Vehicle is a 98 D1 w/78k. K$N 3001 oil filter, 10W40 dino. I have been experiencing noise and low oil pressure at start up. Lasts only about 3 seconds in the morning and then all is fine. Oil light is on very briefly as well. The longer it sits, the longer the duration of noise. If the engine is warm, it doesnt happen. Gotten worse during cold weather. During the summer, I replaced the pickup tube (which was loose and dirty) and switched to the K$N fitlers. This helped tremendously during the summer, but it seems that when the temps dropped the problem emerged again. I've narrowed it down to a leaking oil pump, but would like to ask you ppl your opinion and suggestions before I plop $500 for a new front cover. Or, is this something that is inherent in the LR design and should be tolerated? Any other things to look at? Thanks.

FWIW I used K&N oil filters for over two years. During one oil change I couldn't find a K&N ,so I went with a Wix. My gas millage went up by 1 mpg. I think the K&N filters a very tight and put a strain on the oil pump.

I have actually tried it with NAPA, Wix, and Mann oil filters. The K$N seems to produce the least amount of noise. Hard to tell though. Thanks for the reply.

Its strange that you are only having this problem when the engine is cold, usually an oil pump would be weakest when the engine is warmed up and the oil is most viscous. FWIW you don't need a new front cover, I beleive there is a rebuild kit available for the oil pump, as well as a high-pressure restrictor plate available as well. I would first try running different oil, possibly with a quart of Lucas oil stabilizer added. I run Rotella T 15-40W along with one quart of oil stabilizer and Mobil 1 filters and am very pleased with the results.

Yep, I was thinking the oil pump would show its colors when warm. I was unaware of a rebuild kit for the 4.0 oil pump. I was under the impression that it was built into the front cover.

I have also tried various oils and viscosities, as well as Lucus oil stabilizer. I havent tried the Rotella oil or the Mobil 1 oil or filter, I give it a try next. The noise sounds more like rocker clatter.

Assuming the lifters are hydraulic, could the lifters be loosing their prime or going soft and bleeding down when not under pressure from the oil circuit. Then once the pump is running, the pressure pumps the lifters up tightening the lash. I guess, the lifters would have to be pretty gone to bleed down under no pressure on the plunger. I would think there would be a slight erratic idle while there is slack in the pushrod. Could this be a plausible explanation? Anyone with a similar experience? I guess I could just turn the radio on real loud prior to starting the engine next time.

I don't know if there is a rebuild kit available for the 4.0/4.6 pump, I was thinking earlier models. But I'll check on a price for you on either just the pump or the entire front cover and see what I can do for you.

nevermind, even in-house cost on the front cover here at the dealer is about $900, i would look for one in the used market.

also it is part of the front cover, i am getting my years mixed up.

Its strange that you are only having this problem when the engine is cold, usually an oil pump would be weakest when the engine is warmed up and the oil is most viscous.

Viscosity is the resistance to flow... As temps increase, viscosity decreases (for most oils-doesn't apply to the silicone oil in the viscous couplers).

The 4.0/4.6 oil pumps begin to get weak when the clearances between the front cover and the gears and the cover that retains the gears wear. The fact that this wear has occured at such moderate mileage is very curious.

Now, the cure! If you can disassemble the front end without deciding to buy a new cover (which is much less expensive if you shop around-I can find one if you wish), the pump gears are retained by a plate held in by six philips screws. Remove the screws and the retaining plate. When you turn the plate over, you'll see the majority of the wear has occurred here, allowing the oil to leak around the gear. Polish the retaining plate to remove the wear groove, reassemble, packing the voids in the gears with white lube/90 wt. to prime and reassemble.

Peace,
PT

I would also suspect an internal oil leak. Cam bearings, main cap on backwards, gasket, worn rocker shaft, etc. With the low mileage it is most likely an assembly mistake.

JP

I would also suspect an internal oil leak. Cam bearings, main cap on backwards, gasket, worn rocker shaft, etc. With the low mileage it is most likely an assembly mistake.

JP

Good call! Got stuck in the box again thinking it was all oil pump.

I stand in awe of your knowledge :flipoff2:

I stand in awe of your knowledge :flipoff2:

My new subline.

My new subline.

Yeah, well, I'm older AND smarter on the interweb :flipoff2:

Head, er Chief, yeah, that's the ticket, Chief Minion

Actually, he didn't say anything that my 96 D1 (and others) don't do normally (since new).

When it got cold outside (below 40F), I always had a delay in pumping up oil pressure if the truck hadn't been run within the last 24 hours. Several second delay in idiot light going out coupled with some minor valve train noise. Since it did it from almost new, I take it as a normal.

