Oil pressure light comes on at 65-70mph.

Hello all, My oil pressure light comes on when traveling the interstate at 65-70mph.  When going 0-60mph I have no problems.  I figure I need to do an oil pressure test.  Also, I just got it. It has 135k miles.  It was in a wreck within the past year and had sat for about 2 months.  I don't have the service records. Should I find the last service date/schedule(ex. 120k service) and go down the list?  Thanks, Donnie

Although different vehicle (Dodge Ram Pickip 1998) My dads Oil gague would read 0 after it had started, he replaced the oil pump and sending sensor unit.  No more problems.  I would recommend stop using your vehicle ASAP cause if that Oil pump goes out you going to be looking at a whole lot more then just that.  With that many miles i would be safe than sorry and just replace the oil pump.  Just My 2 cents

I have a 97 Disco 1 with 116,000 miles on it, and i will probally be replacing the oil pump in about 6months or so (I put on 2k to 4k miles per month)

Thanks OxyCoRover.  In response, I've talked to a guy at www.braddysbritish.com. He's a Land Rover specialist in Wake Forest. He said he thought that the connecting rod bearings needed to be replaced. Oh yeah, and he also said it would cost about $800. I know an oil pump would be cheaper. He said it's rarely the oil pump. What do you think? Man I wish Disco Mike would see my post! lol.
Thanks, Donnie

You need to get your oil pressure tested ASAP. Do you get any internal engine noise, has anyone checked your pressure switch, that are known to fail?
How mechanical are you, if it were the rod bearings, you might want to consider replacing them yourself.

Like Mike said, test your pressure. Another thing ti think about is oil ports getting clogged and trapping oil in the heads. Basically running out of oil. Make sure she is full, and stay off the highway until you find out...

I agree with discoguy, your return oil ports are clogged. Switch to a full synthetic oil, it will clean as you drive.
At higher rpm the oil pump is pumping oil into the upper parts of the engine faster than it can drain back into the sump thus running the oil pump dry.
You can test this by driving at slower speeds with the transmission in a lower gear and getting the rpm up to highway speeds.
If your engine is that sludged up I wouldnt do a engine flush, all that crap will break loose and could cause more harm. I think that a gradual cleaning would be best. Just my opinion though.
Yes, after you have the oil pressure tested.

agreed, but after the oil pressure is tested.....

The only noise I've heard was a tapping that corresponded to the engine at the time the pressure light was on. I will check the switch and check the oil pressure. If it is rod bearings, I have a mechanic buddy who said it would be no problem... thank God!

The first thing we did was check the oil. It was maybe 1/2 qt. low if any and looked pretty clean. No highways for me until this things fixed. Thanks to all for the help. Spike555, thanks for the explanation. 

Either way, you still need to do a engine flush and waiting on the synthetic to slowly clean the engine will in fact kill the engine cause it takes months of driving to even begin to clean the engine.
Get it tested and then do an ATF flush right away, pulling the pan afterwards to clean and inspect.
If your engine is that dirty, you will probably need to use a 1 quart Gunk engine flush on your next 3 04 4 oil changes to keep cutting the build up.

Thanks again Mike.

When you flush and drop the pan, get ready. You will need a new gasket for the oil pickup tube and some RTV for the pan.  The thing that sucks is that you have to pull the track rod, steering stabilizer, and sway bar (on the back) to get the pan out. I figured this out after I dropped the pan. The pickup tube won't let the pan drop out. Might also rent a tie rod puller (screw type, not fork) to get the track rod off. You only need to do one side, but I would inspect your tie rod ends (called ball joints on LR's) and replace them while you are down there. I had already done mine, but I did replace the sway bar end links...

If you jack the vehicle up on the chassis and let the front axle hang I didn't need to loosen or remove the sway bar. I did remove the steering damper and the passenger side tie rod end (ball joint) I left the drivers side in and just swung the steering bar out of the way.

Not everybody wants to mess with dropping the oil pan. If his oil pressure is good then all he needs to do is switch to full synthetic and add eight quarts insted of seven and stay off the highway. Then if he were to change it at 2000 miles for the first two times and then go out to 5000 on the third and subsuqent oil changes he would be just fine.
Yes it would take longer than doing it all at once, but not all of use have the money or time to go through all the other hassle.
96se7disco let us all know how it turns out for you.
Whichever way you descide to go, there is no wrong answer as long as your trk is fixed.

