1997 E320 Blown Timing Chain

[Bigdaddybenz]

Purchased a 1997 E320 2 months ago, noticed oil leaks (typical) around timing chain cover and possibly head gasket (car has 72,000 miles on it)...Pointed this out to "Used Mercedes Dealer" and he agreed to pay for repairs.....Car was sent to an indepedent with factory certified MB techs and they head gasket was replaced & timing cover resealed, got the car back and 3 days later while driving at about 40 mph the car shuts down...Open the hood and the valve cover has about a 5 inch piece of itself missing, timing chain's exposed and sloppy......Needless to say it's back at the shop now.....Wondering if I should dump this car as soon as I get it back???????....Are these engines that crappy????? My 1987 300E with the 3.2 runs like a charm.........I've never been so disgusted with a Mercedes Benz product in my life!

[stevebfl]

When they get done with the simple act of repalcing your head gasket (let me point out that they are still working on that job) you will have one of the most durable engines know to man.

ONE THAT NEVER BREAKS TIMING CHAINS!, unless worked on improperly. They undoubtably did something wrong and my guess is they didn't do the chain tentioner right. It is a ratcheting tentioner and it will protrude when unloaded and stay TOO long if not dealt with properly. Look here for more info:
http://www.continentalimports.com/ser_ic100345.html

There is a better description and this picture of the tentioner apart. It needs to be this way and then reassembled. If they didn't do that it explains the chain. I can think of no normal reason.

[Evan]

Speaking from someone who just did the timing chain on it, if the chain tensioner was not set correctly it would cause the chain to bind and snap i would imagine... so it semms as though the tensioner was not properly handled.. hope this helped..

[Kestas]

It sounds like one of the timing chain guides is broken, again, because of improper tensioner reset. The tensioner is essentially a one-way ratchet that needs to be disassembled and properly reassembled and set ONLY when the timing chain install is complete, including both cam sprockets and the chain guides.

[Bigdaddybenz]

Thanks, Steve and Evan, your views appear to be the most logical......I have to ask: Is there a good chance that the valves were also bent due to "piston slap" caused by the timing chain damage???????...I was never a MB tech but was an ASE mechanic........ My research has also shown that I probably should have opted for a later model E320 as they are equppied with the so called "bulletproof V-6".........Are E300 Diesels hard to come by? .....I have had far more better experiences with the mercedes diesels that I have owned!........

[Ali Al-Chalabi]

They MUST have screwed up when they replaced the head gasket. I would get on the shop that replaced the headgasket about this.

This engine will not break a chain when cared for. It has a double row chain with a short run and no complicated turns and bends. With proper oil changes there is no reason the chain won't last a min of 200k-250k miles. And even then, it won't break without giving ample stretch warning.

Each engine has its own minor faults. The M104 with the headgasket leak and the M112 with the harmonic balancer issues. You have a bullet-proof engine, trust me.

[stevebfl]

I agree with Ali, you have a great engine. I'll never forget MBDoc's answer to a question about why MB went from the 119 motor to the 113 motor. It went something like this: the 119 long block cost 25,000 and the 113 cost 13,000. That is undoubtably the correct reason. (I am estimating the numbers - they are close to what he said).

The newer motor is really nice. It may go forever, but it wasn't designed to be fixed. There are areas in the head that can't be dealt with without factory type equipment (not tools, but ovens and assembly jigs of a manufacturing nature - don't remember the whole story). The one area that most techs have been into is the front cover and a new cover doesn't even come with the holes threaded. The bolts are sort of self tapping, what kinda crap is that, but they work fine until broke. The cover we know about because of the balancer issue.

This is a whole different kind of machinery than that old 104 motor. Hard to say whether it is better. They work great! I really like that old 104 motor though and find it the best of machinery. But I like things made to be fixed.

[blackmercedes]

Having seen a few engines apart, I can say that in my limited experience, the line of MB engine with iron blocks and alloy heads produced post 1985 are some of the most robust gasoline engines ever shoved under the hood of a car.

The M111, M103, M104 and M119 are all very tough engines and I've yet to see one fail that hasn't been badly abused. Each has it's quirks, but they're minor and in no way cause complete failure. The M103 has the slight weakness of a single row chain, but in it's SOHC configuration, the chain is short and durable. It should be watched a little more closely than the chains in the others.

