Author Topic: Any Thoughts.?  (Read 2426 times)

chetbrz

  • POC MEMBER
  • Senior Forum Member
  • ****
  • Posts: 1168
    • View Profile
    • My Space on the Web
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.?

Chet…
http://www.1948Plymouth.info           Web Master - Forum Administrator - AACA member

29UJohn

  • FOUNDING MEMBER
  • Senior Forum Member
  • *****
  • Posts: 362
  • 1929 U 4 Door Sedan
    • View Profile
Re: Any Thoughts.?
« Reply #1 on: May 26, 2008, 08:46:28 PM »
Chet,

Wow - I think you fixed a big problem that could have lead to major engine damage.  I had a similar experience with my engine's relief valve after I had the oil pump rebuilt.  The oil pressure was 40 at idle and 55 at 40 mph.  After a short drive the back pressure on the pump striped the pump drive gear and damaged the cam pump drive gear, which lead to a replacement cam shaft. 

After talking with a knowledgable mechanic (something I should have done more of first!) he explained to me that a good oil pump is capable of putting out 100 psi.  He advised me to set the oil pressure relief valve as follows:  At idle, initally set the relief valve to about 20, then drive it at normal operating speed (~40 mph) and check the oil pressure.  It should be between 35-40, and should not exceed 40 psi.  If it exceeds 40 psi, turn the pressure relief screw counter-clockwise one half turn and reinsert the cotter pin, then repeat the test.

As for your question of what else to do, if I were were you, I would pull the valves (numbering each with masking tape) and take them to a machine shop to have the faces reground.  If they are badly worn, you may be advised to replace them.  Then I would grind (or lap) each one in its valve seat.  (Detailed instructions are in the operators manual, or you can consult a Dykes manual.) If you do not want to do all that, as a minimum you should check each valve face visually to see if the faces are worn badly.

Regarding your concern that excess pressure may be blowing oil past the cylinders, that is not possible on this type engine.  The cylinders are lubricated by a spray that comes from a small hole in the rod bearing.  If the engine were burning excessive oil, then the rings may be suspect.  Did you check the cylinder pressure before you pulled the head?  If so, you might have been able to determine if the rings and or the valves were suspect before you pulled the head.

If your engine is not burning the oil, it may very well be leaking from the rear main seal. (The oil will drip out the weep hole vent under the flywheel cover.)  This is not uncommon with these engines.  Did the previous owners have the rear main seal replaced when they rebuilt it?  Note that originally these used a rope seal.  Rope seals work well if installed properly.  However, it may have been replaced by a "modern" split steel and neoprene seal.  But, unless the block was modified properly, this type seal will not seal properly (which was the case with my engine when I bought my car.)   

As for the carbon you found in the cylinders, these engines will build up carbon deposites rapidly.  I would not be concerned about that.  The operators manual advises owners to pull the heads and clean out the carbon occasionally!

Hope this helps a little.

John

P.S. It looks like your block is missing a stud.  You can have one made, but I saw a new one on sale on ebay.)



« Last Edit: May 26, 2008, 09:03:57 PM by 29UJohn »
John
1929U 4 Dr

chetbrz

  • POC MEMBER
  • Senior Forum Member
  • ****
  • Posts: 1168
    • View Profile
    • My Space on the Web
Re: Any Thoughts.?
« Reply #2 on: May 27, 2008, 10:49:38 AM »
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…

http://www.1948Plymouth.info           Web Master - Forum Administrator - AACA member

Don Coatney

  • New User
  • *
  • Posts: 1
    • View Profile
    • My Photobucket
Re: Any Thoughts.?
« Reply #3 on: May 27, 2008, 01:40:07 PM »
Chet;
If you need a head stud I have a spare or two. Let me know and I will drop it in the mail.
Don Coatney

29UJohn

  • FOUNDING MEMBER
  • Senior Forum Member
  • *****
  • Posts: 362
  • 1929 U 4 Door Sedan
    • View Profile
Re: Any Thoughts.?
« Reply #4 on: May 27, 2008, 09:16:26 PM »
OK.

