What's the reasoning behind all the hex head bolts used on one these cars? (and other cars)

They seem a lot harder to get a bite on, fill up with dirt and grime and since it's a female connection, a lot harder to clean that grime out before inserting your allen bit.

As of now I'm specifically referring to bolts that are used to hold on the engine oil pan and other bits and bobs around the engine/transmission (trans hardline clips, vac modulator, dip stick, etc etc)

All of them are filled with grime and half of them strip out when I try to remove them. I have been replacing the stripped ones with new hex head bolts. If I remember off the top of my head correctly they are m6 x 10 thread.

After thinking about it I would like to change them to regular 6 sided m6x10 bolts (I don't know the proper term, just always have refered to them as bolts) so they are not so hard to clean off and remove in the future.

Just wondering what the reasoning is behind using the hex heads? and if replacing with standard would be an issue?

I also see hex heads used in higher torque higher strength applications (like flex disc and etc) what's the reasoning?

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First off, let's use the proper terminology.

Those are "socket screws/bolts" NOT "hex" bolts. Just one of the reasons for using them is for allowing for a closer fit around surrounding components.

Socket bolt/screw


Hex head bolt

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

They can be a pain I'll agree. I use some sort of hefty needle like thing - lately a scratch awl that looks like an ice pick - combined with copious use of a WD40 can that still has pressure and the nozzle. Even so they can be fragile.

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1986 300SDL, 362K
1984 300D, 138K

If you clean out the socket they are pretty hard to strip. They provide more room around the head and you can use a more compact socket to get them on or off. Clean it out and keep your drive square and you will grow to love them.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Why would we know Mercedes's reasoning. The other issue is Mercedes expects the vehicle to be serviced by their trained Mechanics and scrupulously kept clean.

When there are assembling the Car at the Factory perhaps there is some advantage to using socket head/Allen screws. When you stick an allen head bolt on the allen wrench it retains some alignment. You can insert the bolt with it still on the tool and it will go right in the hole.
With hex head bolts it is more reliable to insert the blot into the hole by hand and then apply the tool.

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84 300D, 82 Volvo 244Gl Diesel

That's a big one.

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1986 300SDL, 362K
1984 300D, 138K

hahaha yes this is correct. thanks !!!

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I literally waste at least an hour per job big or small Cleaning out bolts. haha I hate it

all in all basically I was just asking if my oil pan or etc would leak for some reason if I switch the bolts. doesn't seem like it.

it's just hard to find grade 8 or 10.9 in these bolts for less than $2 a piece

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It won't leak but clearance to get a wrench on your bolt heads might be a problem.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Ace Hardware usually has a wide selection, all grades. Don't remember ever paying $2.00 apiece for them.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Finding a metric bolt in Grade 8 is impossible. Grade 8 is an SAE specification.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Grade 8.8 metric

yes I obviously don't know the correct terminology I'm just refereeing the stronger bolts

And I yes I just went to ace hardware last weekend I bought 4 of these hex socket m6 bolts for that were 3/4 of an inch long for $1.69 a piece. So ya I am exagerating and bit but that was just for a small size the bigger ones got up to $2.

Seattle does seem to more expensive than the rest of the world for some reason tho

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Don't know the correct terminology I'm just refereeing the stronger bolts. But haha ya I just figured the store didn't carry the metric sizes of grade 8.

And I yes I just went to ace hardware last weekend I bought 4 of these hex socket m6 bolts for that were 3/4 of an inch long for $1.69 a piece. So ya I am exagerating and bit but that was just for a small size the bigger ones got up to $2.

Seattle does seem to more expensive than the rest of the world for some reason tho

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Ya it does have that lip there on the edge of the pan huh

So it seems tool clearance and being able to put the bolt on your tool and maneuver it into place, rather than fumble and squeeze into tight places with your finger or socket, are to pretty good PROS for these type of bolts.

Now you guys got me thinking and it's making a lot more sense as to the certain applications of both bolts

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