noise - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bigbadchev72 · 05-12-2008, 04:28 AM

So I just picked up a 1990 fuel injected 350 fullsize blazer, its got a 350/205 that someone swapped in and has a strange noise. I am all to familiar with lifter and rod knock and it is definately not one of those, If you could imagine a rubber ball shaking in a pringles can. that is what it sounds like.

It does it more so right after being started for about 10-30 seconds goes away then only does it sparaticly, I have been trying to figure out where it comes from with a fuel hose to my ear, but cant track it down just yet.

It does it when driving, I never drove it over 25mph but it dosent seem to do it when revving to 3-4grand but will apear when it comes back to idle.

I pulled the inspection cover on the transmission and the flexplate isnt wobbling and I also unbolted the torque converter and slid it back away from the flexplate. started it and the same noise. Can a broken flexplate make noise with the convertor not hooked up?

I have also pulled the serpintine belt to eliminate any of the accesories it still did it. Any advice?

bigbadchev72 · 05-12-2008, 11:23 PM

Ok got the transmission pulled today. Flexplate checks out. I pulled the oilpan and everything passed a visual. Pulled the plugs, looked to be running a little rich I will install new plugs tomorrow and dump some water down the intake while it is running to clean up the cylinder heads.

I did notice that there is no oxygen sensor on this thing. Could that have something to do with anything?

I have also pulled the valve covers and everything seems ok there too.

Maybe it is a rod knock? How can I diagnose which one it is?

05-12-2008, 04:28 AM	#1
bigbadchev72 People know me Join Date: Jun 2007 Location: Hermiston, oregon Posts: 840	noise So I just picked up a 1990 fuel injected 350 fullsize blazer, its got a 350/205 that someone swapped in and has a strange noise. I am all to familiar with lifter and rod knock and it is definately not one of those, If you could imagine a rubber ball shaking in a pringles can. that is what it sounds like. It does it more so right after being started for about 10-30 seconds goes away then only does it sparaticly, I have been trying to figure out where it comes from with a fuel hose to my ear, but cant track it down just yet. It does it when driving, I never drove it over 25mph but it dosent seem to do it when revving to 3-4grand but will apear when it comes back to idle. I pulled the inspection cover on the transmission and the flexplate isnt wobbling and I also unbolted the torque converter and slid it back away from the flexplate. started it and the same noise. Can a broken flexplate make noise with the convertor not hooked up? I have also pulled the serpintine belt to eliminate any of the accesories it still did it. Any advice? __________________ 1972 k/5 blazer CST 4X4 Crate 350, th350/205, dana44with trac-loc/14 bolt with detroit locker, 4 wheel discs 4.56s, 8" suspension lift using 73-87springs, 1" zerorate custom front crossmember, HAD CV drivelines and driveshaft e-brake, full cage, PRP seats, Full autometer gauges, 38x14.5x16 Toyo M/Ts, 16x10 Polished aluminum rockcrusher wheels 1967 longbox 4x4, Strong 400/400/208, 44/12bolt 4.10s, 6" lift, 35" Toyo M/Ts on corvette rally wheels Last edited by bigbadchev72; 05-12-2008 at 04:28 AM.

05-12-2008, 11:23 PM	#2
bigbadchev72 People know me Join Date: Jun 2007 Location: Hermiston, oregon Posts: 840	Re: noise Ok got the transmission pulled today. Flexplate checks out. I pulled the oilpan and everything passed a visual. Pulled the plugs, looked to be running a little rich I will install new plugs tomorrow and dump some water down the intake while it is running to clean up the cylinder heads. I did notice that there is no oxygen sensor on this thing. Could that have something to do with anything? I have also pulled the valve covers and everything seems ok there too. Maybe it is a rod knock? How can I diagnose which one it is? __________________ 1972 k/5 blazer CST 4X4 Crate 350, th350/205, dana44with trac-loc/14 bolt with detroit locker, 4 wheel discs 4.56s, 8" suspension lift using 73-87springs, 1" zerorate custom front crossmember, HAD CV drivelines and driveshaft e-brake, full cage, PRP seats, Full autometer gauges, 38x14.5x16 Toyo M/Ts, 16x10 Polished aluminum rockcrusher wheels 1967 longbox 4x4, Strong 400/400/208, 44/12bolt 4.10s, 6" lift, 35" Toyo M/Ts on corvette rally wheels



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