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Messages - chetbrz

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General Discussion / Re: Does anyone know....
« on: June 30, 2008, 07:41:20 AM »
If no one from this forum responds, then try the Plymouth Owners Club Forum.  You don't have to be a member of the POC to join the board.

See link below.

Good Luck,  Chet…

General Discussion / Re: Hand Cranking your Old Car.
« on: June 26, 2008, 08:30:32 PM »

Be careful.., it’s too early in the driving season for any casualties.  Try it with a hot engine first.  It should be easier to start.

Good luck…  Chet...

General Discussion / How Sweet it is... :)
« on: June 24, 2008, 07:54:47 PM »

I drove the 29 to work today, just a couple of miles.  After the oil pressure odyssey I decided to take the old girl out for a spin after work.  I drove a good 35 miles and on the home stretch I pushed her up to 50 mph on the car’s speedometer.  I sustained that speed with throttle to spare for a good 2 or 3 minutes.  Oil pressure was rock solid at 45 psi which in reality is 40 psi.  The engine remained nice and quiet with no bearing nock.  At idle she maintained 20 psi which was telling me that the pressure relief valve was closed and all that wonderful oil flow was going to my engine components.

When I got home I parked her under the shade tree in the front yard and snapped a picture.

What a great day after a very scary time.  I have to admit that Walter P. picked a very hearty engine for his Plymouth line.  After driving a good 40 miles round trip to the car show on Father’s Day with minimum oil going to my engine components and a ton of bearing nock the old girl bounced back in good stride.   It just goes to show you what a great car old Walter P. built in 1929.  As an aside the wife followed me back to our rented garage and reported that I was no longer blowing smoke out of the tail pipe.

How Sweet it is,  Chet…

General Discussion / What I have learned from all of this...
« on: June 24, 2008, 08:34:44 AM »
What I have learned from this adventure...

The pressure relief valve is nothing more then a plug held in place by a spring.  When oil pressure is applied to the plug it will push in depending on the tension of the spring.  When the plug is pushed in.., an outlet to the engine’s oil sump is exposed and excess oil pressure is drained off into the crankcase.

Theoretically the spring is designed for a defined tension and the adjustment is available for a minor compensation.  I believe when you get into the later 6 cylinder flatheads I was told that the valve wasn’t adjustable although three different spring weights were available.  The springs were color coded

My Observations:

  • The valve is least effective at low rpm which produces minimum oil pressure.  If you wish to increase your low idle oil pressure the relief valve will have little to no affect.
  • The relief valve is designed to drain off excess pressure and is most affective at high rpm when your pump is providing maximum oil pressure to the engine.

From discussing this subject with others who own 28 to 30U Plymouths.  I have founded out that in the earlier modal cars the oil pressure gauge is connected between the oil pump and the pressure relief valve.  On the later modals it is connected to the engine oil path after the pressure relief valve.  In my opinion the later connection between the valve and the engine path is the better of the two designs. 

My suggestions before you do anything.

  • Determine what your problem is before you compensate with an adjustment.  The adjustment may provide a better reading on your gauge but basically may not help your oil problem or provide better oil flow.
  • For high-pressure problems the most likely cause is clogged or restricted engine oil paths.  For low-pressure oil issues you may have leaky bearing caps which are allowing the oil pressure to bleed off or possibly a worn out oil pump.

A good rule of thumb that I have always used in my professional life as well as with my hobbies is “If it ain’t broke…, don’t fix it.  My oil pressure odyssey was started because of excessive and escalating bearing knock and not the gauge readings.   Sorry I don’t mean to lecture just pointing out that this is an area that should be very rarely played with.

What I have learned and been told by others during the course of my trouble shooting.

  • Pressure between the pump and the valve should be no more then 45 psi at high rpm.
  • Pressure in the engine path should not be higher then 40 psi and could be as low as 28-30 at high rpm.
  • Since the low pressure reading isn’t affected by the valve I have been told that pressure as low as 10 psi with a hot engine at low idle was acceptable and presented no problems.
  • Don’t trust your old gauge.  After 70+ years of service it stands to reason that it wouldn’t be dead accurate.  Hook up a new modern high quality auto gauge to evaluate your actual pressure readings.

