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1980 LWB 280GE
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Discussion Starter · #1 ·
I got the timing chain in the mail yesterday from Germanstar for $49 so I'm ready to swap it in.

My mechanic says $300 to swap the timing chain if I give him the chain, and I remove my York on board air compressor from the stock AC compressor position before I bring it in to him. He says even just doing the chain in an M110 takes two good men an hour and a half.

I was going to try to build myself a rig so that I could put the new chain in, end to end in a double length loop with the old chain, get it all tensioned up nice and then just turn the engine by hand to wind the new chain in.

But now I don't know.

Should I chicken out and take it to the shop?
Or should I try it at home?

Has anyone done this job on an M110 before?
Is the tensioner particularly fiddly to deal with?

Flounder's experience with the V8 gives me a little confidence, but if someone out there has done it on the M110, I'd apreciate any advice or caveats you have.

It sure would be a great feeling of accomplishment to have a set-up to allow this to be a one-man job. But is it worth the risk? (dropping the chain means pulling and disassembling the engine)

All opinions welcomed!

[:)]

-Dave G.
 

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Go for it.

I did this on my 230SL it isn't that bad of a job. It just takes patience. I rigged up a failsafe to prevent the chain from coming off of the sprocket on either side. Still it made me nervous, knowing what lay in store if I messed up. Your engine is more difficult since (I think) you have two cams and thus they may pull in differing directions.
 

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1992 300 GDL
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Dave
I've done this on a SOHC diesel but I had a hand to do it. I've also done plenty of work on the 110 engine in my 280E.But not actually exchange chains
I would be hesitant to try it without help but if you spent time making your tensioner it might be OK.I would recommend a second pair of hands

The tensioner isn't a problem. I think it's a 19 mm allen socket to remove the outer cover and then a 14 mm allen socket to actually turn the tensioner itself. Although it's not threaded in. It just "pulls" out but there is little or no grip until its been pulled out a bit so the only way is to turn the allen key whilst applying a little pull to the socket and hopefully it comes.Once out it is harmless enough, it doesn't fly apart or anything

Once its out the chain tensioner rail is allowed to move away from the chain and rest against the casing giving the chain a solid base to pull against.

Remove the spark plugs and if you can the rockers on the inlet cam side to reduce the load on the chain. Actually removing the rockers is move difficult than the chain without the special tool. I used 2 long screwdrivers but I had someone else to actually remove the rockers as I had my hands full . Reassembly is even more tricky. So I would actually try it without removing them . The thing is if it slips a tooth on the gear and the cam timing goes out you can correct that after you have done the chain exchange.

Don't worry about dropping the chain. Tie a piece of string to the free ends or the chains, if it slips down you have a chance of recovering it. But if you use your double looped chain that is less likely to happen.

I have just bought a chain for my 300 GD but I can't do it myself because it has the rivetted link only. The manual says that's all that MB produce now. Presumably you have the DIY link.

Keep us posted
 

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Really no rocket science here Dave. Dropping the chain could happen to someone with even 30 years of wrenching but it is very unlikely if you're patient. I say just do it, you'll thank yourself and build even more confidence when you're finished.

Just remember to tightly pack rags before changing the master link. This is really the most hairy part of the job (easy to drop) but with rags tightly packed even this becomes no worries.
 

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1980 LWB 280GE
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Discussion Starter · #5 ·
Thanks guys!

In the end, I just can't resist the challenge. :^)

I'll use Flounder's "2-vise-grips" tip from our last go-round with this, and do all I can to be sure I don't drop the chain.

The 110 timing chain setup isn't just differnt from a single cam, it's even different from most DOHC setups I've seen. In most setups the chain goes over the top of both cam sprockets, and the sprockets turn the same direction (say both clockwise). In the M110 the chain goes UNDER one sprocket and OVER the other, so the cams turn in opposite direction. Are we sure there wasn't some Buddhist influence in the design of the G? Between the counter-rotating front axle, and the reverse-twirling cams, I see a lot of this yin and yang, opposites in balance, stuff going on. Maybe it's why they last so long. [:)]

I really like the idea of eliminating the rocker tension, but without the right tools, it sounds like it could be another job unto itself. If the rocker tension is gone though, then it REALLY becomes a no-brainer I think. But I'm sure I'll end up doing it with rockers in place.

