Oil Pressure

Dennisfly

Dennisfly

Senior Member
I bought a 1935 Model 48 Standard Tudor Sedan. This is my first early Ford V8. It is very clean and has been owned and maintained by the same family for 46 years. According to them, it was restored in the late 1980s to include a professional engine rebuild on the 21 stud engine. The car was run regularly but from the restoration to now they estimate only 10,000 miles. The car runs and drives great for the 40 miles I’ve driven it since purchase. It is smooth, quiet, and powerful. No knocks or unusual engine noises.

As a Standard, the car was manufactured with no oil pressure gauge and no temperature gauge, and it had none when I bought it. After purchase, I installed a new after-market oil pressure gauge and a temp gauge for each water pump. The temperatures are good at 150 to 170 in the current Virginia weather, depending how you drive it. However, the oil pressure readings give me some concern.

I’m using Rotella 15W40 T4 oil, freshly changed. At startup the pressure is 20 PSI at low idle and 40+ at high idle. As the engine heats the pressure drops as expected. At operating temperature, the pressure is about 10 PSI at 25 MPH. It is between 10 and 20 PSI at 45 MPH. After running at 45 MPH for a while if you slow to 25 MPH the pressure reads from 0 to 5 PSI. Then if you idle at a stop, it is 0. Still no unusual noises.

I did a search on the Barn and there are various opinions on the subject from days past (www.fordbarn.com/forum/showthread.php?t=68702&showall=1). Some say this is normal, don’t worry about it, just drive it. I think about climbing a steep grade in the summer and wonder what damage could be done!

So, it could be caused by excessive main or rod bearing clearance, excessive cam bearing clearance, or a worn or clogged oil pump. Some say that there is an oil bypass valve in the valley that can be shimmed for higher pressure but if this is the cause why do I have 40+PSI at startup?

I would like to have confidence in the engine and have it last a long time. Any thoughts on how I should proceed!
 
Sounds like my '52 F1 pickup, except I use 20/50 wt. of whatever brand the Dollar General or Family Dollar stores nearby me currently have on their shelfs.
Been driving it like that for 10 yrs. w/no issues..........F F
 
Dennis, I recently went through a similar issue with my '36 pickup, which has a 21 stud poured-bearing motor, probably the same as what you have in your '35. See this recent thread of mine for details:


https://www.fordbarn.com/forum/showthread.php?t=317742


My best advice would be to drop your oil pan and find out exactly what situation you are facing-for me working under jack stands, this takes the better part of a day and is a bit aggravating but not a terrible job. It will allow you to do several things:


1-See how much sludge you have (it may be a surprisingly large amount)
2-see what kind of oil pump setup you have and the condition of the pump
3-check bearing clearances with plastigauge


Long story short, my motor has fairly large main bearing clearances, another 'Barner has characterized this as "worn, but not worn out". I chose to go the route of installing a good quality high volume Melling M-15 pump, which now gives a reliable #45 at 55-60 mph and #15-18 at idle when hot, with 20W-50 oil. Whether or not this will extend the life of the motor is unknown, but it certainly runs extremely well and my goal is to get some more years out of it without needing a full rebuild (which is not a simple thing for a poured-bearing motor). I've been driving this truck for about 15 years and enjoy it quite a lot. I will say that when I first got it and dropped the oil pan, the amount of sludge was VERY impressive.


Adam
 
Ford Freak - Thanks for the reply. I have seen several threads where people have driven cars with little or no pressure for a long time. I would like to drive on some tours and to see little or nothing on the gauge really bothers me. I'm a retired pilot, and if I was flying, this would be an emergency!


Marko39 - That's what I suspected.


Adam - Thank you for your response. I also found your response to my air filter very useful. I have the same 221 poured bearing engine as you. You seem to be blazing the trail for me! I found your thread with Old-Ron very interesting. I should pull the pan and do the sludge, pump, Plasti-Gauge checks but it sounds onerous. Hoses, fuel pump, spring u-bolts, wishbone, motor mounts, lift engine, pan, etc. I'm still mulling this over but it is probably the right thing to do. Your after new pump numbers sound really good. The Melling-15 pump, doesn't it require a new extended pan? By the way, with regard to blazing the trail, I think I'm just one year younger than you!
 
Dennis, I would call it onerous but necessary.I know some prefer to actually pull the engine for this rather than work from below, but that seems a lot more complex to me.My engine had at least 3/4" of sludge in it 15 years ago and I don't think that is too unusual especially for these older motors without oil filters-unless you have a really good sense that it has had regular 1000 mile oil changes with modern detergent oil. I used the procedure outlined in the "1932 -1936 engine and chassis repair manual" (see photos below) which is available from various vendors. I work under jack stands, if you have access to a lift it would be a piece of cake. There is no need to touch the front spring, remove the fuel pump or move the crank pulley forward. You do literally need to drop the radius rods about 10-12" and raise the motor 2 1/2"-I use a scissor jack to lower the radius rods, and cut scrap lumber for supports. You can use the opportunity to take care of various other items, this time I put on new radiator hoses and rebuilt the Bendix starter drive which had some worn teeth. The stock oil pan works fine for the Melling M-15, there is an internal baffle which needs to be removed (easy with a die grinder + cutoff wheel), this doesn't affect anything. The 8RT pickup and screen are available from many vendors and easy to install on the pump. I got the pan gasket set from Mac Van Pelt, he supplies fiber type gaskets which I think are more durable than the cork gaskets.Hope this is of some help, it does seem like we are moving along the same path!


Adam
 

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It's been a long time for me, but isn't there a specific crankshaft position where the front counterweights are in the "up" position that makes it easier to slide the pan out?

Sorry if it mentions it in your attachment; that print is just a leettle too small for me to read.
 
Adam - Thanks for your reply, very good info. I have the manual you referenced and read the pertinent section several times. I have a friend that has 40+ years of early V8 experience and he suggested pulling the engine, claims he pulled one and replaced it with another in 8 hours when he was younger and then went on a date in the car! I have the cherry picker hoist and he will loan me a rotisserie style engine stand. It does appeal to me to be able to work standing up without oil dripping in my face and I'm concerned about getting the pan gasket properly aligned so I don't get it back together and have a leak. I think this would be easier with the engine out. I'm still considering both methods, thinking about a parts list and sources, and getting in the right mental state to tackle this. I need to meet with my friend again and have him read the manual because it does sound simpler. The exhaust pipe bolts look really old and rusty and I can see possible trouble ahead with those no matter which way I do it. I guess penetrating oil, heat, patience, and luck will be in order.



Tubman - The fine print says the counter weight of the front throw will be in the down position when the number 1 piston is approximately 1 7/8" down and the number 5 piston is approximately 2 3/4" down.
 
Dennis, I'm really not the person to compare the two methods since I've never pulled the motor on my truck, I would imagine working with someone who was very familiar with that route would be a considerable benefit. If you do put the motor on an engine stand be sure it attaches to the side of the motor, not the bell housing, as apparently there is a real risk of cracking the bell housing when supported just from that end. I had no problem with gasket alignment, my technique is to use a copper spray-a-gasket compound to affix the side gaskets to the pan while locating them with a couple of bolts in the holes, this way they once it sets up they don't shift. I also use a dab of silicone seal at the ends of the front rope seal(left 1/16th inch proud of the pan) and also at the ends of the rear cork gasket strip that sits on the rear main bearing cap.


Tubman, the procedure for getting the crankshaft front weight properly aligned is as Dennis noted


Adam
 
Blue Point made a special Jack, the purpose of which was to be able to get the engine up so you could remove the pan without removing the hood of the car. I have one at my other house, or I’d post a picture.
 
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