300E, 1993 3.2L M104 timing belt too tight and Direction of crank rotation
 

Quote:
Originally Posted by MikeTangas
Anytime you do anything with the timing chain, such as replacing or removing for head work, you should always manually roll the engine over at least two complete revolutions. You roll it over at the crank bolt and two revs takes you through a complete cycle. If you did this before hitting the starter, then likely your timing is retarded. If timing was advanced, you would not be able to make two complete revolutions by hand due to piston/valve contact.
I am having similar problem with my car. It is Mercedes 300E, 1993 V6, 3.2L. I made a mistake of not setting my crank on TDC before I changed a leaking head gasket. I have tried 100* to set my timing chain in vain. I have followed all the procedures outlined in the manual and what the MB experts have adviced hear to no avail.
-Everytime I set TDC and dowel marks as adviced and set the intake camshaft in the retarded position, the engine will not go through two complete revolutions without getting stuck. I am rotating the engine clockwise while standing infront of the car facing the engine/ motor. It this the correct engine rotation or am I doing it wrong?
- I tried to set everything again as above and rotated the engine counter clockwise(CCW) and the crankshaft completed 2 revs to get back to the previous mark (TDC). However, I could not rotate the crank/engine when I tightened the chain tensioner all the way in and my timing chain is getting very tight to the point that I am afraid it might break. Please help me with:
*direction of the engine rotation. Why do I have valves touching the top of cylinder in clockwise crank/engine rotation. Not so much when I rotate it in CCW
=timing chain tightness issue...what would be the remedy? I always disassemble the chain tensioner before I put it back to manually rotate the crankshaft.
I am waiting dumbfounded. I don't want to mess this baby because the body and interior are in such an excellent shape.

hello

engine rotation is clockwise.

IMPORTANT: i've done some research on the the m104 timing chain, and if i remember correctly, you do not want to turn the engine counter clockwise because it can cause chain guide damage.

your problem might be that you have not turned the intake camshaft adjuster clockwise to the retarded position (with chain off turn the adjuster clockwise until it stops, then put the chain on the intake cam sprocket.)

good luck

Timmyr,
Thanks for reply. My confusion is if the engine rotation is clockwise in relation to being in the driver's seat facing the front or clockwise standing infront of the car facing the engine/motor.

Clockwise was a bit brief. It's clockwise when you're standing in front of the motor.

What you feel as resistance when you turn the engine may be compression in the cylinders. Try removing the spark spark plugs which will relieve the compression.
If you are turning the engine and feel a definite netal to metal contact then either your intake or exhaust gears are set at wrong position.
Having the chain tensioner installed should not have any bearing, it should be in.
I don't see how the timing chain is getting so tight it might break - that is an incredibly stong chain that I doubt you could break by hand turning the engine.

From experience in doing an engine timing when the valves did hit the pistons, you can tell the difference between it and compression VERY easily - as in you can go within a few seconds quite easily if it was compression whereas the binding will prevent movement again and it can be difficult to back off that point via the crank as well.

Are you saying you turn the engine with the tensioner out? That'd be a nono... esp if you turned the engine CCW. The timing could be WAY off as a result of that.

You can tell the difference between compression resistance and valves hitting pistons but someone else doing this job the first time may not. The compression resistance can definitely be strong enough to think you are doing something wrong...until you learn the feel.
I don't know how the binding feels and whether its hard to back off - haven't been there.
Reg timing chain, what I said was it should be in. My meaning about it having no bearing should have been more clear - meaning the tensioner should not cause the timing chain to break and it should not be removed to crank the engine by hand. Without the tensioner in, the intake gear position was off. Soon as the tensioner took its place the intake gear snapped to proper position (tensioner took up the slack/I couldn't feel any slack was even there)

I finally decided to and buy an engine hoist after($108 after tax...ouch) after renting for one day ($47) and putting cylinder head back together. For Every turn I was tryied to align my TDC with the dowels and do a manual rotation by hand, it looks like I took a lick on top of the piston surface. It's not major but it's definitely visible. I hope it's not significant enough to cause a loss in compression once I put the engine back together. I will keep you updated.....and yes you can tell when you are hitting those pistons with valves when you are trying to set the timing chain. It's going to be small resistance with compression but once you hit the piston head it is going to be a binding stop...no movement at all.

