Well, here I go... pulling the motor.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Yeah, I don't see where it goes either.... ID Parts clearly thinks it should be there, though, and I'm inclined to believe them over some dumb Mopar fiche.

layback40 · **Posted:** Fri Nov 08, 2019 7:08 pm

For what ever its worth~
On the 425 (It looks like it has the same rear main design & it precedes the 428) there are 2 Orings in there. The big one that seals around the main carrier & a small one that seals the flywheel against the end of the crankshaft. When I had my 425 gearbox out, I took the Orings into my favorite bearing shop & had them match them. I used only viton Orings as standard ones dont have a high enough heat rating.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Thanks for that - I will check it out this weekend!

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Ok, I think I found it.

There is an oring around the carrier where it seals against the block tunnel, and another small round plate (might be "thrust washer") between the RMS and crank flange. There is an oring on that plate. I will throw up a photo later on.

WWDiesel · **Posted:** Fri Nov 08, 2019 10:41 pm

thesameguy wrote:

Ok, I think I found it.
There is an oring around the carrier where it seals against the block tunnel, and another small round plate (might be "thrust washer") between the RMS and crank flange. There is an oring on that plate. I will throw up a photo later on.

So diagrams are correct?

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Yep... a little unclear as to the order of parts, but correct in the quantity.

This is the thing:

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Here is how - it appears - the things bolt to the rear end of the crank:

The thrust washer (o-ring is on the other side) sits against the crank flange, then the RMS, then the flex plate adapter. What's interesting to me is both the RMS and the thrust washer have sealing features, so the RMS seals against the thrust washer and the thrust washer against the crank flange. That's a lot of sealing.

The FSM indicates the preferred method to install is to remove the rear carrier, install the RMS into the carrier, then put it back on the motor. I'm sure that makes for a fun time aligning the holes in the crank flange, but the motor is out so no worries.

This is making sense to me.... so hopefully I have it right.

The only thing I'm struggling with is whether the RMS spins within the rear carrier, or whether the center section of the RMS rotates against the seal surface. It doesn't really matter, I suppose, I'm just curious.

I'm putting the order in for the head set, so I can bolt the head back on and then I'll deal with the bottom end. The FSM cautions about moving pistons without a head - apparently the cylinder liners can shift (!!!)… so I'd like to get the head on there before I spend any more time messing with the bottom end.

Mountainman · **Posted:** Sat Nov 09, 2019 11:47 pm

[quote="thesameguy"]Some more nitty gritty stuff...

Here's the outward-facing side of the carrier:

Something I hadn't noticed before, but flange on that left-side bolt is chewed up. It reaffirms the concept that *that* bolt was bouncing around in there and that's what chewed up the carrier.

I've found those bolts loose or missing on more than one of these engines. I blue locktite them, along with harmonic balancer, and some other bolts that are commonly found loose.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

The guy who I had do the RMS really seemed like an attentive purpose, and he was really a pleasure to deal with. When I picked up the car he had already put 20-30 miles on it (drove it home one night & back) and there's no way it could have been leaking. I made it probably 20 miles before it started leaking again. I *love* the idea that maybe these bolts are just prone to coming loose, and that wouldn't be far-fetched given all the damage, the re-appearing leak, and me finding them loose AGAIN.

If nothing else, it's great to hear it's not a unique problem... I will *definitely* threadlock them in. I just can't help but wonder *why* they're prone to this.... what in the design should be different to keep a darn main bearing carrier in place. Maybe an errant torque spec? Wrong fastener? I hate the idea of burying a potential problem.

GordnadoCRD · **Posted:** Sun Nov 10, 2019 6:39 am

It could be simply a tolerance stacking issue in manufacturing processes.
Many many many of these don't have that problem when things are done right, but there have been enough that the issue is definitely not unheard-of.

geordi · **Posted:** Sun Nov 10, 2019 11:56 am

Bear in mind that I have only disassembled two of these while attempting salvage of the block, and have not tried reassembling them. Perhaps the continuing leak problem is related to a missing shim ring? I seem to recall on the two that I pulled apart that there were shim rings somewhere in the process.

I can't see any reason with the design why the carrier would move independently of the crankshaft hub, and cause the bolts to back out. There has to be an imbalance somewhere, or something loose. If everything is tight fit and very close tolerances... Then the carrier bolts should not be vibrated loose - certainly not in as little as 20-50 miles from assembly!

