Okay have 97 4x4 blazer 4.3 Vortev 170k. Truck would start, idle, run great otherwise. Bought about month ago as-is with intermittent hesitation while cruising and constant check engine light. First I tried maf test then cleaned, it. No real change. Then assumed it was o2 sensor or catalytic converter. It had started to clatter when starting and shutting off one the last week. Then yesterday started really hard and hesitating worse than ever while driving. Today won't start at all and have isolated chattering while turning engine over to oil pan. I'm hoping it's the oil pump alone that has gone bad. Any advice before I spend money on a new pump?

 

If you hear chattering in the oil pan the i would say no on the oil pump. Take it apart and find the problem first. Unless you have the money to buy parts first then return unused parts. I had (what i would call) chatter on a jeep liberty and it turned out to be rod bearings. Low an behold after changing them and my short sightedness the main bearings where going out to. But i don't think your oil pump will cause a (what i consider) chatter.

 

Did you pull the codes to see why the cel light was on?

 

I agree with JMPARKER82 - i have never heard of a oil pump chattering - bet you lost a rod or main bearing - check them out while you have the pan off and at 170k change the oil pump out too couldn't hurt

 

Thank you for the replies. I'll get back as soon as I can get it opened up and see what I find in the oil pan.

As far as the cel, the previous owner had checked but there was no code stored. I've seen it flash on two occasions while driving but haven't had it checked as of yet.