M117 Timing chain tensioner rail problem

[alabbasi]

All

I have a slight problem. I sent the 450SLC 5.0 to my Mechanic to get the chain done. It appears that there was a problem when removing the tensioner rail on the left side engine. This is not the banana rail but the top rail.

The mechanic attempted to remove the tensioner rail pin by screwing a bolt into the rail pin and then sliding it out but the bolt broke.

I'm not sure how it can come out now as there is no way of getting a vice grip onto the bolt.

My mechanic says that at worse case, he can break the rail and try to get the tensioner pin out with the bolt by pushing on it from the inside of the head. However he does not think that there is a need to remove it right now because the older M117 engines did not suffer from the same issues as the later M116 engines and whenever a rail would break it would typically be on the right bank.

I don't fault the mechanic for what happened as these things do happen. I would like to get some opinions on his comments regarding rails not breaking on the M117 engines.

If a new rail is not required, then I would prefer to just run a chain in and not mess with this any more out of fear that the pin is completely siezed and once the rail is broken, there will be no going back.

Thoughts and opinions appreciated.

[Mike D]

I'd pull the radiator for access and then drill the broken bolt out using a left hand drill bit. It should spin out pretty easily as it shouldn't have been torqued.

You KNOW what will happen as soon as you leave the one old rail in place!

[Tomguy]

If it's the plastic rail then the pin will be able to be removed if it's snapped off. One of those jobs I'd DIY any day... what I would do is I'd take the next smallest wrench, dremel a slot into the pin it can be hammered onto very tightly, and then use the wrench to twist and push (and potentially even hammer) out the pin. The rails can break - they tend not to on that side as much because the other cam tends to help keep the chain from moving the wrong way on that side - but they still can break and have broken, and caused issues. It's just a long shot, but didnt a long shot win the Kentucky Derby?

[ctaylor738]

I bet he broke the bolt because he bottomed it out in the pin, and/or he used a cheap bolt.

He should be able to remove the bolt with a small easy-out. Then he needs to use a proper tool to extract the pin - either a slide hammer or the screw type extractor.