With any luck I can develop a method and tool that others can use.

As far as grinding the link goes, I'm hoping that the chain Erwin put in when her rebuilt the motor 120k ago was a chain with a removeable link. My new one has the removeable link, but it'll be more difficult to make the double loop without a second master link. I'd have to wire it together or something, and even soldering the wire I'd still be worried about it breaking.

One thing that woulld be interesting that I plan to do is to measure the new chain before I put it in and then measure the old one that comes out to see how much stretch it incurred over 120,000 miles.

Oh yeah, and I discovered we have a nice bore scope here at work. I think I'm going to borrow it and use it to inspect my cylinder walls. I hope I can figure a way to get some digital pix!

Oh well, we'll see how it goes. I'll let you all know what happens.

-Dave G.
 

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As always, I am very glad that you take the time to document the work you do[:D] I will be very interested to see how much longer the old chain is, as my 280 has about 105k miles on it now. Keep us posted Dave and good luck!
 

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1985 300GD LWB 5 Speed
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I, for one, am very pleased that you are not a proctologist. They have some very nice equipment with flexible camera-lights-action capability - but the thought of that stuff doing double duty on the weekend gives me pause.

The dual cam engine does sound a little tricky. I opted not to do my little 190 2.3 sedan, and sure enough one of the guides had little chips out of the rail. This led to inspection of the bottom guide - same thing... In the end, with the pan needing to come off and engine needing to be lifted... I am happy someone else was doing this job. The five cylinder diesels are easy to do with the method you note.

Wow! 120,000 miles on the original chain. That would give me a little anxiety. There will likely be significant lengthing of the chain with at many miles.

Good luck, Dave.

tom
 

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Discussion Starter · #8 ·
What would Dirty Harry do?

Well I read through the procedures in the workshop manual for replacing the timing chain in more detail last night, and after doing so, and considering other things going on right now, I think I'll leave it up to the pros.

One of my favorite Clint Eastwood movie lines is:
"A man's got to know his limitations." I think replacing this timing chain might be beyond mine at this time.

The manual specified removing the rockers from the exhaust cam, a process that looked like it'd be a royal PITA without the MB valve spring compressor tool. It also called for a tool to manually position the timing chain guide after the automatic tensioner is removed. I could have fabricated both these items in addition to the double chain support rig, but I started to think I didn't want to be that deep in a stupid timing chain job, and that the time it would take me would outweigh the $300 Mark wants, even if I didn't have a single problem. Could I shortcut one or both of these items? Maybe. But the longer I have the G the more respect I gain for the folks that wrote these manuals and the less I tend to second guess things they say are required.

So, bottom line is it'll go in the shop for the timing chain job on Tuesday. I'll still measure the new chain and ask them to save the old on e for me so I can compare.

This is actually the second timing chain replacement for this engine. Erwin did it when he rebuilt the engine at approximately 180,000. It now has a little over 300,000 on it. Erwin said the chain he removed didn't show much stretch at all after 180k, so that makes me feel good. We'll see what this one looks like.

Of course, it's not a total cake walk. I still need to pull the air compressor and generally make sure there's no silly labor for the mechanics to do before getting right after the timing chain. I'll do that stuff this weekend some time.

Anyway, more on Wednesday.

-Dave G.
 

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Discussion Starter · #10 ·
Some timing chain results

I finally measured my old timing chain and can say something about stretch.

My method of measuring was that I clamped a bar to my work bench and pulled the new chain out flat on the bench straight against the bar. Then I marked the center of the pin-hole in the first and last links on the bar.

When I got my old chain back from the mechanic I laid it out the same way next to the bar and aligned the mark at one end with the center of the first link hole.

