Impact to loosen head bolts? - PeachParts Mercedes-Benz Forum

cscmc1 · #1 05-27-2009, 10:21 PM

OK, the 602 has me confounded. I have broken TWO of the 10mm triple squares off in the head bolts on the 300d. The last one ripped my hand open good when it let loose. I got 4 of the bolts loose with LOTS of torque, but this 5th one is really irking me.

Any reason I can't try the impact on it (whenever Napa and/or Autozone can get me replacement tools)? Apparently King Kong must have torqued these when last they were done. I really don't see how else I am going to get it out; the torque was being evenly applied with a decent sized breaker bar. Stealership is too far away to make a run for the $30 Mercedes wundertool...

Oh, and I have the tip of the last tool stuck down in one of the recessed bolts (under the cam bridge). That'll be fun to get out!

What a PITA...

Thanks for letting me vent!

sixto · #2 05-27-2009, 10:26 PM

Do you have an impact rated triple square/double hex bit?

Sixto
87 300D

cscmc1 · #3 05-27-2009, 10:29 PM

Quote:

Originally Posted by sixto

Do you have an impact rated triple square/double hex bit?

Sixto
87 300D

Apparently not, if I broke two of the ones I do (did) have by hand, huh? I just figured that at least if I break another one with the impact, I won't tear my hand up any worse. I honestly thought maybe I had broken it on that last one. It's still numb as hell 2 hours later.

Thanks for the quick reply, BTW!

awsrock · #4 05-27-2009, 10:35 PM

Geez, sorry to hear about your hand.

I can imagine the frustration you must have right now!

cscmc1 · #5 05-27-2009, 10:41 PM

Quote:

Originally Posted by awsrock

Geez, sorry to hear about your hand.

I can imagine the frustration you must have right now!

Just be glad you weren't within earshot, Dan. I think I could have offended the saltiest of sailors.

All: please keep the suggestions coming. I'll be logging off soon but would very much appreciate as many thoughts as possible when I get a chance to check in again in the morning. Meantime, I'll ice my hand with a nice cold ale.

Brian Carlton · #6 05-27-2009, 11:12 PM

Quote:

Originally Posted by cscmc1

Just be glad you weren't within earshot, Dan. I think I could have offended the saltiest of sailors.

All: please keep the suggestions coming. I'll be logging off soon but would very much appreciate as many thoughts as possible when I get a chance to check in again in the morning. Meantime, I'll ice my hand with a nice cold ale.

If you can heat the bolt, it will lengthen slightly and the torque required to remove it will drop significantly.

Naturally, heating the head of the bolt........and not the head........is a bit of a trick.......

Lexxani · #7 05-27-2009, 10:39 PM

thats really strange that you've had that experience. When I did mine in my m117 the head bolts came loose with a little pressure from a 1/2 inch bar and a high quality bit. I used an air ratchet to pull them quickly, but I broke them free by hand.

I did buy the $28 tool from mercedes as it was the only way to get at the right bank rears as the brake booster was in my way, worked like a charm.

I think if you used a non impact bit on your gun and turned the psi down a little bit (id try 60psi and make incremental adjustments from there) you should be in a better position.

cscmc1 · #8 05-27-2009, 10:43 PM

Quote:

Originally Posted by Lexxani

thats really strange that you've had that experience. When I did mine in my m117 the head bolts came loose with a little pressure from a 1/2 inch bar and a high quality bit. I used an air ratchet to pull them quickly, but I broke them free by hand.

I did buy the $28 tool from mercedes as it was the only way to get at the right bank rears as the brake booster was in my way, worked like a charm.

I think if you used a non impact bit on your gun and turned the psi down a little bit (id try 60psi and make incremental adjustments from there) you should be in a better position.

