Broken bolt in the bildge of my '96 GTX

[bz1mcr]

I found a broken bolt in the bildge. It was just laying in the bottom of the boat. The bolt has a 13 mm head an 8 mm shank and the broken length is just over 25 mm from the bottom of the head. Where did that come from?

 

[kustomkarl]

I would check all the bolts you can see. It is possible that it was from the previous owner that broke it and lost it in the hull and never removed it.

Karl

 

[bz1mcr]

Karl,
That is possible but not likely. I have owned it for over 8 years. I doubt it has been bouncing around that long. I inspect things pretty carefully and should have noticed it during winter prep or season setup. Also, I have looked around and not found anything missing. My guess is it came from some place I can't see looking in from the top.

I was hoping someone knows where bolts of that size are used, and might give me some places to check.

 

[kustomkarl]

I have seen exhaust bolts that size just vibrate and snap off. Try using a mirror to see in the tight spots.



Karl

 

[bz1mcr]

In the parts breakout linked to the top of page button above I found three M8X40 bolts in the engine/exhaust diagram. One mounts the exhaust pipe to the rear of the engine. If that is out there should be two rubber bushings floating around also. I did not see those so my guess is that is not it. I also found the rear engine mount is secured to the hull with 4 M8X40 bolts. My guess is that is where it came from. I have another post about one cylinder cutting in and out at high speed and that has to tough on the mounts as it is comes and goes like the ignition was being turned off at full throttle! I may have to remove the output shaft cover to see the area. I'll check when I get back to the lake later this week. I'll post after the next look around.

Those parts pictures are golden! Tremendous value for the site. I just learned about them today.

 

[derek]

these guys are famous for vibrating until they break exhaust bolts. the one from the pipe to the side of the exhaust manifold is the most likely culprit. the bushings are probably still there where the bolt belongs.

 

[bz1mcr]

derek,
I'll take a look tomorrow.
Don

 

[bz1mcr]

derek,
You were 100% correct! It was from the angle bracket that holds the pipe to the front of the engine. Will it damage anything to run with out it? The pipe still seems very well supported. Maybe it broke because it was over constrained.

 

[derek]

i would buy an exhaust manifold on ebay. they are cheap. and replace it. the broken bolt in the man is stainless and the man is aluminum. it is a machine shop job to get it out. the bolt broke from vibration. now the whole pipe can vibrate more. it may have been like this for a while. don't park it until you get the manifold, but keep an eye on the 4 top exh mounting bolts.