Adjust for maximum pressure at high rpm.  Whether the oil is cold or warm the Maximum pressure should not exceed 45 psi before the valve and 40 psi after the valve.  Probably checking the adjustment with a warm engine might be best but shouldn’t matter, pressure is pressure at any temperature.  Turing the screw in will increase the pressure reading and turning the screw out will decrease the reading.  Feeling little resistance against the screw is normal and not a problem.

My thanks to everyone who provided information and discussion points to this topic both from this site, through email, and from the POC forum. 


Thanks John for the information, that was very helpful,

The point I was trying to make previously is that when faced with oil pressure problems adjusting the pressure relief valve is not the correct answer or wasn’t in my case.

The problem I was having was that my oil pressure was too high and by lowering the pressure without resolving the reason for the high oil pressure, especially in the 28Q & 29U which measure oil pressure before the valve, is a major mistake.   

As discovered over the weekend the oil path in my engine was gummed up and restricting the flow of oil to the bearing caps.  This was the reason for the high-pressure reading between the pump and the valve.  With the restricted oil flow going to the bearings all the pressure was applied against the only other path.., the pressure relief valve.   By lowering the pressure to minimum I still couldn’t get the operating pressure range correct.  (Never could get the pressure below 35-40 psi at slow idle) But by adjusting the pressure down I was in effect starving the bearings of what little oil they were getting.

Over the weekend I cleaned out the oil path as best I could with out removing the main bearing caps.  Through the use of high-pressure oil & air flow I was able to restore good flow through the engine.  I am still not 100% sure that all restriction has been removed.   After washing out the clog I was able to adjust my pressure relief valve quite a bit in from the minimum pressure setting I had prior.  (which is screwed out to the point that one more half turn and the Carter pin would no longer fit into the pin hole)

After some experimentation I was able to read 45 maximum psi (with a modern gauge) between the pump and the pressure relief valve both at medium and high rpm.  The pressure relief valve is now set at a more reasonable mechanical position and is neither at Max or Min but someplace in the middle.  The old gauge in the car reads 50 psi to the modern gauge’s reading of 45 psi. 

Current operating conditions using the old gauge, which reads 5 psi high on the high end of the scale:

Straight 30 weight oil

Cold engine slow idle:   35 psi
Cold engine high rpm:   50 psi  ( gauge no longer maxs out )

Hot engine slow idle:   25 psi
Hot engine high rpm   45 psi  ( gauge no longer maxs out )

The probable reality is 30 to 45 cold and 20 to 40 hot.  My engine bearings have quieted down so I think my problem is now finally fixed. 

Some corrections to previous statements.

I guess never say never but before you fool with pressure relief valve settings truly understand what is causing your oil pressure problem.  I believe the setting very rarely changes for no reason.

After further experimentation and observation the vacuum side of the fuel pump presents little affect on the oil pumps ability to provide adequate oil pressure.   My initial theory concerning plugging off the vacuum side of the pump was inaccurate. 


When you have a chance could you provide a picture of where your oil gauge line is attached to your engine.  Hopefully there is a plug in mine that will allow me to measure pressure after the pressure relief valve.

Tks,  Chet...

General Discussion / Father's Day in Virginia...
« on: June 19, 2008, 06:48:01 PM »

This is a continuation of my Post “Any Thoughts”

Cleaning and adjusting the pressure relief valve on the 1929-U was both good & bad.  It was good to clean it but very bad to adjust it and here is why.  (Use the crude diagram below for reference)

The line, which feeds the oil gauge, is between the pump output and the pressure relief valve.  Because of this the pressure relief valve only affects the pressure of the oil going to the motor parts. The gauge reading is only affected by the valve adjustment when the valve is opened to much thus causing a dangerous drop in oil pressure to the motor parts.  My assumption is that this is the reason the Plymouth Instruction Book states “…never to adjust this device…”.  The adjustment will have little affect on the gauge reading unless you completely deplete the amount of oil going to the engine bearings. 

