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Engine sounds terrible - unknown part under car!

66 Sat

Well-Known Member
Local time
4:58 PM
Apr 26, 2015
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Help required! Drove the car Friday night, running great. Blew a bit of the carbon off the plugs as usual, but nothing too crazy, maybe a few 5,500rpm runs. Parked the car, no issues.
Went to drive it today and it started fine, oil pressure fine etc but was sounding terrible, like an exhaust manifold gasket had blown out. I shut it off and went out in my other car.
I thought the driver's side manifold was leaking slightly since I removed and replaced it recently to fit a mini starter, in anticipation of the headers that are being installed in early May. I left the leak alone as the manifolds will be removed soon and it didn't sound too bad, so I suspected the leak had finally blown through fully.
I started it again this evening to see if I could pinpoint the noise but it's hard to tell, almost like the gaskets on both sides are blown which is strange.
When I was lying on the floor trying to hear the leak I saw this piece on the car under the front of the engine. For the life of me I can't work out what it is. It looks like part of the kickdown assembly maybe as it's a similar diameter and has the grooves for clips but the kickdown is intact and works ok when I run it by hand, both from the top and from underneath. The shaft is snapped, you can see the ragged break, but I'm stumped where it broke off from, and if it's related to the noise (surely it is?).
I've inspected the (non-working) manifold heat riser and that seems to be all there (there's no buttlerfly valve inside but the outer part is still attached to the manifold). I can't see or think of anywhere else it came from and whether it's coincidence or not.

Any ideas?



Did a spark plug blow apart? Is that the wire end part of the electrode?
I accidentally left a plug untightened on a 318 once, and it vibrated loose and fell out. Awful exhaust leak sounding noise when it happened.
The shaft broke and the bushing is still on it.
I think you're right. I was just looking up images and the shaft looks exactly like it. I'll start it up tomorrow and put my hand over it and see if I can feel it blowing through.
Thanks for all your help.
If you have the access, the manifold shaft hole can be tapped and plugged. I would recommend a pipe thread and plug.
I've used a 3/8" -18 tap.
Run a 3/8" bolt in that has an unthreaded shank and cut off any excess inside and out.
Looks like a previous owner tried to plug the hole on the exhaust manifold either side, and one side just let go under pressure from the exhaust gases with the high RPM bursts.
It almost looks like that shaft was cut with a hacksaw.
Terry W.
It was...I did it! I remembered last night.
About 3 years ago I pulled the manifold off to check if the valve was in there and was stuck partially closed (I had that problem on my old Barracuda).
The valve was gone but the shaft was still there. In the interests of maximizing flow I cut it out only leaving the 2 ends. The inside end has blown out - I felt around there and can put my finger in the hole.

Question - do you think if I cover the shaft piece with JB Weld and push it back in it will hold? It only has to last just over a month before the headers go in and I haven't got the time or inclination to remove the manifold to fix it properly. I could spread a bit of JB Weld around the outside too once it was seated - not sure if the pressure will be too much though.
Push it back in and tac weld it in place
Then do it like they would on the farm. Drill a hole through the end of the shaft you are holding big enough to feed some baling wire through. Put it back in the exhaust manifold with a long piece of wire through the hole you drilled. Bring the wire around the manifold and twist the ends together until it's tightly held in. It only has to last a month, right? If you don't want to drill a hole, just tightly wrap the baling wire in the grooves already in the shaft. twist it tight, reinstall in manifold, bring the wire ends around and twist to hold the shaft in tight.
Terry W.
JB weld will not hold up under that heat.
If you are in Syd, you can remove the man & I Can weld a plug in for you.
Thanks for the kind offer Geoff, there's a guy on the Gold Coast who would do it for me but I'm not pulling the manifold now when I'm getting headers early May.
I've bought the JB Weld Extreme Heat Paste and I'll see if that works. I'll also reinforce it with some wire as Terry suggested above.
Update: I used the JB Weld Extreme Heat paste and put it on the shaft, pushed it back in, then formed a mound right around the outside of the shaft against the manifold.
Left it 24 hrs and then drove around the block at idle to fully cure it.
Took it for a cruise to the beach this evening and it's holding fine. Didn't exceed 3,000 rpm so will just take it easy for the next month 'til the headers go on.