I had the Land Rover Dealer install a new oil pump on my 2004 Discovery (I didn't have the time to do it myself). The readings they took from the pressure test were 15-20 lbs at idle and 35-40 at 200 RPM. I typically run 10-30 Mobil 1 synthetic, they had put in 10-30 Castrol. so, the same weight. Should I be worried that at 2000 RPM it's not 50 and only 35-40?

 

Was your pump cracked? or just replacing for peace of mind? Those numbers are on the high side at idle and seem low for 2000rpm. Its possible if your pump was cracked for a while and that your bearings could be worn from the low pressure, but I would be surprised if you would pull those numbers at idle. I would go buy a cheap harbour freight gauge and verify the numbers.

 

the old pump was fine (not cracked).... I was in there and just wanted it changed for peace of mind. I will double check the numbers... good idea. in the event those are the correct numbers, what can be done about it? change oil weights?

 

See https://landroverforums.com/forum/di...estions-46975/

A pro shop has real pressure readings before and after swap out of oil and filter, and this may guide you. My tired old Disco makes 42 PSI hot, but that is within spec for it. IMHO the 30 weight oil may certainly play a part in this.

You are correct that the idle PSI exceeds spec for the D2, but the running speed PSI does not. Of course, this could be other things as well, like wear on bearings, oil viscosity, filter design, etc. But is it the dealer's fault that a new pump can't make the pressure through your choice of oil and filter, and the bearing wear inside your engine?

The least expensive path is oil (make the jump to Rotella) and filter change. The Purolator filter in that post has a 35 PSI bypass rating, and if you dig a little deeper you find another Purolator/MANN filter the same size and low restriction, that has a 10 PSI bypass rating, closer to stock.

 

Sounds like they just pulled some numbers out of thin air and didn't actually check. I'd absolutely verify those numbers. With 30 weight and oil at operating temp 12-15 idle is about right on a good/new pump and mid to upper 40's @2K - 2500.

Given any combination of variables their numbers just don't make sense. Obviously ambient and oil temps are a huge factor - but still very fishy. Without knowing the conditions under which the readings were supposedly taken it's difficult to do anything other than speculate but the ratio of low/high pressure they gave you doesn't add up which is why I would verify.

The oil pump is only one of many factors when it comes to oil pressure. If somehow the numbers are correct a heavier oil will bump up the pressure and make you feel better but not really solve the problem. Even at 35-40 there's sufficient lubrication so I wouldn't loose sleep over it but I would monitor the situation as well as install a pressure gauge. A lot of times we get caught up worrying about specs and forget the bigger picture. Change is the real concern. If you see a continued and rapid decline it's time to worry but you numbers could very well be abnormally "normal." If they'd just installed a new motor that's a different story.

Personally, I'd switch to the Mo1 0-40 or 15-50 simply because they've a better additive package for the application.

 

Mobil 1 15w-50 is thinner when hot than 10w-30.
Their 0w-40 is very hard to find.
Mobil 1 is just a waste of money.
10w-30 is to thin for these engines.

Shell Rotella, 5w-40 or 15w-40 are WAY better choices.

 

And isn't the pressure from the pump also "limited" by the performance to the by-pass and relief valves in the front cover? This may vary from truck to truck. Rover considers them "measure or replace the whole cover", but they do show exploded diagram and give some points on acceptable condition and very light cleaning methods. Spring length is 60 mm. Seems like we have had a post about an incorrect spring length.. See attached pages.

But before I go down in those weeds I'd advise retest with 40 weight oil.

 

M1 15W50 is almost twice as thick when hot as M1 10W30. If you are talking about another company's 10w30, I'd like to see those numbers.
And the M1 0W40 is the best oil Mobil makes, and can be found at Walmarts, AutoZone or Advance, and is without a doubt a better oil than Rotella.

 

I'd double check the facts on that. 15W-50 is thicker at temp than 10W-30.

As far as additive packages, the Rotella and 15W-50 Mo1 have the same zinc and phosphorous levels. Maybe Rotella is cheaper and more readily available but I wouldn't emphatically say better or that Mo1 is a waste of money.

Tear down a Rover V8 that has had Mo1 from day one, vs one that has had Dino oil and other "synthetics." Then look at the overall condition of the motor, bearings etc and tell me Mo1 is a waste of money. I'm not saying it's the best or only oil to use, in fact I think Motul makes a far better oil for the RV8 but Mo1 15-50 is a great oil, readily available and doesn't cost a fortune. Oil's a personal thing, we all know that, use what you want but there are many oils that are a good candidate for the application. I don't know that it's even possible to fully comprehend if you don't tear these things down all day long but Mo1 is a very good product.

 

I am a shop foreman for a dealership... I can tell you right now we don't do pressure checks unless we need to. If you showed up and asked for a pump R&R... you got a pump R&R.. Not because we dont want to but because that's the nature of a flat rate tech. Least work as possible.