Thread: 4.6 Oil Pump ?

I read recently somewhere or maybe it was talking to Gary at CLR, that there are two types of timing case gasket, one for camshaft driven pump and one for crankshaft pump, and if you use the wrong one you lose oil pressure because there is not a hole in the gasket where it should be.

Can anyone amplify on this as IMHO it would be pretty hard for a crank driven oil pump to wear out, and otherwise the pressure relief is the only other likely explanation.
Regards Philip A

Originally Posted by PhilipA

I read recently somewhere or maybe it was talking to Gary at CLR, that there are two types of timing case gasket, one for camshaft driven pump and one for crankshaft pump, and if you use the wrong one you lose oil pressure because there is not a hole in the gasket where it should be.

When I first bought my '87, I did a camshaft/lifter change & fitted a later timing cover gasket instead of the correct one. While it appeared to fit OK, the oil pump would not prime no matter what I did due to one hole not sealing the cover correctly.
Lesson learnt .

I have 2003 D2 V8 4.0 (130 000km), I was sand driving and oil light came on whilst idling, I continued driving to safer grounds and then came loud ticking noise. I replaced oil and filter,engine stopped ticking and light went off, so I drove home.
The next day I started engine but the light came on at idle again.I decided to pull down engine,removing timing cover to find a CRACKED outer oil pump gear..
I replaced with new the timing cover (includes oil gears,relief valve,pressure sender and seals) New timing gears and chain as they where badly worn,exhaust manifold and flange gaskets all with new genuine parts ,I also replaced oil pickup o'ring, sump gasket and installed a oil pressure gauge, all done by the rover overhaul manual specs and thoroughly cleaned all parts before reassembling.
After all that work, and adding a thicker oil (15-50w instead of recommended thin 5-40w) I started engine to find it was running much smoother and quieter BUT still has zero oil pressure at idle after engine warms up ???? The pressure rises when engine is revved but then rapidly falls back to zero when revs drop??
So I have pulled the engine down again to find more issues!! the upper conrod bearing shells are partially worn down to copper?? I have replaced conrod shells but My guess is that the big end bearings also needs to be replaced whilst the engine is pulled down? but I dont think it is possible to correctly replace the big end bearings without removing the engine as it looks near impossible to achieve the correct torque settings that could result in catastrophic engine failure...
Why is my bottom end in such bad shape? this is a low km well maintained Disco that has had an easy going street life (soccer mum suv) and has never been off road until recently?
Im guessing the top end is also in need of a rebuild?
This low oil pressure problem has already cost me $2000 not including tool costs and thats doing the work myself, I would hate to know what a rover mechanic would have charged me..

Could the low oil pressure have caused issues to bearings, etc?

I'd imagine it wouldn't take long to kill a bearing with no oil getting to it!

Cheers
Keithy

I notice this is an old thread which has been bumped into life by James445F.
BTW James, when you find your issue – make sure you post back the result so we all benefit.

The oil system is an open system. If the resistance to flow on the rocker circuit is lower than the big end circuit then total oil pressure measured at the pump cover will drop considerably.

Oil pressure leakage at the top end is a very common culprit for low oil pressure.

Most people jump straight to the oil pump or the bottom end to solve their low pressure – however the first place to go is the top end.

Remove the rockers and clean them carefully. Note carefully how they are assembled before disassembly – because if you reassemble incorrectly you will have no oil pressure.

Now inspect carefully all parts for cracks and excess wear - Rocker stands, rockers and rocker shaft or rocker shaft plugs. Severe wear or cracks will lower oil pressure considerably.

I can illustrate this by a recent experience. After renewing the stem seals on my P38, I had a helper refit the RH side rockers arms and torque them down. On start I noticed the oil pressure 5 psi lower than normal at at 45psi,( Normal prior to the work was 50), then as soon as the block got to operating temp the oil pressure began to slowly drop until it settled at 10psi – on revving it would go to 25psi. I rechecked oil pressure with another guage to confirm and the hot idle result was the same, however cold idle pressure was now only 40psi.
Before the work, cold idle was 50psi and hot idle was always 30psi. This vehicle has 195,000km on the clock – guage is accurate to plus or minus 2 psi.
On pulling off the rockers we found the RH side forward stand had cracked – my helper had set 38 ft/lbs instead of 38NM on the torque wrench and the forward RH stand had cracked as it expanded. The crack was about 0.5mm wide at the bottom of the stand - obviously more as it got to operating temp.
The oil feed to the rockers is via the front and rear stands.

