Battery drains then clicking and oil light - fine w/full battery
 

My Disco died on the highway the other day, and I had to have it towed back home. It lost acceleration and then eventually died, fortunatly I could get off the highway before it turned off. Before it turned off, the oil light came on and the engine made a clicking noise The oil level is fine, as well as all brake, power steering, coolant, etc. Temperature levels were fine.

I found that if I fully charge the battery the disco will run fine for about 10 minutes, then the battery will drain and it will have the same problem again.

I swapped the battery from my other car and ran the disco's battery just fine for a few days, so I don't believe this is a battery problem.

I took the alternator (remanufactured bosch) in to murrays and it passed the diagnostics test 10 times. We also tried pulling the + off the battery when the disco was running, and it continued to run, so the alternator is at least sort-of working.

The symptoms I am noticing are a clicking noise from the engine, or around the engine. I can't quite pinpoint it. It is tied with the engine RPMs. When it starts clicking the oil light comes on on the dash. This happens after about 10 minutes of running on a full battery. The battery is low if I test it at this point.

My guess is that while my alternator is performing well enough to pass a 10-second murrays test, it really isn't putting out enough juice. Although I'm surprised that the battery would drain so fast, I'd expect maybe more like 30 minutes instead of 10 on a fully charged battery. Or, perhaps the alternator is warming up and something is expanding/disconnecting/shorting/coming loose. It is about 10 degrees F outside right now. I'm thinking the clicking is the result of the engine computer or a sensor not getting enough power so the computer's timing is getting off... same with the oil light?

I've cleaned and tightened all connectors, put die-electic grease on everything, and checked all fuses and wires that I can think of.

Anyone experience this before, or have any ideas? I'm stuck as murrays won't replace the alternator since it passes their tests... and I don't know what else to try. Any help would be appreciated.

RE: Battery drains then clicking and oil light - fine w/full battery
 

What year is your Disco? Have you tried to pull any codes from the ECU? Does your RPM slowly start dropping down then dies, or just dies at normal idle RPM?

The clicking may or may not be associated with the battery draining so fast. Have you checked to see if there is any power being drawn with everything turned off? You may have a short somewhere. Have you check the engines ground cables? Try to get Murray's to test the Alt under load for at least 10 minutes. The clicking may be a byproduct of the voltage dropping, clicking relays, not enough voltage to hold the contacts closed, so they could start to stutter. Oil light may be coming on because of to low an RPM for the pump to sustain enough pressure.

There are a few LR mechanics lurking around on this forum, hopefully they have some insight on your problem, as this may be a known issue.

Daniel

Bad oil pump? Thought it was the battery - was aparently wrong.
 

Upon further investigation I think the battery may have been a false lead. The battery was certainly dead, but it could have been a side-effect of having the hazards on for a while waiting for a tow-truck, or the 0-degree weather... the day before my wife said the battery light came on and the headlights flickered after driving for about 30 minutes on the highway, but after she turned the lights and radio off the battery light went away after 30 seconds.

Today I carried out further diagnostics:
I ran the disco for about 30 minutes before I had the problem. The engine warmed up and I held the RPMs at about 2500 and then the oil light started to flicker and I heard the nocking start. I had a meeter on the battery and alternator and didn't see any drop in voltage. I now believe that after the oil warms up the pressure is dropping and causing nocking in the engine due to lack of oil. I immediatly shut the disco down.

I am thinking that either my oil pump has failed, or my pressure valve is stuck opened. When the disco is cold the oil pressure would be high and fine, but as it warms up the valve, I believe, should close to keep the pressure high but it may be stuck. Perhaps the spring is bad in the pressure valve?

My next step is to change the oil, get a good look and make sure I don't have any clots or anything. I used generic oil a while ago while on a trip because I couldn't find any name-brand and I was getting low - as with all discos I leak fluids (oil, power steering, etc.. all get checked and filled on a regular basis). I also got the gunk brand oil treatment, and a new filter. I don't think this will fix the problem, but for $15 it is worth a try!

The next step after that, or at the same time if I can, is to hunt down an oil pressure gauge and verify that indeed the oil pressure is low and it isn't a sensor as I was guessing earlier.

After that... guess it is a new front cover for me if I find the pressure to be bad. Maybe just the spring for the pressurer valve if I can get to it. I'll be asking for tips with this if I get this far.

Thanks for any help/suggestions/etc...

1998 Disco 1
V8i
Auto
150k miles

RE: Bad oil pump? Thought it was the battery - was aparently wrong.
 

It sounds like the oil pump by-pass valve may be stuck half way open.
After you flush the oil may want to add some Marvel Mystery oil to
the oil this will help clean the inside of the motor alittle more
just slower.
If the by-pass valve was opened all the way you would have
little or no pressure ,the other way and you would be blowing
oil filters off.
Or the oil pickup tube could be getting pluged.
LOL Mike.

RE: Bad oil pump? Thought it was the battery - was aparently wrong.
 

arrkerr : You may want to pick up a copy of the Haynes service and repair manual
book # 3016 it gives step by step oil pump repair.
LOL.
Mike