| larryb346 | -- 09-18-2013 @ 4:58 PM |
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I have a 46 mercury coupe. I haven't driven it in quite some time since it has very low oil pressure.Once it warms up the oil pressure drops to zero. This is on two different manual oil pressure gauges. It had 30 lbs until it warms up slightly the it drops like a rock. The car only has 43,000 miles. I am considering changing the motor and trans out for a later model. I am reading about a open drive shaft adapter. It appears they make them for 6 or 10 spline rear ends Is there any way to determine prior to taking it apart which rear end it has? I have had the car for 7 or 8 years and am tired of it setting and need to sell it or get it where I can drive it. I have a 302 and standard trans so other than the minimal cost of making motor and trans mounts and drive line it would be a fairly cheap swap for me. Thanks This message was edited by larryb346 on 9-18-13 @ 5:38 PM
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| deuce_roadster | -- 09-18-2013 @ 8:20 PM |
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Larry, if you are going to make that engine/trans swap, change the rear end too. You most likely have a 6 spline pinion. However, if you use that rear you still have the old axles. In my roadster I am using a flathead, 39 trans and 40 rear end but I had the axle housings modified so I can use 9" Ford axles and brakes. Still is a banjo with 3.55s but I no longer worry about an axle end breaking off. My 2 cents
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| supereal | -- 09-18-2013 @ 9:13 PM |
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If you plan to convert to an open drive line, you will have to also change to a set of parallel rear springs as the transverse original will no longer prevent the twist of the axle. As to the low oil pressure, we just finished a '39 Ford with the same problem. The pressure relief valve in the front of the valve chamber was stuck open due to a bad spring. We replaced the oil pump with an 80lb version and a new pickup screen. It now holds 25-30 lbs at idle. We suspect the car, a "barn find", was originally parked due to lack of oil pressure, and someone tried to stretch the relief valve spring. The owner is now very pleased. Making a late model engine and transmission trade done right is seldom a "cheap swap". Last year, we transplanted a V8 into a very nice old "cab forward" Ford pickup. We fabricated all the mounts for the engine and the auto transmission. As the original engine was an OHV six, the engine was a tight fit. The larger radiator was next. While it ran well, it was obvious the old rear end was too high ratio, so a later axle was located, and we had to make up a new drive shaft, an additional three grand. It is a unique "ride", but not an inexpensive exercise. This message was edited by supereal on 9-18-13 @ 9:16 PM
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| woodiewagon46 | -- 09-19-2013 @ 6:56 AM |
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Larry, sounds like you have a major decision to make. Once you start to modify your car there's no turning back. You can get everything you need, motor mounts, trans mounts, wishbone splitting kit, and parallel rear spring kit from Chassis Engineering, www.chassisengineeringinc.com, 319-643-2645. My '46 Ford's exterior is totally restored to stock but the entire drive line is modern and you would not know it's modified if I didn't tell you, so you can have the best of both worlds!
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| larryb346 | -- 09-19-2013 @ 9:30 AM |
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Thanks for the suggestions. I really hate to change out the car. I have several street rods and have built a lot of them over the years. Supereal Thanks for the suggestion. Is the pressure valve in the pump? If so would any other changes be necessary to put in the 80 lb pump? This is a really nice mostly original car. It has been parked most of it's life. It was bought new in Peoria Il. The owner died in 1956 and his brother got the car and drove it here to SW Missouri. He said he didn't like the way it drove. So like so many cars he started it ever few weeks then every few months and then the battery went dead and it sat a couple of years then sat for 15 years or so. Friend of mine bought it and couldn't get it running right and it sat another 20 years. He had it painted in late 70's or early 80's the original maroon. In that process they removed the fenders and found a rust spot the size of a dime and fixed that. I bought it about 6 or 7 years ago. He had removed the wiring and had purchased all new original wiring. I got it all back together and fixed all the issues and it runs great, just no oil pressure. I have bought re chromed bumpers and had most of the pitted chrome replanted and the car is very nice, just getting tired of not being able to drive it. If there are no other modifications required to put in a 80 lb pump, no more work that it is to drop the pan and try that I had much rather leave it original and drive it Thanks again and sorry about the book but I guess I am just very frustrated with this car. This message was edited by larryb346 on 9-19-13 @ 9:30 AM
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| supereal | -- 09-19-2013 @ 1:55 PM |
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The pressure relief valve is on the 80lb pump, itself. The pump bolts right in. Be sure the pump pickup is firmly attached to the mounting flange. The increase in oil pressure makes the stock gauge mostly inaccurate. The '39 we converted now has a mechanical oil pressure gauge. These cars need to be frequently driven to keep them in reliable condition. Starting them now and then is an invitation to filling the engine with sludge. I try to avoid starting my cars unless I plan to drive at least ten miles.