I'll let ya' know what happens. We plan to crack it open Sunday.
thanks

Time out.  You said add 8 quarts of oil instead of 7.  How many quarts is it supposed to hold normally?  7?  I think my manual says 6. I'm not sure though. Thanks.

quote:

ORIGINAL: Spike555

Not everybody wants to mess with dropping the oil pan. If his oil pressure is good then all he needs to do is switch to full synthetic and add eight quarts insted of seven and stay off the highway. Then if he were to change it at 2000 miles for the first two times and then go out to 5000 on the third and subsuqent oil changes he would be just fine.
Yes it would take longer than doing it all at once, but not all of use have the money or time to go through all the other hassle.
96se7disco let us all know how it turns out for you.
Whichever way you descide to go, there is no wrong answer as long as your trk is fixed.

You NEVER, EVER put 8 quarts of any oil in a Disco unless you plan on blowing out both your front and rear main seals.
I am not sure where you got that information but it is so completely wrong.

Yeah, I thought 8 quarts was incorrect.  Thanks Mike, but why would he say 8 quarts? How would that help my purpose?  Would it cause me NOT to have LOW oil pressure? But isn't HIGH oil pressure bad too? lol. Thanks.

He was thinking that by adding more, you would still have enough in the pan at high RPM, if it is getting pooled in the heads. When you do this, the level is higher and the pistons start slapping the oil and blowing it out of your seals. I just saw this post, like Mike said, NEVER do that.
 
Have you tested your oil pressure yet?

Yeah, my point was to add one extra quart so that it wouldnt run low when it was all inside the valve covers and then the oil light wouldnt come on, one extra quart wont hurt anything.
But if his only takes six quarts then two extra would not be good. His is a '96 and mine a '97 and mine takes 7 quarts so I assumed that his took 7 as well.
So I apologize for any mis-understanding.
On that note, why does his take 6 and mine 7? They are the same engine, does mine have a bigger sump for some reason?

Yours takes 6.95, same as his. 6.3 in the sump and .65 in the filter. More if you use the larger K&N. Never fill anything above the fill line.
 
Look on page 143 of the manual. He is not thinking about the filter....

Read your manual, under capacites, oil and filter change is 6.1 quarets.
The engine sump will handle 6.9, only 6.1 drains out during an oil chaqnge.
The easy way to tell is do 6 quarts, start the engine,let it warm up for a minute or too, turn it off, let it sit for 2 or 3 minutes and then see where the oil level is on your dip stick.

Actually I did read the manual but I couldn't remember at the time of the post. I was aware of the  0.65 for the filter. But the manual said (and Mike just said) that you should ALWAYS check the dip stick. I did that after about 6.5 quarts and warming it up and it was topped off. I will check the oil pressure Sunday as I just got a pressure gauge.  Thanks to ALL of you guys for the help. That's why I love this site. 

Ok guys, after a long Sunday we have results. We inspected the oil pump: the gears are a little worn, the housing was in great shape. Overall pretty good. We inspected the sump. OMG, nasty. We did an engine flush before hand. Needless to say I'm going to replace the oil pickup. Someone used some type of "Make a seal" all over the place. They applied too much and it started breaking off in the pan and the pickup was VERY clogged. Also, I had put new oil in before the flush and it came out black and gunky. It will need it again later. I also found out what the ORIGINAL champion(black) plugs look like! I changed the plugs and wires. The timing chain was very loose so I will be replacing that. It just needs a little TLC, ok, a lot.  Meanwhile, the wind was blowing very hard and my basketball goal fell and poked a hole in the hood of my Trans-am and I'm really pissed off! Oh yeah, I ordered parts. I'll keep ya' posted. Thanks.

I used Berrymans B12 on the sump pan and the pick up tube screen and it made it all look like brand new. If your pick up screen & tube is really bad leave it to soak for a while, it should clean up good, no need to buy a new one. The oil pan needs no gasket, but you have to use that "sealer". I think the black RTV is recommended? And yes becareful not to put too much on as to where it oozes out into the pan. I used the grey sealer they use on Honda & Toyota's. It seems to set up harder.