Hood prop stay

[280sl1968]

Looking thorugh the old forum posts it looks like this has been raised a few times in the past.

The tension rod on my car won't hold the hood up. There seems to be a lot of spring tension in the rod itself, but when it sits in the prop block it just slides out and the hood falls. I thought the prop block might be worn, so fitted a new one, but the same thing happens.

From the point where the rod exits the bushing plate at the hood (where it forms the 90 degree right angle, to the end of the rod where it forms the hook shape that should sit in the block, it seems to have a noticeable shallow U-shaped curve rather than being straight. I wonder whether that is why it won't sit and stay in place in the prop block.

As I say, there is a lot of tension in the rod already, so I think another turn, while it would probably help, might be too much. I will try and post pictures shortly, but any suggestions would be appreciated.


Thanks

David

[enochbell]

I had the same issue about 10 years ago.  I replaced the torsion bar and that solved the problem.  Also, you can't add any turns to the bar, it only loads  with the 180 degrees of tension you get with correct installation.  Be careful, if you let it slip while installing...yikes.
Greg

[RBYCC]

Adjusting the block should remedy the problem.

[280sl1968]

Not sure how else to adjust it. There is some adjustment backward and forwards, but the rod end just doesn't seem to want to stay. I can only think that the angle in which it enters the block Is too shallow because of the curve that has developed in the rod.


David

[280sl1968]

Given their relatively low cost, I have ordered a new tension rod today from MB (P/N A1138870263).

If it doesn't work, then at least I've eliminated one possible culprit.

I have read the rod replacement instructions in the Technical Manual, and it sensibly advises removal of the hood first.

However, am I right in thinking that it is possible to remove and replace the rod with the help of a few people while the hood is still attached to the car?

I realize many will say DON'T DO IT because of he risk of snap-back damage and injury, but I can't help thinking that with a lot of care and time, it could be done.

The thought of removing the hood and then not being able to get it perfectly aligned again afterwards really makes me reluctant to do it the 'right' way.


David

[drmb]

The hood must be removed to replace the torsion rod,the rod must be pretensioned one revolution otherwise it will not work.
The hood has to be rmoved to remove the old one also.

[280sl1968]

OK. I guess what I can't figure out is how the rod could be turned one full revolution. When I look at mine, it can only be turned trough 180 degrees (ie. half a revolution) before you hit the hood again in the other direction.

David

[Benz Dr.]

I've run into some faulty prop rods that weren't made right. There was no that you could make them work regardless of what was tried.

[enochbell]

The bar can only be tensioned 180 degrees.  You need to remove the hood to accomplish R&R.  Mark the position of the hinges with grease pencil, that will make it easy to replace and keep proper alignment.  Be very careful to protect the perimeter of the hood when removing, use towels to protect the fender and cowl areas.

There is a special tool Mercedes uses to capture the short side of the torsion bar under tension.  I used a heavy duty wire coat hanger, which worked just fine.

Greg

[280sl1968]

OK, I have now fitted a new block and a new tension rod. If I'm honest, it now seems to have less tension than the old one I took out, doesn't hold the hood up, and now also wants to shift sideways out of the block.

What am I doing wrong?

1) The old rod I took out had been installed with the passenger/right side 90 degree short bent end pointing towards the back of the car.
2) Comments in this forum suggest that is wrong because the end is forced upwards against the hood skin when under tension.
3) So, I fitted the new one with that end pointing towards the front of the car.
4) Afterwards, before any tensioning, the left side of the rod sits at about the 5 o clock position looking at the hood side on. I was expecting it to be pointing towards the front (ie the 9 o clock position) so that I get the tension as I wind it back.
5) Accordingly, bringing the rod up to the temporary S hook (i.e. around the 3 o clock position) while I refit the hood was easy and there was nowhere near the tension I was expecting

I'm obviously doing something wrong here but I just can't see how I get more tension into this thing. There doesn't seem be a way to turn it a full or even a half revolution because the hood is in the way.

I really need some smart suggestions here as I'm out of ideas.

As a start, can I clarify that the right (short) bent end is supported to be pointing towards the front and not the back?

Thanks

David

[enochbell]

Hang in there, you will get this.  Yes, the small end after the 90 degree bend faces front.  It has to so that. when you rotate the support arm counterclockwise (RHD car) the pressure is exerted on the underside of the hood structure as opposed to the skin side.  If it is properly in the block then you will have tension immediately upon rotating the support arm upward and toward the rear, ready for capture by whatever method you are going to use to secure it to the hood in preparing to reinstall.  The blocks are "L" and "R", make sure you don't have them reversed.

Greg

[280sl1968]

Which block exactly are you referring to as being L or R? The actual rod support block looks symmetrical to me.

