Massive Noises from Engine

[Two93SHOsguy]

Help all you SHO-Pros out there: My 93 ATX SHO is making HUGE rapping noises! I thought I broke a connecting rod, but she starts right up. It won't idle, but she runs with incredibly loud clatter. Did I bust off a cam pulley? Did the flywheel crack? In lieu of a recording of the noise, here is a description: Take a 13" TV, and place it against the cooling fan blades of a V8. Ya, it's loud. No warning lights, no CE codes, all fluids fine, and recent plugs, wires, and O2 sensors in her.

 

[pete c]

sounds like you got a shot rod bearing or three. Prior to this happening, did you experience flickering oil pressure light at idle? Or what sounds like valve train noise on start up after sitting overnight? I ask because I am getting these noises and I think I'm gonna pull the oil pan and do the bearings before they do the crankshaft, which, I fear, is what you are looking at.

 

[pete c]

one other thing, did she run hot prior to this? I would consider the needle getting past the N in normal to be hot?

One other possibility. My father-in-law's buick century wagon made what sounded to me like a bad rod bearing noise and it was in his tranny.

 

[Two93SHOsguy]

Thanks pete c. No low oil pressure detected, no sounds before. She didn't run hot, but she did 'use' oil - about a quart per fillup. Some leaked, and some burned. But she was running fine. Noise: take a 16 oz hammer, and tap it loudly against an intake manifold. Jeeze, I had a mechanic remove the intake manifold for the new plugs, wires, and oil leaks into the plug wells - I wonder if he dropped a screw into the manifold which got pulled into a valve, sticking it open? S%$#t. Could a piston smack the open valve?

 

[bradman]

The SHO V6 is a non-interference engine so it's probably not a piston hitting a valve even if the valve is stuck open, but if something got past a valve, then it sure could cause your noise. How long since the timing belt has been replaced? It's a long shot, but a loose or partially broken timing belt could be slapping the timing belt cover.

 

[Two93SHOsguy]

Glad to hear that. I bought it at 80k, and though I'd been told "all maintenance was done", one can never be sure w/o slips. How would timing belt cause noise like that? What else could?

 

[Wildstar]

I'll lay money on a rod bearing. I described it as that God awful banging noise. Drop the oil pan and take a look.

 

[SHO2NV]

Definately check the timing belt first. Happened to a guy I know and that was the culprit. Good luck.

 

[Mans442]

If you can drive it, get it up to New England SHO Specialists <www.neshospecialists.com> in Cumberland, RI.

They should be able to tell what broke and provide economical options.

Good luck.

Jason M.

 

[Mans442]

If the timing belt was broken, the car would not fire at all.....

 

[bradman]

I didn't mean a completely severed timing belt. Many times the belts begin to shred before they break completely and stop the car. That's what happened to me on my former ******. I've also heard many accounts of loose timing belts (here on the forum) that were loose enough to slap the timing cover, which I would think could be mistaken for an internal noise. Like I said, it's a long shot, but I think worth checking.

 

[Two93SHOsguy]

This definitely sounds like metal hitting metal. Hard. In the heads or cylinders. I can't believe that this is a non-interference engine, as it makes so much hp, and is high compression enough to require premium fuel. I haven't yet started work on it - I'm SO ****** off. It's only gone a couple thousand miles since the last grand I dumped in.

 

[91MochaSHO]

Two93SHOsguy:
It's only gone a couple thousand miles since the last grand I dumped in.

If i could show you all my repair bills I have you would laugh. Its got 159K on it and it only gets worse as it gets older. I have a 3-ring binder full of them and now it just failed emissions due to bad cats.. Oh well, i finally came to a conclusion that I allready dumped enough money in thus far and I wont do it any longer. Im just gonna run it the way it is until they reopen the emission stations and then sell it for parts or whatever if someone wants to do work on it. I feel your pain!!! As much as I love my SHO, it drives me crazy at the same time.

 

[Two93SHOsguy]

Seth - thanks. Insane pain in the brain: I have TWO '93 ATXs!!! Both for sale, one with the new and fun option shoot "Massive Noise in the Engine".

 

[brianl]

My '90 gets a rather horrendous sounding 'clacking' from the valvetrain every once in awhile. It's done it since I bought it at about 80K miles. It's only ever done it after I hammer it up to (maybe even past) redline, with the limit getting lower and lower as it's gotten older (about 160K now). It is definitely coming from the valvetrain, and not rod bearings (for me), and it tends to be easier to 'trigger' if I'm a little low on oil.

Of all the opionions I've gotten, timing chain tensioners seems to be he most plausible. I'm not saying that it's not the rod bearing's, but it could be these. I believe they're filled with oil, and can, lose their 'prime', for lack of a better word. It takes awhile for them to pump back up.

I get the clacking noise very briefly on startup (less than a sec, just immediately after the engine fires), and after I've driven it really hard. It will stay that way for about 10-15 minutes of normal driving, then the noise goes away.

While I've heard bad rod bearings in other cars, I haven't heard them on a SHO. But, IMHO, my noise is _not_ rod bearings, this is definitely coming form the top of the motor.

If your cam chain tensioner has totally failed, you've got a cam chain bouncing around in there, and it will make a helluva racket.

My $.02