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Oil Pressure Problems, 92 Ford F150
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subvet
New User
Jul 8, 2007, 1:31 PM
Post #1 of 7
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Oil Pressure Problems, 92 Ford F150
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Hello, Sorry this might be long winded......
Last year my sister through a rod in this 92 ford 5.0 Liter F150. As we could not afford a new engine, I found a 86 5.0 liter engine that had been in a Thunderbird. It had a lot of miles on it, so I rebuilt it with new bearings, rings, gaskets, oil pump, etc. The only things I used from the old motor was the intake/induction, oil pan, oil sump pickup, and distributor. I got the engine installed, got it running fairly smooth, and turned her loose with it. About the only problem it had was transmission related, the transmission would not shift into overdrive (it's an AOD that I have already replaced once in the life time of this truck), and the transmission would not always down shift to first when you stopped at a stop sign. Anyway, she went on a trip of about 20 miles in it, and for some reason, the shift cable popped loose from the transmission, resulting in her making the trip in first gear apparently. She had also overfilled the oil by about three quarts, I have no idea why, she said she was used to adding oil before going anywhere, and never really checked the dipstick. Anyway, when she called me, it was overheated, and when I started it, there was no oil pressure. I had it towed home. I am trying to fix this truck again now. I replaced the transmission shift cable first thing. I dropped the oil pan, it was full of extremely sludgy oil. I cleaned it out, took the sump off and cleaned it out, put a new oil pan gasket on it, refilled it with oil and coolant. I started it up, sounded real bad. I pulled the plugs out, found that number four cylinder spark plug was covered in oil. I pulled the valve cover off, found the push rod had popped clean out from under the rocker and the rocker nut was loose. I put it back in, tightened the nut, the cylinder now fires. Then I fire the engine up, after about 7 minutes, after it warms up a tad, the oil pressure drops to zero, just drops, doesn't fade. I drain the oil again, fill it with new oil, engine flush, and flush it out. After putting new oil in it again, I try it again. It starts right up, runs a little rough, but runs. After seven minutes, as the temperature guage just gets in the normal range, the oil pressure goes away again, instantly, not fading. If I watch it for a few seconds, it will go away, then pop right back up. If I put a distributor in the engine with no drive gears, and turn it with my drill, the oil pressure is rock steady. If I put the original distributor back in, then the oil pressure just poofs out again. I have absolutely no idea where to go from here. There is obviously no overheating in that seven minute period. There is no smoke whatsoever from the exhaust, though there was blue smoke when I first started bringing it back to life. Other than the distributor, the intake, and one sensor mounted on the top of the engine behind the intake that the old engine had, the new one didn't. I bought a new sensor and made a metal pipe tee and mounted that sensor in the heater hose as I was led to believe it was a water temp sensor. Anyway, the engine always bogs a tad right when the oil pressure drops to zero, so I shut it right off. And the bottom line, I don't know what is broke, so how do I go about fixing this. This is 100% repeatable, cold engine, start engine, seven minutes, poof on the oil pressure.
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subvet
New User
Jul 12, 2007, 4:45 AM
Post #2 of 7
(5710 views)
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Re: Oil Pressure Problems, 92 Ford F150
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Ok, so I at least found out that I have a replaced a "knock" sensor in the old block with a second water temperature sensor that I mounted in the heater hoses. Well, I didn't know what that sensor was anyway, and it was the best idea I could come up. Anyway, I am off to a junkyard to find a knock sensor, as I doubt the computer appreciates thinking the engine is knocking as the water temperature comes up............. I have googled away on where I can mount this knock sensor, as the block I have does not have the appropriate hole to put it in. I found two other people had come across this situation. One never provided his solution, but the other said he mounted it to his intake manifold, but he would have preferred to have it in the block. Anyway, if you have any ideas on this, I would love to hear them. If not, then I will just do the best I can do with what I can rig up. As to the oil pressure, I think I should fix this before I chase that, as my understanding of this knock sensor is that the engine will retard ignition timing if it detects engine knocking, which of course lowers engine rpm, also lowering oil pressure. I don't know if this is my problem, but it is certainly something to check.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 12, 2007, 1:38 PM
Post #3 of 7
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Re: Oil Pressure Problems, 92 Ford F150
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I don't know how you had this rig running at all for starters!! The only thing right now to worry about is the oil pressure. Is your gauge/light or whatever accurate? Does it make the sounds of low oil pressure? That's just plain fatal for the engine if driven that way. Yes lower idle will lower oil pressure but not to zero.
I don't know what could have caused this from too much oil and 3 quarts too much is way too much.
You've gone thru a lot with this already and now you have a car engine in a truck that are years apart which is a nightmare by itself.
