94 e420 m119 ate a timing chain - Mercedes-Benz Forum

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post #1 of 23 (permalink) Old 08-18-2010, 10:27 AM Thread Starter
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94 e420 m119 ate a timing chain

Ok, so our 1994 e420 broke a timing chain the other day. It stopped the motor rather quickly, although I wasn't driving, so I can't describe the exact event. No noisy prelude or after party...it just stopped running.

It was towed to a garage, and they've noted that the crank will only move a few degrees in each direction, so the chain is firmly wedged in there somewhere. The car has 172K on it, and was otherwise very happy (except for occasional and unrelated surging idle issues). It's always been serviced regularly, but I now see, poking around, that there's some preventative maintenance in this area that might have been wise.

Anyway, cutting to the chase, what do you all think is the wisest course of action from here? Should we buy a salvage motor and drop it in, or repair this one? This one is obviously a known quantity, with no issues of oil consumption or anything. Assuming the chain didn't manage to do any really deep damage, it should be a matter of extracting the broken one, putting on new guides and tensioner and chain (and obviously inspecting the cam and crank sprockets for damage (likely some, somewhere)). It's a lot of labor and a fair number of expensive parts -- I can't imagine escaping for less than $3K or so.

The other option is to drop in a salvage motor. This doesn't look especially cheap, either. How many hours of work is a transplant? How much should I figure to spend, and how do I know I'm getting a good one? The car has a recently-replaced wiring harness and, like I said, is otherwise very clean and functional. California car, so there's no decay or other factors that would suggest retirement.

Thanks. These motors have such a reputation for immotality that I'm tempted to say we should fix this one, unless you all think that further damage from the incident is going to reveal itself after the direct cause is fixed (e.g., bent crank or rods). If I do go with a replacement, what range of options is a direct drop-in? Any issues with one from an earlier e400, if one looks good? We're satisfied with the current performance, but what are the other displacement options on the replacement?

So, repair or replace, on the motor?


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post #2 of 23 (permalink) Old 08-18-2010, 10:34 AM
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I feel for you. Sincerely. I had an '89 420 SEL, and it, too, had chain-tensioner issues. Fortunately, I was able to nurse mine home when it jumped time.

I want to say these are interference engines, which means Mr. Valve, meet Mr. Piston. Never a good introduction.

Please, someone else chime in and say it's not true.

Kelly B
'05 Cadillac STS, V8, pearl white, 143K miles, my DD - totaled as of April 2016
Wife's ride: '02 Lexus RX300 AWD, all the options but a hitch, 141K miles
'99 Fleetwood Bounder Diesel 39Z diesel pusher motorhome, which has visited 9 provinces, 1 territory, and 49 states under our ownership, 140K miles and many modifications
'98 Jeep Grand Cherokee 5.9L, dedicated 'toad' 175K miles

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post #3 of 23 (permalink) Old 08-18-2010, 10:59 AM
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interference engine.....

open it up an take a look....then decide.....you will probably need some new valves where the chain broke.....it might be not too bad.....

finding a used low millage engine is a good long term investment, but will be expensive...
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post #4 of 23 (permalink) Old 08-18-2010, 11:26 AM Thread Starter
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It was near-idle when it happened, but I do suspect that we'll find some damage somewhere if it's an interference motor. Ugh...that means a head or both would have to come off...more parts, more labor. Hmmm...how far into the repair do we have to get before we can assess that further damage? Can one tell with the valve covers off, or do you have to wait until you can do a compression test?
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post #5 of 23 (permalink) Old 08-18-2010, 11:35 AM
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remove both valve covers and post pics as a start....easy...not sure if you can crank the engine for a compression test at this point, but i am no expert on that....

assuming the chain snapped or something like that happened, this is at minimum a head gasket and valve job with some new valves (in some cylinders not all) ......the fact that it happened at idle could make this a better situation than you think....
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post #6 of 23 (permalink) Old 08-18-2010, 11:56 AM Thread Starter
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I guess that the fact that it's an interference engine would explain the lack of movement in the crank, since you'd likely bump up against a valve after a few degrees in any direction (even if the chain wasn't firmly wedged somewhere to prevent rotation).

I'm about to head over to the garage and have a chat with the mechanic about the situation...and give him the go-ahead on some further debugging, I guess.

Assuming the worst, I'm still seeking advice on fix this one or go with a salvage engine. Does anybody have an idea about how much work it is to pull and engine on these puppies? The mechanic will probably have an estimate.
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post #7 of 23 (permalink) Old 08-18-2010, 12:55 PM
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This is one of those situations where you are better doing the work yourself....

if you buy a low mileage engine (look at ebay), it will cost you some good money

if you buy one with mileage similar to yours, it will be cheaper, but i would not put that in without a new headgasket,oil pan gasket, chain...etc...so additional cost...

if you pull the engine, you are better also doing some work on your transmission (reverse clutch) since you will probably find some wear....

so, it all comes down to how much the car is worth and how long you are keeping it...i would personally just pull the valve cover off, if nothing appears then the heads...if minimal damage then fix. if not then discard in favor of new engine,,,

find a friend - mechanic and do it with him....that makes more sense economically ..

good luck, keep us posted!!!
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post #8 of 23 (permalink) Old 08-18-2010, 02:51 PM
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This is a pretty substantial job to complete correctly, as the front timing cover and both heads need to be removed and inspected for damage. The parts alone are fairly exorbitant. The following is lifted from an email exchange with a noted expert with the M119--he shall remain nameless for now.

"All gaskets and chain rails add up to approx $700, a new chain and tensioner would be an additional $425 (or ~$275 for OEM / aftermarket). Total of about $1125, plus tax and/or shipping.

For my E500 head gasket job, I'm also considering replacing the water pump while it's apart (+$250 for dealer rebuilt & tank), assorted hoses related the timing cover (+$50), new cam sensor (old one was throwing a code intermittently; +$115), new knock sensor (old ones are cracked and falling apart, +$180, Bosch OEM), and some other odds & ends. Most items are not available OEM/aftermarket, most are OE/dealer only. The total adds up scary fast to $2k. Plus a couple special tools, and a few items that are easier to replace while the engine + tranny are out (i.e., the tranny blanket) and I'm looking at $2500. Just in PARTS.

Oh, and 100 hours labor."

Not trying to scare ya, as these are fabulous cars, but a realistic assessment is necessary at this point.
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post #9 of 23 (permalink) Old 08-18-2010, 02:55 PM
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Damn. I hate reading posts like this. Mine only has 84k miles but this makes me want to change the chain. So if the parts are $1125 then what is the labor cost?

2008 E350 4matic wagon
2000 E320 4matic wagon (sold)
2001 E430 4matic sedan (sold)
1989 300SE (sold)
1994 E420 (sold)
1988 300TE (sold)

Last edited by alexnatt; 08-18-2010 at 03:15 PM.
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post #10 of 23 (permalink) Old 08-18-2010, 04:33 PM
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I had mine done a couple years ago with around 100k miles at about 1200, I believe. But the 2 560's cost me 1600 each, a little more. Even their mileage are low, just want to get over with.

94 E420 200K, 92 500 SL 60K, 90 560SEL 69K, 90 560SEC 64K, 13 E350 5K
1989 300E 143k (Totaled)
1987 Porsche 930S 38K (Sold)
1987 300Z 138K (Sold)
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