Knocking Noise

[Matthew]

I have an 89 SHO with 175000miles. The car still runs very strong. Besides from some minor leaks and a power steering pump going out no problems can be reported. However, recently the car has been making a loud clanking sound around 2500rpm. The car persists to make that noise clear up to red line. Considering the mileage my guess is that I'm suffering from an overdose of valve lash. I know the valves were adjusted at 60k. However, past that point I have no records of service to the valves and cams.
When I took the car to the mechanic, he expressed a deep concern for the noise. Having experience working on SHO's he felt that a piston pen could be loose. Perhaps it has worn and the piston is shaking around due to lack of proper support.
Finally, to my question, what is going on with my car. What should I expect or do you know what my problem is? I'm going to need the car for school next year so resolving the problem is important. When you have a chance let me know what's going on.
Also, Is adjusting valve lash a problem. Besides taking one year of autoshop in High School I'm not mechanically vested. Do you guys recommend the SHO Shop valve kits or what?

 

[sdpatt]

Excessive valve gaps will sound more like a loud tick and you most certainly have have that problem, but your real concern is the clanking noise. There is no reason to spend the time and money on the valve gapping if you have a piston pin or rod bearing that is about to fail. First things first.

You have to do the preventative maintenance that this engine requires to prevent the type of problems we have been seeing more frequently. There are too many SHOs being allowed to die because the owners (usually the past owners) aren't doing the required preventative maintenence. I'm sorry to hear that your engine may be in this condition. Very sorry.

 

[naval-avi8or]

Man you guys and your clicking SHO's' Please no body else do this. If you here your engine clicking at any RPM don't see if it will still do it at a higher rpm, cause wether or not you can hear it over the other engine noise or not it is still making the noise and possibly sending your SHO to the BONE YARD.

 

[Mike Kopstain]

Damn straight! There is no clicking/ clunking/ knocking noise that a SHO can make that doesn't mean imminent disaster, except for the injectors.

I'm sorry to rant in your post Matthew. I know it's not your fault, but dying SHO's are starting to become a common sight.

 

[Matthew]

You guys make it seem like the problem is terminal. Which it could. However, the car runs like a Swiss watch. Buddy of mine has a 90 with half the miles and were toe to toe.
Just is hard to believe.
Nonetheless I appreciate the input. I bought the car with 166,000 miles and now I'm having to pay for some neglect. It's going to have to come apart and we're going to have to see what's happening besides obvious valve lash. Who knows what I'll find. God willing a couple grand for expenses. But hey its all good. Matt

 

[naval-avi8or]

It maybe running like a swiss watch while the inside is chewing itself up. Motors don't just stop instantly they do it in a process if noticed early enough and taken care of you can get buy with minimal maintenance and cash. Or neglect the maintenance and when she's through digesting her innards she'll gasp amd take her finnal breath.

 

[Toolman]

Clicking does not mean immenent disaster. There are 24 hardened metal cam lobes banging against 24 solid metal shims. A DOHC engine is not the quietest thing on the planet. While it is not good to ignore those noises, many SHO engines go many (like 100,000) miles with excessive valvetrain noise. My 89 has always made a little clatter (and it actually got worse after it's last valve lash). It has 165k on it and runs like a top and everything is within spec. My 90, which I bought from a guy who thought it had a bad rod bearing, makes a ton of noise because it spit out a shim and ruined the cam lobe. Now that lobe makes a lot of noise as the shim wears down (replacing cam soon). Even without the bad cam though, it makes this disconcerting noise that makes me feel like it will disentegrate at any time, but it has been doing this for 15k (replaced rod bearings already, no change) and I just ran it down the strip 20 times last weekend. So I give up on what the noise is. I will probably just replace the engine soon for peace of mind.

So, do look into any undue noise coming from under your hood, but do not let your hair fall out at every little ticking sound you hear. No engine will last forever.

 

[Mike Kopstain]

Sorry toolman, perhaps I should of used the word good instead of immenent disaster.

 

[Toolman]

No apology needed, just didn't want this guy thinking his car was going to blow up next week (of course, there is not guarantee it won't)

Also, the timing chain tensioners seem to be the culprits at times with a consistent light ticking. They are not much to replace, and would be easy to access during the valve lash.

<small>[ April 14, 2002, 02:14 PM: Message edited by: Toolman ]</small>

 

[Matthew]

Hey, do you think I could be dealing with a faulty rod bearing?

 

[Mike Kopstain]

Well where is the noise coming from? Is it coming from the upper end or the lower and and which side? Can you hear is specifically in any one place. Is it a ticking noise or a knocking noise? Typically a bad rod will sound like a solid knock on an oak door. (If you can imagine what that sounds like )