Discussion
Hi Guys,
I'm hoping your combined knowledge can help. My disco 2 needed a new motor and to give it a bit of upgrade in the process a fresh 4.8 was put in. First start up of the motor resulted in a bit of a knocking noise and the valve train sounded pretty noisy to me. The engine supplier was told about the noise and I got an email back after he head watched a video i sent of the engine running that he thought it was probably a lifter and it just needed a good run and it would clear. Anyway to cut a very long story short after high oil consumption and metallic flake being evident at each oil change the oil pressure light started to come at idle when it had warmed up so motor was pulled and sent back to the UK. (I'm living in Australia at the moment)
When the engine was pulled apart it looked more like it had done 200000km rather than 25000! The engine guy is trying to blame either the oil or me not changing the oil or something to do with the install for the state of the motor.
I've spoken to a couple of V8 specialists who made comment on short skirt pistons being a bad choice for anything other than a race engine and that might explain the noise and may be blow-by. Penrite running in oil for the first 1500km (changed every 500km) then Penrite 10w50 changed every 5000km. The engine temps were always good. The engine was supplied with oil pump and heads fitted.
I'll add some photos hopefully and see what you think. We're pretty desperate to get the car back on the road as it is only car and it has now been off the road since before christmas. I've contacted an independent assessor to look at but now the supplier won't let the engine leave until I've paid him for the shipping back to the UK as well as the import duty and VAT!! It's a bloody nightmare!
I'm hoping your combined knowledge can help. My disco 2 needed a new motor and to give it a bit of upgrade in the process a fresh 4.8 was put in. First start up of the motor resulted in a bit of a knocking noise and the valve train sounded pretty noisy to me. The engine supplier was told about the noise and I got an email back after he head watched a video i sent of the engine running that he thought it was probably a lifter and it just needed a good run and it would clear. Anyway to cut a very long story short after high oil consumption and metallic flake being evident at each oil change the oil pressure light started to come at idle when it had warmed up so motor was pulled and sent back to the UK. (I'm living in Australia at the moment)
When the engine was pulled apart it looked more like it had done 200000km rather than 25000! The engine guy is trying to blame either the oil or me not changing the oil or something to do with the install for the state of the motor.
I've spoken to a couple of V8 specialists who made comment on short skirt pistons being a bad choice for anything other than a race engine and that might explain the noise and may be blow-by. Penrite running in oil for the first 1500km (changed every 500km) then Penrite 10w50 changed every 5000km. The engine temps were always good. The engine was supplied with oil pump and heads fitted.
I'll add some photos hopefully and see what you think. We're pretty desperate to get the car back on the road as it is only car and it has now been off the road since before christmas. I've contacted an independent assessor to look at but now the supplier won't let the engine leave until I've paid him for the shipping back to the UK as well as the import duty and VAT!! It's a bloody nightmare!
PS - your original post is very unclear as to when this work was done, where it was done. - Engine went in last August. Fitted here in Australia.
why the engine has 25,000 km on it if it was faulty from the start. - After numerous emails and discussions we explored numerous potential causes of the knocking noise. It wasn't until the oil pressure light started to come on that he agreed take it out and get it back to the UK.
who stripped it and took photos? - The supplier.
what the supplier is demanding more money for? - He wants money for the shipping back to the UK and the import duty and VAT before he will let the assessor have the engine. I've had no definitive answer as to what happened......hence bringing in the Assessor.
why the engine has 25,000 km on it if it was faulty from the start. - After numerous emails and discussions we explored numerous potential causes of the knocking noise. It wasn't until the oil pressure light started to come on that he agreed take it out and get it back to the UK.
who stripped it and took photos? - The supplier.
what the supplier is demanding more money for? - He wants money for the shipping back to the UK and the import duty and VAT before he will let the assessor have the engine. I've had no definitive answer as to what happened......hence bringing in the Assessor.
Is there any disadvantage of using short skirt pistons? Could this contribute to piston instability within the bore on an engine like this? I've been told by another RV8 builder that they only belong on rally engines which have rebuilds ever year. Could this lead to blow by of oil passed the rings into the combustion chamber?
This is the preliminary report that I had back after it was dismantled. Just to clarify the engine was "remanufactured" so came to me with 0km after a rebuild. The reason it was sent back to the UK was to comply with the builders wish to deal with it himself.
The piston to bore clearance when built was supposed to be 0.0035" according to the builder. It just struck me as odd that even though the noise that concerned me was there from the very first start up I was told categorically that it was not piston slap. Now when the engine is pulled apart the abnormal wear on one of the pistons was probably the noise. At the end of the day if it is something that was done or not done as part of the install I can accept that and take it on the chin. If it was something that was wrong in the block itself from the start then I want to know and someone else should be responsible. I know many people have different opinions on different oils but surely they are all of a good enough quality not to shag motor in that quickly?
