I should add that the situation has become considerably worse after I
put premium gas in it just yesterday.

You could easily be describing an engine with a spun crank bearing.....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos:  Non members can still view!
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"CL (dnoyeB) Gilbert" <Fake@ThisOneIsFake.com>

You need to find out exactly what the problem is, CL.
Don't throw parts at this.
Yes, you may have a bearing problem, but it could as easily
be something else.

I am thinking valve train.  Chains, tensioners, gears, etc.

Running a few tests is a lot cheaper than throwing parts at
this car.

(1) Compression and leakdown will eliminate or indicate some
things.

(2) A worn chain or gear or tensioner, if it applies to your engine,
may take a little more work.

If you have an internal problem like a bearing,etc, you will have
to do deeper surgery.

No surprise, given the stinkin' quality of "advice" you dispense to
others.

Take a close look, folks...this is how an individual with an EE degree
goes about diagnosing a vehicle: By replacing and unplugging parts at
random. Unless, of course, he was lying about the degree.

Open the door and let in whoever's standing out there on the patio.

also known as Wednesday

Ayup, ayour exhaust asystem acould be acoming aloose.

Why not try unplugging...ummmm...the alternator next? And the O2 sensor!

Well, gee, I can't figure out why I ever doubted you. That *certainly*
sounds like EGR trouble, you betchya.

So, when during your EE courses did they teach you that the oil pressure
light and gauge indicate the engine oil level?

I do: They accepted the likes of you as a customer.

...says the engineer...

Yep!

"Well my Blazer is going downhill FAST.  This weekend I put on a new
EgR
hoping that would fix the problem of poor acceleration and knocking.
Well it didnt.  But with it plugged in the acceleration was MUCH worse.
 So I unplugged it, and the knocking got worse but the acceleration
got
better. "

First questions: How many miles on the vehicle? Has it been overheated
recently?

The EGR system is designed to pass a calibrated amount of burned
exhaust gas back into the intake manifold to be burned with the
incoming air/fuel charge. The main benefit of this is a lowering of the
combustion chamber temperature. A non-functional EGR system will make
your engine more prone to overheating, detonation and pre-ignition. You
will also probably fail an emission test for exceeding nitrogen oxide
limits.

Having said that, just replacing the EGR valve will not always fix a
problem with the EGR system. Many times the EGR passage is already
clogged by the time the valve gives up, leaving you with another
problem that is best fixed by pulling the intake manifold and clearing
the passage.

It is possible you have burned up a bearing. It's also possible you
didn't install the EGR valve correctly and you now have a nice exhaust
leak under the hood, which can sound a lot like a bad bearing.

One way to test main bearings is to put the car in drive(automatic) or
4th/5th gear(manual), hold the brakes, and apply a SMALL amount of
throttle/clutch to raise the engine RPM and put LOAD on the engine..
Raise the speed about 200 rpm at the most. A knock that becomes
progressively louder(to a point) would suggest that you have one or
more bad main bearings. Of course if you have an exhaust leak all bets
are off. How to tell you ask? Start the engine when it is stone cold
first thing in the morning. Start passing your hand near the manifolds,
the connections to the downpipe, and the egr valve. If you feel any
pulses you just found a leak. Look for a black streak near exhaust
connections, the presence of any would likely indicate gas is escaping
at that point.

It's also possible the EGR valve is leaking when it opens, and it is
not supposed to be open at idle. On the newer GM computer controlled
EGR valves(the $300 ones...) I don't know how to force it open to test
it. The old style, you use a hand vaccum pump. You will need to have a
helper open the throttle slightly, if you open the EGR at idle it will
stall the engine. What you want to look for is abnormal noises when the
valve opens indicating that the exhaust is leaking OUT of the valve
instead of getting sucked into the intake manifold.

I am assuming you did not do your oil change and radiator flush. I hate
to say it, but I've never had a positive experience with a mechanic.
Ever. They always manage to fix one things and break two others. I
would suggest replacing the oil filter immediately if you choose to do
nothing else. Cut the old filter open and inspect the filter element.
If it is full of metal shavings you just confirmed your suspicion about
'burning up your engine".

Good luck with it,

Chris

Fare ye well old Blazer.  We went through a lot together.  Can't say
i'll miss you though I will miss those brand new tires :(

Engine is shot.  I suspect those bozos put a bad oil filter on, but my
memory is not sharp enough to recall if the problems started before or
after my trip to the EZ-Lube...