I "fix" it in the winter by changing to 5W-30 synthetic from the 15W50 I run when it's hot. Now, even when pretty cold (0-10F), the idiot light goes out within a second or two.

So, HOW long and HOW MUCH noise ??? If it's only the 3 seconds you mentioned...

At the longest about 3sec. Thats when the truck has sat over the weekend. I agree that there is a leak somewhere to explain these symptoms. This may be a normal thing with Discos, but the noise is so disturing that I think there may be a dysfunction somewhere. But, this is my first LR and its been doing it since 65k.

The reason I narrowed it down to the oil pump and the lifters is that these are the only oil "reservoirs". In other words, oil in the bearings (mains, cam, rods) are supposed to drain. How does the rockers get their oil? Is it through the pushrods?

Pendys suggestion of a worn or loose rocker shaft would make sense as well. This noise could be a excess clearance in the rocker shaft that, once running, gets occupied Maybe, Ill try to determine if one bank is producing the noise more. The noise sound too uniform to be a single lifter or couple of lifters failing. Hell, when I replaced the pickup, I was able to remove the bolts by hand. No telling what else is backing out.

Culprit theory thusfar: oil pump, rocker shaft, multi-lifter failure

Anyone have an opinion, advice, suggestion on where to start.

You should have checked torque on the rods and mains when you had the oil pan off.

JP

Should I drop the pan again and check them? May I ask why you mention the rods and mains? Just curious.

Resealed a few oil pans only to find loose caps.

Heard similar stories from other repair procedures.

Look for clean areas that indicate excess oil flow from bearing areas. Which may be hard to locate on your low mile engine. Good Luck

The delay in oil pressure following prolonged periods of inactivity, especially considering the oil is cold, makes me think the oil-pump/pickup is not sealed all too well and may be losing its prime over night (or longer).

If it were bearing wear beyond tolerance or other worn or misassembled parts, I would suspect it to take even longer to develop oil pressure when cranking the engine when hot, because the oil is less viscous. You would see the oil/idiot light more often cranking over a hot engine than a cold engine if this were the case.

Worn oil pump and/or no longer sealed well (maybe the pick-up?). It's losing its prime...otherwise the problem would be more pronounced when trying to start a hot engine.

I wonder if it could be the o-rings on one of the oil cooler lines. The top one sticks in the timing cover quite a ways and has two orings distributing oil out of the pump.

JP

Pendys suggestion of a worn or loose rocker shaft would make sense as well. This noise could be a excess clearance in the rocker shaft that, once running, gets occupied Maybe, Ill try to determine if one bank is producing the noise more. The noise sound too uniform to be a single lifter or couple of lifters failing. Hell, when I replaced the pickup, I was able to remove the bolts by hand. No telling what else is backing out.

Culprit theory thusfar: oil pump, rocker shaft, multi-lifter failure

Anyone have an opinion, advice, suggestion on where to start.

Since you're now onto valvetrain, I'll jump back into the box and suggest a worn pushrod seat.

I doubt it's bearing wear as you'd see the idiot light come on after the engine warmed up and the idle goes low, with the light oging out as revs increase.

Actually, he didn't say anything that my 96 D1 (and others) don't do normally (since new).

When it got cold outside (below 40F), I always had a delay in pumping up oil pressure if the truck hadn't been run within the last 24 hours. Several second delay in idiot light going out coupled with some minor valve train noise. Since it did it from almost new, I take it as a normal.

I "fix" it in the winter by changing to 5W-30 synthetic from the 15W50 I run when it's hot. Now, even when pretty cold (0-10F), the idiot light goes out within a second or two.

So, HOW long and HOW MUCH noise ??? If it's only the 3 seconds you mentioned...

Yep, my 98 has behaved this way since day one. Start her up, tick tick tick, then all good. Now that it sits all weeke and only gets driven on the weekend, it still behaves the same way. No worse, that I can tell. 140K miles so far and still going.

First, thanks all for your time and suggestions... and for being nice to the noob.

As far as the pickup. That was my first thought about 3 mo ago. I decided to jump in and remove the pan. It was scary to see the loose pickup and be able remove the bolts by hand. The other scary thing was that there wasnt a gasket nor lock washers on the bolts. The pickup was filthy, so I got a new one and replaced it. The new one came with a gasket. I replaced the bolts with a new set along with lock washers and a dab of lock tight for extra insurance.

thats the other I noticed the other day. There is a tiny amount of oil on the oil cooling lines near the crimps. Not loosing much oil at all, but could this be a possible source for a leak that would allow oil that is priming the pump back into the pan?

If it were a worn pushrod, wouldnt the noise remain?

This all may be like darkstar and Discosaurus mention... "normal".

Next weekend, when i have some time, I'll drop the pan and check the pickup seal again for shits and giggles.

Thanks again. Have a great weekend.