This clearly illustrates the effect of leakage in the rockers on oil pressure - such al leak at the top end on just one forward rocker stand had a dramatic effect on oil pressure –5 - 10 psi when the oil is at its normal viscosity and a whopping 20psi at its hot viscosity.

A worn rocker set on both LH and RH sides would give the same result. Pressure leakage at the top end is the main culprit for low pressure so go there first. If you don’t fix the top end pressure leakage in an open system,then the bottom end and cam bearings will suffer.

If you repair the rocker sets, and oil pressure has not recovered significantly, then now you should lift the engine and thoroughly investigate – oil pickup screen, pump clearance, bottom end clearances, cam bearing and all galleries
.
As an aside – if the engine has had previous work done and the mechanic used sandpaper or abrasive pads to clean off the gaskets you will probably have severe bearing wear. These abrasive pads contain aluminium oxide which will find its way into the cam and crank bearings. Here they will abrade the bearings in short time. They get past the oil filter either on start when the overpressure relief valve temporarily opens, or is blown around the block when an air tool die grinder is used.
Normal oil film thickness between the bearing journal and the crankshaft is equal to the typical machining clearance - 0.001 inch - but in operation, the crankshaft never spins on centre. As the piston fires the oil layer between the journal and the bearing is squeezed to 0.00004 inches. A typical aluminium oxide particle is much bigger than this and is hammered into the bearing surface whereupon it begins to eat away at the crank

I found enough room under there when fixing the car wees (as my 3 y.o. puts it).

I had the airbags up, but if you sit the stands up high enough for the shocks to top out.

I didnt take the crank out, but did clearance checks on the rear two caps. Hard on the arms but achievable.

Did you drive for very long whilst it was ticking? If it were only 30 seconds or so I don't think that would be the cause - but a few minutes under load would do it I imagine.

Your storey is similar to mine in that I rebuilt the oil pump and it still dropped back to almost zero at idle and 24 when cold at 2500. I'd striped the bolt on the pump backing plate, allowing the plate to flex and draw in air. My torque wrench went down to 15ftlb so just guessed the very low figures on the backing plate. I also reused the pickup oring...
After fixing that up (and buying an inch/pound torque wrench) it was all good. I was very suprised how low the torque settings were on the backing plate though! Trusting the locktite I suppose.

One of the tricks to build up pressure to the bottom end in the likes of the Repco motors was to half the oil flow to the top end. Apparently it made a large difference - so increasing the flow would have big consequences too.

On a side note - if you've got the front cover off and the inlet manifold - its not that much more work to take the motor out.

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Wow this is a lot of good info... Cheers . I decided to buy an engine hoist and stand as it seemed near impossible to do the job properly and achieve the correct torque settings a small price to pay considering and pulled out the engine yesterday. I put it on engine stand, removed the crankshaft and the big end shells were in good condition. After inspection of the camshaft area I found that one of the cam bearing shells has slipped out and is resting against camshaft and one of the lifters ? I would never spotted this without pulling crankshaft out or removing top of engine . Now I can easily rebuild the top and bottom of engine without climbing over and under my Disco.
Overall, removing the engine wasn't as hard as I was expecting as It only took me a day on my own no extra hands needed but the correct tools are essential such as good quality air tools, extension sockets, spanners also good advice ..
I will now pull down the top of the engine and inspect also replace cam, lifters and bearings . I'm considering replacing cam with a piper stage 2 rather than a standard one but I'm not sure if I will need to upgrade anything else such as ECU, valve springs etc??
I will be replacing pistons and heads in the near future to complete my rebuild.
Does anyone have any advice regarding this??
Thanx

Also what's the best way to clean the inside of my engine ?