e90 320 N46 Engine Rebuild

[DarrylvanNiekerk]

Hi Guys, apologies for the long post.

I have decided to go down a path I was advised not to but circumstances are such that I cannot avoid it. Due to financial constraints and the fact that my car is generally in good condition, I have chosen to go ahead with an engine rebuild.

Far too many people have advised to bin the car because it is not worth rebuilding a 320, I have been told they are rubbish and I should rather upgrade, even that I should just buy a second hand motor and be done with it. After sitting for a number of months mulling over my options I came to the conclusion that I don't have the money to buy a new car, if I sell my car in its current state I would get nothing for it and a second hand motor comes with its own potential pitfalls. Besides, I have a lot of spare time on my hands due to the current climate.

So essentially I climbed in boots and all and embarked on a full rebuild and refresh so I can get back the car I really enjoyed driving. It is a 2006 320i with sports pack and on a good day was such a pleasure to drive. A few years ago the gremlins started with an intermittent misfire, just a single hesitation. We could not pin it down and eventually this grew into a complete cluster mess which ended with a burned exhaust valve and a broken piston which scored the cylinder wall.

I have spent hours on the internet, watching Youtube, reading forums, to try and figure out how to deal with the situation but not only were there so many conflicting views but there was a distinct paucity of information on 4 cylinder engines. Almost everything is available on 6 cylinders, I suppose because either the 4 cylinder guys are advised to walk away or the only people posting on these sorts of repairs are the 6 cylinder guys.

I tried to extrapolate from the videos how the 4 cylinder would be similar but alas there are some very distinct differences and I have ended up learning as I go along. It was really scary in the beginning because it felt as if I was in uncharted territory but I have gained a lot more confidence as I have gone along and started stripping pretty much anything I can to see if it needs a refresh or replacement.

The reason for this very long winded post is partly to document my travels but also to make this space available for those who have issues with their 2 litre engines who cannot get their questions answered. I am by no means an expert, this is not my field and I haven't done anything mechanically minded on a car for near on 20 years. But, I have learned so much and figured out how simple most things are if you take your time and are practical about it.

Where I am right now is as follows:

The car finally gave up the ghost almost a year ago and I limped into a garage in Alberton in the hopes they would be able to get me back on the road to get home. No such luck. I left the car there for diagnosis and got a ride home. They called me in and showed me the damaged piston and cylinder wall and advised on a replacement engine as the cost for repair would be too high. If I had a mechanic do the job the costs would be astronomical.

The engine had been partially stripped already so I had the car towed to my house and parked it in the garage for almost 8 months. I finally unpacked all the parts from the boot and tried to piece together what everything was. I spent may hours bending into the engine bay looking at how everything was held together and how it might come apart and in the end bit the bullet and stripped the entire front end to get access. I am very glad I did this as each step of the way I could properly see what I was doing and avoid stripping bolts or screws.

Instead of trying to get the engine out on its own, the bolts that join the gearbox to the engine are almost impossible to reach, I decided to take the gearbox out with the engine. This meant I had to remove the exhaust and heat shield, decouple the drive shaft and gear linkage and then hoist the engine out. It was all surprisingly easy to do. I did mark the position of drive shaft to gearbox flange to avoid a mismatch and imbalance or shudder when reassembled.

The other reason I am glad I went this route is as I was stripping things I could see where maintenance had been lax, corners cut, and how oil had gotten into almost everything. It was also at this stage I realised some of the main differences between the 4 and 6 cylinder engines, apart from the obvious. There has been much discussion about failing DISA Flaps and for the life of me I could not find mine. That is because the 4 cylinder does not have any -the closest it comes is swirl flaps in the inlet manifold. Another thing I came across were the oil non return valves in the block which keep oil up near the head for quick lubrication on start up. These are a service item, BMW don't even have them on their system any more, and with a 6 cylinder you can access them with the engine in the car from the wheel well. Sadly with the 4 cylinder they are only accessible with the head separated from the block.

I have since found that my engine mounts are worn, the gearbox mount bushes have sheared, brake hoses need replacing, clutch and flywheel is gone and so much more. Because the engine hds been moving with the worn mounts something was rubbing on the brake lines and these are very nearly worn through in a few places, this could definitely ended in disaster.

The route I have chosen to go is to have the block bored and resleaved, although only one cylinder is damaged and the rest are good replacing only one could cause the cylinder next to it to become oval. I had the option of a used N42 block with pistons but there were subtle differences and the cost of redoing the block is actually not that much. 3 of my pistons are good, they aren't that worn, so I need to get a 4th piston to match.