As far as the sleeves - Measure them with a feeler gauge. They need to be flush or (IMHO preferably) 2-3 thousands above the deck of the block for the best seal. If you haven't changed them, then likely they are just flush. In all likelihood they won't move at all, but they are only held down with a few o-rings at the bottom, gravity, and corrosion. Usually they are quite stuck if you aren't the one who installed them. Even the new ones I installed were quite stuck after I got them seated. Having them move around while rotating the engine is a possibility... BUT it is quite remote b/c of the corrosion holding them down.

Mountainman · **Posted:** Sun Nov 10, 2019 1:13 pm

Yeah, those bolts come loose in 100,000+ miles, no way 20-30.
And like Geordi said, those liners are cemented in place, the only ones I've had move involved the pistons/rings being severely rusted (seized) to the cylinder walls. Even then, it took a lot of force to move them.

WWDiesel · **Posted:** Sun Nov 10, 2019 1:50 pm

A simple solution for preventing cylinder liner movement. Get 4 large washers and 4 short metric bolts of the same size and thread as the head bolts. Screw them down on top of the liners to put slight pressure on them to hold them in place so you can safely rotate the engine without fear or worry of liners trying move.
Put 2 bolts/washers between cylinders 1/2 and 2 bolts/washers between cylinders 3/4. Kinda like making your own VM hold down tools.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

geordi wrote:

I seem to recall on the two that I pulled apart that there were shim rings somewhere in the process.

Can you describe these shim rings? There are two ring shaped parts - one on either side of the carrier - but they have some functional features... I wouldn't describe them as shims, so I am worried you're talking about something else.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

WWDiesel wrote:

:idea:
Put 2 bolts/washers between cylinders 1/2 and 2 bolts/washers between cylinders 3/4. Kinda like making your own VM hold down tools.

Great idea!! Thanks!

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Picked up the finished cylinder head...

8x new intake valves (five were bad)
8x new exhaust valves (preventative)
16x new valve guides (most were worn)
2x new valve seats
1x crack between valves welded
2x broken studs extracted

The good news is that it was 100% flat, so just wear and not damage.

I have questions now about the "broken exhaust valve" syndrome. The shop indicated they found nothing wrong with the valves themselves, but the guide wear was pronounced, especially on the exhaust side. Multiple valves - including FIVE of the intake valves - were wobbling in their guides. They had been wobbling long enough that reusing them wasn't an option. My guy at the shop - who I've been using since the '90s and have done probably 50 heads for me - said he was surprised valves hadn't already broken. My personal takeaway from this one sample is that replacing valves without replacing guides is throwing good money after bad.

Here is what came out, for whatever it's worth:

And here's what I've got now:

NICE!

The interference on this engine is bonkers to me - but man, there isn't much shroud on those valves!

I'm less impressed with the casting. If I had more motivation, I would smooth this out. But I've got bigger fish to fry, and no performance aspirations. Just, really, I would expect better from a modern aluminum head:

layback40 · **Posted:** Wed Nov 13, 2019 7:23 am

If you still have the rear main bits out, could you please measure the RMS. The OD, the ID & the thickness. If it has any numbers on it, knowing what they are would be useful. I want to see if its the same size seal as the the 425 as I have a spare.
Thanks

Mountainman · **Posted:** Wed Nov 13, 2019 10:30 am

thesameguy wrote:

geordi wrote:

I seem to recall on the two that I pulled apart that there were shim rings somewhere in the process.

Can you describe these shim rings? There are two ring shaped parts - one on either side of the carrier - but they have some functional features... I wouldn't describe them as shims, so I am worried you're talking about something else.

I think you're talking about the 2 oil slingers. And then there's one thrust washer. They're aren't any other metal parts.
https://www.idparts.com/rear-main-seal- ... -3827.html

Mountainman · **Posted:** Wed Nov 13, 2019 10:35 am

This thread has a picture of the slingers.

viewtopic.php?f=5&t=85343

The mistake that at least two of us have made, is where the thrust washer is left out because it hides, stuck to the old seal housing (metal part). The result is the crank won't turn, and the $50 seal gets destroyed...

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Thanks for that - all three of those components are accounted for!

The fitment of the slingers is nifty... the one thing I notice is that one of them can rotate about 5 degrees or so... I cannot tell if the carrier is designed that way or it's worn. It doesn't appear to be a problem, just an interesting detail.

Well, here I go... pulling the motor.

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