Just had to have my new engine that Aelred rebuilt with new pistons and rebored.
After running my new engine in for 1000 miles. It went to be mapped at MRC.
I bought it from Alex aka S2Pearl last year which Aelred Smith had built for him. Engine spec hereThis is the engine I bought
As soon as MRC put the engine on boost at lot of oil came out of the exhaust. The engine was inspected by an engineer and the bore clearance was found to be twice the recommended size. The honing marks are still clearly visible on the bores and the pistons show now wear.
Here's the engineers report:
Customer: MRC Tuning
Product: S2 Inline 5 20v Engine
Service: Engineers Report
To whom it concerns,
Overview
Customer complained of smoking under load and idle along with heavy breathing from the engines breather system. Breather system is installed as recommended on a turbo engine featuring an inline baffled catch tank re-circulating into the intake pre turbo.
Engine was delivered for transport convenience as a short block and cylinder head.
Initial inspection
Close inspection of the deck surfaces confirms no indication of blown head gasket. No oil shown in the intake ports of the cylinder head, a couple of the exhaust ports where slightly wet with oil. Exhaust guides are in as new condition with regards to side play, whereas intake guides appear to be slightly tight. Due to the method of transport whether the oil in the exhaust ports is down to failed oil stem seals or seepage from other areas during transit is currently inconclusive until further strip down.
There is a visual score on bore number 5 (see attached pic) on the thrust side which can be felt by running your fingers across it, it is significant enough that one can catch their fingernail in it. Other than the score all honing marks on the bores as to be expected on a fresh engine so bore wear can be eliminated as a cause of the aforementioned symptoms.
Back and forth piston movement in the bores are significantly more than to be expected from a low mileage engine, further confirmed not only by the visual gap between the bore and the crown when the crank is midstroke but also by the ability to physically being able to part twist the piston in the bore at TDC.
There are small quantities of swarf present in the oil almost like bearing shavings found after bearing failure, the source of these is not apparent.
Short Block
Removal of rod and piston assembly number five shows heavy bearing wear on the outer edges of the big end bearings indicative of small end bearing wear from side to side movement of the rods (see attached pics) However further inspection shows that the small end bearings and wristpin are in as new condition with no signs of wear. There is also heavy scoring on big end bearing too however no damage on the crank journal or any of the mains, making it difficult to determine the source.
Minimal marking on the side skirts of the piston indicate it has covered no more than the claimed running in mileage of 800-1200miles. So they can be assumed to measure near enough identical to the day they were fitted.
Upon measuring of the JE piston side skirt as per manufacturers specifications it was found to measure 3.202” measured at 4-5degrees Celsius. Measuring the bore of cylinder number 5 it was found to measure 3.208” with less than + 0.0005” ovality measured at 4-5 degrees Celsius. Again a clear indication of neglible bore wear.
Manufacturer’s specification stipulates a 0.003-4” bore clearance on their standard range of pistons using the mathematical formulae on their instructions. Also according to JE literature the higher silicone content of the narrow side skirt pistons allows tighter wall clearances to be run where required to prevent piston instability issues from the narrow skirts.
Looking at the bore clearance measured of 0.006”, the only conclusion that can be drawn is that bore number 5 was bored to the bore size printed on the box/documents of 81.50mm (3.2086”) instead of measuring the piston and calculating clearance as per installation instructions.
This subsequently results in poor piston ring sealing due to the sideways instability of the piston within the bore during the duration of it’s stroke, visually confirmed by the unnatural big end bearing wear on the outer edges.
Looking at the piston ring design the type fitted are total seal rings with the top ring being the total seal ring. These are normally recommended for mild to moderate boost application; whereas a total seal second ring is more suited to a high boost application. As the engine was on a low boost running in map this can be eliminated as being the cause of any of the aforementioned issues.
Closer inspection of the top total seal ring led to the discovery that it’s total seal function is null and void as the total seal gaps where in perfect alignment instead of opposing as this is what creates the total seal.
Removal of the top ring and installation into the bore to check ring gaps showed irregular gapping going from narrow to wide which can only be done to poor workmanship/tooling for the application.
