Not quite a murder mystery but one for you detectives out there to ponder.
Long Story Short
325 auto to 330 manual conversion, full donor engine rebuild, block and head machined, standard head gasket, new gaskets throughout, all Elring brand, new flywheel bolts with sealant pre-applied, new rear main seal with high-temp sealant on the bigger two bolts and the rear gallery plug, seated all the way in (learning from 50sKid's oil leak saga).
![Automotive tire Hood Motor vehicle Automotive design Automotive air manifold]()
Process
Engine reinstalled, everything hooked up under the hood, coding done. Removed main relay and fuel pump fuse to prime the engine and build up oil pressure, cranked for about 15 seconds. Reinstalled relay and fuse.
First start - purely to check if she'll fire up, ran for about 10 seconds.
Second start - reinstalled the exhaust, ran for 1.5 to 2 minutes to bleed the power steering and check the gearbox was engaging. Also finished bleeding the cooling system. At this point there may have been some air pockets left still, mistakenly thought the engine needed to be running to bleed it fully. Finished hooking everything up, dropped the car down, torqued wheel nuts - ready for its first drive.
Third start - did a quick run around the block, all of 3km. Engine felt great, lifter tick as to be expected, maximum 2.5k RPM, got up to temperature. Returned to driveway only to find a trail of oil all along the road and a steady drip from between engine and gearbox as can be seen at the end of the video.
That's about as far as I got with it. Ideally at that point I needed to go for a longer drive to start bedding in the piston rings but did not feel secure enough to do that with the magnitude of the leak.
Investigation
Initially suspected I must have messed up when installing the rear main seal. Dropped the gearbox to find the seal bone dry. Now struggling to pin down what could be causing such a significant leak. Engine is fully cleaned and the oil is still new and virtually transparent, which doesn't help in trying to diagnose the culprit.
![Automotive tire Motor vehicle Rim Automotive design Automotive wheel system]()
![Automotive tire Hood Motor vehicle Automotive design Alloy wheel]()
![Automotive tire Motor vehicle Automotive lighting Automotive design Automotive exterior]()
![Wheel Tire Automotive tire Tread Train]()
Oil seems to be running down the intake side of the engine, along the left side oil pan bolt and into the bell housing. No signs of leaks on the exhaust side.
Inspecting the backing plate, there is a wet patch right above the starter area (the most puzzling one) and one below it.
![Bicycle part Grey Bicycle drivetrain part Wood Font]()
![Bicycle part Rim Bicycle drivetrain part Auto part Composite material]()
Main Suspect - Crank Position Sensor
The only obvious leak looks to be the crank position sensor. There is a puddle right under it (the engine had been tilted back and forth and I have been feeling around that area which is why the puddle doesn't appear as big anymore in the photos) so it is possible the oil is pooling up there, running down along the backing plate, onto the oil pan bolt and into the bell housing, although I have serious doubts whether this alone would cause a strong enough leak to be producing such a steady stream. Also suspect it would have made a much bigger mess along the side of the engine if that were the main source.
![Outerwear Sleeve Textile Grey Collar]()
![Outerwear Silver Sleeve Textile Grey]()
The sensor is a brand new VDO (OE) unit with a new O-ring. Looking at it, the design is not great and I feel it would benefit from being held with two bolts, one either side of the opening instead of the one but it is what it is.
Looking at the old engine block, the whole area is severely caked with oil so it does look like it is a very common failure point. Question is - how do I make it seal better? Another new O-ring with RTV sealant applied for good measure?
![Tire Automotive tire Motor vehicle Hood Automotive lighting]()
Again though, I doubt that this alone would produce such a steady stream of oil on its own. And even though it does look like it was quite a severe source of a leak on the old engine as well, it never left any marks on the driveway so it couldn't have been that significant, whereas here it left a whole pool in a matter of minutes. Whilst it is a definite leak, I doubt it is the only one.
Other Suspects
Wondering if it could be the oil pan gasket as well in that one corner? I did install it with the engine up on a stand, all evenly seated, sealant applied on the join between the block and the rear main seal housing, all bolts torqued to 10Nm. One thing I'm wondering about is whether the longer bolts had a different torque spec? The manual only specified by grade and all 4 longer ones were still 8.8 grade bolts, just like all the shorter ones. Weird that a new gasket would start leaking straight away regardless.
