Hi guys, hope you can help:
1986 Toyota SR5. Remember the sound your bikes made when you clothes-pinned playing cards to the spokes? Well, my truck makes the same sound as I accelerate above 20 mph. It goes away during ‘cruzing’ speed, but the second I accelerate, there it is. It seems to be heard under my feet, under the brake pedal area. (fuel injection)
Mechanic says its an exhaust problem. We have changed the TPS, the thermal vacuum valve (a bolt-like thing at the front of the engine) and the egr valve that it feeds at the back, top, of the engine (a small disk size piece with 3 rubber pipes that attach to it). Nothing works. I have suggested gaskets, and muffler, but he says that?s not it. This guy really is a good and trusty mechanic. Been seeing him for years, and have always been treated fairly with fair prices. He’s usually quick to find/solve problems, but I think he’s stumped on this one. I’m getting a bit embarrassed to keep calling him on this, so I would like another opinion. Any suggestions I can take to him will be GREATLY appreciated. Thanks a million.
Mary Ann
Hi guys, hope you can help:
1986 Toyota SR5. Remember the sound your bikes made when you clothes-pinned playing cards to the spokes? Well, my truck makes the same sound as I accelerate above 20 mph. It goes away during ‘cruzing’ speed, but the second I accelerate, there it is. It seems to be heard under my feet, under the brake pedal area. (fuel injection)
Mechanic says its an exhaust problem. We have changed the TPS, the thermal vacuum valve (a bolt-like thing at the front of the engine) and the egr valve that it feeds at the back, top, of the engine (a small disk size piece with 3 rubber pipes that attach to it). Nothing works. I have suggested gaskets, and muffler, but he says that?s not it. This guy really is a good and trusty mechanic. Been seeing him for years, and have always been treated fairly with fair prices. He’s usually quick to find/solve problems, but I think he’s stumped on this one. I’m getting a bit embarrassed to keep calling him on this, so I would like another opinion. Any suggestions I can take to him will be GREATLY appreciated. Thanks a million.
Mary Ann
Which SR5 do you have? The truck or the Corolla? It might matter.
In her post she says, “my truck.” I still have my 1984 Toyota SR5 pickup and I once had a similar problem. Check the flange connection where the exhaust manifold and the exhaust pipe meet. There is a gasket seal there and it may have blown allowing and exhaust leak which makes the sound when you accelerate. Sometimes the fasteners loosen after a time. Also, check the manifold itself for cracks.
Another thing to check is the exhaust manifold gasket where it seals against the head. That can develop a leak too.
I agree with “AlanY”. Especially when you said it sounds like the noise is coming from under the brake pedal area. Its probably the exhaust connection between the pipe and the manifold. There are two “doughnut” gaskets there and 3 nuts that hold the pipe onto the studs of the manifold. If they get loose, exhaust gas can blow right through those gaskets and turn them to ash. Run the engine (if its a 5spd, put it in neutral with the wheels blocked, of course!) and see if any exhaust gas is escaping from that area. This connection can often become loose, especially if one or more hangers on the exhaust pipe assembly are loose.
It could also be the manifold gasket where the exhaust manifold bolts onto the engine, but check both. The first one would be an easier fix.
Thanks alot, guys.
I copied your suggestions and will take them to my mechanic today.
Have a great weekend! 
MaryAnn
One more thing to check Mary Ann! My wife’s Sentra had a similar rattle under the car floor at certain speeds, especially during acceleration. It turned out to be a loose heat shield over the catalytic converter. When the car is in the shop on the hoist and running there is no load on the engine and the shield keeps quiet. When accelerating, the engine and drivetrain will vibrate and the shield, which is fastened only on one end, will vibrate like a big, ugly tuning fork. Your vehicle likely has a shield as well.