Thread: Why do 2.7 cranks break?

Latest instalment of the rebuild and startup by LR Time is now on YouTube. He did an excellent job.

To follow will be some videos on the oil system which will be very interesting. I’m pretty confident he will be digging in to the startup delay and non return valves.

Yeah just watched it and glad to see the hard work has paid off.

Originally Posted by PerthDisco

Land Rover Discovery 3 / 4 - Epic Oil pump test and compare TDV6 - YouTube

Very interesting oil pump video to finish off the engine rebuild from LR Time.

Was an interesting video but light on for making any proper technical conclusions, and Christian added nothing to the theories on why Fabian’s 2.7 spun a bearing. The two tests they did proved very little in my mind - seemed to be more about showcasing Christian’s fabrication skills.

Was expecting some comments on if they consider if the oil pump should have a check valve to stop it draining off the oil overnight when parked up, or if they consider the lower capacity oil pump contributed to Fabian’s engine failure.

Hope they come back with a final close out on this topic.

Originally Posted by DiscoDB

Was an interesting video but light on for making any proper technical conclusions, and Christian added nothing to the theories on why Fabian’s 2.7 spun a bearing. The two tests they did proved very little in my mind - seemed to be more about showcasing Christian’s fabrication skills.

Was expecting some comments on if they consider if the oil pump should have a check valve to stop it draining off the oil overnight when parked up, or if they consider the lower capacity oil pump contributed to Fabian’s engine failure.

Hope they come back with a final close out on this topic.

He picked up on the NRV in the oil filter / cooler housing inlet consistent with our discussion here and the flow of oil through the filter and out through the middle spear.

So, all that can drain is the oil below the cooler housing in the front of the block above the pump which is a short tube (the oil in the cooler is horizontal and can’t drain).

The leak down test showed it’s not a straight drop out out but a slow drain over hours but - and this was interesting to me - the pump at 1bar pushes 2.5 litres in just over 8 seconds.

So, to fill oil back through the gallery up to the cooler and filter, which stays full, would be a microsecond.

The delay getting pressure is on the supply side after the oil filter going through the delivery side.

The argument for a check valve on the oil pump side seems unnecessary to me.

Even your comments PD discusses more theories than LR Time did.

So in the interest of triggering more discussion and hopefully learning more, I will add my comments.

Not so sure about the micro seconds to refill - if this was true then it should not take 2-4 seconds just to get the oil pressure back up above 0.5-0.7bar (the oil light switch setting).

If the true volume to refill the oil pump, galleries, and oil cooler/oil housing is more like 0.5l then this explains why it takes around 2 seconds to get oil pressure back if all is in good condition (good flowing pump, oil housing not seeping oil through drain plug or check valve) - but does not explain why some people see longer times than this when the car has been sitting for an extended period, or if this contributed to why Fabian’s managed to spin a bearing.

A flow and pressure test at “cranking speed” would have been insightful and probably confirm why Fabian’s failed. They could still do this for a future video.

Strangely it was the original 2006 pump that seemed to perform the best on the drain down test. This showed the new FAI pump was not good and was no better than the worn and potentially damaged pump from Fabian’s engine.



This screenshot actually looks like the new FAI pump had drained down more oil than even the worn aftermarket pump. With hot oil I bet the difference is even more pronounced.

The other note was the flow rates between the new and old pumps were not that different despite the 10% increase in size. The difference in measured flow rate was only 2% - even Vera said it was the same but Christian was convinced otherwise (and joked with video editing they will show it to be better - even then it was only just a bit better).



The difference was 298ml/s vs 291ml/s with the back-pressure PCV set at the same point.

A new larger impeller pump which only delivers 2% more flow compared to an old worn pump can not be right - once it is worn and has more back flow and drops a bit of operating pressure it will perform no better than the smaller impeller pump.

At some stage he needs to get a new Ford 15mm pump and redo the flow test.

It is good they confirmed some points but the only new bit of info for me was don’t buy an aftermarket/non-OEM oil pump (we generally assume that), and yet he still fitted the poorer quality FAI pump to Fabian’s engine on the basis that it delivered 2% higher flow rate than the worn and old smaller pump.

Love their work - just was a lost opportunity on where I thought (or hoped) they were taking this and his testing actually showed more issues that raise more questions.

David: “I give it 3 stars - what do you think Margaret?”
⭐️ ⭐️⭐️

Originally Posted by DiscoDB

Not so sure about the micro seconds to refill - if this was true then it should not take 2-4 seconds just to get the oil pressure back up above 0.5-0.7bar (the oil light switch setting).

How long does it take to pump up the hydraulic lifters?
edit: and fill all the galleries?

Originally Posted by DiscoDB

Not so sure about the micro seconds to refill - if this was true then it should not take 2-4 seconds just to get the oil pressure back up above 0.5-0.7bar (the oil light switch setting).

I can only speak to my own experience but the only time my engine takes 2-4 seconds for the oil pressure light to go out is when I have done an oil/filter change. At other times it is always less than 2 secs.

Garry

Originally Posted by 101RRS

I can only speak to my own experience but the only time my engine takes 2-4 seconds for the oil pressure light to go out is when I have done an oil/filter change. At other times it is always less than 2 secs.

Garry

Your experience is correct Garry and how I believe it should be.

Some people though (at least on some forums) see more like 4 seconds after sitting idle for some time, so presumably this is over 1l of oil needed to refill everything - like when doing an oil and filter change.

There was a Territory 2.7 failure discussed on the Ford Forum which had been experiencing extended oil light off intervals before failure and I believe even Ford was unable to work out what was happening. It too spun bearings.

This is the mystery which many have failed to explain. In Russia some smart people have been going to extreme lengths to solve this problem. Probably why someone developed the 19mm oil pump - but this sounds over the top.