exhaust leak or rod knock

[yeehoo]

Howdy,

I have a 93 4.3 tbi 217k in k1500 and I have what sounds like a knock from the passengers side rear top of motor . The thing is, it idles perfect, good oil pressure 20-30 per dash gauge, If i ease into the gas sounds good, If I get on it is when I hear the knock around 1500-2500 rpm. Any thoughts or suggestions would be appreciated.

 

I recently purchased the truck used. Overall its in good shape, body is straight, no rust, I don't think its ever been offroad, no dirt or anything underneath. It has a new complete a/c system, new gas tank and fuel pump, new all terrain tires and a new muffler. It seems that it was well maintained.

[2018GMC]

You sure it's a knock and not a lifter or pushrod? My 79 makes a loud tap tap tap if Sat for a few days or extremely cold for a 10 seconds until hydraulic lifter pumps up then all is normal.

 

Maybe make a YouTube clip and link here

[Motor City Rick]

2009 GMC,

 

What viscosity oil do you use, ...and oil filter model / type is on you truck??? While clicking, does the oil gauge climb quickly in the fist 10 seconds, or slowly climbs? Does it click the same way in very warm AZ weather???

[Motor City Rick]

yeehoo,

 

Is this "claimed" knock all through the rpm range or a specific rpm point???

 

Is it a very hard knock where it's like someone hitting the motor with a sledge hammer, or a light metallic knock???

 

Does the knock come and go at any rpm?

 

Have you put your hand on the valve cover by #6 cylinder? Do you feel the pounding sensation when you hear the knocking??? Is the knock gone when cold then gets worse warm or vise versa???

 

At 217,000 miles, the motor should have excessive rod / main bearing clearances in the motor causing excessive oil leakage through the bearings. If you take the oil pan off, plasti-gauge all rods and mains, bearing failure will be at # 6 or #4 rod bearing or the rearward crank bearings. After repair, install "high volume" oil pump, not a high pressure oil pump.

 

Good luck!

[yeehoo]

No its only at certain rpm up around 2k it's more like a fast drumming sound. Good oil pressure all around. Nice smooth idle. Drives fine. I noticed it has a new oil pan gasket. I pulled the valve covers underneath was clean no build up nothing like they were recently cleaned out. I had glitter in the old oil filter not much but some. I put 10w30 synthetic blend penzoil in it. Purolator oil filter

 

https://drive.google.com/file/d/0B8gErgcbey9UUm9VWjltSEtGRmc/view?usp=sharing

 

you can hear the sound around the 20 second plus in that link.

[Motor City Rick]

Have somebody hold the throttle at the speed of maximum noise.

 

Pull one spark plug at a time on the passenger side when the noise is present,

 

...did the noise change, if so what did it sound like now???

 

If the noise went away, rod bearing issue, possible piston skirt clearance failure.

 

I wish the video sound was better.