So I hear an exhaust leak and after chasing it I find a broken rubber elbow on the passengers side just under the intake hose. The line is tapped from the exhaust, goes outboard then forward to the rubber elbow. From the Elbow it goes down, then inboard parallel to the crank pulley. I replace the rubber hose and the truck starts running like crap. Get a MAP sensor fault light.

It runs like that for a week and the exhaust leak comes back but the truck runs better. The hose is broken again. I'm thinking there is a clog down the line but aren't sure where this line goes or what cold be clogged. This little motor looking think just under the front bumper was making a bad noise but it stopped after a while.

Can some help me out with this? I'm sure it has something to do with the emissions garbage on this truck.


1999 S-10 Blazer 4x4 4.3 W

 

Sounds like you have a bad check valve in the AIR (air injection reaction) pump plumbing. Fix the check valve and reassemble with the proper high temperature hose assembly. Pretty simple and straight forward. No need to get all worked up about...

 

Would a bad pump also cause this?

Well, I bought the new check valve and verified that the one in my Blazer is not doing what its supposed to. Thanks!!

 

Did the new check valve cure the problem or are you in the wait and see mode?

 

I replaced the check valve this morning and have the formed rubber hose on order. Should get it tomorrow.
I can tell you that the check valve I removed was bad because the disk inside the valve was loose and rattling round.
I know I have other issues with this truck. I have a MAP code that pops up after I did a Intake manifold gasket R&R. I replace the Map sensor but no joy.

 

Replaced the check-valve and the formed hose. Had to MAPP gass to get the stupid check-valve off.
The truck ran great for a couple of weeks but then it seems like another hose further down in the system blew. I can hear the exhaust leak coming from under the plastic cover which covers the forward part of the engine from the bottom of the radiator to just aft of the crank pulley. I've been too lazy to remove the 6 bolts and dropping that cover.

I can't believe the other check-valve went too. Too much of a coincidence. Might take stab at it this weekend.