Hi. I got a 99 Blazer 4.3W here in my shop and can not firgure out what is wrong with it. Runs like ***. So I will start at the beginning and hopefully someone can help.

Truck came in with a leaky intake and radiator, changed intake, radiator, and injector while we were there. Did tune up also. Blazer ran great, no problems. 1 week later it was back knocking with low oil pressure. We put a motor in it and it seemed ok on the initial test drive so we went on a good run with it. Didn't make it too far. Blazer started getting very hesitant and misfiring. Ran like ***. Got it towed back to the shop. Turns out its knocking again, same as before. After pissing and moaning about it, we put another motor in it. Again, seemed ok on initial test run but once it cooled down it had issues. It will idle fine but give it any load and it misses and backfires. Mostly bank 2 but some random misses hit on bank 1. When it warms up, that problem goes away and it just gets very hesitant, like it is choking. We changed the distributor, no help. Changed the knock sensor, no help. Checked for vacuum leaks, nothing. Changed cap and rotor again, nothing. changed the 02's, nothing. Put another intake on the motor (because we were using the original one with the new injector), nothing. Just keeps doing the same thing.

Waiting for someone with another blazer to get here so we can swap computers and see if that helps but we are lost on this one. I've about had it with this blazer...

PLEASE HELP

 

Diagnose the problem instead of guessing and throwing parts at it. Too expensive!Are there any codes? On the 2nd motor swap did all the new parts from the first motor get transferred over to the new motor(s)?

What in the world is killing these motors? I wouldnt worry so much about drivability issues if something is taking the bottom end out of these things! Have you run an oil analysis to see why the bottom ends failed? You might have conatminated oil. If the intake was leaking bad enough to allow coolant into the oil, there may have been residual coolant in the remote filter assemble. Cant imagine that little causing damage but still. I would DEFINATELY get an oil analysis done unless you enjoy swapping motors. There is just no way a blazer should eat motors for breakfast.

GOOD LUCK!

 

Its really pissing me off. No codes will show. Probably because we are afraid to drive it very far at all for fear of killing another motor. Each time the oil cooler lines were removed and the filter changed so there's a good chance we got any coolant out. There are no signs of coolant in the oil or vice a versa. I don't know if the misfires are dumping gas down to the oil pan and wiping the bottom end but the oil does not smell like gas. There is nothing anymore that came from the original motor. We had been using the intake and distributor but changed them the other day. As far as throwing parts at it, we have a good relationship with our parts house so most of it we can send back.

 

sounds like plugged up catalytic converter

 

yea sounds like it when my cat got clogged it was knocking my engine also

it got to the point it went up on fire and blew up my muffler

 

I thought the cat also. But the o2's are reading good... maybe I will break out the temp. gun and check it out.

 

my o2 sensors were fine also till it blew up into flames.

i almost lost my truck that day

good thing my dad and i shut the flames off with snow on the side of the road the truck was running like *** also

we thought it was bad gas

 

I have never heard of a cat causing the lower end of a motor to let loose. Get the oil analyze!!! You cant smell or feel what in the oil. Is $30 too much for an oil sample?

 

Sounds like $4000 of work in a $2000 car.

 

Tell me about it. The truck is beat and I feel bad for the customer because he overpaid for it and the used car guy he got it from dissappeared. Now we are fixing it, over and over