Last week I had catastrophic failure on my 2000 740iL. Chain guides are toast but it lasted to 237K. I have another car which I am driving now. It is a 1999 740iL that just clicked over to 121K miles. So, what steps can be taken to lengthen the time before timing chain guide failure. Is it just a matter of frequent oil changes with Synthetic oil? Or is there anything that I can do to make the guides last another 80,000 miles?
I am by no means an expert on TCG. But from what I have read, the largest reason for failure is simply that they are old plastic. As with everything plastic on our cars, eventually they get old, brittle, and fall apart. Great oil doesn't have the ability to drastically affect that. The fact that yours lasted to 223k is more likely attributed to the age of the car and how far it was driven in that time, rather than the mileage itself. I'm not saying your '99 is a ticking time bomb, but the TCG could be expected to fail at any point between now and 250k and there's not a lot you can do to extend the life, from what I've read.
It is often recommended to replace the timing chain tensioner.
I would also add your '99 is indeed a ticking time bomb. You may also want to pull the oil pan and look for any TCG debris. 120k doesn't mean it is safe, they have failed at 80k and 280k and everywhere in between. primary issue is age of plastic.
1997 740iL; 5/96 build. Purchased 12/04. Off the road build project 2013 - 2021. back on road 3/2021. Became daily driver (only vehicle) 6/12/2021. Still not completed. Stay tuned as the adventure continues.
Don't agree about "age of the plastic" as I did my guides at 238k miles in 2015, and they didn't actually need to be changed. No debris in the pan and just the vanos rattle periodically at startup. I religiously change the oil and maintain this car and with the new guides and rebuilt vanos gears, runs like new. I will relent that it can happen at any time and in some cases, I've read, on cars with the same kind of maintenance history as me.
Prolong the guides? Don't know if there is a real answer to that, but I would say maintenance should be kept up.
Last edited by 740iSport303; 01-16-2018 at 09:21 PM.
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'99 318ti Titanium Silver '97 318ti Boston Green; '96 318ti Alaska Blue (sold); '08 X5 4.8i Titanium Silver (sold); '13 X5 3.5i Black Sapphire Metallic (sold)
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Ehem, my 95 isn't going to fail like you lesser M62 guys will :P
M60 gang!
|| 1995 740i || M60B40 || DUDMD || ̶o̶r̶i̶e̶n̶t̶ ̶b̶l̶u̶e̶ Mercedes Brilliant Blue Metallic || Style 168 Wheels 1" Spacers ||
It's not an absolute that they all will fail at around the 20 year mark, nor is it certain that your 2000 is the exact average in terms of cars that have had them fail. Rather, that a LOT of cars in the 18-22 year-old window have had them fail at various mileages (some, at an even younger age when the mileage is over 100k).
The question is how many M62 owners haven't had them fail or replaced yet? We should do a scientific poll.
Great idea Aitch, I made a poll thread!
|| 1995 740i || M60B40 || DUDMD || ̶o̶r̶i̶e̶n̶t̶ ̶b̶l̶u̶e̶ Mercedes Brilliant Blue Metallic || Style 168 Wheels 1" Spacers ||
Currently on my 6th and 7th E38s. Two were 1998 non VANOS M62s, one was a 2000 and the rest are all 2001s with M62TU motors. Never had to open my engines before. Oil changes done every 5-6k with German Castrol 0w30/40. Of course they were all under 100k miles when i got them and when I sold them, except my very first one, which was a 1998 and retired that car at 320k because of transmission failure. But people who bought my E38s are still going strong at well over 100k miles. They call me every once in a while. Lots of highway driving here as well.
We've already had a poll! If I remember correctly the outcome was....er....confusing! There were many more M62TUB44's reported as failed than M62B44's - but there was a lot of argument along the lines that the earlier engined cars were often scrapped rather than repaired whereas the M62TUB44's were repaired skewing the results
It all got a bit ugly......
Here it is:
https://www.bimmerforums.com/forum/s...ing+chain+poll
Last edited by Timm; 01-16-2018 at 05:18 PM.
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Ditch the 105c thermostat and don't buy one with sludge.