If it runs and burns oil - that should be OK for now.  These engines are hardy.  As long as the engine is getting oil, it will probably run OK even if the pistons and rings are the wrong size.

When I first got my 29 (at age 16 in 1973) I put in a quart of oil every 40 miles!  After college I had the bearings re-babbitted and the rear main seal replaced.  After that, I only had to put in a quart every 80-100 miles!  Years later when I rebuilt the motor, I realized that the pistons were .030 over sized - it was stamped right on the piston face, and I missed it!  I had put new rings in myself as a kid - standard size rings!  I also learned that the engine shop had installed the rear main seal improperly.  After I installed new correct oversized rings from Hastings and installed the rear main seal correctly, engine oil consumption dropped dramatically.  I change the oil every 500 miles - and now do not have to add any between oil changes!

Having said all that, as a kid I drove my old car a lot, even though the engine had many problems (that I could not afford to fix) - it still kept running! 

Do not be concerned about the valves not having a Chrysler number on them.  There were several companies that made valves.  I doubt you can find an original Plymouth Chrysler valve for the engine today.

Good luck at the Father's Day car show!

John

John
1929U 4 Dr

chetbrz

  • POC MEMBER
  • Senior Forum Member
  • ****
  • Posts: 1168
    • View Profile
    • My Space on the Web
Re: Any Thoughts.?
« Reply #5 on: May 28, 2008, 01:16:59 PM »
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.?
http://www.1948Plymouth.info           Web Master - Forum Administrator - AACA member

29UJohn

  • FOUNDING MEMBER
  • Senior Forum Member
  • *****
  • Posts: 362
  • 1929 U 4 Door Sedan
    • View Profile
Re: Any Thoughts.?
« Reply #6 on: May 28, 2008, 08:50:58 PM »
Head Torque?  Good question.

There are no official guides for the early Plymouth 4s.  I used to use 55-60 ft-lbs, based on a 36-42 Plymouth Service Manual (I do not have a copy, reference is from Plymouth, the First Decade web site.)  Now I use 60-65 ft-lbs, based on a Head Torgue guide produced by Tom Hannaford of the Antique Auto Cellar.

I scaned the guide, but it is too big to post.  I will email it.

Here is the torque procedure I use, based on Tom's guide:

1) Torque to 1/3 (20 ft lbs)
2) Torque to 2/3 (40 ft lbs)
3) Torque to almost full (55 ft lbs)
4) Torque to 60 ft lbs
5) Start engine and warm it up, then retorque
6) After first drive, retorque while still hot

See Attached PowerPoint for sequence.

« Last Edit: May 30, 2008, 09:33:35 PM by 29UJohn »
John
1929U 4 Dr

Satillite70

  • Full Member
  • *****
  • Posts: 59
    • View Profile
Re: Any Thoughts.?
« Reply #7 on: June 04, 2008, 11:20:51 AM »

    This is great to read, as I am planning next week to start tinkering on the engine, a friend came over the other day and we cranked the motor, but I don't have a compression tester so we did a "thumb test"... number one cylinder blew his thumb right out of the hole, the rest did too, but not nearly as hard.  I am hoping that the motor won't need a rebuild, at least not this summer.  I cleaner out the oil pan and bottom of the motor and painted the pan.  While removing the 1/2" thick sludge I found an unused and un scarred cotter pin stuck to the pan bottom next to the oil plug.  Maybe it has been there since day one, the sludge seemed to have been there that long!  I filled it up with Quakerstate 10w30 high mileage engine oil before cranking it over.  One plug wire is original, ther others have been replaced and all three replacements are cracked.  New wires, cap, etc will be installed.  I removed the side pan to look at the vavles and see if they were moving properly, which they seem to be.  This area is full of hard black deposits and will be well cleaned before I reinstall the side panel.

  I took a couple photos of the carb, as it appears to have been replaced.  It is still an updraft carb, but now I see why there is a new control on the pass side to the choke.  I could find no markings on the carb, does anyone know what this one is?  I am thinking it might be off a different model, or maybe even a different brand of car entirely???

