Help Merc 700 Header Bolt Trouble
 

I am fresh out of explitives. I removed the headers on my 2007 700 SCI's to pressure check them. They were all good thank fully. The boat is a 32 DCB and there is very little access to the outboard header. I removed all the accessories from the 2,4,6,8 side. I got all the headers back on but something is going on with the lower bolt between 6 and 8. It will not start in the head. I loosened up the rest of the bolts so I could really jockey the header around with no success. Spent about 4 hours last night trying. I am bruised up and defeated. There is no corrosion anywhere. I wonder if anyone else has experienced this or has an idea how to get it done? Thanks

If the bolts go in the heads ok then drill the flange a little bigger.

remove header and install a piece of all thread into the problem holes, hang headers on the all thread install nuts on all thread to hold header then install the other bolts snug. remove all thread and replace with bolts 1 at a time. that should solve the problem. If you double nut the all thread it should remove quite easily.
good luck

I would just try a 3/8-16 tap to clean up the first thread

That's a clever trick. Cool.

you could also use studs from the hardware store to avoid any thread problem with all thread where cut, I always use the factory cut ends for installing into my parts.

ARP makes make nice stainless studs. They are expensive! we us 2 per head. Really makes life easier.
Steve

I was just gonna suggest that!! Steve stop reading my mind lol

If you still have those valve covers Big chiefs PM me a price. would like to get the badges off the tops of them.

Thanks for the great suggestions. Im armed for another night with tap, stud, drill bit. Im also going to take a look with a borescope. Thanks again Ill report back.

I got it last night. I used my borescope to take a peek of the problem bolt. Problem was that it did not line up. The borescope was awesome, I could even inspect the threads and see that they were not the issue. I remove the header and enlarged the hole in the direction that I knew from the scope. Used all thread in the problem area. I could not get nuts on it because it was so close to the exhaust tube. Put in the rest of the bolts, removed the allthread and the other bolt went in fine. I think studs would make the job much easier, but it looks like the space is so tight in a couple of locations that you wouldn't be able to get a nut and socket on. Thanks for the ideas!

If you have the tools make a "mini tap" out of the very end of the header bolt . Read that tip in car craft magazine 20 years ago and still use today .can take you from pulling hair out and kicking dogs to done deal in minutes. Also like to use the small 1/4 ratchet and socket for getting them started. Tips for next time i guess

You might want to get stainless allen head bolts when it is that tight...