As was basically mentioned above the starter bolts can be very, very tight and hard to start. Not always if the starter has been off or changed out brfore.

Do not risk rounding off the internal hex in those bolts. Set up for the job the first time in a correct fashion. It has even required a pipe on the breaker bar for me once.

Very simular to the tightness you can find on the rear end drain plugs. You almost think you are going to break out a section of the rear end casing before they let go sometimes.

Having a partner guiding in the hex socket on the top is a good idea. Wrapping the connecting extension(s) and sockets with a couple of wraps of electrical tape helps too.

__________________
Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke

[QUOTE=Brian Carlton;2964288]This solution is strongly discouraged for the following reasons:

1) Driving the allen key with a 12 point box wrench seriously risks rounding the key. Most do not have six point box wrenches.

2) Maintaining the allen key in a perfectly straight attitude into the fastener is nearly impossible from above. There is no capability of providing any forward force on the allen key unless another person is utilized. If the allen key does not remain straight, the risk of rounding the key is high.

The preferred solution (minimizing the risk of failure) is to utilize a 1/2" drive hex bit with about 30" of extension, a 1/2" universal, and a breaker bar with added pipe from below. Forward force into the fastener can be maintained.[QUOTE]




Preferred by who? Sorry I am unconvinced. This may be a required solution. As a last resort. But can hardly be preferred.

You are worried about keeping a "perfectly straight attitude" on the wrench, yet you recommend using 30" of extension and a wobbly? That's funny!

Using 1" of quality hex key fully seated in the starter bolts, from above, is much more manageable in that regard.

Good tip on the 6 point box end wrench BTW. And to be careful if it's tight, you don't want to screw up and strip out the bolts. Also, use heat as required.

It's preferred because the use of the universal joint eliminates the bending moment that would otherwise be imparted to the tool. Furthermore, force can be applied in the forward direction to ensure that the tool remains in the fastener.

In your approach, you apply a significant bending moment to the tool greatly increasing the risk of failure.

Although you might think it's "funny", you don't have any understanding of the mechanics and the forces involved. Your approach, although possibly successful if the fastener is not exceptionally tight, can best be characterized as "risky".

As I stated, you only get one chance. Take your best shot. Your approach is not the best shot.

The post is to inform others on the forum of the danger of your approach.

Impact's dont tend to function well with multiple long extensions...

__________________
1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D

If the allen bit is good quality, a 12 point box will probably break before the allen rounds (personal experience on another vehicle- not Benz). So use a good quality tool for both, ideally a box with a lifetime guaranty.

A six point box ( or a 12 point, although better) may not get the wrench in the right position to put a long pipe extension on and have enough swing to break the bolt loose.

I think the easiest way to break loose the upper bolt is to use a ratcheting box on the cutoff allen, from above with a pipe, or from below with a jack.

I've looked into using long 30" extensions on my 83DT. Crawling under and seeing the oil and gunk on the transmission quickly made that not very appealing.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Yup, I'm with Funola. A box end wrench "choked up" on the allen bit FULLY SEATED in the starter bolt seems well enough to me.

And I may not "have the understanding of the mechanics involved", but I've been skinnin' knuckles on cars for 40 years. Thank you very much.

Y'all don't even know if his bolts are all that tight! All this dire talk on this forum of stripped bolts, crawling under greasy cars with long extensions and wobblies, bottle jacks, possibly removing transmission mounts just to get access to the bolts, needing an army of helpers, etc. Maybe for no reason. I read all the horror stories, and how-tos. How many people really need such extreme measures? Or is it just rehashing the same old threads?

It sure didn't make me eager to do the job. I put it off for months. Turned out to be a non-issue. I did it from above with a ratcheting wrench and an allen bit. And from reading this forum that's not even possible!

Your decision is made on the basis of what is easiest for you, not on the basis of the preferred method to guarantee success with a very difficult fastener.

I'm glad it worked for you, however, the physics involved with your approach dictates that it will fail with an exceptionally tight fastener.

This is for others on the forum who wish to take the easy approach. If it works for you.............terrific. If it fails, you're in a world of hurt.

I'll agree stripping out the bolts will be next to catastrophic. I don't agree the physics of using a 30" extension and a wobbly is better than a box end wrench. Necessary perhaps, but not better. Way more room for error and prone to stripping. I think we can agree to the need for care.

__________________
1982 300TD
1986 560SL

You don't agree because you don't understand the mechanics of it.

The fastener requires pure torque to remove. Anything other than torque will potentially cause the tool to rotate out of the socket head cap screw.

When you apply force with a hex bit and a box wrench, you are not applying pure torque. You apply force on one side of the fastener only. The tool bit must resist that force and it will desperately try to rotate out of the fastener. If the fastener is long enough and the bit is tight enough, and the force is not too great, you might be successful. However, be assured that you are not applying a pure torque to the fastener in any way.

When you use the extensions with the universal joint, you must apply a pure torque to the fastener or the wrench will simply fall down on the floor. One hand applies force downward on the breaker bar and the opposite hand resists that force with an exact counterforce upward. The result is a pure torque on the fastener and no risk of twisting the bit out of the fastener.

Furthermore, you have the capability of applying some forward force on the extensions to ensure that the bit doesn't back out of the fastener. However, because you are applying pure torque, it is highly unlikely to do so whether you apply this force, or not.

I state again that your solution is not preferred by anyone who wants to have the best possible chance of removing that fastener without stripping the head.

I should know better than to argue with a guy with 25000 posts, because clearly you have nothing better to do but wrangle. But what the heck. If one is using a wobbly there is a risk of not applying pure torque, as you say. There is great risk of the bit coming out and forces applied off angle. If more than say, 20 degree of angle I would not attempt without a helper to support the wobbly and hold the bit in the bolt. Your method is not without risk.

__________________
1982 300TD
1986 560SL

If you go and read my posts, I never suggested using a wobbly. I suggested using a universal joint. And, no, there is no risk of applying anything but pure torque when you use a universal joint for the simple reason that it is physically impossible. You may be correct in the fact that a second person might be required to support the contraption if a large moment must be applied while providing the necessary support. The use of the second person, however, doesn't detract from the argument of which is the preferred solution.

You should know better than to argue with someone with a mechanical engineering degree when you, clearly, don't understand what the person writes.

It's your vehicle. Do whatever you wish. For others on the forum, the method suggested by you is not without significant risk. If it works for you.............terrific..............if it doesn't, you're totally screwed.

The universal joint method if seated correctly applies more torque, and does less damage to the bolts.



.

__________________
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So you think my setup with an excellent quality 10mm Allen cutoff and a 10mm Gearwrench with a 4 ft pipe for leverage will deliver less "pure torque" than the setup with the breaker bar with 30" extension? Mind you the Allen is cut to the exact length to seat all the way in the upper starter bolt and the gear wrench is touching the head of the bolt. You have the advantage of seeing what you are doing. The Gearwrench allows you to take up any play in the system to choke it up and allow you to break free the bolt. Ahhh that sweet sounding crack with one quick jerk on the pipe is priceless. Provided the Allen bolt recess is clean and not previously rounded and the bit is fully seated, the only thing that can break is the Gearwrench, which has lifetime warranty.

I did try using long extensions on my 83 300DT. As I recall, it was a real PITA on jack stands. Getting the extensions in and all the pieces connected was next to impossible due to lack of room. On a lift maybe it's a different story.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I didn't find the extensions a problem at all. Assembled them all, slid under the car, fed them up beside the transmission and had my wife feed the hex into the bolt. Turned the breaker bar. Voila. Before I did it I read all the threads on here thinking it was some kind of Herculean task. To the contrary.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13