Today I installed the new motor mount and the head.  I ran a compression test after the install.., cranking the motor with the starter I was able to pump up 65 – 70 psi across all cylinders.  I think I will be back on the road soon.



Chet...

Yes that is a 6vdc high output alternator.

Chris,

It sounds like you found a Split Rim Tool.





Your car is looking Great !!  Keep up the good work,

Chet...

John,

I think you hit the preverbal nail right on the head.  The top of my pistons is stamped X183. Whatever that means.   The diameter of the stock cylinder wall for the 175.5 engine is 3 x 5/8" or 3.625.  I measured the inside diameter of the bore at 3.645 with no taper top to bottom all cylinders.   It appears the engine was bored out 0.020.  This is actually good news, if need be I could go another 10 or 20 thousands down the road apiece.

I don't have the time to pull a piston now and investigate further.  I will put it all back together and see if the oil consumption problem subsides with the pressure relief valve working properly.  If not.., I will suspect some type of mismatch between the bore, pistons, and rings.

Tks,  Chet...

PS...  Don, I have the stud for the head.  The nut & stud decided to come out as a unit. 
PS...  John, How many foot/lbs did you use to torque the head.?

John,

The engine is definitely burning oil.  There are no leaks and no back pressure which leads me to believe that the compression is still good.  I think I ran a compression test when I first brought the car home and it checked out OK but I will definitely do it again after I reinstall the head.

The motor was freshly rebuilt and the pistons and valves are all new.  The cylinders show no appreciable wear and they look like they just came back from the shop.   If what you say is correct about the oil system then I wonder if the rings and pistons were correctly spec. out or installed properly.   Just because things look good that doesn't necessarily mean that the machine shop or the home rebuilder did everything correctly.   

Judging by everything I just said I would not have expected the pressure relief valve to be in such a sorry condition.  The engine might have been hot-tanked with the valve in place so that it might not have been properly cleaned which leads me to believe that the rebuilder was not familiar with this vintage engine or the car was unused for a long time after the engine rebuild.   

I am trying to get ready for a local Father's Day show here in Virginia.  I will put everything back together and hope for the best.  If no improvement then I will most likely pull the engine out and start all over again.   I have a bad feeling that the pistons might be slightly undersized with oversized rings improperly installed.   Before I reinstall the head I will mic. the cylinders and piston gap.    The cylinders are stamped on the top with a part number beginning with X and the valves are marked with manufacture & part number, none of which are Chrysler.

John thanks for your input it all helps with the trouble shooting process,  Chet...

I have been having a lot of trouble with burning an excessive amount of oil.  When at idle the oil pressure reads just under 40 psi and when driving my gauge is maxed out.  The motor runs strong and was rebuilt not too many miles ago by the car's former owners.  Anyway since I was draining the coolant to replace the radiator with an original one I decided to remove the head.  My two purposes are one to inspect the pistons & cylinder walls, and the other reason is to repaint the head silver. 

With the head removed I found pristine cylinder walls with hardly noticeable edge ring.  The cylinders had oil puddled in the cylinders with a lot of black carbon on the pistons.  I cleaned up the area and decided to trouble shoot the oil pressure.



Thinking that my car's gauge was inaccurate I installed a new modern oil gauge and cranked the engine with the starter.  The gauge read 38 psi after about a half a minute of cranking.  This is the same value as my interior gauge so I guess my old gauge is correct. 

I then decided to remove the pressure relief valve assembly.   After inspection I could not push the valve in far enough to allow the port to open.  I disassembled the valve and cleaned the spring, plunger, and cylinder.   After reassembling the parts I could now push the plunger in to allow the valve to open.   I think this was my problem.  I reassembled the valve into the engine and set the pressure one turn from minimum pressure.  I cranked the engine with the starter and the pressure pumped up to 20 psi and with continued cranking would go up to 35 psi.   The pressure looks much better now then when I started. 

Once I get the motor back together I will adjust for 35 - 40 psi maximum when driving at a normal speed.  I think this should help the excess oil burning problem by allowing less oil to blow by the cylinder rings. 

What do you guys think.?  Is there anything else I should do while the head is off.?

Chet...

Quote from: George29 on May 19, 2008, 11:12:42 AM
Just for info. I had my brakes relined by these guys and they did a great job at a resonable price.
The starter on my 29 shorted and I've sent them and email to see what it will cost to have it rebuilt.

Good luck with all your projects
George

George,

I see that you finally got your wheels off and had the brakes fixed.  Too bad about the starter motor.  Hopefully you will get it back and repaired and be back on the road soon.

Chet...

Gary,

You are probably correct in your first assumption.  It might be that this was a storage place for the jack, crank, and a common tool set.   I have noticed this compartment while under my car.  I can't access the compartment because someone replaced the floor and boarded over this area.  Hay wouldn't it be great to open that floor up and find a bunch of money left over from a late thirties Bank Robbery.    Oh well I can dream... can't I.  Most likely nothing there but a pile of rust.

