Engine banging at high RPMS

About 2 months ago I had both my engine gaskes replaced due to a coolant leak. The mechanic said the inside of the engine looked fine inside.

Well a few days ago, I was driving along and looked at my gauges as usual and noticed that at highway speeds, my oil pressure was about 20. At a red light, it went to 0. I freaked out and gave it some more gas to get it back up.

I had to continue driving it to work which was bout 10 miles away. And I drove it home.

Later in the evening, I went outside to figure out what the hell the problem was. I cannot for the life of me figure it out.

On startup, the oil pressure is around 50. As the engine warms up, it starts dropping. I added some STP Oil protection after a fresh oil/filter change and that seemed to help, but I have about 3/4 qt too much oil in the system. The engine has 5w30 in it right now.

But what is worrying me the most is the banging I get at high rpms. The engine sounds perfectly fine at idle and doesn't start making any noise at all until you get over 2500 rpms. You can drive it around and I took it a quick 100 yard drive down the highway really quick to see if it banged at highway speeds and it doesnt. Only when the engine rpms are up. I also noticed that the engine wanted to surge a little when I tried to accelerate.

The check engine light is on, but I believe that is a result of me removing the MAF sensor while the car was running so I could get my head closer to the engine to determine what the problem was. In addition, my cat needs replaced as it is rattling.

I took off the belt to listen to the engine noise and it sounds like it is coming from the passenger side front when the engine is revved. I am at my wits end with this blazer. I have dumped about $2k into this thing for the past year and it continues to break down.

I will list some of the replacements that may attribute to this possibly to help you guys troubleshoot.

- New upper/lower gaskets
- New PCV value and vacuum line replaced
- K&N Cold Air Intake
- New radiator/coolant w/ new hoses
- New belt tensioner
- New Optima Red top battery
- Engine had AutoRX run through it about a year ago
- New fuel pump

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I am about to give up here guys. I am in the process of looking for a new vehicle as I still owe about 1300 bucks on this thing. I about convinced my g/f to allow me to keep this thing and just rebuild the engine to allow me to drive back/forth to work each day and just buy an 07' Jeep Wrangler for in the meantime.

So if you guys have any advice, let me know. I am gonna go buy a scanner at Autozone or Advanced Auto to be able to pull codes to troubleshoot this thing.

I hear the pain - I have 4 of these and not happy either. The 99 had the secondary air injection so see if the check valves and hoses are good and they make a racket as they rust out. The oil sensor is back by the dist so that may be giving bad readings. Switch to 10w-40 high mileage oil. Long term get something new and look at America built like Toyota or Nissan!

I put in some Lucas Oil additive to see if that would help. It did not. Idles fine still, but I have completely lost all power on this thing. I believe I have mechanical failure in the engine somewhere so I am giving up. I am either going to have to rebuilt the engine or find one in a junk yard. Then again I could do the V8 swap for fun, but that would cost wayyyy too much money.

So my Blazer is dead in the water now. Time to look for a new vehicle. :(

It could be a ruined rod bearing from the coolant leak before. It sounds like it is hurt bad from the low oil pressure readings.

Stop adding additives to your oil if you don't know what the probalem is.

chances are you have an oil pump problem or your main crank bearings are shot due to the coolant.

Get rid of it soon, I am selling mine so I can enjoy driving again without worrying that something else is going to go wrong every time I drive the friggin thing.

Kick it to the curb bud, I can say I literally hate my Blazer. And get this, my 300c with a HEMI gets 27mpg on the highway at 70mph and this friggin Blazer is lucky to get 22mpg if I baby it at 55-60mph.

I am enjoying my new ride so much.

I am still stuck with this thing in the garage. Maybe I can use it for a trade in at some point for the wife getting a new car. :)

I would like to drop a new/used engine in it and use it for a work vehicle. I have an 06 F150 FX4 that I am using now and I don't like taking it in the plant.