Engine Mounts, P15; Caution

[Sam Buchanan]

That might work, Joe, I'll give this some thought. Might delete the lower mounts, too. 

Edited August 30, 2019 by Sam Buchanan

[MarcDeSoto]

Sam, I bought new rubber mounts for my 48 DeSoto in the 80s and had the same problem that you are having.  The mounts were purple in color and hard as a rock.  It's like the after market manufacturer didn't care about softness, but just wanted to make something the same size.  I knew they were supposed to be much softer.  So finally switched them out with softer mounts that I got I think from A B, but in the 80s.  Now they are probably made in China with no quality control.  Also here are some Master Tech tips on engine mounts starting after 5:00 minutes into the video.

 

http://www.mymopar.com/index.php?pid=620

[Sam Buchanan]

Thanks, Marc. I'm still unclear on how the original mounts were designed. When I removed the old mounts there was no lower mount, just the upper. I assumed the lowers had deteriorated enough to fall out. But the illustrations in the manual show a small lower mount, much smaller than the lowers that are shipped with mounts nowadays. I've never seen lower mounts from any vendor that look like the lowers in the illustrations. Matter of fact, the original bolts aren't long enough to go through the lowers that are sold now. I had to get 4" bolts to install the lower mounts.

 

So should we install just the upper mounts now? Are the large lower mounts correctly used in some applications? The manual seems to show the large lower washer riding just below the frame cross member. I think I'll do as has been suggested and remove the lower mounts and snug the large lower washer up against the bushing and see how that works.

 

Edited August 31, 2019 by Sam Buchanan

[Sam Buchanan]

UPDATE; Smoothness has returned!

 

I removed the lower mounts and snugged the large bottom washers up against the bushing. The washer does not contact the frame member.

 

The car now runs smoothly as it did prior to replacing the mounts. It appears the lower mounts were the primary contributor to the harshness that has been present since new upper and lower mounts were installed. Apparently it is best to just have the transmission "resting" on the mounts vs "secured" to the frame member via lower mounts. I wonder if this is why Steele only offers new vulcanized upper mounts.

 

At this point I don't know if the new mounts are indeed too firm and elimination of the lower mounts is a work-around or if the new mounts are made from a satisfactory material. Whichever is the case, we seem to have a solution.

 

It has been an interesting saga....hopefully this will help others who are replacing mounts......install just upper mounts!   

Edited August 31, 2019 by Sam Buchanan

[Dodgeb4ya]

You should not be able to crush up tight the rear motor mounts.

This because of the factory bolt length , upper motor mount "T- Tube and Washer"....the tube is welded to the washer  and prevents over tightening the rear motor mounts as long as you are using original design parts.

[Sam Buchanan]

16 minutes ago, Dodgeb4ya said:

You should not be able to crush up tight the rear motor mounts.

This because of the factory bolt length , upper motor mount "T- Tube and Washer"....the tube is welded to the washer  and prevents over tightening the rear motor mounts as long as you are using original design parts.

 

I agree. But the problem is the lower mounts now on the market are not "original design parts" for the P15 application. They are too long and cause the mounts to be compressed before the washer can snug up against the t-tube. I have not seen any lower mounts advertised that appear to be the same shape as the lower mounts in the Service Manual illustration. Here is what you get now when you purchase lower mounts, they are about 1/2" too long:

 

Edited August 31, 2019 by Sam Buchanan

[Dodgeb4ya]

Got it! A lot of current replacement parts are not made right.

Edited September 1, 2019 by Dodgeb4ya
spelling error

[MarcDeSoto]

Are these incorrect parts sold by A. B. as being correct for your car?  

 

[Sam Buchanan]

3 hours ago, MarcDeSoto said:

Are these incorrect parts sold by A. B. as being correct for your car?  

 

 

Yes. They are the same lower mounts seen in all the vendor ads for many early 40's through mid-50's Mopars. Here is the listing on their site, note 1 (L-346) is upper, note 2 (L-347) is lower:

 

 

And here is a listing on Roberts Motors site:

 

https://www.robertsmotorparts.com/lower-motor-mount-6-cyl-dodge-truck-plymouth-truck-fargo-truck-chrysler-dodge-desoto-plymouth-1939-1954-1

 

 

 

And another one:

 

https://www.ebay.com/itm/1939-1956-Plymouth-Dodge-Engine-Motor-Mount-Set-for-Straight-Six-FRESH-STOCK/173244888404?hash=item2856333554:g:f10AAOSw9vlaYRxs

 

 

 

For some reason a lower mount is being marketed by multiple vendors that doesn't match what we see in the Service Manual, I've not seen any mounts that look like the original lowers. My knowledge base is way too thin to know the reasons for this.....

 

Edited September 1, 2019 by Sam Buchanan

[JerseyHarold]

It could be that somebody found a 'near match' from some other application that they are now selling as correct for your car.  That's why the lower mounts are wrong.   Are there any part numbers on the new motor mounts or packaging?  If yes, Google the numbers  to try and find out what they actually fit. 