This is the preliminary report that I had back after it was dismantled.
Externally the engine was in a clean condition, with no obvious
damage or defect. The temperature strips fitted to block and
heads indicated the external surface of the engine had reached
116' C at all three locations. We note that the sump was likely
removed before shipping back to UK, as there was little
residual oil within, which as not allowed us to collect a sample
for lab analysis.
On opening the engine, we were very surprised with how dirty
the interior was. ( See pictures ) All surfaces had a dark
coating of sludge like substance, deposited by lubricating oil.
Inspection of the combustion chambers and piston crowns showed
a heavy build up of carbon on all surfaces. ( see pictures )
Inspection of the pistons showed a very heavy build up of
carbon on lands, skirt and undersides. ( see pictures )
The engine and components were cleaned of dirt with our hot
wash process to allow measurement and further inspection.
Visual inspection of the valve train, camshaft, and followers
showed wear consistent with normal running in, and were
regarded as in excellent condition. The number 3 camshaft
bearing was found to have shifted from its fitted position.
Pistons and rings, once decoked, were found in good condition.
Rings had typical wear from bedding in, less than half the
second taper machined ring had bore contact, consistent with
good running in and use. Pistons were in good condition with
minor scuffing on lower skirt noted on several pistons on bank
one thrust side. No piston to cylinder contact was evident on
the ring lands or other areas not expected to contact the
cylinders.
Cylinder bores. An area extending down all the cylinders, but
particularly the thrust side of bank one was noted to be
scored. This area of damage corresponded with the area of the
lower piston skirts. No Specific embedment or scoring was found
outside of that area. Bore gauge measurement showed cylinder
sizing and shape to be virtually unchanged from new outside of
the damaged areas. Within the damaged spots the cylinder 7
showed worst increase in size, 0.002" over the size of the rest
of the cylinder.
Crank rods and bearings. Light scoring was noted on all
crankshaft surfaces, sizes were within tolerance, and no
ovality or wear could be measured. The Tin Aluminium main
bearings had evidence of some surface disruption. However wear
under the area of the bearings exposed to heaviest load was
found mimimal.
The big end bearings, of the traditional Lead Bronze with
Babbitt overlay type had evidence of disruption of the soft
babbit overlay. On one connecting rod bearing, the overlay had
been displaced to show the bronze backing at the point of very
highest load. All bearings could be described as scruffy, with
evidence of embedment in the Babbitt, yet careful measurement
with a ball point micrometer ( to avoid brinelling )the maximum
size difference of 0.0006" between unworn and most worn parts
of the bearing could be found.
Our view based on visual examination of the embedded particles
within the Babbitt would suggest they are comparatively soft
and colouration would suggest not ferrous.
Remainder of engine ancillaries etc
Oil pump was stripped and inspected. It was noted that at the
oil cooler connections, plugs were fitted, which indicate the
engine did not have an oil cooler fitted. Minor scoring
consistent with normal use and wear. oils seals and gaskets.
Rear crank seal seated and square to crankshaft. No wear groove
or scratches on crank running surface. No visible cuts or marks
on seal edge. Front pulley was missing from engine, so no
assessment can be made, seal visually ok.
Initial analysis.
I have read back at our correspondence since you purchased and
installed the engine. Early on, you reported high oil
consumption and a noise from within the engine to us. The first
fill of oil you recorded to have been drained at 400 KM, and
was reported as dark in colour, to which we replied was typical
of the initial running in period with this engine.
The oil was further reported to have been changed at 500 KM
intervals subsequently over the next 2000 KM.
Our initial finding on strip down was the heavy carbon build up
on the combustion chambers and piston ring lands. A build up
was found under the crowns too. This is in my experience very
unusual, and would not be expected to be found on an engine run
on today's oils. It is my view that the engine has not suffered
a combustion defect such as a lean mixture condition which
could raise piston crown temperatures to the point of
carbonizing the lubricating oil, without any other damage being
present. The engine gaskets, valves, guides, piston rings and
piston ring lands do not show any evidence of excess heat or
damage which could be caused by abnormal combustion.
Despite the fact that no oil cooler was fitted, and no
indication of the maximum temperature of the oil has been
recorded, It has to be noted that Land Rover only fitted oil
coolers to vehicles operating in certain conditions and
territories. I am not aware of the vehicle having been used to
heavy towing. I consider that the engine has been run with a
lubricating oil which has carbonized at normal engine operating
temperatures and conditions. Further strong evidence of the
poor performance of the oil is shown with the dirty condition of
the interior of the engine. Given the frequency of oil changes
reported, it would be expected that the interior of the engine
would be spotlessly clean, as engine lubricating oil contains
detergents and dispersents which maintain combustion products
in suspension within the lubricant. Clearly, it has not been the
case with this engine.
