So R56, N12 (normally aspirated i.e. no turbo), 149K miles and runs perfect. We have every record including every gas fill-up from my Father-in-law, who was the original owner. At 30K the dealer recommend he replace the upper chain guide and install the upgraded chain tensioner as a precaution. He was told that if this is done early on, it would eliminate chain failure risk.

The engine starts great and runs great. There is the slightest bit of knocking for the first second that is barely audible. I run 5w40 full synthetic and change it every 5K. My FIL used mobil1 5w30 then switched to Castrol syntec full syth. Most oil changes were every 3K but he switched to 5K later on.

We have been so busy on it recently taking care of the cooling system. I would hate to start another big project on it especially since I am concerned about getting one little item wrong and causing a self destruction.

Should I do it of let good enough alone?

 

If the noise at idle and/or startup is coming from the timing chain side of the engine(hard to distinguish really) then yeah maybe time to replace the timing chain. Otherwise it could be valvetrain noise on startup waiting for oil to get up there.

However you can do this first:
https://www.pelicanparts.com/techart...eplacement.htm
The first few steps show how to use a special tool to measure your timing chain "stretch". When I measured mine I was right under the max amount, so I just figured time to do it.

I've never been inside an engine, but did my own timing chain replacement following that guide, as well as the Bentley service manual and some youtube videos. I love to tinker though so I wasn't too afraid. Everything went well enough, but not without some frustration. This is my "DIY" car though, trying to learn and also have fun and also save money.

The cheapo cam locking kit i bought didn't actually fit properly to one of the holes but it worked good enough. I found a video on youtube that showed some Peugeot repair guys using a digital gauge to make sure the cams were within an acceptable range of degrees. Which I also did because I find it a bit more precise and scientific than checking by attempting the slip the cam locking tool back into place. Since my tool was cheap i wasn't going to trust it. I stressed out about the cams and timing not getting properly set but it really wasn't as difficult as I thought it would be in the end.

The crank bolt is on with a LOT of torque and then some. So make sure you have a proper tool to apply counter torque, or also have someone applying brake pressure with tranny in high gear. I made my own long bar that bolts to the crank instead of buying one.

Consider replacing water pump while you are there.

Decent amount of stuff going on so keep organized and replace all yield torqued bolts and other one-time use items, crank seal and other seals.

 

youtube.com/watch?v=O4dDr4YVpkE

That's the Peugeot video, it looks kinda old school but it's definitely the bmw prince engine which Peugeot also uses in some models.

 

I would say you have been extremely lucky getting away with a top guide and tensioner. So many of these bicycle chains have wrecked top of engines at 60-70K or earlier on the turbo version, I have an N12 and replaced it at 50K miles, one for noise and loss of performance, the uprated tensioner just reduced noise for a few months, replacing the chain and using the correct timing locks set it up for as new performance, piece of mind and reliability, The old chain guides I removed were friable, the lower sprocket teeth were worn. I fully intend to do this again at 100K and at the same time replace the oil pump sprocket and chain. I wont list the other parts I have done and now at 60K. What I would also do is a new front crank seal, water pump and belt. Me, I think you are on borrowed time.

 

Is it really the "bicycle" chain that is the crux of the problem or the extensive use of plastics? They could have used spring loaded (tensioned) free-running metal sprockets in place of that plastic right? Yeah, it would have cost $25 more per engine.

 

Yes, chain elongates and slaps about the plastic is also makes the timing retarded, metal guides would not help, you are right, saving production costs on each engine saves millions, but not for the consumer!

 

Thanks to everyone for your insights. I have already done the water pump, cam seal and various other items in that area. I am going to take off the valve cover today and inspect the upper chain guide as well as whatever else I can see while I am in there. Is there a way to check for or measure chain stretch or "see" the condition of the two lower chain guides from the top end?

I think the engine is quite at start up especially after re torquing the chain tensioner earlier and replacing a very worn out upper engine mount. Although, it is difficult to tell what are good noises VS bad noises...

 

I removed the timing chain cover to inspect it yesterday. This is what I found:
Compared to my BMW engine, which is also in my Playlist, everything looks very tight to me. I did not see any broken or loose guides. There were no brushed sides (shiny areas from rubbing) on the chain. I looked as far towards the crank as possible and inserted a long flat head to lightly pry. All looked very good.

VC gasket went on with no problems. There are a few tips I could recommend to those who may be interested.

Please let me know your thoughts.

 

The only technical way to estimate chain stretch is to use the dummy tensioner and measure the distance, google that. Over 68mm and chain is mince. What you did means nothing, your guides are heavily stained, probably old and if mileage is higher than 60k on an N12 you should do it anyway. These are not for life. If you had a cam belt you would change that, trouble is bmw do not give service intervals for chain and guide replacement, anyone might suspect they would like your engine to eat itself 😁 Entirely your choice if you hink visualising a chain and sprockets is definitive... cheers

 

Yep it will need measured for slack. If stretched just change the whole kit. https://www.northamericanmotoring.co...nsioner-2.html

 

bear in mind, there is nothing madly bad with these cars if maintained, water pumps, thermostats, timing chains, they all wear, the bad part is bmw saying they never needed maintenance... got a bike? You change the chain? Toyota? Change the cam belt?

 

Well said as usual Scudder44. I guess my challenge is that having driven many cars to over 200k with timing chains, I have never had a problem. Were these plastic guides not used in Chevy’s, or Mercedes from the 90’s and early 2000’s? What changed with these Poegut /BMW engines?

 

What changed was the quality of the chain, they could have made something sturdy but shaved the chain down to bicycle quality, multiply that cost saving and your profits rise. Once the warranty expires they care not a jot!

 

If they made cars robust nobody would have to buy new ones . . .