That's nut where that goes! * Not a Z, but is a SOHC

[Reptoid Overlords]

This didn't happen to my Z, but i thought you guys would find this amusing.  I have a 1991 Mazda B2200 pickup, and about a week ago it started making an awful noise just as i was pulling up to my garage.  I immediately shut the engine down.  Upon inspection I noticed one of the nuts used to hold the air cleaner assy. to the carburetor was missing.  Oh boy.

I figured it thrashed an entire cylinder, piston/valves/cylinder walls etc.  When I pulled the head I found it wedged between the valve seat and the #4 intake valve.  It never entered the bottom end or made contact with the piston.  When I removed the nut I put mineral spirits in the combustion chamber with the valves closed/head upside down and could see only a little bit of fluid escaping the seat of of the #4 intake runner.  Still enough to call it a bad seal, but trivial compared to what could've happened.  The other ones hold fluid for hours.

I ordered a new intake valve,some valve seals, and new hydraulic lash adjusters while I have the rocker arms assy. off.  I'll lap it in and hopefully it'll be ok.  

Guess I'll use LocTite on that air filter housing from now on. 

     

[Racer X]

1 hour ago, Reptoid Overlords said:

This didn't happen to my Z, but i thought you guys would find this amusing.  I have a 1991 Mazda B2200 pickup, and about a week ago it started making an awful noise just as i was pulling up to my garage.  I immediately shut the engine down.  Upon inspection I noticed one of the nuts used to hold the air cleaner assy. to the carburetor was missing.  Oh boy.

I figured it thrashed an entire cylinder, piston/valves/cylinder walls etc.  When I pulled the head I found it wedged between the valve seat and the #4 intake valve.  It never entered the bottom end or made contact with the piston.  When I removed the nut I put mineral spirits in the combustion chamber with the valves closed/head upside down and could see only a little bit of fluid escaping the seat of of the #4 intake runner.  Still enough to call it a bad seal, but trivial compared to what could've happened.  The other ones hold fluid for hours.

I ordered a new intake valve,some valve seals, and new hydraulic lash adjusters while I have the rocker arms assy. off.  I'll lap it in and hopefully it'll be ok.  

Guess I'll use LocTite on that air filter housing from now on. 

     

You got lucky.

I had a similar experience many years ago. I had a 65 Comet, 289, 3 speed. The choke was stuck on one cold winter morning. With the engine running, I removed the wingnut on the air cleaner, and lifted it up. I fumbled the nut and it fell into the carburetor throat. I could see it laying on the throttle plate. I shut the engine off and fetched some tweezers to retrieve the nut. When I was trying to grab the nut I bumped the throttle linkage, and the nut fell into the manifold.

Like an idiot I tried to start the engine. It rolled over, the intake valve opened, the nut fell into the cylinder, and when the piston came up it stopped the engine from rotating.

The next day I pulled one of the cylinder heads (luckily I guessed the correct one the first try), and there was the nut.

New head gasket, new intake manifold gasket, and back in business!