Only other minor concern is the gallery plug. I did take it out and cleaned it thoroughly of the remnants of the old sealant and applied white high-temp sealant, then seated it all the way in. I find it odd that originally, the plug sat almost flush with the surface of the block and thus would not have been threaded all the way in from factory so not sure if driving all the way to the end is the right thing to do? Then again, leaving it half way in and hoping the sealant to do all the work is a bit sketchy too. The area around it was slightly damp to the touch but again, I doubt that this alone would cause such a significant leak.
![Automotive tire Wheel Tire Rim Bicycle part]()
Mystery Leak
The biggest question remains the botch of oil on the backing plate above the starter. Cannot figure out what might have caused that. Looking and feeling around the engine, there doesn't look to be an obvious cause for it. There is no signs of leaks along the side of the engine further up from the crank sensor, nor does it look to be coming from the valve cover or between the block and head. The gallery plug also sits below that spot so really struggling to figure that out.
![Automotive fuel system Motor vehicle Automotive tire Auto part Automotive design]()
![Jeans Tire Automotive tire Motor vehicle Hood]()
Other Considerations
I really wasn't happy with the job the machine shop did. Other grievances aside, in the specific area of the leak, they left a few scuffs and chipped edges. As a remedy, I used a fine file to get rid of the high spots and made sure to apply a decent amount of sealant in the area. Whether that was enough or not, I cannot be 100% sure. The gasket also sits inside where the biggest chips were so should have sealed before getting that far. I also used 400-grit sandpaper to get rid of the remnants of the old gasket.
![Automotive tire Rim Auto part Automotive design Motor vehicle]()
![Wood Gas Auto part Bumper Metal]()
The oil pan that came with the donor engine also looks a bit scuffed up along the bottom so the previous owner must have bottomed out on something somewhere along the line. Pretty weird as the car did have the aluminium reinforcement plate installed when I got it so no idea how it could have picked up this sort of damage.
![Automotive tire Hood Automotive lighting Vehicle Motor vehicle]()
Best Course of Action?
Really struggling to settle on the best course of action. The maximalist approach would be to get the engine out again, clean up the pan from the old engine and seat that on with a new oil pan gasket, new rear main seal housing with the seal pre-installed, new gallery plug with sealant pre-applied, new O-ring on the crank position sensor with a dab of RTV, new flywheel bolts with sealant pre-applied and go again. Basically throwing a bunch more money and effort at it.
Any thoughts and suggestions very much appreciated. I know it's quite a long post with probably more information than necessary but really thought I'd lay it all out there as I'm starting to veer into sheer desperation with this thing. After putting more than a year's worth of weekends and vacation time into this project, I was really hoping to have the car up and running again and this oil leak came as a real kick in the balls. Just want to make sure I get it right before putting everything back together. Not sure what mental state I'd find myself in if the issue were to persist and I'd have to tear it apart once again.
Thanks team
Long Story Short
325 auto to 330 manual conversion, full donor engine rebuild, block and head machined, standard head gasket, new gaskets throughout, all Elring brand, new flywheel bolts with sealant pre-applied, new rear main seal with high-temp sealant on the bigger two bolts and the rear gallery plug, seated all the way in (learning from 50sKid's oil leak saga).
Process
Engine reinstalled, everything hooked up under the hood, coding done. Removed main relay and fuel pump fuse to prime the engine and build up oil pressure, cranked for about 15 seconds. Reinstalled relay and fuse.
First start - purely to check if she'll fire up, ran for about 10 seconds.
Second start - reinstalled the exhaust, ran for 1.5 to 2 minutes to bleed the power steering and check the gearbox was engaging. Also finished bleeding the cooling system. At this point there may have been some air pockets left still, mistakenly thought the engine needed to be running to bleed it fully. Finished hooking everything up, dropped the car down, torqued wheel nuts - ready for its first drive.
Third start - did a quick run around the block, all of 3km. Engine felt great, lifter tick as to be expected, maximum 2.5k RPM, got up to temperature. Returned to driveway only to find a trail of oil all along the road and a steady drip from between engine and gearbox as can be seen at the end of the video.
That's about as far as I got with it. Ideally at that point I needed to go for a longer drive to start bedding in the piston rings but did not feel secure enough to do that with the magnitude of the leak.
Investigation
Initially suspected I must have messed up when installing the rear main seal. Dropped the gearbox to find the seal bone dry. Now struggling to pin down what could be causing such a significant leak. Engine is fully cleaned and the oil is still new and virtually transparent, which doesn't help in trying to diagnose the culprit.