The abnormal damage to the cylinder walls on the contact area
of the piston skirts is in my view the cause for the noise from
within the engine. The 4.8 uses high silicon alloy forged
pistons, which have quite short skirts. The piston to cylinder
clearance has increased by 0.002" on the worst cylinder, and
whist the piston top land has not been making contact with the
cylinder ( generally a prime cause of piston slap noise ) the
piston skirt will have had more clearance than expected and
required. The reversal of piston skirt loading at end of stroke
will generate rythmic engine noise varying with load and speed.
I cannot attribute the damage to a typical dirt ingress
problem, as no damage is present other than on the skirt contact
areas. Dirt entering the engine through intake would be
expected to leave damage predominately above the piston rings.
If dirt was built into an engine, for example during assembly,
damage would be predominately below the rings. Furthermore, it
would be expected that contamination which is sufficiently hard
to cause a scoring type damage would embed in the softer
aluminium piston. It would also, regardless of source be more
generally spread around the cylinder. No embedment of material
is present. I attribute the damage as wear caused by a
lubrication break down on the loaded thrust face of the piston
and cylinder.
Crankshaft and bearings. The extent of the damage found has not
resulted in clearances opening up to the degree which would I
believe would cause excessive noise which could be identified
as an individual knocking or similar sound, but could possibly
result in the symptoms to be expected within a higher mileage
engine, ie typically a slight reduction in hot oil pressure,
and a more general increase in engine noise. Its not possible to
see any identifiable foreign bodies present within the Babbitt
overlay, the damage being I believe to be generated from within
the bearings themselves.
The piston to bore clearance when built was supposed to be 0.0035" according to the builder. It just struck me as odd that even though the noise that concerned me was there from the very first start up I was told categorically that it was not piston slap. Now when the engine is pulled apart the abnormal wear on one of the pistons was probably the noise. At the end of the day if it is something that was done or not done as part of the install I can accept that and take it on the chin. If it was something that was wrong in the block itself from the start then I want to know and someone else should be responsible. I know many people have different opinions on different oils but surely they are all of a good enough quality not to shag motor in that quickly?
This is the preliminary report that I had back after it was dismantled.
Externally the engine was in a clean condition, with no obvious
damage or defect. The temperature strips fitted to block and
heads indicated the external surface of the engine had reached
116' C at all three locations. We note that the sump was likely
removed before shipping back to UK, as there was little
residual oil within, which as not allowed us to collect a sample
for lab analysis.
On opening the engine, we were very surprised with how dirty
the interior was. ( See pictures ) All surfaces had a dark
coating of sludge like substance, deposited by lubricating oil.
Inspection of the combustion chambers and piston crowns showed
a heavy build up of carbon on all surfaces. ( see pictures )
Inspection of the pistons showed a very heavy build up of
carbon on lands, skirt and undersides. ( see pictures )
The engine and components were cleaned of dirt with our hot
wash process to allow measurement and further inspection.
Visual inspection of the valve train, camshaft, and followers
showed wear consistent with normal running in, and were
regarded as in excellent condition. The number 3 camshaft
bearing was found to have shifted from its fitted position.
Pistons and rings, once decoked, were found in good condition.
Rings had typical wear from bedding in, less than half the
second taper machined ring had bore contact, consistent with
good running in and use. Pistons were in good condition with
minor scuffing on lower skirt noted on several pistons on bank
one thrust side. No piston to cylinder contact was evident on
the ring lands or other areas not expected to contact the
cylinders.
Cylinder bores. An area extending down all the cylinders, but
particularly the thrust side of bank one was noted to be
scored. This area of damage corresponded with the area of the
lower piston skirts. No Specific embedment or scoring was found
outside of that area. Bore gauge measurement showed cylinder
sizing and shape to be virtually unchanged from new outside of
the damaged areas. Within the damaged spots the cylinder 7
showed worst increase in size, 0.002" over the size of the rest
of the cylinder.
Crank rods and bearings. Light scoring was noted on all
crankshaft surfaces, sizes were within tolerance, and no
ovality or wear could be measured. The Tin Aluminium main
bearings had evidence of some surface disruption. However wear
under the area of the bearings exposed to heaviest load was
found mimimal.
The big end bearings, of the traditional Lead Bronze with
Babbitt overlay type had evidence of disruption of the soft
babbit overlay. On one connecting rod bearing, the overlay had
been displaced to show the bronze backing at the point of very
highest load. All bearings could be described as scruffy, with
evidence of embedment in the Babbitt, yet careful measurement
with a ball point micrometer ( to avoid brinelling )the maximum
size difference of 0.0006" between unworn and most worn parts
of the bearing could be found.
Our view based on visual examination of the embedded particles
within the Babbitt would suggest they are comparatively soft
and colouration would suggest not ferrous.
