I few weeks ago i was driving my dad's 240 and it blew the timing belt on the highway, so i decided i would do the change since i have done it on my 740 before.
So, last night i was changing my timing belt on my dad's 240. After i marked the car for TDC on the camshaft, i decided to remove the bolt for the camshaft. But right before i went to remove the bolt, i ended up knocking it off TDC. Unfortunetly i forgot to put it back and i went ahead and removed the bolt. I didn't notice my error until after i took the drive belt pully completely off and noticed that the notches were way off. Well, being stupid and thinking i could correct my problem, i went ahead and put the bolt directly onto the camshaft pully and preceeded to move the camshaft. I figured i could move it back to TDC manually. However, i then noticed that i have to way of actually making sure that i'm on TDC now. SO here is my real question. How does one check to make sure that the camshaft is on TDC without being able to check the marks? I've already turned the thing a number of times trying to fix it but now i'm scared to even start it thinking i've knocked it way off.

I figure the only way to correct my problem is to try and match the marks on the belt. Is this true? I don't want to change the damn thing and then turn around and blow the engine when i start it.

Thanks for any help. Its been a long time since i've needed any.
--
-Brandon at FSU '88 744ti 156k miles

Relax.

I figure the only way to correct my problem is to try and match the marks on the belt. Is this true?

Yes, this is true. If the crankshaft is anywhere near TDC all you have to do is match up the marks on the timing belt with the marks on the pulleys, and you're good to go.

If it makes you feel any better, you have a non-intereference engine so it won't be damaged even if you get this wrong. Try putting it together half-way (without the fan, belts, and timing belt cover) so you can watch it when you start it up. That way if you can visually see what's going on and you won't have so far to go if you have to open it back up.

The timing marks that are found on the engine casting (and rear timing belt cover) are extremely reliable. They were placed there by the engine designers.

The timing marks painted on the belt are are extremely UNreliable. The were placed there by some poor 10-year-old kid working 14 hours a day in an Asian sweat shop.

We get your point, but you make it sound like the ten-year-old picks up a belt, counts teeth and paints lines on one. Ha ha.

Agreed. I can't say I've ever used the marks on any belt for alignment purposes. I don't even think all belts have proper marks. The dimples on the pulleys, the covers and casting never change, and are the sure way to put it back together.

The only way you'll have confidence that the belt is installed correctly is to take some time to educate yourself on how enigine timing works. Understand the relationship between the positions of the crank shaft, cam shaft, intermideate shaft, distributor shaft (rotor), and distributor body (case). If you try to "cookbook" this job there is a high probablility you'll screw it up. jp

1) No problem, assuming you meant Crankshaft wherever you said camshaft.
2) Review FAQ Timing Belt procedures before touching any more tools.
3) With the Crank pulley off, there should be "dished" belt guide washers behind and in front of the toothed belt drive sprocket.
4) One or both guide washers will have a NOTCH that matches to a raised reference MARK on the aluminum crank seal housing when the crankshaft is at 0° Top Dead Center for #1 piston. (The mark points up towards CAMshaft). There is also a punch mark on the sprocket itself.
5) You can turn the crankshaft with the bolt as needed to get back to 0° (pull spark plugs to make it easier).
6) Check/align the Cam and Intermediate shaft pulleys.

TIP: When fitting the belt, start with the double lines in the crank sprocket 0° mark. You'll have to wrap the belt about 1/2 way around the pulley to match up the lines to the tooth/space mark. Then jamb something (i.e., clothespin) under the sprocket to keep the belt meshed with the sprocket teeth, as it will "unwind" when you let go. Then continue with Int and Cam pulley fitting, keeping tension on the belt as you go.

I don't know how you loosened the pulley bolt, but I'd recommend the "Rope Trick" to torque it back on correctly (44 ft lb plus 60° more).
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

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You do not have any need whatsoever to mark anything, no need to use any belt marks, nor do you need a sextant and accurate longitude and latitude to get the timing belt on. ALL marks of interest are right there in front of you on the inner t-belt plastic plate, or on the distributor lip itself. It is reallt sesame street simple when you recognize the marks:
1) set the cam to its BMF obvious mark
2) set the crank to its vertical bas relief mark (on the rear belt cover), using the belt guide notch
3) Make sure the distributor rotor is pointed dead set due spot on the mark on the lip when that belt is in place.

You can't go wrong, you will do the job in half the time of an average pro and it will never be off a notch. Just have all pulleys snugged up before the belt goes on.

"What parts do I need?"

I think you forgot a couple...

6) My car doesn't start...
7) My engine dies...
8) I get this clunk in the...

And you left out new threads starting with "The latest in my saga...".