Differences

This shows you the differences between the selected revision and the current version of the page.

exhaust_manifold_bolts 2013/10/26 12:33 current
Line 1: Line 1:
 +OK guys, I had to pull my intake and I wanted to pay very close attention to the ongoing exhaust bolt problem. Here is what I found. I reached up behind the exhaust manifold to see what the bolts felt like on the back side, they felt very rusty. I though this was strange because I know the bolts are stainless. I soaked everything down with PB Blaster and lined up my tools. I used a 3/8ths drive socket and ratchet for this job because I did not want to put to much torque on the bolts, very easy to do with a 1/2 inch drive set. I always use 3/8 drive for anything under 3/4 inch head bolts (1/2 inch bolt). I broke the bolts loose with a fair amount of force, close to what I would have considered breaking point. The bolts turned easy for about two turns and then bound up. At this point I knew what was happening. The bolts are stainless but the manifold is steel. The rust from the manifold was adhering to the stainless bolts because of the disimilar metals. When you back out the bolt the rust jams in the threads of the manifold. When this happens if you try to force the bolt out it will deform the threads in the manifold and on the bolt. At that point you cannot thread it back in or out. SNAP! If the bolts were steel they would rust along with the manifold, assuming they were not rusted off completlely you could back them out because the bolt had rusted giving you the clearance that you are not getting with the stainless bolt that did not rust. I backed out the bolt just until it started to bind and then ran it back in. After a couple of times doing this I could move the bolt by hand, but only as far as the point where it would bind. I forced it about a turn past this point and almost could not get it back in! That was all it took to bugger up the threads. It would actually not tighten all the way up after that. I finally got a butterfly 3/8 impact driver and just kept running it in and out. After about twenty or thirty trips in and out it started to tighten up again so I knew that I had reestablished the threads at that point. Then I just kept running it in and out going about 1/8 to 1/4 turn every other trip out. Eventually it came out. If you are going to use air tools do NOT use a 1/2 inch impact gun! You will snap it off on the first try, I don't care if it is turned all the way down. The 3/8 butterfly gun has low torque and high speed, plus you have a flapper to control direction. Very easy to change back and forth. Consider I went back and forth about a hundred times to get one bolt out and you will see why pushing a button to change direction every time will take a LONG time. You will get frustrated and try to push it, SNAP! For you guys that are going to say "just heat it up". I tried that with the other bolt, do NOT do it! It expands the manifold just like it is suposed to do BUT you now have a bigger gap to jam that rust into. The manifold will cool quickly and you will be jammed up big time. I was lucky, I realized this was happening and quickly ran the bolt in tight and waited for it to cool. For you guy's that already have broken bolts you will probably never get them out the normal way, you will have to run the down and out the back. You will not be able to pull the rust through. When you are done chase the threads in the head with a tap, use new bolts and a lot of neverseize. I hope this helps someone down the road. The key word here is PATIENCE. It took me 45 minutes to get out two bolts and I have a LOT of experience at this so don't try to rush it. 
 +Rick
 
exhaust_manifold_bolts.txt · Last modified: 2013/10/26 12:33 (external edit)
 
Recent changes RSS feed Creative Commons License Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki