Hello All,
First I would like to thank this forum. The knowledge I have gained from reading the numerous posts has greatly assisted me in keeping my blazer running. However, now I need a little help to confirm what I feel I already know from research.
Ok, so First, I have a 1999 Blazer 4Dr 4WD with 121,000 on it. About a month ago, I was travelling to a interview on the interstate. My blazer shuddered and the check engine light came on. The shudder went away and but I placed my OBD reader on while driving, (I know, probably worse than texting). Anyway, it gave a P306 code. I cleared and it never returned for the next 3 hours of highway speeds with normal power and gas milage. I pulled off the interstate at my exit it it was missing like crazy. It pulled a p305 code this time. I milked it to the hotel and then the next day milked to back the interstate, placed some fuel injector cleaner and wing and a prayer back home. Again, no issues on the interstate. NO codes thrown. Back home, codes thrown but only at idle and around town speeds, drove normal on the highway.
So... with some research on here it sounded like a plugged poppet so I got some chevron cleaner x 2 for one tank and well I took my son fishing and on the way home the engine sounded completely changed to a knock that has gotten worse.
I have a posted for the video of the sound at the end. Since I made this video, I have pulled the serpentine belt off to make sure it wasn't a component on that track. I am pretty sure that I need a engine but on the off chance one of you, who is way smarter than I has a thought I would really appreciate it. I haven't drove it in a couple weeks as I have been researching, working on it etc. I am currently riding my 49.5 cc scooter and I look like a monkey on you know what so any help in either direction would be greatly appreciated. Please click on the link below to hear the sound.

Thanks again,

https://docs.google.com/file/d/0B-Mn...it?usp=sharing

1999 4DR 4WD 121,000 miles

 

I am hopeful by the lack of responses that you can't see the link. I am posted it on YouTube as well. Thanks in advance for your help. I would be extremely appreciative for some help.


Thanks

 

Pull the oil filter off and cut it open. That's the best way to see if their is anything wrong inside with out pulling the oil pan. I have seen the flex plates break and they will knock and sound similar.

 

That is exactly the noise ours is making....!

Ran all the scans, tests, drained oil, used a stethescope to listen to what area inside the noise is coming from....right around the dreaded spider!

Going to do some more research, sounds like heck but it runs awesome!

 

kncoks are almost impossible to diagnose over the internet. There are a few things that could make that noise. Crank, rod, balance shaft, or flex plate.

Someting you need to be aware of, missfire codes can be leaking fuel pressure regulator issues, if it leaks fuel into the intake the fuel goes into the gas and since gas is thinner than oil it wipes the crank bearings clean and eats them up.

 

Couldn't agree more on trying to diagnose knocks over the internet! LOL!

 

Dude, that seriously sounds like a mechanical knock. Whether its your valves tapping or a lifter bent, IDK, but I would not ru it till an overhaul is done.

 

Dropped ours off at a friends dad's chevy dealership yesterday ... picked it up late last night with a "nothing to do with engine. motor strong. ran all tests nothing wrong." note waiting for me. Going to call them monday for more info about what tests they ran. wtf....glad I didnt pay big bucks for it! lol! back to old school diagnosis!

 

any resolve on this? I have the same issue.

 

I haven't spent a ton of time on it, been working too much but looks like top end - #5 has low compression.

So....I think that when I get some time I will probably hunt for another motor.....