Remainder of engine ancillaries etc
Oil pump was stripped and inspected. It was noted that at the
oil cooler connections, plugs were fitted, which indicate the
engine did not have an oil cooler fitted. Minor scoring
consistent with normal use and wear. oils seals and gaskets.
Rear crank seal seated and square to crankshaft. No wear groove
or scratches on crank running surface. No visible cuts or marks
on seal edge. Front pulley was missing from engine, so no
assessment can be made, seal visually ok.
Initial analysis.
I have read back at our correspondence since you purchased and
installed the engine. Early on, you reported high oil
consumption and a noise from within the engine to us. The first
fill of oil you recorded to have been drained at 400 KM, and
was reported as dark in colour, to which we replied was typical
of the initial running in period with this engine.
The oil was further reported to have been changed at 500 KM
intervals subsequently over the next 2000 KM.
Our initial finding on strip down was the heavy carbon build up
on the combustion chambers and piston ring lands. A build up
was found under the crowns too. This is in my experience very
unusual, and would not be expected to be found on an engine run
on today's oils. It is my view that the engine has not suffered
a combustion defect such as a lean mixture condition which
could raise piston crown temperatures to the point of
carbonizing the lubricating oil, without any other damage being
present. The engine gaskets, valves, guides, piston rings and
piston ring lands do not show any evidence of excess heat or
damage which could be caused by abnormal combustion.
Despite the fact that no oil cooler was fitted, and no
indication of the maximum temperature of the oil has been
recorded, It has to be noted that Land Rover only fitted oil
coolers to vehicles operating in certain conditions and
territories. I am not aware of the vehicle having been used to
heavy towing. I consider that the engine has been run with a
lubricating oil which has carbonized at normal engine operating
temperatures and conditions. Further strong evidence of the
poor performance of the oil is shown with the dirty condition of
the interior of the engine. Given the frequency of oil changes
reported, it would be expected that the interior of the engine
would be spotlessly clean, as engine lubricating oil contains
detergents and dispersents which maintain combustion products
in suspension within the lubricant. Clearly, it has not been the
case with this engine.
The abnormal damage to the cylinder walls on the contact area
of the piston skirts is in my view the cause for the noise from
within the engine. The 4.8 uses high silicon alloy forged
pistons, which have quite short skirts. The piston to cylinder
clearance has increased by 0.002" on the worst cylinder, and
whist the piston top land has not been making contact with the
cylinder ( generally a prime cause of piston slap noise ) the
piston skirt will have had more clearance than expected and
required. The reversal of piston skirt loading at end of stroke
will generate rythmic engine noise varying with load and speed.
I cannot attribute the damage to a typical dirt ingress
problem, as no damage is present other than on the skirt contact
areas. Dirt entering the engine through intake would be
expected to leave damage predominately above the piston rings.
If dirt was built into an engine, for example during assembly,
damage would be predominately below the rings. Furthermore, it
would be expected that contamination which is sufficiently hard
to cause a scoring type damage would embed in the softer
aluminium piston. It would also, regardless of source be more
generally spread around the cylinder. No embedment of material
is present. I attribute the damage as wear caused by a
lubrication break down on the loaded thrust face of the piston
and cylinder.
Crankshaft and bearings. The extent of the damage found has not
resulted in clearances opening up to the degree which would I
believe would cause excessive noise which could be identified
as an individual knocking or similar sound, but could possibly
result in the symptoms to be expected within a higher mileage
engine, ie typically a slight reduction in hot oil pressure,
and a more general increase in engine noise. Its not possible to
see any identifiable foreign bodies present within the Babbitt
overlay, the damage being I believe to be generated from within
the bearings themselves.
Thank you Pumaracing.....this is exactly why I love Pistonheads!! This gives me a bit more ammo hopefully. My knowledge of engines falls away rapidly when you start talking about the internals but I know when something doesn't sound right!!
Is there any reason why the short skirt pistons were used or could something with a longer skirt have been used without any effect to something else inside the engine.
Cheers
Combustable
Is there any reason why the short skirt pistons were used or could something with a longer skirt have been used without any effect to something else inside the engine.
Cheers
Combustable
The only photos I was sent of the pistons are slightly out of focus....so useless. Still waiting for photos of the bores.
Engine has a Mark Adams ECU so I would hope fuelling was better than standard!!
Running was Cam Breaking a 2000rpm for 10mins then driven with Auto box in Sport mode.......running through the rev range and good use of engine breaking as stipulated in builders running in instructions
Engine has a Mark Adams ECU so I would hope fuelling was better than standard!!
Running was Cam Breaking a 2000rpm for 10mins then driven with Auto box in Sport mode.......running through the rev range and good use of engine breaking as stipulated in builders running in instructions
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