I Have a 1995 Aurora with the 4.0 northstar, I know a little about engine but I'm not certain on what this noise is. Since its DOHC I know that elimanates a lot because it has no lifters and rods. It sounds like to me a problem with something in the valve train. I'm not positive what this car has under the covers. I know you can not adjust valve clearance because it is has hydraulic lash adjusters but do them things ever go bad? Do you think the noise could be the valve hitting the seat, or maybe a worn sping? I have no clue some help would be nice! Thank you

 

if true that it has a hydraulic lash adjuster it sounds like it could be like a flat hydraulic lifter. i don't know much about north stars either but like the hydraulic lifter when they go flat they make a tiking sound. which would make a clearence problem in the valve train.

 

Since the lash adjuster is in the head how hard do you think it would be to change? Should I change one, the four on that side(front) - or do you think all 8? The back 4 four would be a pain.

 

I have a 98 Aurora, and it was ticking. I thought it was the engine ticking, it sounded like valve train noise, but the shop I took it to told me it was a cracked flywheel. I didn't quite believe them so we put the car on a lift and sure enough the noise is comming from the tranny right where the flywheel is. I don't know if this will help you, but that is what the noise was in mine.

 

FYI guys, I think they are actually called cam followers. I am not really that up to speed on OHV engines, someone correct me if I am wrong.

 

A.I.R. tube leaks sound like valve taps

 

Well I had the front 8 exhaust lifters, and oil pump replaced at Cadilliac which cost about $1250 and about a week after that the back head started ticking but i'm not putting any more money in this car it only ticks at certain times so I'm just gonna let he tick. Good luck with yours.