[Sam Buchanan]

1 hour ago, JerseyHarold said:

It could be that somebody found a 'near match' from some other application that they are now selling as correct for your car.  That's why the lower mounts are wrong.   Are there any part numbers on the new motor mounts or packaging?  If yes, Google the numbers  to try and find out what they actually fit. 

 

There was no packaging....except the clear plastic bag they came in.........I suspect the vendor has a large box full of rubber donuts...... 

[soth122003]

Hey Sam, glad to see you got it worked out. Maybe this is why I never had vibes on my car as I didn't install the lower mounts since they weren't there when I changed mine. I remember you said yours weren't there either when you changed yours. Maybe we now know why.

 

Joe Lee

[Dodgeb4ya]

Depending on Serial #  Plymouth's don't use that thick lower insulator only a rubber washer on the drivers side ...factory service info..as noted above.

This out of the 1936-48 Plymouth parts List. 

A lot of vendors don't know what they are selling.

Edited September 1, 2019 by Dodgeb4ya

[Sam Buchanan]

4 hours ago, soth122003 said:

Hey Sam, glad to see you got it worked out. Maybe this is why I never had vibes on my car as I didn't install the lower mounts since they weren't there when I changed mine. I remember you said yours weren't there either when you changed yours. Maybe we now know why.

 

Joe Lee

 

3 hours ago, Dodgeb4ya said:

Depending on Serial #  Plymouth's don't use that thick lower insulator only a rubber washer on the drivers side ...factory service info..as noted above.

This out of the 1936-48 Plymouth parts List. 

A lot of vendors don't know what they are selling.

 

Yes, things are much clearer now than a couple weeks ago, the education continues. I just assumed the people selling parts knew what they were doing when they listed lower mounts for our cars.....silly me.  ?

 

I hope this thread is useful for those considering replacing mounts.

Edited September 2, 2019 by Sam Buchanan

[MarcDeSoto]

I do remember why I changed the on engine mounts my car in the 80s.  The originals were smashed like they were marshmallows!  Hard mounts would never have looked smashed like that!  the originals were soft, that's for sure

[DJ194950]

Mix rubber with oil and heat, wait for 20 years and what do you get -marshmallow consistency thin donuts!

 

DJ

[grea235]

I have been experiencing the same issue with mounts on my 52 Concord.  I was changing them because it wouldn't go into reverse on a decline.  Got uppers and lowers from Bernbaum.  My car had no lowers...don't know if they were removed or not.  Put them in and got a lot of vibration, but got reverse back.  I had to slacken the bolts to where they were just barely tight to get the vibration to go away.

 

I wasn't comfortable with the barely tight bolts and figuring that the rubber was too hard, I ordered the A2014 Marmon mounts from Rock Auto.  I received them yesterday and what I got was extremely hard plastic.  I don't think they are rubber at all and really hard, I mean  probably a 7 on the Moh's scale of hardness.  They are so hard that they are chipped at the top.  The ones I got from Bernbaum were way softer than these.

 

I ended up removing the lowers and keeping the Bernbaum top mounts and don't have any vibration and I have my reverse.

 

[Eneto-55]

1 hour ago, grea235 said:

I have been experiencing the same issue with mounts on my 52 Concord.  I was changing them because it wouldn't go into reverse on a decline.  Got uppers and lowers from Bernbaum.  My car had no lowers...don't know if they were removed or not.  Put them in and got a lot of vibration, but got reverse back.  I had to slacken the bolts to where they were just barely tight to get the vibration to go away.

 

I wasn't comfortable with the barely tight bolts and figuring that the rubber was too hard, I ordered the A2014 Marmon mounts from Rock Auto.  I received them yesterday and what I got was extremely hard plastic.  I don't think they are rubber at all and really hard, I mean  probably a 7 on the Moh's scale of hardness.  They are so hard that they are chipped at the top.  The ones I got from Bernbaum were way softer than these.

 

I ended up removing the lowers and keeping the Bernbaum top mounts and don't have any vibration and I have my reverse.

 

Sorry to hear about your bad experience with these, but thank you much for the information.  I was on the verge of ordering those myself, as well as the front motor mount, which I know I need.  (That sort of thing was not available at all back in 1981 when I reinstalled the engine in my 46, and the mount was broken.  I did my best to fix it, but it's not right, and I do want to replace it before the front clip goes back on, or at least before the radiator is mounted back permanently.)

[Sam Buchanan]

Yes, ordering mounts does indeed seem to be a crap shoot, the Marmon's I got were a rubber that leaves a black residue on your hands.

 

But the best solution so far is to install only upper mounts. The Berbaum mounts I have are pretty hard but work fine without the lowers. Thank you for the feedback and glad you have a smooth ride back---hoping our cars won't need mounts for a very long time. 

 

My engineering degree was awarded under a shade tree but I suspect the vibration is primarily transmitted via the left lower mount as the engine rocks clockwise due to torque impulses. In this scenario the bolt would be pulling the lower washer "up" against the lower mount and creating a path for vibes to travel to the frame. Without a lower mount the washer just rides along without contacting anything. It seems the Chrysler engineers had this figured out nicely, we managed to mess it up due to lack of knowledge of how the mounts should be configured.....and clueless retailers who sell us lower mounts we shouldn't be using.....

