M103 replace chain but not the guides?
 

Hello,

I have talked to a mech who said he can replace my '86 M103 timing chain without taking the front cover off. By threading it in the top. Price is good, but does not include the guides, etc. Said he will do guides if they need them (more money, but still a good price). I came to the mech is on a strong referral, so he should be legit. Does this even make sense?

Thanks

whenever doing a timing chain on a 103 motor it is best to replace the guides while doing the chain. That motor is known for leaks on the front lower and upper cover so why not get it all done at one time?

The 103 has a short, simple chain and a ratcheting tensioner. The chain itself is probably the least likely, of all Benz chains, to fail on its own. Unless stretched, replacing the chain itself is probably pointless. If anything is going to give trouble it would more likely be a broken guide or other part jamming the chain causing breakage.

My $0.02,

Euro 287, did you ever sell all your W124 stuff?

To follow up on Larry's comments, what leads you to belief that the chain needs to be replaced? The 103 chain is very long lived.

Duke

I have 174k, and have almost no history on the car before I owned it. I don't think the chain would need it, but am considering the guides, etc. for preventitive, and while in there might as well renew the chain. I feellike I am on a timebomb with the guides. Am I?

This is purely antecdotal, but I haven't seen any 124's for sale with blown valve timing, nor can I recall any (?) guide-related issues here. If you are determined to spend money, replace the CIS pieces ( air flow sensor, idle air valve, hoses, coil, injectors, temp sensor, OVP, etc.) that seem to plague these cars (my former car included) as they approach 200K.

And don't forget the valve seals.

And save some money for the head gasket replacement!

And if you still have some bucks, go after the climate control so you have heat on your feet! And dependable AC!

My $.01.

Mine has 267K with original chain. As long as the engine has not seen extended oil chain intervals, you should not have anything to worry about. That said, if it makes you sleep better at night go for it, but replace the guides or don't bother.

Have a great day,

Oil consumption is an indicator of guide condition. If oil consumption is "high" - say a quart in less than 500-1000 miles, you can consider having new valve guide seals installed. When the springs are off, the tech can get an idea of valve guide wear by the amount of stem wiggle. At that point you make a decision to pull the head and overhaul it or just throw on the new seals and keep driving.

If you do the head, then the chain can be checked for wear and replaced if necessary. Worn valve guides rarely cause any consequential damage other than high oil consumption, and 103 chains aren't even on the radar screen.

If your oil consumption is no more than a quart every 1000 miles keep driving it. I'm not having any fun at all unless I bang the rev limiter in second gear getting on a freeway at least once a week! 103s are really sweet between 5000 and 6650. ;)

Duke

Dont bother until you do the topend. Then replace the chain, rails and tensioner while resealing the lower cover. While in there I'd make damn sure to get a good seal on the silly step bolt in the fan bearing bracket.



Joe

These cars have rev limiters? I've never had the nerve to stay in it that long.

My Z06 hits the limiter all the time, though. :D

I think I misled, but no bother. I also think I have my answer, thanks everyone. I meant the chain guides (rails) not valve guides.

My oil consumption is not excessive, thought I do use more toward the end of the oil change cycle than when it is fresh. I use Shell Rotella 10/40 every 3.5k to 4.5k miles. Occasionally I get blues at startup, or a puff when I put the hammer down, but not always. I have not felt a rev limiter, but usually redline at the top of 1st or 2nd gear every day I drive it. Yes, the M103 is sweet. Between my father and I, my family currently owns 4 M103's. Yes I love my W124's. I've had my 300TE wagon at redline in 3rd at 105mph on the racetrack. Car ran better after that day.

If you are redlining the engine all the time, you are surpassing the torque peak and the torque is actually decreasing.

These engines are quite strong, but there is no engine that will have increased life by spending much of that life at the redline. They are very peaky engines, maybe too much so. I would personally give up some of the high end for some more mid range torque, it would go well with my manual transmission.

Reving it up is fun, but sooner or later there is a price to pay.

Good luck,

Famous saying on that point ,,,,,,, drive it like a racecar fix it like a racecar,,,,,, yea Capn I still got some 124 stuff layin around I am looking at buying 2 300e's in the next month for play toys. Now on the subject he can do a valve job and reaseal and chain and all the goodys. But if you are mind set on doin a chain do the guides. I have seen 2 chains fail due to rails on 103's ,, thats out of alot of cars though. Now if ya got an old v8 well do it every 100k like clockwork.;)

Thanks again all.

And Really, now, what a heavy guilt trip! I'm not running it that hard! (~_-)