The single eccentric in the oil pump is used to move both oil in the engine and air flow from the vacuum fuel pump.  Because of this, the total pressure out is equal to the sum of both inputs and the viscosity of the fluid.  Since the pump mixes air with the oil…, if the vacuum line is plugged up then no air is introduced to the pump and thus the pump will develop an additional 10 to 15 psi of oil pressure. (reason – air will compress at a much higher rate then oil)    Example:  Take the air out of your brake lines and they work much better.

This is exactly what the problem was with my car.   When I brought the car home it had no vacuum fuel pump and I still have not hooked it up yet.  The point being is that someone plugged the line.   Of course the last owner didn’t have the problem because he had a leaky oil pump cover gasket that introduced the needed airflow.  My problem presented itself after I replaced the leaky oil cover gasket. 

After cleaning and adjusting my pressure relief valve to minimum pressure my gauge was affected by maintaining 35 psi at idle and 50 psi at run.  Good.., absolutely not.  That meant that my engine was not getting the correct pressure at low rpm and probably at high also.   My engine starts to knock when I get into the 40 to 45 mph range and while driving it to the car show on Sunday it was starting to knock between 35 to 40.  I finally discover the above problem after the show.  I drove a total of 35 miles to and fro and most likely took some life out of my bearings.   

I intend to get everything adjusted back to spec before I run the car again.  Hopefully I didn’t do too much damage.  I am glad that the engine pressure stayed pretty close to the same otherwise I probably would have driven the car until I sized it up thinking that I fixed the problem.

The Plymouth manual is correct: 



General Discussion / Re: Hot Days here in Virginia
« on: June 12, 2008, 06:20:35 AM »

I bought it from Steel Rubber.

Seal set, windshield, rubber only, for crank-up windshields. 3 piece set for bottom and sides. Lower strip fits dovetail groove in cowl. Usually for Fisher bodied WPC cars.

70-0016-52.....$ 89.20/set

If you want I can take a picture.  The pieces fit like a glove.  I just had to trim the lengths.  A little pricey but good quality.


General Discussion / Re: Hot Days here in Virginia
« on: June 10, 2008, 09:49:24 PM »

They don't send anything back to you.  When you drive into the park they will ask you if you are pre-registered.  They will have everything waiting for you when you arrive.   I have the 29 in the back porch again while I work on her.  The heat is unbearable in that I get sun in the back from about 1:00 PM on.   I am about a day behind but should catch up a bit with cooler weather.

Since Friday I have completed so far:

- Installed original radiator
- Installed the head, plugs, distributor cap.
- Installed the gas tank
- Installed a new front windshield gasket with tracks.  It now opens & closes real nice.
- Installed new glass on the passenger side door.  Remade the rotted wood pieces and installed new window tracks.

Left to go:   (4 days and counting)

- Button up the cooling system
- Installed the hydraulic rear axel ‘T’ & original reservoir
- Installed the vacuum fuel pump. (with power assist)
- Install the floor covering & pedal trims
- Bring the car to the muffler shop and have a rear tail pipe fabricated.

I think that should do it for now…


General Discussion / Hot Days here in Virginia
« on: June 10, 2008, 07:22:09 AM »
The weather here in Virginia has been abusive in the past couple of days.  I took this week off from work to do a number of needed repairs to my 29-U. 

I installed the refurbished gas tank yesterday.  I think the fabricated Ford gas gauge looks pretty good.  Much better then the painted tin can cap that the last owner used.   It’s hard to tell from the picture but the gauge is reading ¼ tank.

Well..., back to work,  Chet…

General Discussion / Re: Any Thoughts.?
« on: June 06, 2008, 07:13:04 PM »
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.


Yes that is a 6vdc high output alternator.

General Discussion / Re: Under seat storage??
« on: June 04, 2008, 12:06:51 PM »

It sounds like you found a Split Rim Tool.

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


General Discussion / Re: Any Thoughts.?
« on: May 28, 2008, 01:16:59 PM »

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.?

General Discussion / Re: Any Thoughts.?
« on: May 27, 2008, 10:49:38 AM »

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…

General Discussion / Any Thoughts.?
« on: May 26, 2008, 12:43:30 PM »
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.?


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