Hi, I hate to keep on, but I still believe I'm missing something. The OEM manual describes the procedure for changing the tensioner rail as:
1. remove upper guide on right head;
2. remove tensioner;
3. Remove sprocket; 4. remove pin, then tensioner rail, etc. etc.
OK, I can't get the two left upper guides out past the sprocket and chain, though all 4 pins are out. The manual implies the guides can be removed without removing the tensioner or the sprockets, so seems like there is a way, but I haven't found it. My original plan was to change the three upper guides, then bar the new chain in, then change the tensioner and tensioner rail. Thanks everyone.

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=126035%5F568&M=116%2E96%5F288&GA=722%2E324355&L=765%2E706&CT=M&cat=288&SID=05&SGR=015&SGN=01






Have a great day.

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

The point of my question was: the manual clearly states the right sprocket must be removed to change the tensioner rail; it does not state the left sprocket must be removed to change the upper guides. I wanted to be certain this was not just an anomaly of the manual. The exploded view you offer from a Russian manual is not a 116 anyway. I assume you are being sarcastic; if not I apoligize.

There was no sarcasm.
All the data I have shows that the 420SEL was not imported to the USA until the W126.035 M116.965 V8 420SEL 1986-91.

I need more data, year, engine, geographic location.


M 116 4.2
http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=126035%5F568&M=116%2E96%5F288&GA=722%2E324355&L=765%2E706&CT=M&cat=288&SID=05&SGR=015&SGN=01

Please accept my profound apologies; I could not quite get it.
My car is a 1986 420SEL, US model, manufactured in November, 1985.
It has 149,000 miles and is in good condition.
I think I will just buy a spring compressor and remove all the rocker arms; remove almost all the risk at once.
Thanks.

I'm glad you are going to get the spring compressor and do it "by the book". I'm not a professional mechanic, but I'm pretty confident that if I use the right tools and follow the manuals that I can do something, even if it's complicated. After I do something a few times (at the present rate, I'll be on my 6th timing chain when I'm 90 or so), maybe I'll feel confident in taking a few shortcuts.

Once you remove the followers (very easy once the spring compressor is applied, just put em back where you found em), you are right, all risks are over on that side. You can then take the tensioner out, too.

Did you check out the tool rentals on this site. I've been thinking about renting mine, won't be needing them for a while, I hope!

I had to take out my LH gear to get the guides out. I don't see how it could be done otherwise.

__________________
86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

I agree with your last observation 100%; now I don't trust the OEM manual as it implies otherwise. I'll check on the rental of a spring compressor, they seem very expensive everywhere I've looked at new ones.