The V8 Owners Forum -

Hi everyone,

I have recently completed a rebuild of my Defender 50th 4.0 Rv8 Gems engine.

Everything is new in the engine and it runs nicely, but the lifters are bleeding down overnight and it’s driving me mad to hear that rattle on every cold start.

Any pointers to the cause of bleed down would be appreciated.

Thanks, J

Check tappet clearances. Sadly the inlet manifold has to come off for that!

Chris.

Thanks Chris,

I thought I had understood and set the pre loads, but I will take another look.
Yes the inlet removal is a PITA….

Cheers for your reply, J

Is it the right grade oil?

My engine used dinosaur juice 20W50

Not sure what was specified in the Gems engine…. Perhaps it has old style lifters that are expecting the old oil stuff

Ian

Ian Anderson wrote: ↑Tue Jan 14, 2025 9:15 pm Is it the right grade oil?

My engine used dinosaur juice 20W50

Not sure what was specified in the Gems engine…. Perhaps it has old style lifters that are expecting the old oil stuff

Ian

Oil spec from Landrover is based on your ambient temps. Thicker for the Sahara, thinner for the Artic.
My rebuilt 4.6gems works well on 5w40 in the middle of the UK.
I did find my 3.5 preferred 20w50 Dino juice as that was not a fresh engine! bit tapperty with a 40 weight, and got a bit low on idle pressure in the summer when hot.
Got a "feeling" the oil pump also has some influence - the GEMS gerotor pump working better with thinner oils? than the older dizzy driven external gear type pump.

lostinspace wrote: ↑Sun Jan 05, 2025 7:44 pm Hi everyone,

I have recently completed a rebuild of my Defender 50th 4.0 Rv8 Gems engine.

Everything is new in the engine and it runs nicely, but the lifters are bleeding down overnight and it’s driving me mad to hear that rattle on every cold start.

Any pointers to the cause of bleed down would be appreciated.

Thanks, J

Can you isolate it to one cylinder?
Using a stethoscope/long screwdriver listen to each cylinder - to try to determine if it all lifters or just one or two?

Thanks for the replies chaps,

So far I’ve tried all combinations of preload shims from none, to thin, medium and thick all with the same rattle at cold start. Even tried thick and thin together that clearly was to much upon start up.

So I’m back to my original preload shims when I first set it up, which is the medium ones. It ran the nicest and had a really smooth idle on these.

The oil is VR1 20/50 which I also have in a 3.5 motor with no problems for our temperatures.

It has been suggested I have an issue with the oil draining out of the lifter gallery overnight, but quite how I’m not sure. New oil pump fitted and sealed as per overhaul manual.

As you all know to pull all the parts to make the adjustments each time is very time consuming especially when it doesn’t work and you have to do it again. I am getting incredibly peeved now, I have built many engines over the years with no problems, this one is trying my patience.

My next step is to pull the engine, and start again,

Very fed up, J

What's you oil pressure?
Have you checked to see if it is 1 or 2 lifters or all of them?
The GEMS oil pump has a couple of pressure valves - if these can get tight, don't know if that would assist gallery oil loss?

If you pull off the rocker shafts and put a straight edge across the valves, are they all at the same height?, or have you got a low one?

Maybe bad lifters?

Chris.

My new 4.6 has a slight tap at startup also, I think tolerances on the new lifters may not be the same as previous ones, everything is lower quality nowadays.
We have an additive available here Pro ma MBL8 which I have used in many other motors and had good results from which I am going to add to mine.