69 220D tension rail pin (can't remove) - PeachParts Mercedes-Benz Forum

Ralph69220d · #1 11-05-2005, 07:31 PM

First, I want to say that I have the MB Srvc Man for my 69 220D. I also did searches to see if anyone has encountered and/or solved the problem I'll describe. It is the tension rail which needs replacement. I have reason to believe the car had this problem when I bought it. The timing chain seemed to be a bit noisy. I pulled the valve cover and saw the tension rail had somehow moved towards the front of the engine at an angle half-cocked so that it was only pushing on the timing chain at the outer link of the forward chain (double-roller chain). Studying the manual I could see only two reasons that the tension rail could cock itself like this: that would be if the hole on the bottom of the tension rail had broken so that it is no longer secured by the "thrust pin" "pin bearing" (I've seen it referred to in both these ways), or somehow it is possible to miss the tension rail hole with the thrust pin before I got the car. To see how difficult it would be to pull the pin I first pulled the pin on the chain guide adjacent to the cam sprocket with an M6 bolt and washer's. I had no problem pulling this pin. So, when I put the crank at TDC so the recess in the balancer lines up with the tension rail pin I approached it in the same manner. First thing I notice (still using the same stainless stell M6 bolt) is that I only get a few threads in and, I think, but I don't know, it appears the pin is spinning with the bolt. So, I remove my M6 bolt and it looks in good shape leading me to think I'm not cross threading it, though in my temporary living arrangement I don't have access to my tools, and I can't get a good view to see if someone previous to me had damaged the threads in the pin, preventing me to get the pulling bolt further in. The manual lists both a M6 and an M8 bolt for pulling with an extractor (which I don't have). I can't imagine it's an M8 hole or I'd get no bite using an M6.
Is it possible that someone previously had put in a new tension rail and it didn't slide all the way into position and the pin completely missed the hole in the tension rail? I guess the point is moot if I can't get the thrust pin out anyway.
Can anyone tell me if the M6 bolt used to extract the guide rail thrust pin is the same size (M6) to remove the thrust pin for the tension rail? Do you think my guess is correct that the M6 as soon as it gets a bite, but not enough of a bite to extract, is spinning the thrust pin preventing me from getting the bolt to thread in?
One last point in this saga. The chain tensioner thrust rod at some point in it's life rode directly on the chain and chewed it up badly, so it'll have to be replaced. But, it seem's to me that was a previous problem as the timing chain looks in good order and timing is dead on center on the cam/crank.
Any help in getting that thrust pin out for the tension rail would be appreciated. I'm embarassed to say I don't at present even have the cash to rent a proper extractor. The big thing is if anyone has had problems with the pin, the half-cocked tension rail and was the lower part of the rail busted that resulted in this.

t walgamuth · #2 11-05-2005, 10:43 PM

i doubt that that pin is holding anything if it spins right away. if you grab it with vice grips and carefully pull straight out i bet it will come right out. when they are holding things they will resist and not turn. do you have the rad out? if not better get it out of the way so you wont break anything off.
the bolt for pulling is one like or from the thermostat housing. b e careful taking them out they are often very fragile and half eaten away.

good luck.

tom w

Ralph69220d · #3 11-06-2005, 05:47 AM

Quote:

Originally Posted by t walgamuth

i doubt that that pin is holding anything if it spins right away. if you grab it with vice grips and carefully pull straight out i bet it will come right out. when they are holding things they will resist and not turn. do you have the rad out? if not better get it out of the way so you wont break anything off.
the bolt for pulling is one like or from the thermostat housing. b e careful taking them out they are often very fragile and half eaten away.

good luck.

tom w

thanks for the thermostat housing bolt tip. yes, i do have the rad off. vision's of driving something through the rad overcame my temporary confusion. i can only see the top of the tension rail right now, it doesn't look like any of the 3 types of rail in the manual. i've been lucky the chain didn't come off. thank's for all the help you've given me.

t walgamuth · #4 11-06-2005, 08:22 AM

not look right because parts have broken off. or it may have fallen down into a place where it shouldnt be.

tom w

mbshop · #5 11-06-2005, 04:43 PM

stick yer engine on top dead center first.
now take the cam gear off. now look inside and see if the tensioner rail
is worn or damaged. we are talking about the curved rail, right?
ok, you now can also see if the pin is moving while yer trying to
tighten the 6mm bolt into the hole of the pin. if it is then
you need to tap out the hole. if you twist the rail hard it should
be enough to hold the pin so you can tap it out. then go from there.

george

t walgamuth · #6 11-06-2005, 07:42 PM

i dont understand what you mean by tapping it out.
could you offer a little more info please?

tom w

mbshop · #7 11-06-2005, 08:06 PM

Quote:

Originally Posted by t walgamuth

i dont understand what you mean by tapping it out.
could you offer a little more info please?

tom w

you said that the bolt would only go a few threads into the pin.
the bolt needs to go in the pin full length. thus the tapping out
the pin. don't want to strip out the threads.

george

Ralph69220d · #8 11-09-2005, 12:24 AM

Thanks,
Yes, I did tap the thrust pin and a 6mm bolt goes all the way in. My present problem is I haven't found a 6mm bolt long enough to be of use (60mm would be just about right). I'm at my sister's house here in Illinois so I don't have my tools (Montana). A piece of 6mm running thread would be nice so I could make my own impact extractor. I had no problem pulling the guide rail next to the cam as that thrust pin can be taken out with a short 6mm bolt. So, I'm in good shape with cleanly tapped threads in the pin, just need to find running thread or a longer bolt. I know the tnesion rail and chain tensioner are both shot.
Ralph

mbshop · #9 11-09-2005, 02:17 AM

don't know how long yer bolt is but you got a pickle fork?(tierod tool)
got two big screwdrivers?
get a big washer and stick it behind the bolt. now pry between the block
and the big washer. voila, pin is out. variations are allowed.

george

t walgamuth · #10 11-09-2005, 06:13 AM

the bolt from the tstat housing? this bolt along with a stack of washers has always worked for me. you have to work it a little at a time.

tom w

Ralph69220d · #11 11-09-2005, 06:54 PM

Quote:

Originally Posted by t walgamuth

the bolt from the tstat housing? this bolt along with a stack of washers has always worked for me. you have to work it a little at a time.

tom w

Tom, I just bought a new stainless steel bolt. The female threads in the thrust pin were stripped so I tapped them out. I don't have a slide hammer, but vice grips orthogonal to the bolt, using the harmonic balancer to pry against got it out, but it sure is one tight machine fit. I'm sitting here looking at the destroyed tension rail and destroyed chain tensioner. The tension rail is the original steel rail with rubber backing. Half of the face the chain tensioner rides against broke off. The contact surfaces of the tension rail and chain tensioner were both chewed up something horrible. Miraculously, the camshaft timing is dead on where it's supposed to be. Ordering new parts, so should have it up and going in the not too distant future. I'm replacing the other chain guides just as a matter of course. Can't see the bottom one's without removing the little plate, but the top chain guide is pretty worn. Thank you and everyone else for their help.
Ralph

t walgamuth · #12 11-09-2005, 07:00 PM

you have it under control.

good work.

tom w