The head is in decent condition but the exhaust valve stem guides are worn and need replacing. A new gasket set will give new valve stem seals and when the engineering company do the head they will put it all back together again for me. I did have the unfortunate joy of having the cable tie which held the VANOS unit together snap and had to figure out how to put the inlet unit with finger followers back together again.

I have spent ages trying to find who sells what for the car and getting prices together for everything so I know what the final damage is going to be. I have decided to go for a single mass flywheel & clutch replacement because it is not only around half the price but will be a few kilos lighter. There is apparently additional vibration introduced with this but I am not against feeling the car a bit more. Brake hoses from BMW are well over R3k so it will be cheaper to put in braided steel hoses as they are cheaper, last longer and will give better brake pedal feel.

Luckily most of the peripheral parts are in good condition and mostly only need a bit of a clean and new gaskets. My biggest concern was the oil pump as they are no longer made and are apparently very prone to failure. I took my time stripping this and found that luckily there has been no damage from stray engine bits and with a proper clean and rebuild will be fine.

I am happy to add to this as I go along and post pictures if requested. At the end of it I want to attend to a few cosmetic issues with the paint, have the high wear items in the interior such as gearknob, stearing wheel and seat bolsters attended to and I will have an almost brand new car.

So far my expected cost is around R40k all told.

 

[ibs.patel]

I wish you all the best of luck buddy! You are brave and that is worthy of respect. Looking forward to journey to your brand new car

 

[DarrylvanNiekerk]

I wish you all the best of luck buddy! You are brave and that is worthy of respect. Looking forward to journey to your brand new car

Thank you very much for that, some of my best drives have been in this car.

 

[jet li]

Ofcourse its long to read and interesting at the same time. Good luck on your build broer. I will be following this thread.

 

[Dbn540i]

You are brave man especially with all the odds stacked against you with a troublesome car. I have owned one previously and got rid of it quickly. We are living in different times and you have to do what is best. All the luck and may everything work in your favour.

 

[DarrylvanNiekerk]

So, here is the first update on the project:

I got the block back from engineering today, the new sleeves have been fitted.



I have been doing a little (read a lot) of research on the joining together of the block and bed plate and what product to use. At BMW they advised me the Locite primer (green liquid - 4ml) and fluid cost around R 1300. What you do is paint the primer on the top of the bed plate into the machined grooves before bolting the two pieces together and torqueing the whole setup. Thereafter you hammer in the two injector nozzles and inject the Loctite until it comes out at the crank seals and then paint some more primer where the fluid comes out.

It seems both the Loctite (128357) and primer (171000) were developed for BMW exclusively so robots could build the engines. I tried to find better prices from other stockists or even from overseas but the price of the stuff is exorbitant wherever you get it from. I tried to find alternate products but there just is no information on this wherever I look. On top of the primer and Loctite injector you should also purchase the Loctite Injector Tool which allows for steady injection of the product further adding to the cost.

BMW have since amended their processes and use a product called RTV (Room Temperature Vulcanising silicon) or alternatively Loctite 5188 or 5910, which are also ludicrously expensive. These products have more flex in them and cure in the absence of oxygen and are also not broken down by oil.

As to which is the better route to go I still have no idea as there are differing opinions, also the original Loctite products have been mostly discontinued and replaced with newer products.

Here I was worried about various part prices but the most intricate and seemingly expensive part is joining the block and bed plate together.

 

[DarrylvanNiekerk]

I haven't had much time to work on the car for the last while but did manage to make some headway with the recent public holidays. After inspecting the non return valves and adjoining oil galleries I realised I was going to have to do a lot of deeper cleaning in order to get a lot of crud out of the way. I could see thick, dark oil with lumps in some very hard to reach places so went out and bought a few items to help with the task at hand:



With a can of trusty WD40 and its spray nozzle I got to work on getting rid of every last bit of dirt I could find. I would spray WD40, work the galleries, bolt threads and surrounding areas with a variety of brushes and then spray everything out with the air gun. After spraying a little WD40 into the non return valves and giving them a scrub and solid tap every now and then I managed to get them working pretty well again. They were very clogged up and would definitely have contributed to a lazy valvetronic system.

The design on the non return valves for the 320 is very different to the 6 cylinder variants as mentioned before, but basically they are a little cylinder with a spring and ball bearing that get opened by oil pressing against it and allowing this to flow. When the oil pressure stops the spring pushes the bearing down and stops reverse flow:



The design is very similar to the oil spray nozzles in the engine block below the pistons:

 

[///M Individual]

Awesome progress thus far and well done on taking on this task.

 

[Bmwed]

You are right such a looooooooooooooooooong read, LOL i was at the very same point as you and i managed to find a brand new motor with 0km's. Best buy i have ever made. I am 20000km int the new motor and servicing every 10000km as a standard. when I did the new motor n redid the whole cooling system just for incase and yesterday my fuel pump packed up. Just go back from bmw with a new pump so that is me tonight.. People can say what they want about the 320i's but i am happy with mine. I have been the only owner ever and i have looked after it. and bonus i don't owe a cent. good luck with your rebuild.

