trying to figure out engine noise

[gt1985]

my car is a 1994 sho atx 3.2l. i have performed the top and front 60 and 100K service. and the engine runs well. my problem is when you first start the car it knocks-taps pretty loudly at first and as the engine warms up it gradually gets less loud. at operating temp it is fairly light but still definately noticable. i first thought rod bearings(the car has 176K on it) but i used my mechanics stethoscope and the bottom end sounds fine. but when listening to the top end i could definately hear tapping coming fron the top end(putting stethoscope on intake bolts) and more from the timing cover end of engine. when i did the valve clearance procedure i was super careful and i don"t think i could be that far off..it really sounds like valve clearance to me but i really don"t want to tear it back down without having a better idea of what i"m trying to do..when i was in the engine i checked -cam chains and tensioners were good. timing idler and tensioner seemed ok. i'm looking for some ideas on my next move and possibly if somebody knows someone in wash state who knows shos really well mechanically that i could take my car to for some help...sorry for being so long winded,but i really do like this car and have invested over a year collecting parts to bring it back to life...thanx

 

[SHOGUN88]

Was the noise there before you did the 60k?

 

[gt1985]

yes there was

 

[whiteguy3]

Sounds somewhat like what my rod bearings were doing before they went. As you can guess there's a new 3.2 in there. The noise I had sounded like it was not low end, with no oil light, compression test was fine and no shavings in oil. So.....I would do your rod bearings anyways, but you could also check your rear cam chain tensioner. Sometimes it makes a small tapping noise. For the most part though it usually sounds like a chain rubbing over metal especially when the car is warm.

 

[4GIVEN]

It sounds to me like the valves are taping. That usually means your oil pressure is low. Try putting some seafoam in the oil for about 100-200 miles then drain the oil. Valves tap because they get sludge built up around them and they cant move properly. Keep us posted.

 

[gt1985]

thanks, i have the main and rod bearings already. just trying to explore my options..anybody else have any suggestions?? i would be grateful for any help i can get..any body know a good sho mechanic or guru in wash state????sure would like to have someone who knows theese motors take a listen...

 

[frosho]

You have new main bearings? Thought they were obsolete....

 

[gt1985]

e-bay e-bay e-bay i have been collecting parts for over a year...

 

[frosho]

Gotcha.

 

[firstgen89sho]

Main bearings can be bought at any jobber store, but the main bearing thrust bearings are the ones that are oboslete.

 

[gt1985]

anybody have any thought about the engine noise????

 

[JRA2000TL]

I have the exact same problem with my 90. Cyl #1 has a tapping sound and the engine noise drowns it out about 2k rpms. I jacked mine up and checked and I don't have lower end noise. I've been told 100 times that's it a timing chain tensioner, but I haven't had the time or extra $ lately. Plus, I am having someone help me when I tear into it, so I'm waiting until he's free.

I will tell you though, it does not affect the engine's performance. I can floor, it and tach it up to 6500rpms in 2nd and it still has all it's power. I've driven it quite a while with no issues, even though it's not my DD. If the engine gets really warm on a hot day, the noise will almost go away.

I can tell that its JUST at Cyl #1. If I'd spun a rod bearing, the engine would surely have been gone by now, especially after the hard accelerations I've done with it. The same guy that's going to help me tear into it has listened to it and told me it was in the valve train and definitely not a rod knock. It sounds like you're experiencing what I have.

I made a video of mine. Here's the link. Take a listen http://www.youtube.com/watch?v=WVzy84q9n9Y

 

[jessemachone]

i had a bearing that was corroded from sitting too long once (in a 3.0 SHO) it only made tapping noise above 3k rpm. I'd say it is cheap insurance at this point to do them and you can rule them out as being part of the noise problem while you're at it.

 

[gt1985]

thanks for the input...i'm just going to go ahead and do the rod bearings. that way i know that base is covered...the noise seems to come from the timing cover side of engine not the side with the tensioners. but i figure do bearings now and see where i'm at after that...

 

[LJRuddy]

If it is a bad chain tensioner, you still need to replace it quick. I had a frozen tensioner go out on my last SHO and within about 15 miles of driving, there was enough metal shavings in the oil system (chain scrapped the valve cover almost all the way through) that it clogged 2 oil passages to cam journals. My head was destroyed.