Subsequently piston and rod assembly number 4 was removed to find identical measurements/findings to that of number 5; Confirming that the faults found are down to incorrect machining/assembly instead of faulty product/components.
Pistons 1, 2 and 3 suffered from the same measurement flaws however the total seal rings where found to be correctly orientated. This possibly indicates that the rings in 4 and 5 may have spun round due to the excessive bore clearance. However this theory will have to remain inconclusive as no previous experience has been had of such a fault.
Cylinderhead
Lifters and cams all show good condition as does the rest of the valve train. Guides have been freshly fitted and show good valve stem to guide clearance at full lift on the exhaust. Intake guides feel slightly tight.
Strip down of the head confirms tight intake guides from mild scoring on the stems. Fortunately the low mileage has meant no long term wear implications. (see attached pics). Stemseals are all in good condition.
The seat face on the valves themselves show indication of poor refacing equipment/coupled with poor lapping in of the valves. The burn flashes shown on all valves indicate either a poor grinding wheel or worn thrust bearings on the valve refacer causing skipping marks on the surface (see attached pics) something that can be easily overcome by correctly lapping the valves in, so one can only assume that this process was never carried out correctly. Lastly the general burnt deposits around the combustion chamber are that of high concentrations of burnt oil again showing an issue with rings (see attached pics)
Conclusion
The nature of the heavy breathing/smoking of the inline 5 engine supplied can only be assigned to incorrect machining/assembly of components into the short block, not by wear and tear. As confirmed by the aforementioned findings. Although the head showed signs of poor workmanship the faults found within the cylinder head would not have contributed to smoking. The swarf that was found within the oil can not be attributed to any of the findings, due to it’s minimal quantity 3 small flat slithers it can only be assumed to be from a previous bearing failure prior to the engines current life, present purely due to poor cleaning of the engine prior to re assembly.
Legal Statement
All measurements and related findings in the above report are factual and correct to the best of my knowledge/ability. All conclusions from the findings are made without prejudice, nor do I hold any financial interest in the outcome from this report.
Sincerely,
Jean-Paul Schoonbrood
JNL Racing
VAG engine specialist to the trade
After running my new engine in for 1000 miles. It went to be mapped at MRC.
I bought it from Alex aka S2Pearl last year which Aelred Smith had built for him. Engine spec hereThis is the engine I bought
As soon as MRC put the engine on boost at lot of oil came out of the exhaust. The engine was inspected by an engineer and the bore clearance was found to be twice the recommended size. The honing marks are still clearly visible on the bores and the pistons show now wear.
Here's the engineers report:
Customer: MRC Tuning
Product: S2 Inline 5 20v Engine
Service: Engineers Report
To whom it concerns,
Overview
Customer complained of smoking under load and idle along with heavy breathing from the engines breather system. Breather system is installed as recommended on a turbo engine featuring an inline baffled catch tank re-circulating into the intake pre turbo.
Engine was delivered for transport convenience as a short block and cylinder head.
Initial inspection
Close inspection of the deck surfaces confirms no indication of blown head gasket. No oil shown in the intake ports of the cylinder head, a couple of the exhaust ports where slightly wet with oil. Exhaust guides are in as new condition with regards to side play, whereas intake guides appear to be slightly tight. Due to the method of transport whether the oil in the exhaust ports is down to failed oil stem seals or seepage from other areas during transit is currently inconclusive until further strip down.
There is a visual score on bore number 5 (see attached pic) on the thrust side which can be felt by running your fingers across it, it is significant enough that one can catch their fingernail in it. Other than the score all honing marks on the bores as to be expected on a fresh engine so bore wear can be eliminated as a cause of the aforementioned symptoms.
Back and forth piston movement in the bores are significantly more than to be expected from a low mileage engine, further confirmed not only by the visual gap between the bore and the crown when the crank is midstroke but also by the ability to physically being able to part twist the piston in the bore at TDC.
There are small quantities of swarf present in the oil almost like bearing shavings found after bearing failure, the source of these is not apparent.