When I did this, the center of the last link hole was about 1/4" past the mark at the other end of the bar.

1/4" ammounted to about 3/4 of a link. Since the cams are approximately 1/2 way along the chain travel, I can say that the valve timing was retarded by about 3/8 of a link, give or take.

I haven't had time to check how many teeth are on the crank gear for the timing chain, but once I find out, then I'll use 360 degrees, divided by the number of teeth on the gear, times .375 to determine just how many degrees the valve timing was retarded as a result of chain stretch.

I don't have any objective numbers to compare, and it would be hard for a little valve timing to make much performance difference in a low compression engine sucking 2200m air on 5% grades with 500lb load in/on the vehicle all the time...but it seems I get a little extra travel uphill before needing to downshift....but not much. Negligible probably. I'll have it all right after I do the valve lash that's also due.

But the bottom line was that after 120,000 miles I had about 3/4 of a link worth of stretch in the chain. To me, that actually sounds like quite a lot given something as rigid and strong as that double roller chain seems to be.

One thing I realized too late that I should have done was to check for actual WEAR by measuring how much side flex the new and old chains exhibited. Maybe somebody else can tell us their experience. Or I can try to remember in another 100k. [:)]

Based on the ammount of stretch that I DID see, I think 100k is a good change interval, in the interest of keeping the engine performing properly as much as to avoid catastrophic failure.

-Dave G.
 

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1985 300GD LWB 5 Speed
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The 100,000 distance for timing chains is the limit for most MB vehicles. I have always wondered how it is that the 260 and 300 gasoline engines (E300) can live with a single roller chain. I always hold my head in disbelief when owners tell me that they have 180,000 miles on their 300 petrol engine without a chain R/R. It is not one of those maintenance jobs that would just slip by ones attention, since the dealer cost is significant.

I also am of the opinion that diesels have a greater need for timing chain R/R largely due to the way they shut down. The high compression within the combustion chambers stops the engine more suddenly, with less run-on or coasting. This means the cam momentium is stopped faster, with less mutual coasting to a stop as you will see in a gasoline engine. I know this sounds like shadetree mechanic thinking, but the dynamics seem to be there for "growing" timing chains.

Dave, was that a costly change-out?
 

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Discussion Starter · #12 ·
chain replace cost

I pulled the compressor and bought the chain separately (OEM brand chain through Germanstar for $49), and told him to ignore the valve cover gasket as I had a new one I'd install after I do valve lash. Basically I tried to minimize cost by having him ONLY focus on winding out the old chain and winding in the new (with sidebar requirements like tensioner - I didn't ask if they pull rockers, I doubt it).

Even then, it took the top two guys in the shop (the owners - they won't let any of their other guys attempt this) two hours to complete the swap. So four man-hours labor came to $320 +tx.

-Dave G.
 

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I have never done a twin cam MB, but it clearly is more effort than the single. You can imagine my angst when on my 190E while redoing a head gasket, the sprockets looked like new, but the rails had to come out...meaning: the pan had to come off and to do that, the engine had to be lifted. Since I was redoing the head gasket, I told the mechanic to send off the head and with the pan off, lets look over the lower end. All else was fine, and I felt that I got a deal at 1700$US. The double roller chain showed only "a little" wear and expansion, but I had that replaced too.

But now, Dave, doesn't life feel better knowing the timing chain is new and all is right, at least in that little part of the world?
 

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Discussion Starter · #14 ·
Life is good

Thomas.Schumacher - 7/13/2004 11:17 AM
....But now, Dave, doesn't life feel better knowing the timing chain is new and all is right, at least in that little part of the world?...
Yes it sure does. I thrash this poor girl so hard up and down the mountain every day, I was really thinking, "Oh let's see, it would be just about right if the new chain is in the garage and old one breaks and grenades the motor while I'm vascilating about whether to do the job or hire it out."

At least it's done and I don't have to worry about THAT for a few more years.

-Dave G.
 
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