Engine tapping noise - plz help troubleshoot

R

robk46

New Member
Joined
Jul 19, 2006
When my car is warm and under load, I have a tapping noise coming from the drivers side area. The car has 72k miles, I'm running Delo 15w40, the flexplate has no cracks, and the torque converter is tight. The crank bearings look brand new, and oil pressure is good. The tapping is noticable when I'm in gear, the car is warm, and idleing or just coming off idle. I can barely hear it when I'm in park. It's probably making the noise while driving down the road, but I just can't hear it over the exhaust.

How do I check the valve train? I'm familiar with my Pontiac 400, but I'm really new at the Buick 3.8. Anything special I should be checking for? I have a new set of roller rockers, but I'm not sure if they'll fit without modifiying the valve covers. Could it be a worn rocker shaft? What else can go wrong with this valve train? What do I torque the rockers to? 25lbs?
 
Oh, and the car runs great, now that it's been driven a little. It idles smooth, and pulls as hard as I want it too. My scan tool says no knock, and just driving it down the road gives no impression of anything wrong. Did some 0-60 runs a few days ago, and they were in the 5.4-5.7 range, which isn't bad for a bone stock peg leg GN. The tick/tap seems to get worse as the car warms up. What about engine temp? The radiator on this car needs a recore. 190 degrees while driving around, 200 at idle as reported by the scan tool. Maybe the oil is getting a little too thin? Also, can I use seafoam to troubleshoot an exhaust leak?
 
When i purchased my first turbo regal, i had a tapping noise coming from the bracket that holds the ac compressor and alternator on.
I had to slide the compressor forward and tighten a few bolts that hold the drivers side front bracket to the head, its all up front and not really hard to get to.

Depending on what rockers you have, you might have to grind the pedestals down where the rocker shaft mounts to for the larger rocker to fit.

BW
 
robk46 said:
When my car is warm and under load, I have a tapping noise coming from the drivers side area. The car has 72k miles, I'm running Delo 15w40, the flexplate has no cracks, and the torque converter is tight. The crank bearings look brand new, and oil pressure is good. The tapping is noticable when I'm in gear, the car is warm, and idleing or just coming off idle. I can barely hear it when I'm in park. It's probably making the noise while driving down the road, but I just can't hear it over the exhaust.

How do I check the valve train? I'm familiar with my Pontiac 400, but I'm really new at the Buick 3.8. Anything special I should be checking for? I have a new set of roller rockers, but I'm not sure if they'll fit without modifiying the valve covers. Could it be a worn rocker shaft? What else can go wrong with this valve train? What do I torque the rockers to? 25lbs?
Click to expand...

get you a cheap $7.00 water hose from wal-mart or an old one lying around , leave the brass end on it and cut the hose from the end to about 2 1/2 ft. crank the car where you think it is listen for it with the hose (brass end on ear) its worked for me several times mine was a header leak on the pass. side once and cam sensor tapping last which i havent fixed yet. but its cheap and simple way to find that noise and once without the hose i had a cross over pipe leaked that just needed tightening down. man sounds travel all over this car. but try that it should help locate. :wink: i leave that hose in the trunk now.
 
Found the problem!

It's a cracked header. I thought about it today, and I've worked on a lot of engines, but never had a turbo. The whistle from the turbo was masking any noise at higher RPMs. Here's what I found when I took a closer look in the daylight. :mad:
 

Attachments

  • cracked.jpg
    cracked.jpg
    47.5 KB · Views: 466
ooooohhhh that is BIG...u gonna buy the t/a headers? they look pretty good. unless youre gonna go with another used one for that side.
 
If you have the funds I would just replace the drivers side with an after market one. A couple of the venders have stock replacements that work good. The drivers side has always has problems cracking. I've never had a problem with the passengers side header.
 
