Just now as I arrived at home I noticed an odd noise...I opened the hood and it was so horrible I shut the engine off right away. It's coming from the head and it sounds like an impact wrench (minus the whizzing) mixed with a beat up old diesel running on crappy fuel. The oil level is OK, I'm not sure when this started but I would have noticed the noise pulling away from work. The engine's just been fully rebuilt and was coming up on its first oil change. My only guesses would be that somehow oil isn't getting to the head, or one of the camshaft bearings is loose. Help? :( :( :(
I'm going to park it and drive the AE92 tomorrow.
Two things come to mind: a stuck valve which will also make it run rough. Or, if it is running smoothly, the nut/bolt which holds the cam sprocket to the cam is loose (BTDT).
GlennS
HalfDork
6/26/08 4:37 p.m.
this should probable be in the on topic forum.
Sounds like a stuck valve...I noticed the engine's running lower and choppier than usual.
Also make sure the noise is not coming from either the balancer or flywheel bolts.
I gave a CLEAN Mazda 626 (RWD) away years ago because of a similar sound only to find out that it had a loose flywheel.
It definitely sounds like it's coming from the head...I'm going to try to start it again soon, now that the engine's cold. It's going to a shop at the first opportunity in any case.
dan_efi
New Reader
6/26/08 6:59 p.m.
Does your engine have rocker arms? I've heard of them loosening and coming off on recent rebuilds. Super easy fix if that's all it is 
Yep it's a single cam with rockers...I started it cold and the noise was still there, but not as loud. It ran smoother as well.
Jack
SuperDork
6/27/08 9:34 a.m.
Did you rebuild the engine or was someone paid to do it? If it's the latter, call them before you run it again.
Jack
The PO had the engine rebuilt at a shop. I've been reading up on loose rockers, and this problem seems more like a loose rocker than a stuck valve.
Turned out it was the distributor (phew). Replacement from the stealership: $900 
Anyone know of any aftermarket replacements? G13A distributors are known to be troublesome so I don't want to waste time and money smuggling another one just like it into the island.
This might work but I don't know if it would replace everything necessary (I didn't hear first hand but the message was that the distributor was "completely wrecked"):
http://www.shopatron.com/product/part_number=1144A/591.0.26484.26485.0.0.0
I ended up getting a used stock distributor. Also the PO put the wrong timing belt tensioner on it which wore out the timing belt so badly that it was ready to slip. There was also a problem with one of the rockers having stripped threads or something.
A shoddy engine rebuild, a lowsy repaint (possibly a rattle-can job), worn-to-death suspension...I really got ripped off when I bought that thing.