I definitely have to get to a National Plymouth meet and see what one of these cars looks like based on a factory correct restoration.  There was one 29 Plymouth at Hershey last year and I just didn't have the time to find it.  Mostly looking for parts and I only had an afternoon.  This October I plan to spend at least two full days walking the fields.

I would love to see what it looks like under your rear seat.  If you ever have the camera out I would appreciate a photo.

Tks, Chet...

There are a number of things that can keep your brake pressure from bleeding off. 

You can have some type of obstruction in your brake lines.  If all four wheels are locking then the obstruction may be from the tee in the middle of the car back to the Master Cylinder.

Also there is a tiny drain hole in the master cylinder that is there to allow pressure to equalize on both sides of the drive piston. 

See diagram item 9



Master cylinder piston return spring stuck not allowing the valve to open and bleed off the pressure.  Remote but possible  See item 20 above.

Have you done any work to the brake system lately?  If so that might be a good place to start.  If not then maybe dirt and sludge have accumulated in the lines.  Might be a good time to blow them out and clean the whole system.

For what it's worth my 2 cents,  Chet...

Gary,

I call Tom Hannaford at the Antique Auto Parts Cellar to arrange to have my front motor mount re-vulcanized.   We talked a little and he told me that he carries everything mechanical to keep the 28-30 Plymouth rolling including Kingpin sets.

I thought you might be interested:

Antique Auto Parts Cellar
PO Box 3 (6 Chauncy Street)
Weymouth , MA 02190
Telephone: 1-781-335-1579
Fax: 1-781-335-1925
email: Thecellar@then-now.com
http://www.then-now.com/

Chet...

Anyone have any tips or personal experience with changing the return spring on the 29-U starter motor.   

Chet...

Quote from: have parts on May 14, 2008, 10:43:07 PM
I was just thinking about the info. Does anyone have a diagram
of the oiling system they could send us?  Thanks

This is the best I can do.  The attached file is a cut view of the Modal U engine.

Chet...

Open the PDF file below the line.

On the U engine the oil pump is external and is located under the intake and exhaust manifold.  If you remove the front cover crank the engine for a short time to ensure that the eccentric is turning.   I believe there is a little gear that commonly wears out.  If your engine was rebuilt I would assume that this was checked but who knows.

Also there is a pressure relief valve that might be creating some problem.   I know that with modern oil pumps you should always prime them prior to installing them.  I am not sure about the U pump but it can't hurt.  There is a pipe that goes from the oil pump to the engine.  Check that for oil content and if the pump is turning then maybe get some oil in it to prime the pump.

My 2 cents, 

Chet...  & Welcome to this web site.!!

PS... If you are not sure you are getting oil pressure then I wouldn't run the engine. 

Quote from: Doug on May 14, 2008, 08:59:46 AM
Chet, How do you like the floor pads. I have been looking at them. I have my originals but they are dried out and warped. Is it very hard for you to get your floor board up to reach the battery. I have a small rectanglar hole I can lift out to check the water but to get the hole floor out is a job

Doug,

I too have a rectangular hole that allows you to access the battery.   I am not removing the floor just installing a new toe board.  The piece that goes from the floor to the firewall.  I will be putting down rubber mating in the front of the car and for the time being leaving the rear as is. 

My floor is not original and the previous owner laid down tong & grove oak flooring.  Since it is stained and varnished it actually looks real nice especially in the back.  The floor was redone a long time ago so it really has a vintage look to it.  For the 4-door sedan I believe the original floor was plywood with rubber flooring in the front and carpet in the back.

As for the Steel Rubber replacement pads I think they are excellent.  The one for the pedals was copied from an original 29-U item.  If you have a 1928-Q it has to be slightly modified to fit around the steering column.

Chet...

I am getting the 29 U ready for the summer driving season:

Original refurbished radiator ready for installation.

I can't wait to give her a crank...

Kingston Vacuum fuel pump ready for installation:



I purchased some reproduction floor pads for the pedals and the shifter form Steel Rubber.  These are well worth the money and are excellent reproductions.   I will also redo the toe board and install repro rubber floor matting.

 

I have lots of other little things to fix like installing the new Steel Rubber windshield molding and fixing the broken passenger side window.  I hope to be back on the road before Father's Day.  I am excited about getting the old girl out on the open road again in a little better condition then she was the year before.

Chet...

Mr Plymouths

Take a look at Chris's interior.  It looks pretty original to me.  Also the Passenger side front and the drivers side rear have a map pouch.

What do you think.



Chet...

Chris,  My car has no map pouches in the rear.  My interior is leatherette and has a map pouch on both front doors.  (29 Model-U,  US Built approximately March 29)  I don't know if mine is original but the interior is very, very old.  I will post pictures at some point.