My 1970 Coronet 383 Troubles

[jimkf]

Many years ago we ran around in a 70 Coronet RT and terrorized many a neighborhood with our antics. Fast forward to a few years ago and a 70 Coronet wagon popped up for sale not too far from me. It wasn't expensive and seemed to run and drive well so I bought it. Lots of body and interior cleanup were needed but I was happy with the car until one day when it started running rough. Off it went to a local shop where, after pulling the 383, we found that the rear main seal let go and somehow got drawn into the oil pan and the pickup. That caused oil starvation and the need for a rebuild. The bearing photo says it all. One of the main bearing journals is bad enough that the rebuilder would rather replace the block than try to weld and grind. Fortunately, the crank is ok and none of the rods were damaged. Since the engine isn't original to the car we decided to replace the block and were able to source one that's already been cleaned and checked. One step closer to back on the road!

 

[F4R/T]

How the heck is the crank ok after that? That’s chewed up, I honestly can’t see a rope or rubber seal doing that kind of damage but I guess it’s possible.. wow!

 

[pnora]

I find it very hard to believe that a rear main seal got past a bearing and into the pan. If anything oil pressure would keep it away from getting into a bearing. The clearance is to close. Valve seals is what most likely caused your oil starvation.

 

[Don Frelier]

Keep us posted on your 400 stroker build up.

 

[jimkf]

Found a pic of the rear main cap. The slop you see on it was also stuck in the oil pickup. I have no clue how it wormed its way in, but it did. Or, maybe something inside worked its way out. Who knows...

 

[pnora]

Found a pic of the rear main cap. The slop you see on it was also stuck in the oil pickup. I have no clue how it wormed its way in, but it did. Or, maybe something inside worked its way out. Who knows...

View attachment 1652873

That is the outside of the retainer. Not uncommon to see years of dirt and grime buildup esp. with any oil weepage.

 

[jimkf]

That is the outside of the retainer. Not uncommon to see years of dirt and grime buildup esp. with any oil weepage.

Right. I should have snapped a pic of the other side because it looked just as sloppy. Again, who knows what got into the pan, but it didn't do the engine any favors!

 

[MWbirdLOVER70]

Many years ago we ran around in a 70 Coronet RT and terrorized many a neighborhood with our antics. Fast forward to a few years ago and a 70 Coronet wagon popped up for sale not too far from me. It wasn't expensive and seemed to run and drive well so I bought it. Lots of body and interior cleanup were needed but I was happy with the car until one day when it started running rough. Off it went to a local shop where, after pulling the 383, we found that the rear main seal let go and somehow got drawn into the oil pan and the pickup. That caused oil starvation and the need for a rebuild. The bearing photo says it all. One of the main bearing journals is bad enough that the rebuilder would rather replace the block than try to weld and grind. Fortunately, the crank is ok and none of the rods were damaged. Since the engine isn't original to the car we decided to replace the block and were able to source one that's already been cleaned and checked. One step closer to back on the road!

View attachment 1652856View attachment 1652857

Gorgeous looking wagon

 

[YY1]

Is that a factory big block car?

Cool.

More pics?

 

[ckessel]

Bitchin wagon! I have a 67 myself.

 

[jimkf]

Yes, it’s a factory E61 383 car that was sold new in California. The body isn’t perfect but the interior is near perfect. We just need to get the engine assembled and back in the car.

And yes, that’s a Charger rear seat center I’m using as an arm rest.

 

[YY1]

Ooooh, big block, AC wagon.

 

[jimkf]

Well, the 383 rebuild didn't quite go as planned. Compliments of the main seal clogging the oil pickup, the rear main bearing spun and gouged the seat enough that the rebuilder wasn't comfortable trying to salvage the block. While that meant sourcing another block, it wasn't big deal beyond that since the engine in the car wasn't original anyway. I do have the 69 date coded non-HP block in the event anyone thinks they can do something with it beyond using it as an anchor or doorstop.

Another block was obtained and at that point I decided to have the 727 gone thru since it was a sluggish shifter. One thing led to another and we rebuilt the rear end as well. And, since we were there, why not do the brakes too.

A few weeks later and the car is together but we cannot get the front end to behave. That led to a new steering box and pump, upper control arms and ball joints and completely rebuild lowers. We also decided to replace all of the front end brake hardware as well.

I now have a mechanically new 1970 Coronet 440 wagon. It runs, shifts, steers and stops as is should....and it better given what I now have in this car!

 

[ckessel]

Gotta love the snowball effect.

 

[Kern Dog]

Gotta love the snowball effect.

 

[eldubb440]

View attachment 2043125

remember, I named you Pvt Snowball

 

[jimkf]

Ohhh...and the trouble continues. Started the near new engine with less than 1500 miles on it a few days ago and zero oil pressure. Shut it down, restarted and still zero. I pulled the filter and almost no oil in it. So, I filled it with oil, reinstalled and yes, still zero oil pressure. So, back to the rebuilder it went to figure out what happened. To say that I am not happy would be an understatement of biblical proportions....

 

[Don Frelier]

The odds of that are nearly ZERO.
(Unless there was a rag left in there or something similar?)

 

[69conv]

Dang! Wanna hear what the shop has to say.

 

[69Bee]

Found a pic of the rear main cap. The slop you see on it was also stuck in the oil pickup. I have no clue how it wormed its way in, but it did. Or, maybe something inside worked its way out. Who knows...

View attachment 1652873

So, this is what happened. First off, the motor was OLD and worn out; bearings getting thin and low oil pressure. You finally lost the oil wedge on #5 main bearing, metal on metal on the crank, started to spin in the bore as the bearing shell welded to the crankshaft. So much heat was created by that, it melted the rear main seal causing the "Muck" that you see. The rear #5 cap and crank were black as night from the heat and burning oil, the cap pulls in at the parting line as the cap is stretched in the 12 and 6 o'clock direction which is why the block could not be economically salvaged with a line-bore. Aftermarket billet steel caps, line-bore, followed by a line-hone would likely be a grand or more and you can find another block for less than that like you did. The crankshaft was at least able to be turned for it to be okay. I am actually surprised you didn't spin and rod bearings. As far as the chunks in the pickup, those were bits of old valve seal and cannot get sucked up past the screen. This was the result of too much bearing clearance from age, and not oil starvation.

I would be curious to know what was replaced, not replaced, did a mechanic shop do this, was the engine machined and built by a machine shop? There is no logical reason a "fresh" machined and built engine should lose prime after only 1500 miles. Be careful what you do so you don't smoke the new bearings.

ps... nice wagon!!