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ashr
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32 Posts
Discussion Starter · #1 ·
So, I've scoured the forums for information on the oil pressure sender, and possible causes of low oil pressure light.

I finally went and had the dealer run an oil pressure test (the hassle of it put me off of doing it myself).

The Shop Lead Tech told me not to bother wasting the money on the test, because his guess was that it was a spun cam bearing (which I hope is wrong).

Here's the behavior: some days, after the engine warms up, when the car comes to a stop and idles below 750 RPM (usually right at 700 RPM), the oil pressure light comes on.

Unrelated possibly is that when accelerating we sometimes experience a hiccup in thrust/power ( i think that's a vacuum advance issue) especially when going uphill.


The numbers are 10PSI at cold idle and hot idle, and 20 PSI at cold and hot 2000RPM.
They said they tested it both hot and cold and the numbers were the same. They did not say whether the light was on during the test at idle.

Any suggestions?


Ash
|| 2004 Disco II (165k miles named Gilly) ||
 

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disco biscuit
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1,061 Posts
I don't know much about a spun bearing. From what I know its when the bearing comes loose from the journal in the block and spins a little or freely.
I can tell you I had some oiling problems due to worn cam bearings. It definitely will lower oil pressure as it flows freely from the gap where the cam used to ride in the bearing. They wear out on the bottom of the bearing. So far since rebuilding the motor without a new oil pump everything is very good.

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And I didn't even submit a proposal...
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202 Posts
It is very strange that you get the same pressure warm and cold. If they did not bother with the pressure test, then where are the numbers coming from? If the light comes on only after the engine has warmed up, then the pressure is obviously not the same warm and cold.

I'd sure try to obtain more answers from that Lead Tech before deciding on a course of action. Also I'd go take a look at the pump. They are notoriously weak so that would be my first suspect.
 

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disco biscuit
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1,061 Posts
Yeah before I started working on mine I would a dogged somebody out for not rebuilding the oil pump at the same time as a rebuild. Hell I might have.

After talking with a very experienced rover guy I used for parts I started really evaluating the oil pump rebuild. The main thing on the centrifugal oil pump in our vehicles is the 03s had a tendency to crack the gears. My gears were in pristine shape and being paranoid i brought them to work and had our non-destructive testing contractor do a penetrant test on them to look for cracks. I checked tolerances on all of it. Besides that the only other wear part on the oil pump to present problems is really the aluminum front cover it rides in. The gears themselves just slide around inside there; the cover provides the pumping/sealing surfaces and oil passages....and is the aluminum part that is more sacrificial. The gears are steel and suffer from little to no marring or scratching damage.

If you really want the ease of mind rebuilding the oil pump you better order a front cover. Mine was in excellent shape. My oiling problems were pressure leaks lost through the bearings. I suspect a lot of oiling problems on these vehicles are caused from the same thing. I also did this based on very trusted advice...like I said from the very experienced rover guy and a good friend of mine who's a daily mechanic. All that just peaked my curiosity and after further investigation I found their logic to be sound and tolerances/mechanical condition of mine impeccable. I had 162k mi on mine when I took it apart.

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ashr
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32 Posts
Discussion Starter · #7 ·
Yeah before I started working on mine I would a dogged somebody out for not rebuilding the oil pump at the same time as a rebuild. Hell I might have.
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2 things: I've never rebuilt my engine, though I felt I was when I replaced the head gasket and a few other major seals.
I wasn't dogging you out, was just asking, if you're rebuilding the engine, seems like you might as well replace / rebuild the oil pump, but I stand corrected. Sounds like you made a good decision.
 

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ashr
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32 Posts
Discussion Starter · #9 ·
DB, 94svt50: Is there anyway to know for sure that a cracked gear in my oil pump is the culprit? Pull the oil pump and do a full rebuild? Or pull the oil pump and do an inspection.
I'm not afraid to do anything on this vehicle unless it requires a torch. That's the only thing I don't know how to do right. I'm sure more open to rebuilding the oil pump than trying to replace the cam-shaft.

Lowest Bidder: They did test the oil pressure, and I'm not buying the answer regarding the temperature at test. I'm gonna call up the shop and grille the tech.
 

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And I didn't even submit a proposal...
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202 Posts
If you intend to keep the truck for a while, one of the cool add-ons is a precision oil pressure gauge. I installed an electronic gauge under the dash, so I can always see the pressure and get a feel for what's normal. Also there's a relay contact that will close at a pressure you decide, and you can connect it to a buzzer so you are immediately alerted if the pressure drops. It's pretty easy to install, and not very expensive if you shop around. For the cost of one visit to the dealership, you'll have an invaluable tool for the remainder of the life of your truck.
 

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disco biscuit
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1,061 Posts
Yeah I word things really crappy sometimes on accident but I know you weren't dogging me out or whatever. I think an important point not to let slide is ...I thought it would be crazy to rebuild without doing the oil pump. After inspection proved the gears good, research and reading here over the years showed cracked gear problems to be mostly related to alignment issues with the front cover. If your gears are cracked you should investigate whether the alignment of the thing is correct. Also the cover takes most of the wear concerning oil pumping function. You should look further into it before just tearing into it.

Also worth note. I wouldn't jump to the pump right off. You listed your mileage either here or in the thread concerning the rear seal. +160... All those things mentioned here and in the rear seal thread make me think it would be easier for you to pull the motor than the tranny. Buick internal bearings fit in these motors.

Rear Main Seal/Cross Seals
http://www.landroversonly.com/forums/showthread.php?t=112033
 

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Registered
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Inspecting the pump is pretty straight forward. Pull the front housing following instructions in rave. Take off cover plate and the gears just fall out, cracks will be obvious. New gears are cheap might as well have them ready to go while you have it apart. It probably took me a day the first time and I changed water pump while it was off. Just make sure the face of the gears with chamfered edge goes down into the cover.
 

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ashr
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32 Posts
Discussion Starter · #15 ·
Yeah, I had to deal with all that when I replaced the oil pan gasket, I also replaced the crazy sensor I think it's the Crank Position Sensor? It was a total bitch to do, ended up having to take the entire front exhaust system down to get to it.
 
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