’03 BMW E46 M3
This E46 M3 was bought as in the south of France towards the end of 2017. The previous owner owned the car for over 14 years and decided to let the car go once the engine started to make a “knocking noise”. According to the dealership were it was maintained, a issue with the VANOS. That would would turn out rather different…
But, first things first: The collection. The M3 was bought unseen with only the option list, mileage and the service history. Collection was arranged, and the first photo’s arrived:
Just before collection on the truck:
Fast forward to when the M3 arrived in our workshop. First thing we noticed: The car was incredibly dirty! Everly part of the car (inside included) was cover in a layer of fine sand. A good example is the engine bay, which was impressively dirty:
Offcourse we began with a proper cleaning, followed by polish the car to regain the gloss the M3 deserves. We always like to clean the car before we start, as it gives helps you to work neath and clean as well as it is a good way to do a proper inspection before you start working on the car.
The car has some dings en dents, but has no rust what so ever. Perfect for it’s purpose.
Next step was to check the engine for damage. No need to start the engine with out at least inspecting the VANOS, as it was diagnosed by the BMW dealer. We did not found any obvious issue with the Vanos components, but since we had everthing open we did a full rebuild. At the end of the day we started the S54 for the first time. Within 30 seconds it was clear: Rod Knock.
Next step was to inspect the compression: low on 4 of the 6 cylinders. We knew enough, time to pull and rebuild the engine!
A advantage of pulling the engine is that we are able to remove over 14 years of dirt and replace all hose and lines which are normally hard to access.
With the disassembly of the engine, we quickly found the compression issue. The headgasket had failed on 3 places, but mainly between Cylinder 1-2.
Whether detonation (for instance due to a bad injector) caused the head gasket to fail, or wether the failed headgasket caused the detonation is uncertain, but the detonation did cause service damage to the cylinder head. The cylinderhead was cracked between cylinder 1 and 2.
The conrod bearings were beyond worn. Expected is that these were never changed, although it’s a well-known maintenance point! I had the crank machined and ordered +0.25 bearings.
The crankcase is in good condition. Of course we had it chemically cleaned and honed to be able to use new piston rings. Also, we had it machined on top, to eliminate the markings caused by the detonation between cylinder 1 and 2.
Next up, the cleaning and inspection of all the subcomponents. The larger parts when in the parts washer:
All the smaller parts went in the ultrasonic bath. An example:
The oilpump is special point of attention for obvious reasons. Beside the inspection, it is very rewarding to make the pump like new again;
The ITB’s were completely disabled and repolished. Quite a difference;
The valves went through several cleanings and ultrasonic baths, before being finished on the lathe.
Before we can start the reassembly, we’ve checked the diameter, roundness and taper of the cylinders and compared with the with BMW specification. All within spec, so we can proceed.
To be able to install the piston without the possibility of damaging the piston rings, we made our own tool. The slowly compresses the piston rings while the piston is pressed downwards. Since the tool is exactly the correct size for the engine and made from POM, the possibility of damaging the piston or piston rings is almost zero.
We’ve measured the conrods to be sure the diameter and roundness is still within specification. All 6 conrods are well within spec.
While we’re at it, worth check the weight of the conrods. Normally when selecting new conrods, they should also be checked if the balance (top/bottom) weight is within certain tolerance, however since these came out of a engine a set, the overall weight gave us enough confirmation.
After a good cleaning, the conrods are ready to be installed.
Next step was the cleaning and inspection of the pistons. We’ve found a micro-fracture in one of the pistons, which gives you the importance of cleaning and inspecting. Offcourse the piston rings are discarded and replace with new ones.
Meanwhile, we finished all 24 valves.
The oil jets are cleaned and tested as well.
eer wat progressie kunnen maken met de S54.
Time to start the assembly.
We begin with installing the crankshaft.
With the crank installed, we could start “gapping” the piston rings. A time consuming job, but important to get right.
Before we can install the pistons, we have to connect them to the conrods. As it is a bit tricky to installed the piston circlips, we made a special tool.
Finally time to install the pistons in the engine, off course with the TEG-made tool.
Pressing down the pistons into the engine block by hand gives a lot of satisfaction!
This S54 uses the newer type conrods, so I could use new bolts. We torqued the bolts 3 times, to make sure the bolt reach there ultimate tensile strength. With the conrods connected to the crank, it starts to like like a engine again!
The oil pump installed.
We moved over the otherside of the engine: The cylinderhead. The valves and valve seats are machined and tested on vacuum to make sure they seal as should again.
Before we can installed the cylinder head, we first installed the timing chain with new chain guides and O-rings.
To install the timing cover properly, you require a special BMW tool. Off course we made our own TEG version. Part 1 of the our tool:
…And part 2, to make sure the sealring is on the right position.
Then, finally time to mount the cylinderhead!
Next up is mounting the camshafts. BMW recommends a special tool for this, but in reality it is not required as long as you know what you are doing. If not, you risk damaging or even breaking the camshaft. The hubs are mounted, with the upgraded torx hub bolts.
The VANOS unit was polished. Normally we are not a huge fan of polished metal under the hood, but a polished S54 unit looks real good together with the S54 engine cover. Besides that, a standard unmodified Vanos unit does not have the greatest surface finish.
With installing the Vanos unit, you also set the timing. It is important to have the VANOS control unit set all the way to “0”. When installed, the engine is turned a few rotation, timing check again, spot on!
Next step is installing all engine components. Off course all parts are cleaned, checked and checked again. This also a good moment to set the valve clearance.
The ITB’s installed as well. Looks the part!
The ITB’s were completely taken apart, so had to be re-set again. You set the each throttle valve compared to valve #1 by sliding the linkage over the axle, to let it open earlier or later.
The next step is were we differ from the BMW procedure.
BMW (Tis) Procedure:
BMW describes to press the linkage all the way “closed” and then tighten the bolt to lock the linkage in position. With pressing the linkage down, all the play is eliminated. Doing this for each TB, should results in a similar opening point for each TB.
The problem with this that not all the linkages have exactly the same amount of play, which results directly in a different point of opening of the valve.
Our procedure is to measure the point of opening directly, which is what you are after. For this we designed and fabricated our own tool.
The design is 3D printed in PLA and test fitted:
A second tool is printed and they are mounted. The step on the tool helps setting the tool perfectly straight compared to each other:
Then, the throttle axle is rotated slightly (as the servo motor would when you operated the throttle paddle) and the opening is measured and compared.Before:
This procedure is repeated until all valves open at the same time compared to valve #1. We managed to set all TB’s within 0,1mm.
Next steps are straigth forward, all remaining components are being mounted. The last step is to install the wiring loom.
Engine ready to be installed.
While to engine was out, it was a good moment to investigate to play in on the steering wheel. The steering rack was faulty, so a good moment to replace.
The flexible joint was replace as well. A point of attention for these cars now that there getting older, it often makes a significant difference.
The car came with a brand new clutch and flywheel, so not need to replace these. It is a good moment however to change all heater lines and vacuum lines.
The installation of the engine is straight forward. The dramatic difference between before and after:
The M3 ready!