To be clear, this is the procedure I followed:

1) Insert rod through left side of hood from the outside.
2) Pull it through and insert the short bent end through the inside right of the hood, pointing towards the front, not the back.
3) At this stage I have done no pretensioning.
4) Tighten all the screws on the grey plastic bushings
5) Pull the support rod counter clockwise and attach to the temporary S hook on the edge of the hood. (From where the rod was untensioned to the S hook is barely 90 degrees, so it is adding some, but not much tension.

Am I missing a crucial step? It feels like it needs at least another half rotation to give it some more tension?

Such a disappointment when an afternoon project like this doesn't turn out as planned!

Thanks

David

[enochbell]

Just to be sure, here is the orientation of the passenger side block, is that what yours looks like?

Greg

[280sl1968]

Yes, visually that looks the same as mine.

I have seen other posts where the describe making a 360 degree rotation of the support rod before hooking it into the S hook.

That is exactly what mine could do with to get the tension in there but I just don't see how you can twist this through 360 degrees (ie one full revolution) unless you can pull the rod sufficiently far enough to the left so that it clears the hood edge as you rotate. Maybe I'm missing a step here?


David

[enochbell]

David,

Sorry, this is now beyond my pay grade, I am just a tinkerer.  But if you have even less tension with this one than with the last, which was obviously fatigued, then I would say that Dan may be right: you have a faulty rod.  What I can tell you is that, when working as it should, there is enough tension with 180 degrees load to be scary.  Does the rod form a bow shape, following the convex shape of the hood, when it is loaded?  It should.  Hopefully it is not to difficult to exchange the rod and try again.

Greg

[drmb]

With a new rod it's a two man job,put masking tape on the side of the hood one hold the hood the other turn the rod up to 360 deg.
then fit the safety hook.

[280sl1968]

I took this all apart today and started again. After a few hours work, I finally have a hood that works like a dream, so thanks for everyone's input.

I found that it is possible to put a full turn in the rod, but the way to do it is to ensure that the short bent end on the right side of the hood is not fully pushed into place. Push it about 75% of the way into its hole in the hood (pointing towards the front, of course) and this leaves the longer bent end on the left side just proud of the hood edge so that you can get a full revolution in the rod and enough tension to hold the hood up. The shorter bent end can then be fully engaged in the slot once the longer bent end is in the S hook.

After that, it is exactly as set out in the Technical Manual and other posts in the forum.

Happy to help if anyone runs into problems with the same job.

It is a minor thing in the scheme of things but having been on the to-do list for a long time it feels great to finally cross it off and throw away the old broom handle.

David

[frankenbenz]

Did this mean that you did not have to remove the hood? Or do you still have to remove the hood to do this? Lining that hood back up is such a pain in the butt, so I have my prop rod in place with an S-hook but un"wound". Plus, when the engine bay got shaved for a non-standard motor, the mount for the block just above the wheel well got cut off, so I'm waiting for a new one of those.

I'll definitely reach out to you if the day comes when I want to engage this bloody hood spring! Sounds like you were in the exact same position I was, but at least you figured it all out!

Ken

[280sl1968]

Given that I needed a full revolution of the rod to get the tension, the hood had to come off. There is no way to do it with it on the car, and the reality is, it is much easier to do with the hood off the car and on a stable surface.

I was reluctant to do it because of the whole hood alignment issue afterwards, but following the instructions in the Tech Manual (ie. just remove the hood bracket bolts on one side and leave the other side in place, and then slide the hood gently off the still fixed hinge), it went OK. Take your time and protect the paintwork as much as you can.


David

[searcher]

Sorry to resurrect this post (http://www.sl113.org/forums/index.php?topic=18654.0), but I have the same problem with my hood prop and this post has some really helpful information, so thanks all.

David (280sl1968) you mention an "S-hook" in a couple of places in the post and I'm not really following what you refer to with this. Are you calling the receiver block in engine bay that the hood prop rod slides on?

thanks,
Jason
1969 280sl
1987 GL450

[280sl1968]

Jason

No, the S-hook is a temporary item used to retain the prop (reasonably) safely under tension ie. pulled fully back anticlockwise towards the rear of the hood so that it sits in the S-hook in broadly the 3 o clock position when you look at the hood edge. This will let you focus on refitting the hood without the prop springing forward dangerously while you work.

I made my own S-hook but you can get them at the hardware store that will also serve the purpose.

Your left side hood edge should have a hole for this purpose that one end of the S-hook will slot into. I have heard one or two people saying they can't find a hole - could be that it's been filled in error at some point or that it just isn't there on some hoods.

I can take a photo if it helps you visualize everything.


David

[searcher]

David,

I follow you now - thanks for clarification. No need for picture.

Thanks,
Jason