I have a tap tap tap sound that stays along with the rpm. I dont think its the valves because i used the hose method and they sound ok(no noise). I listend under the car and its louder than it is under the hood. Sounds like its coming from the exhaust. I know the drivers side exhaust manifold to y pipe bolts are loose maybe this is it?
Also when you rev it up it doesnt get louder.
Any ideas?
Car runs great still
I've heard rod knocks before and its not that
Its not like a knock more of a tap.

 

i had the same thing it was from where the y pipe meets the manifold the braket was loose

 

reach under the car and knock on the cat. if it rattles.... It could be a heat shield as well. An exhaust leak will sound like an open exhaust, you can test for one by putting your hand around where the manifold is and feeling for bursts of air (with the exhaust cold of course).

 

Cat has no heat sheild on it
I know i have at least one exhaust leak from the drivers side exhaust manifold to y pipe. The bolts are slightly loose and i dont have a long enough ext to reach them from under the car.
Its much,much louder under the car then under the hood.
Maybe my cat is crapped out from when the head gasket went?
I've heard several rod knocks and bad bearings(on other cars) so i know its not that, but this is a noise my car hasnt made before.

Probably a cracked y pipe due to this cold weather here in philly.


btw 3.4 will be put in this summer

 

I had that tap tap on s10 engine. It was where the headers were meeting the heads, and the bolts were loose.

 

Good call Brobert, you will LOVE what it does for you! The 3.4 is a much better foundation to build on in my opinion. After the work getting it together, it's SOOOO worth it. Good luck!

 

The heat shield is NOT on the CC but above it, separating the CC from the floor boards.
You seem to have it isolated rather well.
I do believe you do have exhaust leak.
When my manifolds leaked (one was cracked), you could DEFINETLY see a "trail" of some type. Either white powderery or dark sooty stuff.
This time it may to visit an exhaust shop & just have them tighten down the stuff for the pennies.
Air tools are wonderful things.
Amazing what ya can hear with a short section of hose, isn't it?
The 3.4 power plant is a wonderful upgrade.
Don't expect to win every race, but you will have much more fun trying!

On my Blazer "Y" pipe, I eventually discovered I had a poor weld on the TOP of the junction pipes, one that could not be seen until I dropped the "Y" pipe. When I dropped that section of pipe, I could definetly see a trial. A FYI.

 

Thanks guys, when i replaced the head gasket i reused the old exhaust manifold bolts so i was a little scared of tightening them and snapping them. I think ill go buy some new ones and put them in. With that little hose i could even hear the inside of the alt turning!

I made the 3.4 choice after i saw how cheap they are on car part.com in my area. 350-500 for a low milage one, some even had 6 mo warr.

The 350 crate i was looking at was 1200, plus i would need a mani,carb,dist,trans,fuel pressure reg,on top of the 1200 for the motor. The total was getting close to 2800 real quick. this doesnt include springs/exhaust work either....


Hmmm lets see, 400 for a 3.4 plus gaskets swapped in in a weekend vs 2800 and a **** load of work(compaired to the 3.4 swap)..


I dont race really at all anymore,just looking for a little more power and reliability.And from what i've read from people who have done it, the 3.4 is the way to go..... Cant wait till summer...

 

I made the 3.4 choice after i saw how cheap they are on car part.com in my area. 350-500 for a low milage one, some even had 6 mo warr.

Man, I wish I could import, to PA from CA, a beat up decent 3rd Gen & just swap the stuff & sell the whole rust free 3rd Gen F Body car w/3.4 power upgrade & rebuilt tranny for primo price back east!

Yeah hose section works great as does a long wooden tipped screwdriver.
Replaced one exhaust bolt at time then torque down alternating pattern. Support the pipe from below, to reduce stress on adjustment. Then have the bottom checked tightened at a shop.

 

First off, check the studs/nuts at the bottom of each manifold for tightness. A common leak is at those flange joints and is noisy and annoying to put up with, not to mention you get the fumes in the car if you are sitting at a light with the heater running.

Second, take the same V8 crate, add a transmission and clutch or torque convertor, front springs, engine and trans mounts, and then see what you come up with. I would probably add a TPI injection system to the top of the engine rather than deal with carburetion. The V8 trans is not the same as the V6 as it has a different bolt pattern and different input shaft (if we are talking automatic). Why it was done that way, I don't know. Probably so the dealer could charge you more for more power , which is what everyone wants, right?

 

i checked the exhaust mani bolts, they are tight. I think its the y pipe . Oh well ill deal with the tap tap tap till summer and throw a 3.4 and new y pipe in it. A friend of mine has a crack in his y pipe and it sound just like my car does.btw valvoline 10 40 SUCKS ***! as soon as it heats up its as thin as water.

 

i was having cat problems. it was clogged.
then i just removed it.
i had the muffer just welded to the y-pipe
with some tubing. Mandrel bent
luky i live in a state where its not required to have a visual check of your exaust .

 

Maybe i have a cat problem, i just replaced a head gasket not too long ago. Maybe the coolant mist killed the cat.

 

smell your exaust. If it smells really rich, its probably clogged.

 

exhaust is ok , not rich at all but im sure the blown head gasket didnt do the cat any good so i guess ill hollow it out some day soon.

 

have fun, that takes like a good day of work.
its really not that easy.

 

mine isnt like the normal cam/bird cat. Mine is bolted on one side and clamped on the other so if you take it off its a straight run, no bends do it shouldnt be too hard.

 

That would be the standard F-body cat. I got one of those "direct-fit" ones from AZ before I started having probs, and guess what? Due to the DPO it was not a direct fit. I had to cut the flange joint off and find a 2"ID-2 1/2"OD adaptor to get the damn thing to fit-the DPO took out the factory cat and welded in a "test" pipe. Those pipes are usually drop-in replacements, but apparantly the original cat must have needed to be cut off or something...