 

[evnmopwr]

Subscribed!!!
Love threads like this.

All the best on this venture

 

[trevor_e36m]

Many years I went the same route on my honda civic 150i, car had a rod knock, gave it to a mechanic who didn't know what he was doing, rod knock returned after a few km. Took matters into my own hands, scoured the internet, bought a torque wrench, trolley jack , rings , bearings , feeler gauges , valve spring compressors , valve stem seals.Tackled it in my mothers garage .Ran like a champ afterwards , very rewarding

 

[Nick]

If you ever feel alone and sad, plz refer to this thread.

https://www.bmwfanatics.co.za/threads/the-official-e90-320i-owners-consolation-thread.76665/

 

[Bmwed]

How's the build going?

 

[DarrylvanNiekerk]

Hi there,

Apologies for the lack of info, I ran into a bit of a family medical emergency that swallowed a whole lot of time and resources so a lot of things got put on the back burner.

The only thing I have managed to get done in the last few months is have my injectors tested and cleaned, the car is gathering dust and is looking very sad indeed.

I suppose this part of the journey in itself is quite interesting because I was informed the whole engine demise was most likely caused by injector failure. I looked up on the interwebs how I could test if an injector was bad and couldn't really find any kind of definitive test. They all talk about connecting a specific power source and listening for a click and all that jazz but to properly test an injector and its fuel delivery needs some really complex and expensive machinery. The general consensus was also that injectors rarely fail.

I tried to find out the cost of replacements and phoned a Bosch supplier who promptly asked for a code, I thought you could just get one for an N46 320 and be done. I checked my injectors whilst on the phone and saw that mine are Siemens injectors and so the salesman told me there could potentially be issues with replacing the injectors with Bosch ones and suggested I find a Siemens supplier. Easier said than done.

Eventually I got hold of BMW spares and asked them for a cost (over R4k each mind you) and then asked them if they could let me know whether they were supplied by Bosch or Siemens and if they had an actual product code. All we could ascertain was that they are black in colour and not green, in other words Siemens.

I tried to find a company that could test my injectors and could only find companies that test Diesel injectors. I was directed to Bosch repair services who said they could test them at R 500 each and then service them if there was a fault which could cost R2k each. All in all not a huge amount less than replacement. I finally got directed to a company called Rodac Diesel and spoke to a guy called Paul who said he could help out, not a very talkative guy but extremely helpful. I threw caution to the wind and went past and dropped the injectors off in Honeydew and then waited.

Long story short it took about three weeks before my injectors were ready. They were badly clogged with carbon, the spray patterns were all over the place and one of them wasn't closing properly and leaking - no wonder my car was running like crap. So many mechanics had told me they had cleaned my injectors but this basically boiled down to soaking them in solvent and not dealing with the issue, as Paul informed me there isn't much that will dissolve carbon.

Although this was a diversion in the grander scheme of my rebuild plan the whole thing would have failed because of the injectors. It cost me just over R2k and now have the confidence that my injectors are in good shape and will work properly for another 100k kilometres.

It seems that a lot of people are having injectors issues across the board because of the poor quality petrol in our country. Cars are throwing up codes that aren't being diagnosed properly and parts replaced costing thousands when a simple injector clean will resolve a whole host of problems. Had I known what I do now things would probably be really different but hindsight is always 20/20.

 

[trevor_e36m]

Makes me wonder how one would mitigate injectors clogging up. These fuel companies constantly wax lyrical regarding detergents in their fuels, i wonder then which brand of fuel one should stick to.4k per injector is astronomical!

 

[DarrylvanNiekerk]

Exactly!

I enquired about fuel additives and supposed cleaners and all that stuff and he basically said there was no definitive solution or brand to stick to that would prevent the problem or deal with it once started.

 

[trevor_e36m]

I see, out of interest check this out

found it very informative

 

[DarrylvanNiekerk]

Yeah, I guess all of these things have relevance in more "1st world countries". I don't know whether it is true or not but I was told that immaterial of which petrol station you stop at you may not necessarily be buying the brand you expect to be buying. The theory is that fuel is imported and then stored with other brands, this may or may not be true.

One has to wonder how often the main storage tanks are decontaminated, what other particulates or chemicals have come into contact with the fuel and so on by the time it gets into your tank. Unless you know emphatically that the owner of the petrol station you always and only stop at has control over what is sold you run the risk of getting rubbish in your tank.

For me this is probably the issue we are dealing with in this country.