Short Block
Removal of rod and piston assembly number five shows heavy bearing wear on the outer edges of the big end bearings indicative of small end bearing wear from side to side movement of the rods (see attached pics) However further inspection shows that the small end bearings and wristpin are in as new condition with no signs of wear. There is also heavy scoring on big end bearing too however no damage on the crank journal or any of the mains, making it difficult to determine the source.
Minimal marking on the side skirts of the piston indicate it has covered no more than the claimed running in mileage of 800-1200miles. So they can be assumed to measure near enough identical to the day they were fitted.
Upon measuring of the JE piston side skirt as per manufacturers specifications it was found to measure 3.202” measured at 4-5degrees Celsius. Measuring the bore of cylinder number 5 it was found to measure 3.208” with less than + 0.0005” ovality measured at 4-5 degrees Celsius. Again a clear indication of neglible bore wear.
Manufacturer’s specification stipulates a 0.003-4” bore clearance on their standard range of pistons using the mathematical formulae on their instructions. Also according to JE literature the higher silicone content of the narrow side skirt pistons allows tighter wall clearances to be run where required to prevent piston instability issues from the narrow skirts.
Looking at the bore clearance measured of 0.006”, the only conclusion that can be drawn is that bore number 5 was bored to the bore size printed on the box/documents of 81.50mm (3.2086”) instead of measuring the piston and calculating clearance as per installation instructions.
This subsequently results in poor piston ring sealing due to the sideways instability of the piston within the bore during the duration of it’s stroke, visually confirmed by the unnatural big end bearing wear on the outer edges.
Looking at the piston ring design the type fitted are total seal rings with the top ring being the total seal ring. These are normally recommended for mild to moderate boost application; whereas a total seal second ring is more suited to a high boost application. As the engine was on a low boost running in map this can be eliminated as being the cause of any of the aforementioned issues.
Closer inspection of the top total seal ring led to the discovery that it’s total seal function is null and void as the total seal gaps where in perfect alignment instead of opposing as this is what creates the total seal.
Removal of the top ring and installation into the bore to check ring gaps showed irregular gapping going from narrow to wide which can only be done to poor workmanship/tooling for the application.
Subsequently piston and rod assembly number 4 was removed to find identical measurements/findings to that of number 5; Confirming that the faults found are down to incorrect machining/assembly instead of faulty product/components.
Pistons 1, 2 and 3 suffered from the same measurement flaws however the total seal rings where found to be correctly orientated. This possibly indicates that the rings in 4 and 5 may have spun round due to the excessive bore clearance. However this theory will have to remain inconclusive as no previous experience has been had of such a fault.
Cylinderhead
Lifters and cams all show good condition as does the rest of the valve train. Guides have been freshly fitted and show good valve stem to guide clearance at full lift on the exhaust. Intake guides feel slightly tight.
Strip down of the head confirms tight intake guides from mild scoring on the stems. Fortunately the low mileage has meant no long term wear implications. (see attached pics). Stemseals are all in good condition.
The seat face on the valves themselves show indication of poor refacing equipment/coupled with poor lapping in of the valves. The burn flashes shown on all valves indicate either a poor grinding wheel or worn thrust bearings on the valve refacer causing skipping marks on the surface (see attached pics) something that can be easily overcome by correctly lapping the valves in, so one can only assume that this process was never carried out correctly. Lastly the general burnt deposits around the combustion chamber are that of high concentrations of burnt oil again showing an issue with rings (see attached pics)
Conclusion
The nature of the heavy breathing/smoking of the inline 5 engine supplied can only be assigned to incorrect machining/assembly of components into the short block, not by wear and tear. As confirmed by the aforementioned findings. Although the head showed signs of poor workmanship the faults found within the cylinder head would not have contributed to smoking. The swarf that was found within the oil can not be attributed to any of the findings, due to it’s minimal quantity 3 small flat slithers it can only be assumed to be from a previous bearing failure prior to the engines current life, present purely due to poor cleaning of the engine prior to re assembly.
Legal Statement
All measurements and related findings in the above report are factual and correct to the best of my knowledge/ability. All conclusions from the findings are made without prejudice, nor do I hold any financial interest in the outcome from this report.
Sincerely,
Jean-Paul Schoonbrood
JNL Racing
VAG engine specialist to the trade
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