[jk99]

Hi everyone,

I know this issue has been discussed previously but I'm looking for some advice. I have a 4L 2002 Disco with 88k miles on it. I've had it for 20k miles and done regular oil changes every 5k miles - Shell Rotella 15W40 oil with Mobil 1 oil filter as suggested on this forum. The oil has always been very clean and looks nearly new on the dip stick when I change the oil.

Recently the oil pressure light started blinking intermittently at a hot idle after about 10-15 minutes of driving accompanied by a ticking noise. Took it to a local shop and they put a pressure gauge on it and suggested it was likely the oil pump (~7 psi). I had them replace the oil pump, timing cover and timing chain while they were in there. The oil pump gears and timing cover were worn and the oil pick up screen was dirty so they cleaned it up as well. While they had the oil sump off they checked the bearings and they say they are in excellent shape.

Now that everything is back together, the oil light is still coming on intermittently at a hot idle. The shop pulled the valve covers and said there was quite a bit of build up under there.

My question is how likely is it that an engine flush will increase the oil pressure at this point? Or am I looking at something else causing the issue? What else would cause low oil pressure on this vehicle? The shop is suggesting it might be the cam bearings. Is there any way to narrow the issue down further?

Thanks for your help!

 

[Disco Mike]

Do not even consider starting that engine till you do another oil pressure test, cold at idle and 2000 RPM's then hot at idle and 2000 RPM's. Get those numbers back to us before anything else is done.

 

[Bosnian Discovery]

DO NOT do a flush - flushes destroy engines. The only way to clean engine sludge is to shorten your oil change interval to 2000 miles and let the fresh oil slowly melt the sludge. Flushes will wreak havoc on seals, bearings, and vital head components. They're too aggressive.

Did they check the oil PSI after you replaced the pump? Does the ticking still happen when the oil light comes on? Your problem could be as simple as a bad oil pressure sender. Get the additional numbers that Mike requested and we can diagnose from there.

On a side note, I'm having trouble believing you when you say that your oil looks "nearly new" after 5000 miles. I use the same oil/filter combo that you do and after my 4000 mile interval my oil is BLACK. It still retains it's lubricating properties, but I imagine that after an additional 1000 miles you would get oil degradation severe enough to damage engine components. The MAX recommended oil change interval is 5000 miles - this is for a new D2 with low miles. As the engine ages and gets miles it starts to be a lot harder on the oil and 3000-4000 mile intervals are much better. At a cost of $50/oil change it's cheap insurance.

 

[jk99]

Thanks for your responses.

My mechanic just got back to me with the pressure:

Hot:
4-5 psi @ idle
20-30 psi @ 2k RPM

When it was cold it was at 9 psi @ idle. He didn't check the psi at 2000 Rpm when it was cold.

Any thoughts or insights would be appreciated.

 

[Bosnian Discovery]

Your numbers are quite low.

Hot idle numbers should be over 10 psi and hot 2K numbers should be between 35-40 for a vehicle of that age. Cold idle, and I mean cold - where the oil hasn't had any chance to warm up, should be over 40psi. Either you got a wrong reading on that or there is something really wrong with your car.

Could be a cracked oil pump again due to incorrect installation - I'd take it back in to have them look at it again.

 

[Disco Mike]

Again, stop driving it or you will land up with a boat anchor under the hood.
Yes, you numbers are way to low. Normal oil pressures are 30ish at cold idle, 50ish at cold 2000 RPM's 10 plus at hot idle and low 40's at hot 2000 ARPM's. First thing you must do is pull the oil pan, check/clean the pick up tube and pull a couple of crank bearing to inspect for wear, then pull the front cover and replace your oil pump. While in there, also replace your timing chain set.
You have gone over 5 days and are still running it, I am serious, every time the oil light comes on your check book balance is getting lower.

 

[jk99]

My disco has now been parked since I had the mechanic check the oil pressure. I will be getting an oil pressure gauge and rechecking the pressure myself in the next few days. The oil pump, timing cover & chain have all been replaced and the pick up screen cleaned. The mechanic checked the bearings while the oil sump was off and said the ones he checked were in excellent shape. Having said that, my usual mechanic left on holidays after having pulled everything apart and checked the bearings etc and before the new parts arrived. The timing cover etc were replaced by the other guy he left in charge (don't really trust him) for the next week or so. How likely is it that the timing cover was replaced incorrectly and the pump is now cracked?

Assuming everything was installed correctly, what is the next step to take (other than rechecking the oil pressure)? I forgot to mention that after hitting a deer just over a year ago insurance replaced the oil cooler (used according to my records). Is it possible the oil cooler was partially blocked and could have accelerated/caused the problem? The old oil pump and timing cover were clearly worn but definitely not cracked.

 

[jacko]

low oil pressure at hot idle

I have the exact same problem with a 4.6 HSE 2002 P38 V8 and have not been able to find a solution anywhere.
I have cleaned the sump, the oil pick up and the delivery pipe, I have installed a complete new front cover and enclosed oil pump, I have redone the heads and all over head galleries and still I have this problem.
Best of luck to you and if you do find a solution please let me know so that I may redeem my sanity.
regards Jacko