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| larryb346 | -- 09-19-2013 @ 7:01 PM |
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Thanks for the info. So sounds like dropping the pan and cleaning it out and replacing the pump with a 80 lb pump is in my future. I really appreciate the suggestion. I was thinking likely the cam bearings were bad and that's where the oil pressure loss was coming from. I really want to keep the car original. Larry
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| supereal | -- 09-19-2013 @ 8:58 PM |
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Compared with today's close tolerance engines, the old ones are very loose, even when first assembled. Lots of old cars didn't provide pressurized oil to the rod bearings, Chevrolet chief among them. A trough and dipper system was used instead. The wide clearances require a plentiful oil circulation, thus the short drain intervals. Without the arrival of detergent oils and excellent additive packages, there would be far fewer running old cars today.
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| larryb346 | -- 11-01-2013 @ 7:09 PM |
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Somewhat of a update. I changed oil today and the pressure is somewhat higher. I had thought I would have to drop a lot of the front suspension to remove the pan to change the oil pump. It appears I can drop the pan without removing any other parts. I am guessing some gas perhaps contaminated the oil. I replaced the fuel pump and will rebuild the carb before it runs too much. It now holds 20lbs or so at rpm equal to approx 40 mph, and 5 lbs at idle. still not good but a lot better.
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| 40 Coupe | -- 11-02-2013 @ 5:20 AM |
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5# at a hot idle is not bad! For the flathead it is more about the volume that the pressure. You may want to go to 20W-50 oil, if the engine is broken in with enough mileage. If your using a mechanical gauge change back to the electrical and it may read good even when warm.
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| 40 Coupe | -- 11-02-2013 @ 5:22 AM |
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Ford changed from the 10 spline to the 6 spline about 1935. yours should be 6 spline.
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| TomO | -- 11-02-2013 @ 5:31 PM |
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The stock 50# oil pump does not have a pressure relief valve. The pressure relief valve is under the intake manifold at the front of the engine. Your current oil pressure readings sound very normal with 10W-30 oil. You will get slightly higher readings with 20w-40 but it is not necessary, you engine will survive and run well with 10w-30. If you change to an 80# pump and wish to use the dash gauge, change the sender to an 80# sender. With the 80# sender full scale is 80# and half scale is 40#. It sounds like it is a very nice car, and in my opinion it would be a shame to make it into a hot rod. A complete engine rebuild would cost less than making the changes to install a later drive train. If you are having handling problems, check for wear in the front end, tie rod ends and king pins. Reair any wear in these parts and your Ford will drive like it should. Tom
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| larryb346 | -- 11-03-2013 @ 5:33 PM |
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The gauge reading are from a mechanical gauge. I am using 20/50 castrol. The weather here is in the 50's so think pressure will be lower if the weather was 90 degrees. I would still like the pressure to be higher but at least I am not afraid to drive it 5 miles or so now. I plan on driving it some tomorrow and see what the pressure does. I likely still need to drop the pan and see how much sludge there is and clean it out and change the pump. So am I understanding it right I can't increase the pressure using a 80 lb pump because the 50 lbs relief valve is in the intake area?
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| TomO | -- 11-04-2013 @ 10:06 AM |
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After going over some reference material, you may already have a 80# pump in your car. They were introduced in the 46 Mercury as P/N 41A-6600A. There will be a pressure relief valve on the side of the oil pump, just above the pickup. You should check to see if the spring in the valve chamber has 80 oz pressure at a length of 1.380. The P/N for the pump relief spring is 8BA-6654. Tom
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