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EFV-8 Club Forum / General Ford Discussion / low oil pressure - new engine

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Posted By Discussion Topic: low oil pressure - new engine -- page: 1 2 3     jfarrell 07-11-2012 @ 4:14 PM reply profile send p.m. Member Posts: 46 Joined: Oct 2009 I've got a problem. The flathead engine in our 49 Ford was just rebuilt. I've put 44 miles on the engine. Because the intrument panel oil guage read 20 lbs of pressure or less, even on a cold engine, I replaced the sending unit with a mechanical guage. It still reads 20 lbs or less on a cold engine. Everything inside the engine is new. Any suggestions on how to troubleshoot from this point or suggestions on what could be wrong? Thanks. Jim Farrell supereal 07-11-2012 @ 4:28 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 As an engine rebuilder, I can say that there are many possibilities, all of which will likely require pulling and disassembling the engine. The 8ba type engine uses a different oil pump pickup from the older type. It uses a press fit tube that tends to come loose. We braze them, just to be sure. The pressure relief valve on the pump may have a weak spring. If the cam, main, and rod bearings were not properly sized, that could account for it. I'd have a talk with the rebuilder. I hope you have some kind of warranty. ford38v8 07-11-2012 @ 7:41 PM reply profile send p.m. Senior Posts: 2883 Joined: Oct 2009 With only 44 miles on the engine, you may not have a problem at all. New engines require a break in period to seat the rings. 20 lbs pressure is adequate to provide lubrication under mild runniung conditions. Log your pressure, mileage, and ambient temperature each day you drive, and watch for some improvement, which youshould see before your 500 mile oil change. Alan supereal 07-12-2012 @ 6:03 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Could be, Alan, but I'd be concerned about the low cold starting pressure. A 40 lb oil pump should produce more than 20lbs at that time. Piston rings do affect oil consumption, but not pressure. A loose bearing (s) certainly would. We always examine all bearing inserts before installation. It isn't rare to find one or more sets of the wrong size mixed in a box set. It only takes one to affect system pressure. We open all the crankshaft plugs to clean the oil passages on old ones, then tap and replace them. It is possible to lose oil pressure if any are leaking. I wouldn't run an engine with such low cold pressure, as damage is likely. Stroker 07-12-2012 @ 7:01 AM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 One additional thought....you didn't mention what you were using for oil. Oil viscosity can greatly affect cold start-up pressure. I'll "side" with Super though regarding the fact that the problem isn't going to improve after additional miles. It's time to find the cause; correct it, and hope that you were just lucky enough to get two really pessimistic pressure gauges. deuce_roadster 07-12-2012 @ 7:04 AM reply profile send p.m. Member Posts: 284 Joined: Oct 2009 I would agree with Super on this. I thought the 8ba engines had 80lb pumps in them but even with a lower pressure pump there must be something wrong. If there is no external leak it has to be an internal leak of some kind for a newly rebuilt engine to have only 20 lbs pressure cold. I would suspect poor bearing clearence somewhere or maybe a defective releif valve. If the engine is quiet, maybe mains or the cam. Must be very disappointing, sorry you are dealing with this. I hope the rebuilder stands behind the job. TomO 07-12-2012 @ 8:02 AM reply profile send p.m. Senior Posts: 7385 Joined: Oct 2009 I agree that you should have more than 20# pressure cold and I doubt that it will get better with driving. An 80# pump should deliver at least 50# cold with 10W30 oil and you should not be using a thinner oil than that. I would go back to the rebuilder and ask his opinion of what should be checked first. Tom joe b 07-12-2012 @ 12:18 PM reply profile send p.m. Member Posts: 389 Joined: Oct 2010 Just a thought but it could be your sending unit. I installed a new crank and bearings in my '41 engine. It always had good high oil pressure. I decided to put a new sending unit on the engine for appearance as the one on the engine was dented here and there and looked bad. I ordered a new 80# unit. The engine oil pressure never got above 20# no matter what. This with 20-50 oil. Another sending unit and I was back in business. Either the part was mis-stocked or it is another example,of foreign cr*p. Ask your builder about the sender-you never know supereal 07-12-2012 @ 5:47 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 I mentioned the 40# pump to say EVEN with a 40# pump, the cold pressure should be higher. I didn't say it quite right. I doubt the sending unit is at fault, as the post said the low pressure was verified with a mechanical direct gauge. This message was edited by supereal on 7-12-12 @ 8:19 PM mdurhan 07-14-2012 @ 3:04 PM reply profile send p.m. Member Posts: 64 Joined: Mar 2011 I'll be begging your pardon, Alan, but piston rings really have nothing to do with oil pressure..... Bearings? Yes. Oil pump? Yes. Oil pump by-pass valve? Yes. Oil viscosity? Yes. Mike There are more "barn finds" than barns.

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