RE: [Chrysler300] 300 G Rear Main Seal
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RE: [Chrysler300] 300 G Rear Main Seal

Good point Tony; following is totally opposite to ‘common wisdom”!! But along same line. I drive a 78 or 79 Dodge 318 stepside (love it) with about 120k on it; it barely ran, one weak cylinder causing visible skip at idle, ,  and used a lot of oil when I got it , low $ for what it was, “has a tired motor” after about 100k of slow driving in rural Vt. . Planned to use as body parts for another stepside truck,(‘engine shot”)  but it was too nice , no rust, came from “older guy” (like us!!). Like a quart in 300 miles first few weeks. So , got same story from mechanics, local mopar friends, and the usual chin strokers---engine shot etc.   BUT: most of this cannot factually be true !!! ----as we have guys like Jerry Kocur going 350k + on a stock 300K 413 engine. And that Volvo with 3 million or something on two engines. A hemi (392) with 250 k was not uncommon. 100k is a spring chicken.


So started thinking about it, where would it (oil) go? Tail Pipe was a little dirty, some smoke on start up ,especially cold AM--- Well,  ‘worn rings” is the first screech from engine rebuilder types. But think about Jerry….? 350K, rings ok?  If you think carefully about it, leaks and especially hardened or cracked  intake valve seals (the Chevy disease)  are a primary suspect to me . So tightened up stuff , (carefully, no distortion..all of them seemed ~ finger tight after 100k, , gaskets squeeze down/relax—notice how old motors are always coated in oily grime? )  So,  tightened up oil pan ,valve covers, front cover,  and then replaced intake valve seals , in place , with Viton, maybe 200$ to a shop for that(need the right tools) . (exhaust does not matter) Then (the against the grain part) filled it with mobil one 10-30. ( supposed to “leak out everywhere”—that is pure BS) . Then drove it 3-4  times , about 80 highway miles to summer place at 80mph – 100 occasionally , thinking loosen up stuck rings,  some clicking lifters , all that. All the junk will end up in filter. Plus synthetic has many additives that are kind to hard seals. And powerful detergents to carry the junk away. Now 10-20k later truck runs like it is a brand new truck , a quart every 1500 and getting better. Bad cylinder came up, no skip. Freed up the rings,  and stopped the valve seal leaks..and NO crank seal leaks. MPG went up 15%. Kind of same vein,  as you,--- I think the synthetic oils are good for seals , get in there and clean it out, maybe soften it some. Dirt , and age / heat induced hardness, are the enemy of rubber seals.


Except rope! Rope ought to just come back….if it swells a bit (= thin high lubricity oil, run it hard.)


I have done this now on 2-3 engines, all acting shot. All got better , takes a few hours of high speed running . (the old “clean it out” ideas of the 30’s??) As you know synthetics came from aircraft turbine lube development, long polymer chains all about the same length .Regular oil a natural mix of various length chains, sort of uncontrolled. Synthetic has higher bearing PSI ratings than other oils, despite intuitive, incorrect  thoughts about thin and thick oils. Runs cooler too, less friction. Heavy natural oils thin out a LOT more at high temp, maybe thinner than synthetic when really hot, they try to fix that with viscosity additives (additives are NOT lube oil= less oil) ---synthetics stay the same more or less .


All this is from just thinking about it (!) and personal experience. Pratt and Whitney know what works in a 300k-3 million$   airplane engine the best. I’ll go with it.


Bottom line, I think many good engines are overbored and rebuilt within our club for nothing !!!  You open up, no ridge. Nothing gained, maybe many things are made a lot worse, rebuilder gets a boat payment. . . ** kind of like the 300 leading shoe brake drum saga, turning them may make your troubles a lot worse. Seals though can go either way, I realize that. I was lucky,  maybe.


** have to add, I once rebuilt a late 50’s Plymouth 318 / 301 (blown up/ destroyed rod journal—got the broken down car on the side of route 2 , for free) .  I had zero $, about 17 years old, rolled block around in dirt/grass  in my back yard on a blanket , not even the ridge reamed , new bearings and rings , that was it, maybe 40$ in parts OTC stuff at the time.(“If you do not take ridge out, it will blow up,  crack piston lands , etc etc” ---from the cynics) Junkyard crank for 20$. (had to pull apart 3 motors in junk yard myself , including taking out of car , before a good one, $ days are like that!!) . JKG method to get crank, ----after pulling first one the usual way? ?    A 20 foot 2” pipe in window, rope on pipe, hook steering column, you can flip it on side(!!), look at crank / rods by getting pan off  .  Anyway it went a real 350k miles , used no oil, made it to Baja, Mexico, 57 Plymouth coupe , driven hard from Boston by a carpenter friend in Aspen , Colorado for 10 years .


On rebuilding.,  It is like asking a guy with a brand new Sunnen CK10 cylinder hone if honing is good, should you do it??  Or he owns a boring bar, should you over bore it? Measure old one first….Can laugh now.. (just drive it,-- worked 3-4 x!) . 


From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Tony Rinaldi awrdoc@xxxxxxxxx [Chrysler300]
Sent: Wednesday, August 24, 2016 9:34 AM
To: John Nowosacki; Val Jeffers
Cc: yahoogroups
Subject: Re: [Chrysler300] 300 G Rear Main Seal


Hi Val & all,


Of course there is a modern replacement for the rear seal with retainers and rubber seal replacing the rope. 


I experienced rear main seal leaking despite the new setup. 


When I switched from 10W-30 to:

Brad Penn Motor Oil, Grade 1, Semi-synthetic, 10W40, ZDDP Enhanced the leaking stopped. 

The thicker weight oil is available from summit racing. 

Presume it may help with Val's existing rope seal leak?

Certainly if it did, it would save a lot of money and effort either doing the seal replacement with the engine in or out. 

Just saying! Don't have much to lose in trying. 

This thicker weight oil works in all seasons except cold winters. Most of us put our beasts (brutes) in hibernation during the cold months anyway. 





Sent from Yahoo Mail for iPhone

On Wednesday, August 24, 2016, 9:00 AM, John Nowosacki jsnowosacki@xxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:


If you're really good (and I'm not) you can potentially deal with this with the engine in the car.  You have to move steering parts out of the way, loosen motor mounts enough to get oil pan out of the way, and then do the job from under the car by loosening/removing bearing cap(s).  I drove all the way to Skowhegan ME to have it done by Dominick Rinaldi many years ago on my G coupe.  That's when I found out from him that "someone had been in there before", because my G had a windage tray in the oil pan!  It cost significantly less having this done in the car by him than it would have to pay for engine removal/disassembly/re-install.

Local engine folks all wanted the engine out, and then of course they said they might as well do a bunch of other stuff since it was out and on the stand, but it was like $300 instead of $3000 by just having Dom do the seal.  I believe that car ended in 17087 as VIN number.  Would be interested in knowing where that car wound up.  I sold it to a person in CT, who I believe then sold it to someone in PA?


On Tue, Aug 23, 2016 at 6:56 PM, Val Jeffers edward1108@xxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:


  Hi All,

              Mine has been slowly leaking for a very long time. I understand replacing the seal (which is a type of rope) requires removing a cross member and transmission. Am I correct ?




                                                                              Val Jeffers



"A government big enough to give you everything you want, is big enough to take away everything you have." ... Thomas Jefferson

Conservatives believe government action is an obstacle to our freedom. Leftists believe our freedom is an obstacle to government action. 


Posted by: "John Grady" <jkg@xxxxxxxxxxxxxxxxx>

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