Noise is still there - getting frustrated

We just can't seem to nail the source down. After we had the header welded, we still got the noise. We've checked flex plate bolts and flex plate, oil pressure, injectors, rest of the exhaust, and valve train. The tick happens most of the time while the engine is under load, and is only noticeable outside the car while in gear. It dissapears when driving because of turbo whine and exhaust noise, but I think it's still there. It seems to be coming from the transmission/torque converter area, however when in neutral I could have sworn it came from the front cover area. Can I make this any more confusing? :frown: Anyone in the Stuart/WPB Florida area got some time and experience to share? I'll buy the beer :biggrin: We're going to try disconnecting the serpentine belt tomorrow, then if that doesn't work, move on to the suspension and turn up the radio. :rolleyes:
I've used a long screw driver to listen to both valve covers, cam sensor, oil pan, both headers, all the fuel injectors, power steering pump, alternator, and ac compressor. I'll try listening to the water pump and transmission pan tomorrow.
 
Can I check the thrust bearing clearances with a feeler gauge, or do I need a real micrometer? If I can do it with a feeler gauge, where do I do it from?
 
Have you checked the crank sensor? Sometimes if it's not adjusted right the crank interrupter ring can hit it causing noise. Also, if you didn't get the crossover to header sealed good it will make some noise too. Most of the time when you have an exhaust leak your BLM's on your scantool will be high, 145 and higher. I've had a ton of exhaust leaks over the years and besides the noise, I would always check BLM's and when high I knew I had a leak, just had to search for them and always found one, or two.
 
DonnieShort, how do you adjust the crank sensor. Also, whats your trick for finding exhuast leaks?
 
Here's my list of things to check / double check

Exhuast leaks, front balancer, crank sensor, cam sensor, valvetrain, flexplate bolts, crank endplay. . . is there anything I'm missing?
 
try pulling the valve covers to see if the rockers are contacting them,may have to add another gasket
 
Well, I stood on top of the engine bay and listened. It's coming from the driver's side rear head area, so I think the freshly welded header is warped. I went ahead and ordered some Felpro 1400 gaskets from Summit. Hopefully this will fix the problem.
 
Thought I'd resurrect this post. I've done a lot to the car since last October, including gaskets to the headers. I still have the tick, and now that I'm almost done with the car, it's time to look at it again. I have steady vacuum of 17PSI in gear, no jumpy needle, BLMs are rock steady at WOT (128), and I've tightened everything up. Here's what I'm pretty sure is not causing the problem:

Cam sensor, flex plate, headers, crossover pipe, front accessories.
I have the day off tomorrow, so I'm going to put it on the ramps and try to figure it out. I'm going to use my trusty long screwdriver with the metal top to try and listen for the source. Here's what I'm hoping it's not: Thrust bearing or rod bearing. :eek:
 
Are you sure it's not the header? In addition to the spot in your photo, mine also leaked at the flange at the rear cylinder. I had them welded separately, and they both have held after 5 years daily driving. I found it with the "hose in the ear" trick.
 
Wish it were the header, but I leak checked them today. They both have Felpro 1400 gaskets. I'm going to take a video tomorrow and post it.
 
robk46 said:
Thought I'd resurrect this post. I've done a lot to the car since last October, including gaskets to the headers. I still have the tick, and now that I'm almost done with the car, it's time to look at it again. I have steady vacuum of 17PSI in gear, no jumpy needle, BLMs are rock steady at WOT (128), and I've tightened everything up. Here's what I'm pretty sure is not causing the problem:

Cam sensor, flex plate, headers, crossover pipe, front accessories.
I have the day off tomorrow, so I'm going to put it on the ramps and try to figure it out. I'm going to use my trusty long screwdriver with the metal top to try and listen for the source. Here's what I'm hoping it's not: Thrust bearing or rod bearing. :eek:
Click to expand...

Ummm. You should only look at BLM's at a hot idle. At WOT the BLM's lock in at 128 no matter what. That might tell you the problem there.
 
You must log in or register to reply here.

Similar threads

SETXTurbo
Help Diagnosing a Hard Contact Point/Noise
Replies
9
Views
941
AN/GSC-52
AN/GSC-52
D
PCV Help?
2 3
Replies
43
Views
3K
Clark6
C
D
Engine Harness Connector ID?
Replies
9
Views
906
Chuck Leeper
Chuck Leeper
G
100,000 mile engine service - a few questions
Replies
11
Views
824
granitestategn
G
B
1966 Special
Replies
18
Views
2K
TType85
TType85
Top