Hey all,

My blazer recently started making knocking noises from the engine. I've put 6k miles on it since the noises but hasn't gotten too bad. I was thinking of taking out the entire front differential(all joints are sagging and old) and also the steering system. Would this open up enough room for me from under to take off the pan and and replace the bearings?

I was also considering changing the rear main seal and the front timing cover cuz both are leaking.

Any insight is appreciated

 

It's still pretty hard to get the pan off with the crossmember in the way. You're better off in the long run to pull the engine out. It's not that bad of a job, really.

 

I wouldn't bother with the old engine unless you're going to at least put a crank kit in it (reground crankshaft + bearings). This will certainly require the engine to be out and on a stand. However, spinning a crank in with the pistons in place is not for the novice (too easy to ding up the crank with the rod bolts) - and rods/main should really be resized anyways (but you might get away with just a crank kit). You end up with the engine completely disassembled to do a crank replacement right - and the rest of the engine is still untouched. Better to go find a used replacement engine or even buy a GM rebuilt long block if the vehicle is worth 2K of repairs. Otherwise you are most likely in for a lot of work for nothing, and will end up with a vehicle that doesn't run. Sorry

 

And the fact if it is a rod/rods bearing/bearings after 6k miles you have egged and trashed the rods

 

thanks for the input guys. It seems better to just pull and do a full rebuild or buy a rebuilt one and swap it.

Is it common for knocking to last this long without throwing a rod? My initial plan was to drive it until it throws a rod because its not really worth selling as is. However, the knocking is intermittent and not really getting worse or atleast not at the rate that I would expect.

 

I drove mine with a knock for a while. It seemed to mostly go away sometimes, but it always came back. Never got any worse, though. I even pulled the pan and looked to see if there was anything obvious (bits of bearing material, blued bearing caps, etc.) and I didn't see anything. I ended up replacing it a couple of weeks ago with a Goodwrench long block and, while I haven't had a chance to do an "autopsy" on the old one, I did notice it had about 1/8" of crankshaft end play, which is WAY too much.

 

That surely sounds familiar. My engine also had a knock when I first got my Blazer. Turned out thrust bearing (crank endplay) was also very loose - #1 & #4 Rod bearings and #1 Main bearing were really worn - worn enough to bleed off enough oil pressure (when hot) to let a lifter collapse on #1 cylinder. Here is a video of it making the noise back when I was a Blazer newbie trying to diagnose it. Admittedly I was all over the map during most of this thread.

Never made any noise during the test drive when I purchased it back in 2014. Only after driving it 100 miles back from Chicago. https://blazerforum.com/forum/2nd-ge...g-valve-87514/

Seems that a lot of 4.3 owners have this collapsed lifter "ticking". I now believe it is a result of bearing wear from leaking intake gaskets. I know that my intake gaskets had been replaced before I got the vehicle.

After a lot of $$$$$ and work - and my first failed rebuild of my life, I also ended up with a Goodwrench engine (to get it running again and because I didn't trust the old engine anymore at the time). Later I figured out what I did during the first rebuild to cause the failure. You can read about it in my saga (post 67). Moral is NEVER prime oil pump with a drill when you have the intake off of the engine.

The Goodwrench rebuilt has been a good engine. 40K miles on it now. Bought it from Jegs. At the time was no tax, no shipping, no core, and they price match - kept a VERY nice plastic engine shipping container. Now they charge tax.

 

I bought mine from Karl Chevrolet in Iowa. Shipping was free, there wasn't any tax, and the $200 core charge was included. OTD price was a little under two grand. It's really not worth paying shipping to return it, so I get to keep it and one of those nice plastic shipping crates, as well.

I'm going to head over to your other thread now and read about your misfortune.

 

that's a really good price! Iirc mine was slightly over 2k.

Now I cringe a little at all the mis-diagnosis I seemed pretty sure about. But that's what I thought at the time.

Bottom line is that I ended up with 12K total in my Blazer including the purchase price, failed rebuild, Goodwrench long block, and the trans which was done at a trans shop. At 40K miles I figure I'm about 2/3 of the way through driving my money out of it. Fortunately it still looks good. Just a couple more years........

 

I very seriously considered rebuilding mine myself, but I don't really have a ton of spare time, and that warranty was just too nice to pass up.

I'm glad I made that decision.