 

[trevor_e36m]

Yeah, I guess all of these things have relevance in more "1st world countries". I don't know whether it is true or not but I was told that immaterial of which petrol station you stop at you may not necessarily be buying the brand you expect to be buying. The theory is that fuel is imported and then stored with other brands, this may or may not be true.

One has to wonder how often the main storage tanks are decontaminated, what other particulates or chemicals have come into contact with the fuel and so on by the time it gets into your tank. Unless you know emphatically that the owner of the petrol station you always and only stop at has control over what is sold you run the risk of getting rubbish in your tank.

For me this is probably the issue we are dealing with in this country.

indeed , i really do wonder if the same quality control is applied here

 

[DarrylvanNiekerk]

Well, it's been over 2 months since the last post but I have finally managed to get some time to pick up on the project and have had to overcome some pretty interesting hurdles.

I purchased a head gasket set and sent the head in for repair work - replace valve stem guides and seals, remove two broken water bolt studs, replace a burned exhaust valve as well as a broken hydraulic lifter then reassemble and if necessary deck the head. I also dropped off the block with the 3 usable pistons and crank so they could measure the block, supply a second hand piston and polish the crank. I should get everything back in the next day or so.



I have since found out the place I took the block to weren't the best choice as not only did the remove the engine number when skimming it but they also didn't hone the sleeves with enough clearance for the pistons to fit properly. I am going to have to arrange for police clearance when this is all finished, something I wanted to avoid by repairing the exisiting block. Lesson learned.

In the interim I have started with stripping the brakes and cleaning the wheel arches as there is many years worth of dirt and grime there, it also gave a great opportunity to clean the inside of my mags. I bought a replacement set of EBC braided hoses because they are cheaper than OEM hoses and should supply a nice pedal feel. At the same time I took the opportunity to replace the brake lines which were damaged by the engine rubbing on them because the engine mounts were completely shot. One of the lines was close to being completely perforated, a bit of a scary thought.



I didn't realise how hard it would be to replace the brake lines and couldn't find any info or videos on how to do it. Everything else has been made easier by searching through forums or looking for info online, there are usally a number of videos explaining how to but there was a complete void on this one. I ended up having to strip most of the fascia at the back of the engine bay which was a mammoth task in its own way. Trying to remove the old lines without bending them helped to provide an answer on how to get the new lines in again all the time worrying about getting brake fluid on the paintwork.



Luckily none of the control arms are damaged and all bushes and connections seem to be in good shape. Reading up on how to strip the brakes directed me to looking at minimum thickness for brake discs and upon measuring have found my fronts are at minimum spec and the rears are way below so the costs keep on mounting. An interesting tidbit is that the minimum specs are printed into the hat of the disc which makes it easy to find instead of relying on opinion. All sensors and cables are in good condition so no worries there.



stripping the rear brakes proved to be a bit more of a challenge. Firstly the disc would not release even with some pretty heavy hammer work, I eventually had to use a lever between the brake caliper carrier and the disc to get it off. Having not done this before I was intrigued to find out the drear discs are both disc and drum as the handbrake shoes are housed inside the discs. The shoes seem to be in good shape so I will not replace them but had to do a bit of Googling to find out how to remove them. Under the handbrake lever in the cabin there is a locking pin which you have to depress to releave the tension on the handbrake cable, this requires a screwdriver and a lot of pressure.

I have found the boot on one of the brake calipers is torn so I will have to find a replacement and most likely service the caliper to clear out any gunk that has built up on the piston as I don't know how long it has been in this state. The outer brake hose looks relatively simple to replace but the inner hose is quite deep in the myriad of stabiliser arms at the rear and will be quite tricky to replace. One has to wonder quite why BMW designed the rear brakes with two sections of hose instead of a solid line to near the caliper?

I have been trying to do as much research on the actual engine rebuild as possible as I really don't want to make any mistakes. One of the scariest parts in my mind is making sure the oil pump is primed so when it is first cranked over there is proper oil flow and pressure, I came across quite a few horror stories. Luckily I was recently introduced to a very decent independent mechanic who has offered me both advice and physical help. when the time comes I know I can have someone come around and assist me for minimal cost so at least I am still doing most of the work myself. He is really clued up on e90 engine rebuilds and has been a great source of knowledge which has given me the confidence to move on with the project.

I was planning on only replacing the front shocks but in all likelihood the rears will have to be done as well. Bump stops on the front are definitely well worn so these and top shock mounts will have to be replaced. So many service items need to be done at the same time which does add to the bill but also means I will have a fully refurbished car once it is all done.

Unfortunately with the dry and dusty weather the car is looking a bit like a barn find but with with the light sprinkling of rain we got this morning I am ready to give it a little wash so it doesn't look completely neglected.