Is this truck worth this aggrevation? Now would be a good time to decide before it costs too much,
T
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subvet
New User
Jul 12, 2007, 4:55 PM
Post #4 of 7
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Re: Oil Pressure Problems, 92 Ford F150
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Well, as far as I can tell, the computer cares not whether the engine that is in it started life in a thunderbird or an F150. The original motor had a piston with a huge hole melted in it from a leaking head, that had been leaking for over a year. When it finally threw a rod, on the same piston, it took a huge chunk of the cylinder with it, so the block was toast. Anyway, in rural arkansas, that particular block was not to be found just lying around, and a new block was out of the question in costs. So shade tree mechanic that I am, I found what I could find, rebuilt the mechanical guts of the block with parts made for that block, added the "newer" distributor, which is the same size as the old one, just with different guts, so the ignition is the fired the same, used the "newer" intake and fuel injectors (well most of them, I junkyard fuel injectors till I found a combination that had good spray patterns - as an aside, if you tie wrap the fuel injectors to the fuel rails, hook up the electronics, and suspend the entire assembly in a cat litter box, you can get a real good idea if everything is working as it's supposed to be). Anyway, the freshly rebuilt engine fired right up, and I honestly thought it was one of the smoothest running engines I have ever shade tree rebuilt. And as far as the knock sensor, frankly I didn't even know what one was, having only worked on "old" mopars and chevy's in my life time, this is my first ford. I asked on the internet, I must not have described it very well at the time, as the consensus seemed to be it was some kind of temperature switch for the computer. Anyway, I will get the knock sensor rigged to the block (sturdy seems to be the way to go) somehow this weekend, and give it a go. I have no intention of driving it till the oil pressure guage is rock steady. I don't drive it now, and as soon as I see the guage drop, I shut it off. As for the accuracy, well, I do know that popping my pre-oiling distributor in there and turning it with my drill makes a steady pressure on the guage for much longer than seven minutes. And I do know that the oil pump was brand new when I put it in there, and the motor has maybe 30 miles on it total.
As for if it's worth it, well it was the truck my dad bought for my mom before he died. She loves the truck, and had my sister haul her around in it everywhere. Well, she did before it through a rod. So, sentimental reasons, sure it's worth it. It's also become a bit of a contention to me; I know it's a ford, my experience with fords was nill before this, but this should not be that hard to fix. It's a gasoline engine with pistons and a crankshaft, nothing special. I refuse to just give up the ghost on it. As for being a car engine in a truck, my mom is 66, the only thing she will be carrying in the back is groceries, the hardest that engine will ever work is when she is sitting at a stop light with the ac on.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 12, 2007, 6:33 PM
Post #5 of 7
(5705 views)
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Re: Oil Pressure Problems, 92 Ford F150
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OK, you said you had a sentimental attachment to this truck and that is that. The key problem is of course getting the oil pump going and staying working. I can't think of a reason why it will work with your drill and not on its own. Surely you have inspected the distributor. I think most of the 5.0 Fords of the general era are the same. The engine for a car or truck isn't the world that I know of but they just did some things differently with the same basic engine.
If these two engines were much newer this would be a total mess to make them work. I've never had a knock sensor go bad in a 5.0 and until you just mentioned it I didn't know they ever made them with that. No telling what it is really adjusting when it thinks it's knocking but it may change more than just timing.
Best I can say about the oil pressure is that the pump itself has a problem and what a PITA to dig into it just to take a look see.
I have know the Ford 5.0 very well. I own 3 right now. None have ever needed an oil pump, timing chain cam or bearing problems at all - never. This with millions of miles on these with family, friends and customers with only one surprise with one at 150K -- every other problem was predictable or ordinary with miles and time on them??
T
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subvet
New User
Jul 12, 2007, 7:26 PM
Post #6 of 7
(5704 views)
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Re: Oil Pressure Problems, 92 Ford F150
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Yes, I inspected the distributor, as best as my eyes can inspect it. They key way in the bottom of the distributor looks exactly the same as the key way on my distributor with no gear on it that I use to turn the oil pump. It looks to be a very hard metal, but I suppose there certainly could be wear there, the engine had 230,000 on it when it finally threw the rod. However, from what I remember about the actually shaft that drives the oil pump, it's a made of a pretty soft metal (aluminum? don't know) and I would expect it to have worn before the key way in the distributor. I do remember one oddity about this small shaft, on end had a ring around it, the other didn't. When I put it back together, I had no idea whether the ring went on the end that slid into the oil pump, or up at the top, where the distributor would meet it. I think I left it on the bottom, didn't seem to make a difference either way that I could comprehend. It was actually to far up the shaft to suggest that it's purpose was to prevent the shaft drilling itself through the oil pump, but as I said earlier, I don't have any experience with fords. I have contemplated getting another operational distributor, one that would work with the computer of course, but for some reason, this distributor that has a wiring harness and connector coming out of it instead of the big side connector on the distributor, is just about impossible to find at a bone yard.
My dad always used to say that the weak point of this engine was the cheap hose that pipes coolant to the intake plenum. This hose blow many times in the lifetime of this truck, and was eventually the reason the head got cracked in the first place. Of course, as I said, this engine ran over a year with a cracked head and a melted piston........ That's seems to suggest to me that the engine is pretty bulletproof if it can be gotten road worthy in the first place.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 13, 2007, 3:44 AM
Post #7 of 7
(5703 views)
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Re: Oil Pressure Problems, 92 Ford F150
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Ok: There is a question about the distributor that may be the key to this. Get that straightened out with all bushings where they belong. I have broken bushings that are held in with a roll pin that when that is out the bushing doesn't like to slide off the shaft with just slight coffee like stains on the shaft. That needs to be known good and I'd bet that will solve the oil pressure problem.
As for the metal hose that goes under the plenum they have been a pest. Last one the let go I was able to get a new one but I think that will be hard to find right now and hard to just rig up with hardware plumbing as it does have a smaller hose to the plenum (upper intake manifold) as you know.
Go for that distributor and I think you'll be back in biz,
T
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