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Discussion Starter #1
OK... I'm stumped. I'm removing the old engine pipes from my 380sl. The passenger side bolts were 12mm and both of them snapped when I applied force. No surprise there, I expected that I would need to remove the exhaust manifolds anyway.

My problem is on the drivers side (left side). The bolts don't appear to be 12mm but they aren't 13mm either. A 12mm socket won't go over the head of the bolt but a 13mm socket is too big. The closest socket I have that fits the bold is a 1/2 inch but it fits a bit too loose for me to dare try to put any force on it.

The last thing I want to do is round off the head. It would be nice if the bolts come out but I don't expect them to... I expect them to snap like the passenger side but not being able to get the right socket to fit is making this very difficult. Its not like I can't get to it... I can see and get to the bolt very easily. I can even come in from the side if I turn the wheel all the way to the right... but no socket fits. Any suggestions? :confused:
 

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Maybe rust has made the bolt heads bigger? Try using a top shelf penetrating oil on the remaining bolts like Kroil. PB Blaster, WD-40 and most everything you can get off the shelf sux.
 

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Discussion Starter #3
Already soaked the bolts in Kroil for several days.

Update: I got the bolt out... in fact, it came out rather easily with a 1/2" box wrench. I measured the thread and the bolt is defiantly a M8 but the hex head is not metric... it measures exactly 1/2". In metric it measures 12.7mm. I cleaned the bolt on a wire wheel to make sure it wasn't rust I was measuring but nope... with the bolt head clean and shinny it measures 12.7mm. Go figure.

Now I need to remove the other bolt. This one is harder to get to. I'll let you know.
 

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Discussion Starter #5
What is the headmark on the bolt you removed?
Got the 2nd bolt out using the same 1/2" box wrench. Cannot determine head marks... too much corrosion. The bolts measure 8mm x 55mm with a 1/2" hex head. I'm the original owner and I never had any exhaust manifold work done nor did I do any myself. As far as I know this is the first time a wench was put on those bolts since the factory installed them 35 years ago.

Here's a photo of both bolts.

MercExhaustBolts.jpg
 

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Discussion Starter #6
Does anyone know the part nbr for the seal between the engine pipes and the exhaust manifolds on a 380sl? We used to call them donuts but I can't find any reference to them in the EPC.
 

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Discussion Starter #8
Could be but I have nothing to check it against. I could buy them ($16 wow) and see if the fit but I might just go down to AdvanceAuto and buy 2 that have the same dimensions.

Next question: EPC shows a nut and a bolt to hold the engine pipe to the exhaust manifold but it looks to me like the nut on my manifolds is welded on. Are they supposed to be welded or am I looking at 35 years of corrosion? :confused:
 

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I removed the passenger side exhaust manifold so I could get to the broken bolts that connect the engine pipe to the manifold. It turns out that I didn't have to do that because the nuts are pressed in and I could have used a drift to punch the swagged nut out and then just used a standard 8mm hex nut.

In the process I ran into that same strange situation... the 8mm bolt heads are 1/2" but the 8mm hex nuts are 12mm. What am I missing? :confused:
 

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Could be but I have nothing to check it against. I could buy them ($16 wow) and see if the fit but I might just go down to AdvanceAuto and buy 2 that have the same dimensions.

Next question: EPC shows a nut and a bolt to hold the engine pipe to the exhaust manifold but it looks to me like the nut on my manifolds is welded on. Are they supposed to be welded or am I looking at 35 years of corrosion? :confused:
Its a special nut that requires a special tool to install. Tool cost about $60.00. But I can loan it to you if you are interested. The nuts are swagged in with the tool. They can be easily knocked out from the bottom. Somewhere I have a thread on how to do this.
 

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Discussion Starter #12
Its a special nut that requires a special tool to install. Tool cost about $60.00. But I can loan it to you if you are interested. The nuts are swagged in with the tool. They can be easily knocked out from the bottom. Somewhere I have a thread on how to do this.
Thanks for the offer, I have a squeezer that will press those nuts in with no problem.
 
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