Just how often should a timing chain be replaced? - PeachParts Mercedes-Benz Forum

Greg in Oz · #1 10-17-2003, 04:53 AM

At the risk of asking a question that has been discussed many times previously (a search of "timing chain" gives too many responses), how often should timing chains be replaced on various MB engines? Is there a listing somewhere?

I know that for say an early alloy M116 (3.8) with the single row chain the answer is "very often". The early M102 with a single row chain also requires regular chain replacement. For the M103 the popular opinion seems to be "never", despite that engine using a single row chain. How about the later M102 with a double row chain? Some suggest it does not need replacing.

My '90 190E-2.3 (double row chain) at 220,000km has a little chain noise until the oil pressure rises, mostly on a hot start. Should I replace it or maybe just the tensioner?

How about the chain in my '73 350SLC (3.5 iron block M116 with double row chain)? I replaced it about 120,000km ago. Recently I was getting some chain noise at idle during warm up. A new tensioner silenced it although while doing a valve clearance adjustment recently I noted that the right bank camshaft is probably half a tooth (or more) late due to chain stretch/wear. Time for a new chain again?

How about some other popular engines such as the M104 six and M111 four (each with double row chains)? Do they need chains replaced at any particular interval? Do I really not need to worry about our M103 now showing 180,000km with its single row chain?

When replacing chains are the joining links with clips satisfactory or should a rivetted join like with the original chain be used? Should tensioners also be replaced at the same time? How about guide rails and tensioning rails?

Does anyone have definitive information on this subject for the various engines? Maybe some of the knowledgable techs would like to offer their thoughts on this. It certainly seems to be a topic of concern for the members here.

MikeTangas · #2 10-17-2003, 12:27 PM

I believe 10* of chain stretch is the limit at least for V-8's, most seem to change chains at about 8* stretch. If you are about 1/2 tooth off due to stretch that would put your chain stretch at a guesstimated amount of 7*. You're close to chain time.

I've done chains on both of mine, used the "C" clip masters. Have had no problems with them. On the 560 I have logged about 20K+ miles since the change.

The inlines seem to require less chain replacement, most likely due to their short travel distance. Remember, with the V-8, the chain is 6 feet long and makes numerous turns as it wends it's way around. All those turns add a little more wear to the links (compounded big time by extended/neglected oil changes).

G-Benz · #3 10-17-2003, 01:42 PM

Quote:

Originally posted by MikeTangas
All those turns add a little more wear to the links (compounded big time by extended/neglected oil changes).

That's the real key...the oil change intervals. If you (or the PO) have been lagging in this department, expect to do the replacement sooner than you think...

blackmercedes · #4 10-17-2003, 04:27 PM

For the single row early M102 engines, I would change the chain and tensioner at 200,000kms (about 125K-miles), even with good oil changing history. I paid close attention to mine and they were in pretty good shape at 200K, but better safe than sorry.

We did the 190E 2.6 chain and tensioner at 250,000 kilometers, again for peace of mind. It wasn't stretched much, but for about $300 it seemed like cheap insurance.

The single row chain in the US spec M116 3.8L engine needs really frequent changes, but even that doen't seem to work 100%. I've met a few owners that did regular changes only to have the chain break at some ridiculously low mileage. Updating to double row seems the only real solution. Rare to find one that hasn't been updated as time marches on.

On the M111, I'll probably start paying close attention to the chain past 200,000 kilometers. I've seen some M111's at over 250K, all with their original chain, and none making noise. All with good oil/filter histories. Before 250K I'll probably open it up and check the chain, guides, etc. Little engine, short travel, double row, Mobil 1 every 5K-km's...should last a long time.

The M103 seems to have very long chain life despite being a single row. It has a very short length and no major direction changes.

suginami · #5 10-17-2003, 06:41 PM

While I can't comment on M102 and other engines, M103 and M104 engines have a ratcheting tensioner, which is another reason for timing chain durability. It uses oil pressure as do others, but as the chain loosens the plunger "ratchets" to keep the chain tight, even after the engine is shut down. Since there is no looseness during that cold start up, it does not hang up on "stuff" causing things to break, like timing chain guide rails.

Rockman59 · #6 10-17-2003, 07:47 PM

how often should timing chains be replaced on various MB engines?
___________________________________________________
Most of the info I have read on this board says 100,000 miles and/or 10 years. Seems that most of the problems come not from the chains breaking but stretch and/or the plastic parts associated with the timing chain system. The plastic gets old and brittle, breaks, drops into the chain/tooth and causes the big problem.