Ah yeah, thought I remembered something like that. I didn't read the whole thread again, but I grabbed the data, consolidated the TU and non-TU numbers (and dropped the M60 zeros) and got this:
When you look at it this way you're just looking at mileage and not age. It shows that as you approach 200k you're at a 50/50 whether they will have failed or not. Only 10% of the 50 respondents had managed to go over 200k, period. 4 of those were non-TU engines, in which the TCG hadn't failed. I think it's possible the theory of older cars simply being scrapped is true regardless of whether the TCG fails or not, they're just being scrapped due to TCG failure or general age/wear and tear. Within this small sample size, it's the early non-TU engines which have gone the distance.
Some of the cars got different design chain tensioner which could also led to premature fail of the guides. The new part number has longer spring reducing he slack of the chain.
Saved my engine for sure. I got my car with bad rattle from guides, a lot of sludge in the pan and clear marks on the timing chain from wear on the sprockets. Rolled the dice. I changed the thermostat from 105 to 80, dropped the pan (no pieces) installed new style timning chain tensioner and the sound is gone. Did 3k miles never heard the dreaded cold start chain slap even though car was sitting for two weeks
Last edited by chucknorium; 01-16-2018 at 06:32 PM.
You, need a therapist..
- - - Updated - - -
I've come to the below:
1. Harsh 5 second rattle at startup is usually caused by a weakened timing tensioner spring. Prolonged slapping of the chain (at startup) against the tensioner rail weakens the plastic. Changing the timing tensioner after say 20k miles worth of startup rattle kills the tension rail in circa 5k miles after the tensioner cahnge.
2. I've been told by a member (with 2 e38's over 220k miles each, owned each for at lest 80k, same guides) that his secret is Lucas oil riser(synthetic) with every oil change. I've incorported this into my oil change regimen
Some Places remain unknown because no one has ventured forth. Others remain so because no one has ever come back......
Timing chain guides can be finiky. Some manufactures seems to never have an issue and sometimes there is the complete screw up by supplier, ie BMW N20 motors. I briefly talked to some in the industry on this and 90s BMW probably used PA6GF15 plastics for the guides. But only internal docs or analysis of the plastic would confirm. I bet anyone with a good "3D Printer" could make better ones. Supposedly Stanyl nylon 4.6 would be good to make guides from now.
Last edited by ZEKTI; 01-16-2018 at 07:21 PM.
5 second rattle is much more likely to be non-drainback valve behind the VANOS solenoid related. I put new guides on my car, startup rattle stayed and really don't care. Clean your old tensioner if sludged up, don't buy a new one.
The issue with the M62 is how hot it runs, and most importantly the fact it doesn't have an idler sprocket. Even cold running S62s will need to have their guides replaced soon enough, some already have failed.
Last edited by XAlt; 01-16-2018 at 07:49 PM.
[QUOTE=XAlt;29933243]Clean your old tensioner if sludged up, don't buy a new one.QUOTE]
Why not buy a new one?
For one the spring tension can weaken, but the biggest issue is some models have a older shorter design (I don't know what years). When buying new you get the new design: with the new one having a longer and stronger spring, thus better able to maintain tension as chain stretches. here are a few pics of what I found when I replaced mine during TCG job.
DSC01841.jpg
DSC01843.jpg
DSC01846.jpg
Not scientific, but simple illustration of spring strength difference.
DSC01852.JPG
DSC01848.JPG
I think the tensioner should be part of a routine maintenance; 60k or 100k?
1997 740iL; 5/96 build. Purchased 12/04. Off the road build project 2013 - 2021. back on road 3/2021. Became daily driver (only vehicle) 6/12/2021. Still not completed. Stay tuned as the adventure continues.
[QUOTE=cyclops2;29933990]Agreed 100%, OEM is around $40, original $100 and it takes probably 15 minutes to change it.
I'd like to know how to change it and 15 minutes? i have that before april
I think a critical point is being missed. We all use mileage as the guide post but what has the most effect is revolutions. If you are cruising at 60mph and the engine is at 2000 rpm you have 2000 revs/mile. If you are sitting in traffic at 0mph and 750rpm you are screwed and should have bought a honda. If you are like me you are doing 130mph at 6000 rpm you have 2769.230769revs/mile. But it doesn't matter because I bought the right car and when I have to change the guides I will know why and have a big smile on my face.
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