I just drove 60 miles from a friends, and when I got closer to home I noticed a knock or ticking sound coming from the engine area. When I get down on my hands and knees it sounds louder and somewhere underneath the engine area. It seems to only do it at a lower rpm, and once I get up to speed it diminishes. I checked the oil and transmission fluid and they are fine. I am also not leaking any fluids, and their is no error/warning dash lights on. I overtook a couple vehicles on the highway that were driving slow today. After the second time is when I noticed that something sounded different with the way the truck was running. My top acceleration was not over 75 mph, and I did not stomp on the gas when I did this. My blazer usually runs very quiet, and now the engine seems to shaking a little more than usual. Any advice would be greatly appreciated. I placed the vehicle in the garage until I can get a mechanic to look at it.

Nathan
1999 Chevy Blazer
4X4 4.8 L Vortec
99,600 Miles
Automatic

 

If the sound is coming from the lower engine, it unfortunately may be a bearing. When the mechanic dianoses it, please update this thread and let us know what it is.

 

Sounds almost like a lifter tick. How is your oil pressure at idle? What viscosity of oil are you using?

A rod knock or other bottom end problem should not go away as the RPMs rise.

 

Thanks for the advice guys. I am having someone look at the truck Friday. Still can't pinpoint the location of sound. I will let you know the results then.

Nathan

 

Finally had a mechanic take a look at the truck today. He said he cannot pinpoint the exact problem, but believes it is either a piston or a connecting rod issue. He suggested that I either swap motors or sell the truck. Any advice? I am going to take the vehicle to another mechanic for a second opinion.

Nathan

 

Without witnessing the noise, it is very difficult to tell you what you should do about it. If the mechanic thinks it is a bottom end problem then you are probably looking at a new motor (rebuilt, used, crate) or rebuilding yours. Well, that is if you want to keep the truck.