Edited September 5, 2019 by Sam Buchanan

[Sam Buchanan]

6 hours ago, grea235 said:

I have been experiencing the same issue with mounts on my 52 Concord.  I was changing them because it wouldn't go into reverse on a decline.  <snip>

I ended up removing the lowers and keeping the Bernbaum top mounts and don't have any vibration and I have my reverse.

 

New mounts solved your reverse shift problem, but for future reference, it can be necessary to adjust the shift linkage after replacing mounts. This was the case with my P15, with new mounts it wouldn't go into reverse. The solution was to "shorten" the gear selector rod since the rear of the transmission was now closer to the shifter. The nut on the gear selector rod was tightened a few turns and reverse was then able to be engaged.

 

Here is an illustration from the Service Manual:

 

 

Edited September 5, 2019 by Sam Buchanan

[grea235]

Thank you for that Mr. Buchanan.  It is working ok at the moment, but I am pulling the motor in a month or so to do some work on the motor and I will be changing the front motor mount.  A new front mount may affect the reverse, so at that time I will more than likely need to adjust the rod.  I really appreciate the diagram!

[Eneto-55]

On 8/15/2019 at 9:59 AM, Sam Buchanan said:

 

....

The illustration in the manual doesn't show a "thick" bottom mount.

 

Which service manual is this photo taken from?  I'm asking because my Plymouth Service Manual (for models P-15 P-17 P-18 P-19 & P-20) DOES show a lower bushing.  I looked at mine, which I assembled w/o benefit of this forum (in 1981), and I DO have lower bushings installed.  But this car was dismantled when I bought it, and the original engine was already gone, and a 55 model 230 included, also already torn down.  (The guy I bought the car from said that the PO had said that this engine had been installed, but I always doubted it, because some things like the exhaust manifold are different, and would not have matched up w/ the original exhaust pipe.)  

Anyway, I do have bolts in that are a good bit longer, but that means little to nothing, because a whole bucket of bolts came with the car.  (I did pull the original engine out of the 49 P15 parts car I have, but that was way before digital cameras, and film was expensive.  So I don't know how that one was, either.)  But my upper engine biscuits are really squashed (I didn't replace them - hard to find any replacement parts like that back then), and also have deep cracks in them.  But they ARE still soft enough to push your finger into them.

 

I did just meet a guy here locally on Saturday that has a P15 (in a parade here - I ran after him to the place where everyone was turning around...), and it looks unrestored, so I might go see him, if I can take a look at his.

[Sam Buchanan]

18 minutes ago, Eneto-55 said:

Which service manual is this photo taken from?  I'm asking because my Plymouth Service Manual (for models P-15 P-17 P-18 P-19 & P-20) DOES show a lower bushing.  I looked at mine, which I assembled w/o benefit of this forum (in 1981), and I DO have lower bushings installed.  But this car was dismantled when I bought it, and the original engine was already gone, and a 55 model 230 included, also already torn down.  (The guy I bought the car from said that the PO had said that this engine had been installed, but I always doubted it, because some things like the exhaust manifold are different, and would not have matched up w/ the original exhaust pipe.)  

Anyway, I do have bolts in that are a good bit longer, but that means little to nothing, because a whole bucket of bolts came with the car.  (I did pull the original engine out of the 49 P15 parts car I have, but that was way before digital cameras, and film was expensive.  So I don't know how that one was, either.)  But my upper engine biscuits are really squashed (I didn't replace them - hard to find any replacement parts like that back then), and also have deep cracks in them.  But they ARE still soft enough to push your finger into them.

 

I did just meet a guy here locally on Saturday that has a P15 (in a parade here - I ran after him to the place where everyone was turning around...), and it looks unrestored, so I might go see him, if I can take a look at his.

 

 

The illustration appears to show lower mounts but they are nothing like the lowers that are available today, I've never seen lowers like the illustration offered for sale. There were no lowers on my car when I changed mounts, I just assumed they had deteriorated to the point that they had disappeared but a parts book creates doubt as to whether or not the P15 should have lowers.

 

Compare the illustration to the lowers I recently purchased. These mounts are so much thicker that a longer bolt is required and it is impossible to snug the nut up against the metal bushing without extremely compressing the mounts.

 

 

 

 

Yep, the uppers can be pretty squashed..... 

 

Edited September 9, 2019 by Sam Buchanan

[Eneto-55]

Thanks.  I was confused as to which manual I saw the other picture in.  My manual actually shows the same picture as you posted earlier.

 

What i was thinking of was what I'd seen in a Plymouth Parts Manual I downloaded off of this site back in July of 2010.  (Each page was a separate PDF file, and I combined them all into a single file, then added bookmarks.)  The front cover wasn't included, but here is the title page.

Then also I will post the picture of the engine supports.  

 

[Sam Buchanan]

That is interesting, looks similar to the lower mounts we have, but not what is in the Service Manual illustration....best I can tell. 

 

Well....I don't know what we should be running, but I do know my P15 (and her driver) is perfectly happy with just uppers.  

 

I would love to have a copy of your master PDF file. 

Edited September 10, 2019 by Sam Buchanan