I was hoping maybe to try just this. These bits I have are lifetime warrantied, so it can't hurt to try it. Odd that I broke two by hand. I my have to break down and order the Mercedes part if these keep breaking.

babymog · #9 05-27-2009, 10:45 PM

On my SDL I found two of the head bolts with the head filled with hardened steel, I'm pretty sure it was broken triple-square bit tips.

Anyway, the rest gave me no trouble with an S-K bit I bought decades ago for quattro CV/Axle nuts.

Back to the ones with bits inside: Drills wouldn't do it, burned up several special hardened bits, couldn't even center-punch them for drilling. Back to Autozone for the IRWIN brand internal-helix type bolt extractor set, about $20 in a nice blue plastic box. For the one external to the cam cover, the extractor worked great, no problems. For the one that was in the cam-tower, I had to grind the external hex off of the extractor for it to fit in the hole around the bolt head, but tapped it down lightly using the socket extension and a brass mallet, and it easily gripped and removed the bolt. I was tempted to use the extractor for all of the bolts instead of the triple-square bit, but no broken bit so it worked okay.

Wish your car were closer, we could do a 2 for 1 here, I am just starting the head R&R on my 603 before installing it in the '95.

cscmc1 · #10 05-27-2009, 10:49 PM

Quote:

Originally Posted by babymog

Wish your car were closer, we could do a 2 for 1 here, I am just starting the head R&R on my 603 before installing it in the '95.

Ah, if only... an offer like that, and I'd shine your shoes for life after that last debacle. Geez, this job is frustrating; I thought I had hit the downhill sprint after I got those guide rail pins out (FINALLY).

Thanks for the suggestions. I have the Craftsman extractor set... thought about trying it but spooked myself after I tore my hand up.

babymog · #11 05-27-2009, 10:54 PM

The important part of the IRWIN ones (might be the same as the Craftsman?) is that they are external, they grip the outside of the bolt head (the top/cylindrical part anyway), like a socket with an internal helix. Most of the extractors I've had/broken relied on a hole in the bolt.

I understand your pain somewhat, one of the reasons I've been dragging my feet on pulling a perfectly good M104 out of the '95 to do the swap. Murphy stalks me.

pawoSD · #12 05-27-2009, 10:57 PM

Interesting, I bought a set from auto-zone of the triple square sockets, and used the one that fit the head bolts on the 617 motor....I was able to loosen them all with my 18" half drive breaker bar without a problem...they were very tight, but all came loose with some power from the arm guns.

No broken tools....the set was only $12 for 3 different sizes.

cscmc1 · #13 05-27-2009, 11:01 PM

Jeff -- yep, my Sears set is the same... but I bet I'll have to grind them down to fit, too.

Pawo -- the AutoZoo set is the second bit I broke. They are out and won't have any more in 'til next week. Grrrrrr... the first bit was a Napa tool. That was the last one they had in stock, too. It actually twisted quite a bit on the first few bolts (!). You could see the twist in the splines above the section that was seated in the bolt head. These didn't round off one bit, they just snapped!

Thanks again, fellas; I need to get to bed, but please keep the ideas coming. I appreciate it.

babymog · #14 05-27-2009, 11:06 PM

Just grind the hex part round, I didn't need to get into the strength of the part. I suppose there's some risk of losing the temper if you get aggressive with the grinder and overheat the socket. Smooth is best when you're finished, any notches can be stress risers and allow the tool to stretch or break.

mytmousemalibu · #15 05-27-2009, 11:34 PM

Heat works wonders somtimes, but dont wanna get it too hot and soften the bolt. A micro butane should do. I would also put a punch down in the bolt head and give it a good rap with the hammer. I would also give an impact a shot, the fast whack of the internal hammers will put more twist force to the bolt than a slow pull by hand, but use descretion

I have gotten by doing that a few times, even on non impact rated tools. I'd wear some safty gear and prehaps wrap a towel aound the area to stop flying bits should there be any. And should you have anything want to strip, a small dab of valve lapping compound will add some bite. Hope that helps!