or if it need to be refaced. Thanks for the help.

Lowspeedlife · May 05, 2015, 03:32:40 PM

Wow! Ring gear welded to the flywheel in eight places! I think that's what they call "overkill". Gonna make it tough to replace if it the teeth get chewed up.

Scott R.

mr.precision · May 05, 2015, 07:45:02 PM

Thanks for all the input, guys.
The seal I used is indeed a Timkin 455189.
My flywheel has no "lip" as illustrated in the picture. The seal area on the backside of the flywheel was polished smooth, except of a rough area maybe 1/8" or so where I suspect the lip should be. I polished that before putting the flywheel back on, although I did not remove any metal. in terms of making it undersize.
Both dowel pins were in place.

So now I have a dilemma.... what to do? The crawler isn't practical to use with it leaking oil like it does. And I suspect the clutch disc will soon be soaked........ and we know what happens then.
I don't mind taking the whole thing apart again, if it can be fixed.
Any suggestions at this point??

Lowspeedlife · May 05, 2015, 09:10:20 PM

If your flywheel does not have the "lip" that is facing "up" in the picture above I would say you need a new flywheel. That lip is the surface that the seal, seals against.

In this very crude drawing I hope you can see that the "lip" on the back of the flywheel fits over the back of the crank shaft, if the "lip" has been removed, there is nothing for the seal to rub against to prevent the oil from slinging out. In that case a new flywheel would be the repair.

Scott R.

ObsoElitist · May 06, 2015, 01:09:42 AM

VW used a similar system and they had an O ring where the flywheel slid onto the crank, and a paper gasket on the end of the crank to keep oil from leaking out of the dowel pin holes. Could that be happening? Did you check the seal diamer on the flywheel lip before installation? Are there any oil galley plugs inside the bellhousing?

mr.precision · May 06, 2015, 01:39:54 PM

I misunderstood what you mean by the term "lip". My flywheel is identical to the one illustrated and does have a lip. I understand how the seal works, and apparently it isn't working properly in my case.

Good point about checking for other leak paths in the bellhousing and on the dowel pins, although I don't believe there will be anything found.

One question - when I installed the seal, I gently tapped it into place with a rubber mallet and block of wood. The face of the seal I took out was flush with the front of the crankshaft. The seal installed was about 1/8" deeper, i.e. behind the face of the crankshaft where it bolts to the flywheel. I am thinking that maybe the seal interfaces with the rough area at the end of the flywheel lip, and therefore doesn't seal properly. The shop manual doesn't specify if the seal is seated or just tapped in until flush with the crankshaft face. Thoughts?

Robert Barbour · May 06, 2015, 03:19:18 PM

My Hercules engine manual states that the seal body should extend 5/64" past the bore in the bellhousing. That would have to be measured from the back side of the bellhousing. Not easy to do with the bellhousing installed. So one would need to measure the length of the bore and the seal width and figure out how far in from the front the seal should be.
The manual states that this dimension is important!