****HELP! Strange sound only at full throttle****

T

tufbuick

Member
Joined
Nov 27, 2003
Last few months I have put Gessler ported heads, RJC head gaskets, ARP head bolts, Cottons downpipe and Razors Alky on my car. All these items were installed by well known and respected Buick technitions. Car has never run this good and I am very pleased with the results.

All of a sudden, a few weeks ago I get this noise that sounds like the down pipe could be hitting the passenger floorboard at full throttle only. Like a BAA-BAA-BAA-BAA at full boost. Half throttle...no sound...three quarters throttle...no sound. We had the car on the lift for hours and nothing is hitting anything. We even shoved rubber hose in between close suspect areas, did some runs, still get that sound.

20lbs of boost--alky set at #6....I use straight methanol.
as soon as boost comes up full throttle.....BAA-BAA-BAA-BAA

15lbs of boost--alky set on full....same thing

13lbs of boost--alky off.....no sound

Spoke to Jack and he said might be a head gasket. Back up on the lift, no signs of exhaust leak or gasket pushing out at head/block. No coolant leak, no funny oil.

The guy who installed and torqued the heads might have skipped the last torqing sequence. The car is going back to check compression etc, etc.
I really don't know at this point if it is a gasket or not,but can the RJCs be retorqed if there not blown out.

Has anyone ever had strange noises like this before......HELP !
 
its a head gasket!!!!!. ask jpratt on the board he will tell you. disconnect the wastegate and drive the car at wot and i bet you the sound will be gone. your heads are lifting
 
Make sure your rad is full. Go for a run and watch the BRA-BRA-BRA fill up your coolant resevoir.....done it twice now, as soon as the boost pressure is higher than the rad cap rating, it starts slapping up and down.
 
We've had an instance on two occasions, two different cars, where the racegate springs were too stiff and the electronic controller couldn't handle the duty cycle. The wastegate valve would start to cycle open and closed slapping the valve against the seat. Made a helluva weird noise. We reduced the spring pressure and then the controller could regulate.
 
noslo6 said:
We've had an instance on two occasions, two different cars, where the racegate springs were too stiff and the electronic controller couldn't handle the duty cycle. The wastegate valve would start to cycle open and closed slapping the valve against the seat. Made a helluva weird noise. We reduced the spring pressure and then the controller could regulate.
Click to expand...

I have two old style Turbonetics Wastegates from the early 90s that have never failed me. One at the turbo and the other on the crossover pipe. We tested both of them for vaccum and pressure and they're both functioning and showing us the same #s. Whatever boost I lock them on is where the boost stays.
 
tufbuick said:
I have two old style Turbonetics Wastegates from the early 90s that have never failed me. One at the turbo and the other on the crossover pipe. We tested both of them for vaccum and pressure and they're both functioning and showing us the same #s. Whatever boost I lock them on is where the boost stays.
Click to expand...

My car does the same thing under high boost. I turned the boost down to 21 or so and it hardly ever does it now. I have not boosted the car for more than a few seconds. Don't want to tear the car down till this winter. I am using Cometic gasket and believe that the heads are lifting and relieving the boost. I also have studs and was told that this can happen if the block or heads are not perfectly level. I have driven the car a few hundreds miles and have seen no ill effect as of yet, but I don't run the car under boost for more than a few seconds at a time.
 
Is your coolant resevoir filling up, or no? If you have a 15psi rad cap, that would make sense that there is no noise under 15psi boost. Empty your overflow, fill your rad and go for a full throttle run and see what happens. There was no other visable sign when it happened to me either.
And.............go!
 
There are no signs of coolent in the overflow tank ever. I have the small tank that comes with Razors Alky kit.

I do have the original 15lb Radiator cap which I'll replace and test when the rain stops in N.Y.
 
Could that quite possibly be the sound of KARMA?:D

I have heard that sound before,and I think thats it.
 
I think I've got the same thing going on. Last month I installed a set of ported gn-1's w/ cometics. It started at around 12psi of boost. Mine sounded kinda like a pack of fire crackers going off under the hood. Retorqued heads to 80 psi and noise went away till last night. Now it starts at 23 psi. My fasteners did back off to 50to60 psi per fastener. What next?? Oh I was loosing coolant and getting hot prior to retorque. That part is not a problem now.
 
I had a wery similar noise happen to me over the winter when getting into 20psi on 93/110 mix of fuel. I replaced the head gaskets as a precaution while doing some other mods and it appeared they had combustion gasses on the outside of the gasket steel ring. I was also running 3.8L NA head gaskets too. Is what I described symptoms of a lifting head?
 
you guys are experiencing boost that is firing outside between the head and block toward the header. it will not fill your overflow up. put on felpros and be done with it.!!!!!!. like i said before dissconnect your wastegate and go wot and i bet you it is not there
 
tufbuick said:
13lbs of boost--alky off.....no sound
Click to expand...
You've answered your own question. It's the alcohol. This is exactly the same problem I had. Since not using alcohol I've never replaced head gaskets. I now run 26-27lbs. of boost with 110 octain leaded gasoline. Turn the alcohol off,use 93 octain plus Lucas octain booster. You'll probably be able to run close to 20 lbs of boost with no noise. This will prove that the alcohol is the problem. The looseness of your bolts is another clue. After quitting the alcohol I found no loosenes upon retorque. I've never found the reason why this happens and have never been offered a good theory for it from anyone on the boards. It can't be the alcohol in and of itself,because others are running it successfully. Some will say it's your tune but will give no specifics. This is useless information.
 
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