Possible causes of engine tapping
Possible causes of engine tapping In January I had my lifters replaced, 5 went bad all at once, sounded like gravel in the engine 
This past saturday I started hearing a tapping noise, but duller than the clatter the lifters made. At idle it is audible, but not bad, becomes much more noticeable at 2500RPM and up. As I rev it, it gets faster, but if I rev it up to, say, 3000RPM, then let off the gas the sound pretty much disappears until right before the RPM gets down near idle and the sound then comes back with the first few taps much slower and slowing down between each tap, then to the steady tap-tap-tap at idle (about 3-4 taps a second at an idle of 800-900RPM - this is my V6 A4).
I used a hose to the ear and traced it to cylinder 3. Hose at the top of the valve cover, nothing much. Base of the valve cover, right above the exhaust manifold it is quite audible through the hose. This leads me to believe that it is either a pushrod or a lifter. Thinking it probably isn't a lifter because the sound is duller tapping compared to the harsh clacking the lifters made when they went bad. Someone also suggested it could be an exhaust leak, could an exhaust leak sound like that? Makes me wonder since the sound goes almost totally away when letting off the gas.
Since this has started, aside from a quick rev here and there when I was tracing it, I haven't let it get above 3000RPM in case this could be more major.
This past saturday I started hearing a tapping noise, but duller than the clatter the lifters made. At idle it is audible, but not bad, becomes much more noticeable at 2500RPM and up. As I rev it, it gets faster, but if I rev it up to, say, 3000RPM, then let off the gas the sound pretty much disappears until right before the RPM gets down near idle and the sound then comes back with the first few taps much slower and slowing down between each tap, then to the steady tap-tap-tap at idle (about 3-4 taps a second at an idle of 800-900RPM - this is my V6 A4).
I used a hose to the ear and traced it to cylinder 3. Hose at the top of the valve cover, nothing much. Base of the valve cover, right above the exhaust manifold it is quite audible through the hose. This leads me to believe that it is either a pushrod or a lifter. Thinking it probably isn't a lifter because the sound is duller tapping compared to the harsh clacking the lifters made when they went bad. Someone also suggested it could be an exhaust leak, could an exhaust leak sound like that? Makes me wonder since the sound goes almost totally away when letting off the gas.
Since this has started, aside from a quick rev here and there when I was tracing it, I haven't let it get above 3000RPM in case this could be more major.
Also, unrelated, but don't feel like creating a separate thread for it... I cleaned my MAF and while I was at it pulled the IAC and it was quite dirty. Sprayed it with some of the MAF cleaner (stupid me) and it cleaned gunk off, but then I read right after that to never spray the IAC valve with anything (oops 
). Car seems to run fine normally, except if I put the car in reverse and turn the wheel simultaneously it'll stall out half the time, or get close to stalling.
Could a messed up IAC cause that? Besides cleaning the MAF that's the only thing I did to it, so I'm guessing it could be. $32 at Autozone gets a new one though so no biggie if I did screw it up. I did forget to pull the battery connection after cleaning the MAF to reset the computer, so I did that last night. Who knows, maybe that'll fix it.
). Car seems to run fine normally, except if I put the car in reverse and turn the wheel simultaneously it'll stall out half the time, or get close to stalling.Could a messed up IAC cause that? Besides cleaning the MAF that's the only thing I did to it, so I'm guessing it could be. $32 at Autozone gets a new one though so no biggie if I did screw it up. I did forget to pull the battery connection after cleaning the MAF to reset the computer, so I did that last night. Who knows, maybe that'll fix it.
Not super well versed on the 3800, but it sure sounds like you have bigger fish to fry. The odds of 5 lifters failing for no reason seem pretty high to me. What was the failure with them, and did you replace all of them? How many miles on the engine? Was there any problem with the rockers? Pushrods? Everything adjusted correctly? You may want to pull the valve covers and have a look. If you didn't soak the IAC in crap, it should still be fine. It is a stepper motor, and doesn't like contamination in the windings. There are several things that could be causing your noises, and the fact that it speeds up with engine speed tells you that it is related to rotating assembly or valve train. Was there any damage to the cam? Oh, and that mirror is easy to change.
I didn't do the work myself, I would have but I had neither the time nor a place to do it unfortunately (could have saved a bundle if I did). They failed back in January. 110K on the clock. All the lifters were replaced since 5 were bad. The camshaft was OK, no abnormal wear. He never said anything about rockers or pushrods so those should have been fine at the time. I'm going back home this friday (I'm a college student) so I'm taking it over to him and he said he'll listen to it. I'm hoping it is minor, or maybe a defective lifter because that wouldn't cost me much.
I think the stall issue is resolved, pulling the battery and having the car relearn seems to have fixed it, I tried to stall it several times today and it wouldn't.
Oh yeah the mirror is easy, took a look at it a while back, just haven't wanted to do anything with it until I'm ready to fix the rest of the bodywork and paint it. This mirror may be damaged but it is still functional and the color matches at least
I think the stall issue is resolved, pulling the battery and having the car relearn seems to have fixed it, I tried to stall it several times today and it wouldn't.
Oh yeah the mirror is easy, took a look at it a while back, just haven't wanted to do anything with it until I'm ready to fix the rest of the bodywork and paint it. This mirror may be damaged but it is still functional and the color matches at least
Well I found out today that I have basically spun a bearing 
So now what do I do? I don't have much money, only a few hundred, another V6 engine with 50K miles looks like it'll cost around $2500 installed. Considering the shape of the rest of the car (body work primarily), is it worth it? Assuming i could come up with the money somehow... I'm a college student, I don't have a whole lot of money to throw around.
This burns, replaced lifters 2 months ago and now the bottom end quits at 110K miles. I shouldn't have bought this car seeing that it had been abused...
Any input?
So now what do I do? I don't have much money, only a few hundred, another V6 engine with 50K miles looks like it'll cost around $2500 installed. Considering the shape of the rest of the car (body work primarily), is it worth it? Assuming i could come up with the money somehow... I'm a college student, I don't have a whole lot of money to throw around.
This burns, replaced lifters 2 months ago and now the bottom end quits at 110K miles. I shouldn't have bought this car seeing that it had been abused...
Any input?
TECH Apprentice
Joined: Jan 2008
Posts: 330
Likes: 0
im also in college and bought a 95 formula about 4 months ago and was driving down a country road, got on it and bam, threw a rod. I was in the same position as you... I would suggest you taking out a low interest student loan (what i did) and either give someone the car plus cash for a different car, or buy the new motor. up to you, but i was poor as hell and the loan helped a shitload, especially since I don't have to start paying until 6 months after I graduate...try Salle Mae (or however you spell it).
im also in college and bought a 95 formula about 4 months ago and was driving down a country road, got on it and bam, threw a rod. I was in the same position as you... I would suggest you taking out a low interest student loan (what i did) and either give someone the car plus cash for a different car, or buy the new motor. up to you, but i was poor as hell and the loan helped a shitload, especially since I don't have to start paying until 6 months after I graduate...try Salle Mae (or however you spell it).
I guess the plus of this is my worn water pump, alternator, and seeping PS pump (so I was told, hadn't had to top it off yet) are all taken care of this way since the "new" motor has all that already.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