Check the cranks and journals on those engines. The V-8 parts from SBC's look weak in comparision.

As to the head gasket issue, pretty much every maker that produced mixed materials engines had difficulty mating aluminum heads to iron blocks. BMW, Toyota, Subaru, and others, have had this problem.

MB has been under intense pressure to compete on price. They have become a mass-market "luxury" maker that has to compete against Lexus, Infinity, BMW, VW, Audi, GM, and they no longer see an engine designed to last 500K or more as a sales advantage. Not many people are keeping their cars past the last lease payment anyway. That's not to say that the M112/113 engines won't last a loooong time, but the idea of cars as disposal items is becoming more and more prevalent.

Also, for those that plan on keeping their cars, MB would much rather sell you a crate engine than have people opening them up and fixing them.

Back to the topic...

It's obvious that the repair was performed incorrectly and should be rectified. When the head is back off, any damage to the valves and pistons will be visible. The M104 is an interference engine.

[MB Life]

BigDaddyBenz:

I also have the 96 E320 with the straight 6 with over 140,000 miles on it. It has never had an oil leak nor any timing chain problem. Maybe your car may have been had some abuse or neglect from the previous owners. Once its fixed, it should be solid and very reliable. Don't let one setback make you think this car is problematic.

[suginami]

Originally posted by Bigdaddybenz
My research has also shown that I probably should have opted for a later model E320 as they are equppied with the so called "bulletproof V-6

I don't know what gave you the impression that the new M113 V6's are "bulletproof". They have never been described as such.

One of the main reason for developing the V6 is cost. It can use the same tooling as the V8. They just cut off two of the cylinders.

The problem is that a 90 degree V6 is inherently unbalanced, and requires the use of counter-rotating balancing shafts to make it smooth. The V6 is definitely lighter because it is an all aluminum engine. It is also cleaner burning, due to not only better engine control management, and improvements in fuel injection, but mainly due the single overhead cam design with two spark plugs / 3 valves per cylinder. And this, I have read, is the other primary reason for developing this engine - having one cam, instead of two, produces significantly less smog emissions at start-up.

Another imortant reason why MB went to a V-6 over the I-6 is to lower the hoodline and shorten the engine for better packaging, both for safety reasons and aero reasons. The latter engines take up a lot less space in the engine bay, which makes service easier.

It is a shame that reduced cost and lower emissions were the primary reasons for developing this engine, instead of things like more hp or greater longevity.

[Bigdaddybenz]

Engine Totaled!!! independent filed insurance claim and $6400.00 later I finally have the car back! Now, after 2 days, check engine light is on "Engine Electronics", car misfires, lacks power.....stopped by the place that i purchased it from and they ran a scan "cylinders 1, 3 & 6 misfiring"......removed spark plugs, they look great.....replaced spitfire plugs with Autolites, car appears to run great.....I notice that the fault is triggered when accelerating over 2,000 rpms, early in the morning or when the ambient temp is over 80 degrees!.......I'm leaning towards wiring harness issues.........what are the chances that the wiring harness was effected by the engine swap???????

[suginami]

When you say "engine totalled", do you mean that they rebuilt your old engine, or that they dropped in a new one?

Your engine wiring harness should be fine. They were fixed back in 1995.

Misfires are usually attributed to bad coil wire connectors / resistor boots.

[Bigdaddybenz]

They dropped in a "so called" certified used engine that had about 25,000 miles less than my original engine!...All of the accesories came off of my engine as the new/used engine came as a long block. After, I picked up the vehicle it ran and accelerated better than it ever did in the past......Prior to the engine swao, I never had "check engine electonics" issues!.......I was concerned that the wiring harness my have not "liked' being disturbed...........

[suginami]

I don't think "disturbing the harness" has anything to do with it as it does not have bad insulation like 1993-1995 cars.

[Bigdaddybenz]

Sorry, I forgot to mention that the damage was caused by the technician forgetting to tighten the camshaft sprocket bolts during the original head gasket replacement job..........These things happen! Hopefully, not toooooo often!