Oil seems to be running down the intake side of the engine, along the left side oil pan bolt and into the bell housing. No signs of leaks on the exhaust side.
Inspecting the backing plate, there is a wet patch right above the starter area (the most puzzling one) and one below it.
Main Suspect - Crank Position Sensor
The only obvious leak looks to be the crank position sensor. There is a puddle right under it (the engine had been tilted back and forth and I have been feeling around that area which is why the puddle doesn't appear as big anymore in the photos) so it is possible the oil is pooling up there, running down along the backing plate, onto the oil pan bolt and into the bell housing, although I have serious doubts whether this alone would cause a strong enough leak to be producing such a steady stream. Also suspect it would have made a much bigger mess along the side of the engine if that were the main source.
The sensor is a brand new VDO (OE) unit with a new O-ring. Looking at it, the design is not great and I feel it would benefit from being held with two bolts, one either side of the opening instead of the one but it is what it is.
Looking at the old engine block, the whole area is severely caked with oil so it does look like it is a very common failure point. Question is - how do I make it seal better? Another new O-ring with RTV sealant applied for good measure?
Again though, I doubt that this alone would produce such a steady stream of oil on its own. And even though it does look like it was quite a severe source of a leak on the old engine as well, it never left any marks on the driveway so it couldn't have been that significant, whereas here it left a whole pool in a matter of minutes. Whilst it is a definite leak, I doubt it is the only one.
Other Suspects
Wondering if it could be the oil pan gasket as well in that one corner? I did install it with the engine up on a stand, all evenly seated, sealant applied on the join between the block and the rear main seal housing, all bolts torqued to 10Nm. One thing I'm wondering about is whether the longer bolts had a different torque spec? The manual only specified by grade and all 4 longer ones were still 8.8 grade bolts, just like all the shorter ones. Weird that a new gasket would start leaking straight away regardless.
Only other minor concern is the gallery plug. I did take it out and cleaned it thoroughly of the remnants of the old sealant and applied white high-temp sealant, then seated it all the way in. I find it odd that originally, the plug sat almost flush with the surface of the block and thus would not have been threaded all the way in from factory so not sure if driving all the way to the end is the right thing to do? Then again, leaving it half way in and hoping the sealant to do all the work is a bit sketchy too. The area around it was slightly damp to the touch but again, I doubt that this alone would cause such a significant leak.
Mystery Leak
The biggest question remains the botch of oil on the backing plate above the starter. Cannot figure out what might have caused that. Looking and feeling around the engine, there doesn't look to be an obvious cause for it. There is no signs of leaks along the side of the engine further up from the crank sensor, nor does it look to be coming from the valve cover or between the block and head. The gallery plug also sits below that spot so really struggling to figure that out.
Other Considerations
I really wasn't happy with the job the machine shop did. Other grievances aside, in the specific area of the leak, they left a few scuffs and chipped edges. As a remedy, I used a fine file to get rid of the high spots and made sure to apply a decent amount of sealant in the area. Whether that was enough or not, I cannot be 100% sure. The gasket also sits inside where the biggest chips were so should have sealed before getting that far. I also used 400-grit sandpaper to get rid of the remnants of the old gasket.
The oil pan that came with the donor engine also looks a bit scuffed up along the bottom so the previous owner must have bottomed out on something somewhere along the line. Pretty weird as the car did have the aluminium reinforcement plate installed when I got it so no idea how it could have picked up this sort of damage.
Best Course of Action?
Really struggling to settle on the best course of action. The maximalist approach would be to get the engine out again, clean up the pan from the old engine and seat that on with a new oil pan gasket, new rear main seal housing with the seal pre-installed, new gallery plug with sealant pre-applied, new O-ring on the crank position sensor with a dab of RTV, new flywheel bolts with sealant pre-applied and go again. Basically throwing a bunch more money and effort at it.
Any thoughts and suggestions very much appreciated. I know it's quite a long post with probably more information than necessary but really thought I'd lay it all out there as I'm starting to veer into sheer desperation with this thing. After putting more than a year's worth of weekends and vacation time into this project, I was really hoping to have the car up and running again and this oil leak came as a real kick in the balls. Just want to make sure I get it right before putting everything back together. Not sure what mental state I'd find myself in if the issue were to persist and I'd have to tear it apart once again.
Thanks team
