Help!! Oil pressure problems - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 12-06-2000, 11:29 PM
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Help!! Oil pressure problems

I have an 83 Full size Bronco. I have rebuilt the 351W. After I bolted in the engine, I started it up and the lifters where knocking like crazy. I let the engine run for a few minutes as I thought maybe the lifters needed to "fill up". Then I shut it off (no pressure gaugue only the idiot light on the dash, registered low) and pulled a valve cover to see if any oil was evident into the top of the heads. When I started it again, there was no oil present, and I oiled the rocker arms with a oil can and they quieted right down. So I pulled the oil sending unit sensor off of the adapter and lo and behold oil came out of it when I started it back up. I put a new oil pump in the block and tested the oil pump prior to installation and it worked, soaked the lifters overnight before installing them, and have no idea as to what is going on now! The oil on the dipstick was aerated, lots of little bubbles present.

My questions are as follows:

1) How long should it take the oil pump to supply lubricant through the whole block upon initial start up?

One auto parts guy has told me that he has had to run engines upwards of 10 minutes or so to initially "pressurize" everything. I thought that was excessive and do not want to risk damage to the engine attempting this.

2) what would be the most logical way to troubleshoot this problem?

I have thought about mounting a gauge off of the adapter to check the pressure level at the sending unit but do not know how to check the pressure levels through the top of the engine. The only things I have guessed about are the following:

Cam bearings not installed properly, (Hope not had a machine shop do this).

Crankshaft bearing gallery holes not lined up. (Don't think so though was pretty careful checking those during reassembly).

Internal freeze plug blown out?

Block cracked? (Had the block hot tanked and magnafluxed, don't think so).

Bottom line is I would like to figure this out before I go through the hassle of pulling the engine back out and starting from scratch. Any ideas would be greatly appreciated, thanks in advance.

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post #2 of (permalink) Old 12-07-2000, 09:22 AM
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Re: Help!! Oil pressure problems

It's not a good idea to start a new engine up dry. You should prime it first. They make a simple tool that attaches to a drill and goes down the distributer inlet to the oil pump.

post #3 of (permalink) Old 12-07-2000, 11:16 AM
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Re: Help!! Oil pressure problems

Or, you can use an old distributor shaft (with the gear) and put that in your drill to prime the system. You could pick up an old distributor cheap at a salvage yard. Good Luck.

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post #4 of (permalink) Old 12-07-2000, 11:57 AM
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Re: Help!! Oil pressure problems

That would work if you can keep the system sealed. If it's not, oil will blow out of the hole and you won't be able to pressurize the engine, not to mention it makes a huge mess. You can borrow a sealed drill attachment at Autozone for free or you can just buy one for about $20.

post #5 of (permalink) Old 12-08-2000, 08:49 PM
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Re: Help!! Oil pressure problems

1) A few seconds - otherewise, a vehicle that is used seasonally would run dry for 10 minutes each time it is removed from storage (or one that had sat on a dealer's lot for an entire model year).

2)Start at the pan and work your way up through the engine: Is the pickup tube blocked? Is it sealed to the oil pump? Is the oil pump turning (broken drive shaft)? Is the oil pump working (pumping oil when it spins)? Is the filter clogged/blocked/correct? Is pressure reaching the filter? etc.

Freeze plugs are in the water jacket - not the oil system. Improperly installed bearings will only affect themselves - oil does not move from one bearing to the next; it seeps out each bearing back into the pan. If the oil is reaching the filter, but not the engine, I would surmise that either the oil journal from the filter is blocked, or all the journals in the engine are packed with crud.

Good luck!-)

83 Custom w/95 4.9L EFI, 78 NP435, 83 NP208, 83 D44IFS 3.07, 87 Ford 8.8ABS 3.08, Michelin LTX AT 31x10.50R15
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post #6 of (permalink) Old 12-10-2000, 02:43 PM
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Re: Help!! Oil pressure problems

I read about a guy w/ a problem just like yours in car craft...he wrote in to the tech tips page or something like that...anyways, he put the motor on a motor stand, took off the oil pan, had a buddy hold a coffe can full of oil under the pickup, and then primed the oil pump w/ one of those oil pump primer gizmos and a drill and watched to see where the oil hemoraged his case, one of his cam bearings hadn't been installed right and oil just gushed out of the journal....

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