Chris



chetbrz

  • POC MEMBER
  • Senior Forum Member
  • ****
  • Posts: 1168
    • View Profile
    • My Space on the Web
Re: Any Thoughts.?
« Reply #8 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.



Chet…

Yes that is a 6vdc high output alternator.
« Last Edit: June 06, 2008, 07:16:23 PM by chetbrz »
http://www.1948Plymouth.info           Web Master - Forum Administrator - AACA member

Old Plymouths

  • Guest
Re: Any Thoughts.?
« Reply #9 on: June 07, 2008, 04:04:03 PM »
Just an added thought on valves: The original valves in these engines lose their hardness over the years. I think it's the hot/cold cycling that has gone on long after Chrysler ever thought their cars would still be on the road. I did a valve job a few years back and was shown the difference between new hard valve stock and my old Plymouth ones. The guy dropped a couple of the Plymouth valves on to the concrete floor and they bounced maybe 2" and settled down very quickly. He then took a new valve and dropped likewise and the thing bounced a foot off the floor and continued to bounce for several seconds. The difference was obvious ,the Plymouth valves had softened over the years.
 Consequently I didn't go looking for NOS valves, I took his advice and left a couple of Plymouth valves with him and he asked me to come back in a week. When I did he presented me with a set of brand new valves made out of new stock. He had gone to the books and ordered new valves with the same diameter and valve head but too long in the stem. All he had to do to make copies of my Plymouth valves was to put the new ones in his lathe and cut them to length and cut in the keeper slot. I believe he said they came from a Chev engine of the 50s.
  Although exhaust valves are harder than intake valves,but the 2 are the same size, he just ordered all hardened exhaust valves to keep it simple. Since the replacements were meant for a high reving, high compression V8 he stays the new ones will most likely be the last my low reving ,low compression engine will have. They cost $6 each and I think he charged me $20 shop charge.
  I also found the stem of the original Plymouth valves had worn where they moved in the guides. They were a few thou thinner right in the guide 'area'. I didn't do anything with the guides and just put in the new valves with their 'full diameter' stems. Voila! The tightness with the new valves was excellent so I just put the engine back together,after lapping the valves to the seats ,and it has run very well since and stopped it's excessive oil use.
 I think as said in one of the posts,these engines are very robust and don't break easily. They were built out of virgin steel, the first time this iron was ever used in an engine or body. Today we drive old toasters and washing machines. The reason modern vehicles rust and break so quickly.   
  The place that did this was a machine shop that rebuilt engines and by chance the guy running it has a 1929 Essex he and his father had restored. This perhaps was the reason I lucked out. But maybe you could use my experience to relate to a machine shop in your area and get them to do the same thing.                 
« Last Edit: June 07, 2008, 04:07:44 PM by Old Plymouths »

29UJohn

  • FOUNDING MEMBER
  • Senior Forum Member
  • *****
  • Posts: 362
  • 1929 U 4 Door Sedan
    • View Profile
Re: Any Thoughts.?
« Reply #10 on: June 07, 2008, 10:56:17 PM »
Chris,

Not sure, but I think your carb may be a Tillotson.  I beleive they were sold as replacement carbs for Ford Model As.  When I purchased my 29U in 73 it had a Tillotson carb on it.

I see it looks like you have an original air filter.  Advise you hand onto that, they are harder to come by than the original Carter brass bowl carbs that came with these cars.

By the way, you are very fortunate to have such good interior handles on your car.  All but one on my car had disintegrated.

John
John
1929U 4 Dr

Satillite70

  • Full Member
  • *****
  • Posts: 59
    • View Profile
Re: Any Thoughts.?
« Reply #11 on: June 13, 2008, 07:43:26 PM »
Hi John,
    Thanks, I'll see what I can dig up on that line of Carbs.  I plan to get her mobil by Sunday if possible.  I have to clean out the break and gas lines, reassemble the breaks and then onto the carb and plug wires.

    On the handles I have posted another note in the topic on interior.

Chris