GrahamPaige29

High Oil Pressure on Graham Paige

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Hi guys.  Thanks to your help I finally got the engine running on my '29 Graham Paige.  I still haven't finished the cooling system hook up but I did have it running briefly to test the timing etc.  One thing that concerns me is the oil pressure seems very high.  I had a gauge hooked directly onto the sender unit and once the engine got going it registered over 90.  According to my manual, 40 is about normal.  Also, where the water pump has a oil passage connected to it, I found there was excessive oil leaking during running which would mean to me that there is a lot of pressure there.

 

I did try to keep about 2 thousands of an inch clearance between the journals and bearings by using shims and measuring with plastigauge.  Now I'm nervous that some of the passages are clogged up somehow or there's another issue. 

 

Do you think the problem will sort itself out once I have the cooling system done and can let it run longer or should I pop off the connecting rod caps and see if anything's clogged? 

 

Sorry guys but I'm a nervous newbie.

 

Geoff

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First, before you question what you've done with the engine and go tearing back into it, how sure are you the gauge is accurate ?   You be shocked at how far off many (even new) pressure gauges can be when checked against lab-grade gauges.

 

Was that 90 psi with a cold engine at start up, or 90 after a good 20 minutes of running at fast idle to heat the oil, as some manufactures specify ?   What's Graham's specs for that 40 psi ? Does it say under what conditions and with what oil it should read 40 ?   

 

Paul

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Just re-read your topic "6 Volt Booster Starter Necessary ?". I do not see the "Oil Discussion" there. I seem to remember one member firmly locked in to 40 weight non-detergent oil for his new engine. Pretty sure it was a new Packard engine. Adhering to that fictitious myth will simply insure earlier renewal for the next time , and inferior performance over the abreviated period. Actually not a HUGE engine destroying deal , but , yes , a bad choice. Running Amsoil Z-Rod 10W/30 will accord your engine the greatest performance , both running and during lay up. BUT DO NOT USE IT FOR BREAK IN ! Amsoil now has a SYNTHETIC (!!!!!) break in oil ! Look it up. Warm up , and drain what is in there. Adhere to Amsoil instructions , and you will be treating your engine to the very best. Just as you do with your family ! I consider my cars family. If anyone can prove a better oil than Amsoil Z-Rod , I will use it , and drop Amsoil like a hot exhaust manifold. I have no relationship with Amsoil other than being a customer. They are not really family , they just treat my family better than any other lubricant manufacturer at the present time. Make sure to use their Synthetic grease also. Please let me know if you want impartial corroboration for my bold , in-your-face recommendation. But please look it up first.

 

The above is preamble to the following : Dr. Spinney' has asked an extremely relevant question. Along with Paul's pertainant response , it stimulated my above. It is quite normal for oil pressure at start up cold to be double the fully warmed up running pressure. My Maserati ran 160 at start , 80 warmed up. But that was with a huge external oil pump , a detuned Colombo racing engine , and specified straight 40 weight oil Winter , 50 weight Summer. If I still had the Maser , I would run 20W/50 Z-Rod all seasons. 80 psi was at the half point on the oil pressure gauge. Fine for a Maserati , WAY too much for a 1929 Graham. Verify the condition of your oil pressure relief valve , change to Amsoil Synthetic  break in oil for a few hundred miles , and monitor the oil press. Normally you cannot fully warm up an engine if it is not under load , unless you impose water or airflow restrictions to simulate load temperatures in a static "laboratory bench test" environment , or run it on a dynamometer.                           I am glad things are going well for you , and look foreword to following your progress !    - Carl 

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To reinforce one of Carl's points, in my experience it's very common for cars through 1935 or so to *normally* show twice the specified running/hot oil pressure at cold start.  I do agree with the use of multi-grade which I run in all of mine, although I use dino oil rather than synthetic.

 

What I want to emphasize in this post is that you have a relatively narrow window to break your rings in properly.  Fast-idle no load is NOT the way.  You must work the engine fairly hard and load the rings by pulling hills at half throttle or more for a minute, then back off for another minute.  Do it in 2nd and 3rd gear, but semi-lug to load the rings.  Repeat, repeat, for 30-50 minutes.  This is especially important if you installed cast iron oil rings.  So please defer your gratification on hearing the engine run for awhile.  Short period of fast idle is OK to check for fluid leaks and to correct them, if any, and to set timing pretty close.  Then work that engine!  Especially if you've used a modern sandwich gasket with a (plastic) asbestos substitute, you will need to retorque the head several times.  I strongly recommend retorquing pre-war engines overnight-cold due to (essentially) Grade 2 head bolts/studs and the relative softness of the threads in the block. 

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HI guys.  Thanks for the tips.  I actually had to drain the engine anyways to double check on my pistons.  I had a hunch that I had carelessly installed one of them 180 degrees off (rotated) which would mean the oil passage would be misaligned.    I have corrected that and will refill with break in oil.  Here is a pic of my oil pressure regulator.  Bit of an odd one.  I will take it off and examine it and send you guys some pics.  I have the dash gauge on it right now (green tape is just holding the number plate in position).  I am almost finished repairing the water cover plate and rad and will install them after Christmas.  I'm off for a week which will mostly be spent on the car.IMG_0460.thumb.jpg.f5734aee029a3fd98bdbe205b348b6b4.jpg

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Grimy, please explain how lugging the engine facilitates breaking in the rings. What different forces are affecting the rings when the engine is under load versus at idle ? 

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Restorer32, thanks for bringing this up.  I wish I hadn't said "semi-lugging," but it was late and I was hurried when writing it.  My friend GLong (not very active on the forums these days) had a very good explanation in a post of a year or two ago, but this morning (I've got a busy day today) I couldn't find it in the first two pages of his content.

 

Let's start with what I recommended but call it level ground rather than hills.  Assuming the G-P is a 45 mph cruise car, if it were mine I'd start on the level at 20 mph in top gear, give it more than half throttle and accelerate rapidly to perhaps 38 mph, then let it coast back to 20, and repeat.  Full charge of fuel in an acceleration mode puts much more load on the pistons in their downward travel, AND adds heat to expand the pistons and rings against the cylinder walls--and thus the rings are subject to better break-in to the position they will take under future normal use.  The coast-down lets the rings relax a bit and wear in at their coast-down position.

 

At idle, even fast-idle, but no load, the rings are not subjected to full heat expansion under "loads" roughly defined as burning a full charge of gasoline rather than a quantity sufficient to merely keep the engine running.

 

I don't claim to know it all and am interested to see what turns up on the other, similar thread you started this morning.

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It is my understanding that "lugging" an engine during break-in is not so good. Wear is occurring, including in the bearings, and you want the temperature cycling of loading and unloading the engine, but not "lugging" coz the oil pressure is low and the bearings may suffer excessive wear, rather than just the high spots being worn off (i.e. machined surfaces being smoothed). Actually, I understand that "lugging" an engine is bad at any time because of the possible minimal or insufficient oil film on the bearings.

 

I have posted on Restorer32's topic what Dyke's had to say about it in 18th Ed. 1937.

Edited by Spinneyhill (see edit history)

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My 3 Graham engines 64, 827, 610 all start up cold at around 60 psi (running 15-40 oil) it takes them a good 10-15 minutes of driving to get to full operating temperatures.  Normal operating pressure is 25-35psi, around 20 at idle, none of my engines have been rebuilt, all under 50k miles.

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