HELP! - 2 broken camshafts!!!

I NEED SOME HELP/INFO/ADVICE!!!

Let me provide some background info on the problem.

Car - 1993 190E 2.3 (CA emissions)

Head gasket blew Jan 2000 @ 150,000 miles. Replaced head gasket and had a valve job and head surfaced while the head was off. After putting it all back together and receiving assurance from the machine shop that the head was not warped/damaged in any way, at the 1000 (approx) mile mark the camshaft broke (oem cam). No one could provide an adequate explanation for this except that it was an extremely rare occurrence. I learned from my parts place that this was a fairly common incident in Europe (2.6 engines also) and that MBenz wants to keep it quiet so they don't have to do a recall, don't know how true this is however. After again removing head/intake/etc (what a pain in the %$#) replaced camshaft with aftermarket hardened steel camshaft, low and behold at the same 1000 (approx) mile mark again the camshaft broke. SOMETHING is definitely wrong but I don't know what and nobody else I know that is mechanically inclined has a clue either. If anyone knows the problem/cause or has the cure or any other helpful info please reply.

Unless I can figure this mess out, I am contemplating replacing the head/cam and going from there, or possibly the entire engince and/or replacing the 2.3 with a 2.6. Thank you in advance for any response.

Rick

[Benzmac]

You have a warped head. The bottom surface may have been cut straight, but the top can still be warped. I have never seen a cam break in a Mercedes. The other thing is to check the amount of oil getting to the shaft.

You can take out the rockers and install the cam without the bolts in the bearing caps and just look to see how things are. This will give and idea of the condition of the straightness of the head.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

[stevebfl]

It seems to me that the 102 motor uses a ratcheting chain tentioner. If you have clean breaks with and no gaulling I would suspect that you are assembling the tentioner improperly and the chain has been running overtentioned.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

rick,

This dufus that told you that Benz cams are breaking all the time and that Benz is trying to keep it quiet. Did this dufus also tell you that blue aliens have infiltrated our government?

Both camshafts had clean breaks just behind the chain gear-wheel and before the first camshaft roller bed. On both occasions after reassembling everything, when driving the engine made an unfamiliar noise like it was stressed or over-tensioned. It also idled very rough while stopped and still in drive (stop sign/stop light) but smoothed out once moving again. This makes more sense to me than a warped head, but if I am installing the chain tensioner incorrectly I guess I don't know how to do it correctly. It seems pretty straight forward on putting it back in and torqueing down to specs. What am I doing wrong with this tensioner installation?

quote:

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Originally posted by stevebfl:
It seems to me that the 102 motor uses a ratcheting chain tentioner. If you have clean breaks with and no gaulling I would suspect that you are assembling the tentioner improperly and the chain has been running overtentioned.

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[stevebfl]

As I said in my personal email (w/pictures I can't show here), the tentioner is a ratcheting type whitch has to be assembled on the motor with the chain in place.

The body goes first then the piston and then the spring etc. If it is assembled out of the motor it extends all the way and WILL NOT GO back.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

[Benzmac]

Wow!! Having all of the info helps. Steve is right!!!!

The issue here Is the tensioner. I had a shop do this to my dad's 2.3. The timing chain snaped in less than 1 week. I had to do a complete valve job on the car.

You have to take apart the tensioner. take out the piston by pushing it through with a screwdriver or punch. Install the timing chain and rails and cam...
Install the new tensioner piston with c-clip and go one snap. Install tensioner into engine. NOW install the tensioner spring and outer cap. (after it is in the engine. When oil pressure hits, it will auto adjust and you can forget about it.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

[mbdoc]

From the sound of it the person who did the head gasket has caused quite a lot of problems. The chain tensioning rails are plastic & when this type of thing happens, this rail will wear out & plug up oil pick-up screen. The front cover & oil pan should be removed for inspection & NEW parts.

Thanks to all for the responses and info, I feel pretty confident it was that %#$@ tensioner!!! All your info was extremely helpful and the diagrams will help tremendously in putting it back together for, hopefully, the last time.

Any other info on tech/perf stuff for the 2.3 would be especially when r&r'ing the head.

THANKS AGAIN, Rick

Gee you blokes are slow..............

BTW the first clue to a broken camshaft is a hot and slow starter motor....amongst other things....