Everything back together on 93 300E 3.2L but won't start
 

Hello everyone, the car is finally back together but it will not start. It does crank up but will not start. Just one of the problem I had that I think might be contributing to my no-start condition:
Everytime I tried to align the dowel marks and the TDC, I could not make two complete crank rotations without hitting piston surface with valves. As a result, I was only able to align TDC and intake cam dowel only while exaust cam dowel stayed about 50-70 degree above leveling surface.
--Now I am debating if I should take the cylinder head cover off again to try aligning the exhaust cam dowel though I tried so many times to no avail? Could there be any other reason that the car will crank but not start after changing head gasket? Please help with any troubleshooting ideas so that I can get this baby back on the road.
...side note: when I am cranking, the engine feels a little whimpie (could it be there is no enough compression for spark and start the car) hence cranking but no start diagnosis? I went and tested the battery and it shows the battery has got full strength. I feel stuck really bad.

If the timing is off the valves aren't fully closed on the compression stroke so the engine will never run. Why would you ever attempt to start the engine if the pistons hit the valves when rotating the engine manually? That condition will result in major damage.

hello,

if i were you, i would not remove the cylinder head again.

try the following instead:


1 disassemble/remove A) Radiator B) Timing chain cover C)Valve cover D)Air pump E) remove fan blade F) remove auxiliary serpentine belt

2 by hand, turn the crankshaft pulley clockwise to 30 degrees BTDC(Before Top Dead Center) = this will allow you to turn both camshafts without any piston interference

3 then remove the timing chain tensioner

4 then remove the exhaust camshaft sprocket, and make sure to keep an eye on the timing chain(i usually tie it to the thermostat housing with some wire) , you dont want it to fall off the crankshaft sprocket, if it does you will have to remove the lower timing chain cover, which is a very difficult job.

5 now take a good look at both camshafts, near the number 5 cyl (1cyl=closest to the radiator; 6cyl=closet to firewall) you will notice that the cams have flat spots, find the appropriate sized wrench(roughly 29 mm), and turn each cam clockwise until the timing markes/holes on each cam are aligned with the cylinder head surface(4mm drill bits can be inserted in each timing hole, turn each cam til the 4mm drill bit is touching/level with the top of the cylinder head surface)

6 now you can untie the timing chain and begin turning the crankshaft(clockwise) by hand until the OIT mark on the crankshaft lines up with the crankshaft pointer.

7 proceed with chain installation, just make sure to turn the intake camshaft adjuster clockwise to the retarded position (with chain off turn the adjuster clockwise until it stops, then put the chain on the intake cam sprocket)

8 after you've gotten the chain on the intake cam, take care of the exhaust camshaft as well. NOTE:make sure that the chain is properly seated in each of the chain guide rails before moving on to the next step

9 now you can install the chain tensioner (remember to take it apart completely, install the tensioner body/housing first, then proceed with the tensioner plunger/piston)

10 you should be able to turn the engine over by hand, without any piston interference. double check your timing marks, make sure that they all line up correctly.

hope this helps.

good luck

Thanks Timmy. I will follow your procedure and give you updates

I can not proceed past step 6 of your procedure Timmyr
 

Do you have any suggestion of how I should proceed? I knew I had tried many times to set the dowels and crank TDC with no success. I always hit cylinder head with valves when I do hand manual rotation. Should I try 40 or 50 BTDC and keep increasing until i get a clearance or my thinking is wrong here? I am dumbfounded why other people have been successful and i can never seem get the 2x manual rotation once I set dowels and TDC in place. Please reply I am waiting.

Dejavu.
 

There is a stray link on the timing chain where it comes off the crankshaft. I've dealt with this problem more than once, especially on M111 witch has almost identical timing mechanism. That also explains the overtensioning of the timing chain. To fix this you need to remove the tensioner and both camshafts, find a t-shaft and 27mm for the crankshaft. Set the timing to TDC and grab the timing chain by hand pull it upwards not using to much power just to take of the slack. Turn the crankshaft 20-30 degrees both ways until you feel the stray link straighten out (you feel the chain getting longer) re-assemble and set timing.

Daddi,
I figured what was was casing ''too tight timing chain''. I was not assembling the chain tensioner properly.... First the hub, then the spring and finally the metal plunger insertion and the end cap before installing it in place. I do not have a tight chain anymore. My problem and concern is that when I install the timing chain correctly, I get valves hitting the cylinder heads. I have tried several time and I can not get past this point. I have tried to align the dowels slightly off the TDC but then I think I have ran into another problem....no enough compression stroke to start the car. It will crank and turn the engine over but will not start. Now I am contemplating if I should just align the dowels and TDC and ignore the valves hitting the pistons/cylinder heads and try to start the car. I know I will risk cracking cylinder heads or bending and cracking valve stem but I seem to have run out of ideas. I have scoured the forum and done google search many times and I don't seem to find my way out. Does anyone out there know any trick that might help me out? Please!