Duke2.6 · #7 10-17-2003, 07:49 PM

At some point did the M103 receive a double row timing chain?

What model year?

Can a single row 103 be "upgraded" to a double row timing chain?

An inline six will have less load variation on the chain due to the greater number of more closely phased lobes, which will contribute to chain life compared to an inline four.

Duke

blackmercedes · #8 10-17-2003, 08:06 PM

Quote:

Originally posted by Rockman59
how often should timing chains be replaced on various MB engines?
___________________________________________________
Most of the info I have read on this board says 100,000 miles and/or 10 years. Seems that most of the problems come not from the chains breaking but stretch and/or the plastic parts associated with the timing chain system. The plastic gets old and brittle, breaks, drops into the chain/tooth and causes the big problem.

That 100K mile rule is a good one for the various older M116/M117/M119 V-8 engines. They have very long chains that change direction. The 116's have brittle plastic guides that go bad with age, and can really do some collateral damage when they break.

The inline engines are a tad different. The chains are not nearly as long, and don't have huge direction changes like the V-8's. Even the twin-cam M104 and M111 engines have much shorter chains than the V-8s.

That said, 100K-miles is not a bad interval for all engines to be looked at. If I owned a low mileage M116 420SEL W126 car with it's original chain and guides, it would be going to a shop first thing tomorrow! On a C220/230 with an M111, changing the chain at 100K-miles is overkill by a huge margin.

blackmercedes · #9 10-17-2003, 08:07 PM

Quote:

Originally posted by Duke2.6
At some point did the M103 receive a double row timing chain?

In don't think so, but I could be wrong. I think the double row was added when the twin-cam head was dropped on and the last number went from 3 to 4.

deanyel · #10 10-17-2003, 11:21 PM

I think that's right - the 103 motor was always single and the 104 was always double. They are both very solid - the 103 because it's so short and the 104 because it's double. I once had a 103 motor with 275k miles. My mechanic didn't want to change it because it wasn't acting up and he'd never seen a problem on one. His theory was that if it's not acting up you introduce risk by changing it. Bu it worried me so we did it. It turned out it was the original and it showed no real signs of wear. Most mechanics I've talked to have never seen a 103 timing chain problem. I really haven't heard about any 104 problems either, of course they're typically not as high on the miles.

Greg in Oz · #11 10-20-2003, 11:05 PM

Thanks for all the replies, it's amazing how much interest timing chain threads generate. The responses were much as I expected.

From this I would conclude that for my family's current "fleet" the following applies:

My '73 350SLC W107 (3.5 M116, double row chain) could probably use a new chain despite the current one only being there for the last 120,000km and with 6 monthly (2,500 to 5,000km oil/filter changes).

My '90 190E-2.3 W201 (8 valve M102, double row chain) at 219,000km I probably need not worry about for some time yet.

Our '90 300TE W124 (M103) at 179,000km I need never worry about.

My parent's '93 E320 W124 coupe (M104) at 130,000km I need never worry about.

My parent's '96 E230 W210 (M111) at 110,000km I need not worry about for a long time yet.

My wife's parent's '99 C200 W202 (M111) at 60,000km no worries for a long time yet.

How about other related components? Does everyone replace just the chain or do they replace the tensioner and various rails and guides as well? In some situations I believe the guides and rails can be the actual cause of chain failure rather than the chain itself.

#12 10-20-2003, 11:25 PM

well, when I had my cracked head repairs, the mechanic that did it for me noticed no significant strech on the chain and advised me not to change it. He did replace the tensioner though.

MikeTangas · #13 10-21-2003, 12:46 AM

Definitely do the rails and tensioner (do them first) then check the chain for stretch. If after replacing the rails and tensioner your chain still shows 8*-10* stretch, roll in a new chain. Upper rails aren't too difficult on the V-8's and the tensioner is only a matter of a couple bolts (but holding the new tensioner against the block is a be-itch while trying to start the bolts).

This is in regards to the SLC.

suginami · #14 10-21-2003, 12:50 AM

Oh, don't forget to check out Thomaspin's website:

www.pindelski.com

He has great pictorial DIY articles on his three MB's: 380SLC, 560SEL, and 300SD. He has done the chain and rails on the SLC and SEL, I think.

Freestyler · #15 10-21-2003, 02:43 AM

I asked my mech about the timing chain on my 103. He told me that he had only replaced one timing chain on a 103 in his life. It was replaced at 850000 km (530000 miles) and could easily have made to a million..!

Now THAT'S quality for ya'!

Freestyler

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