1997 w/ a motor tap

1997 ls blazer 4dr 4x4 4.3

As some of you know i have a bit of an oil pressure problem. I put in some thicker oil to bandaid it for now till i got my feet on the ground with college. After taking the 300 mile trip w/o a problem i noticed what sounded to be a tap.since i drove it to school i probly only drove it 10 miles. Tonight i poped the hod and reved it up. there is a signicant tap at high rpms(above 3500-4000) what sound like its coming from deep in the motor.(main, conecting rod bearings) I had an older jimmy before with the same tap and the tap over time slowy came down to a point it would be a very loud knock at idle, and im sure this will happen again and POP there goes the motor. im not gonna drive at all or as little as possible. What steps should i take in to finding where this knock is coming from, and/or what i should do about it. Money is an option........ I dont have any haha school aint cheap im wondering if im at the point now where i spent so much, should i get rid of the biggest headach of my life or am i in to deep to get rip of it

1.) What filter are you using?
2.) Ever done a flush?
3.) What oil are you using now?

Wrong approach on a Blazer - use the 5w-30 as GM states, good filter, and I've had great luck on all mine with the high mileage oils. Also check the coolant level for a drop as the lower intake leaking internally can cause this noise. Fill the reservior to full Hot line when cold and then check every few days when cold and see if it is slowly dropping.

acdelco filter
No flush yet
Pensoil 20-50 i think is what i put in there. it was only for the drive out though i was plaing on outtin 5-30 back in, what i always have put in. only reason i put thicker oil is was the lower oil pressure. I was affraid that i would ruin the top end on my trip out there. the thincker oil did help the pressure. Oil and filter has 400 miles on it.

Coolants good. I just did the lower monifold, so the whole coolant system is in tip top shape

acdelco filter
No flush yet
Pensoil 20-50 i think is what i put in there. it was only for the drive out though i was plaing on outtin 5-30 back in, what i always have put in. only reason i put thicker oil is was the lower oil pressure. I was affraid that i would ruin the top end on my trip out there. the thincker oil did help the pressure. Oil and filter has 400 miles on it.

Coolants good. I just did the lower monifold, so the whole coolant system is in tip top shape

20w50?!!!

Oh COMON!

Since when does the 4.3L need thick goop like that to run. Never EVER run thick oil to counteract what you might be thinking is a low oil pressure problem.

Plus you probably did more harm to the engine seeing it was trying to pump and circulate oil that is way to thick for it to handle.

Dump the oil and filter and install a cheap oil filter and 4qts of cheap no name engine oil.

Dump in a bottle of gunk engine flush and allow it to idle for around 30-40 minutes AT IDLE ONLY!!! The bottle says less but don't you worry, it won't harm a thing doing it for 40 minutes and you will be sure it is completely working.

Dump oil and leave the filter on.

Pour in 4 qts of cheap oil ($0.99 stuff is good for this) and allow the engine to run for about 15 minutes to circulate and to remove all the flush.

Dump the oil again and remove the filter. Allow everything to drain completely and add some good 5w30 engine oil and keep with the AC Delco filters. Maybe even try a Wix.

Don't worry about higher mileage oils. They are just a marketing scam. They charge more for essentially the same oil. If you want a perfect 5w30 then use Castrol GTX. One of the best conventional oils around.

You should be good now.

ok i will do that. I know it was a bad move its what i get for listening to the wrong people. Ill give it a shot BLT and hope for the best. :banghead: :banghead: :banghead: i gotta learn some how.... even if its the hard way

I just checked it. I let it warm up, idle for about 10 min and reved it up. If i rev it up gradualy its hard to notice. But if i burb it hard around 3500-4000 rpms there is deff a crankshaft bearing knock. I herd it before. I will still do the flush, but is there any saving the bottom end by doing this, or will it last me 500 miles and give up

Well if you hear a good tap deep inside the motor, I'd hate to tell ya, but your on borrowed time. 20-50 is too thick, but a little thicker oil won't harm it, say a 10-40, 5-50, that will help the oil pressure when warm, but will keep oil moving through the engine. Unfortunatly it sounds like you need to tear it apart, rebuild it, or replace the engine. Good Luck.

acdelco filter

I just did the lower monifold, so the whole coolant system is in tip top shape

Stop driving it NOW!

Improper torquing sequence or torque values on the lower intake will cause immediate damage to crankshaft main bearings, due to block distortion.
Do not use a flush now as it will cause further damage to the bearings that are distored. The only fix is to retorque the manifold and hope for the best. You have probably already damaged some main bearings so it would be best to pull the motor and check / change bearings. This is alot of work, but if you don't address the bearings, they will ruin the crankshaft and make the eventual repair even more $$.
There are some older threads here that show the GM TSB that describes this problem that begins with the new intake in 1996 and later. SEARCH!

let's not start doing the sky if falling type of scenario.

He could just have a dirty lifter and just needs a flush to clear out the sludge in it.

Several people have had a knocking or tapping noise and this fixed it.

Let's try the simplest things first and go from there.

He doesn't need to rip his engine apart yet.

here is the link showing the tsb.
http://www.automotiveforums.com/vbulletin/showthread.php?t=526911

The key fact is that the problem appeared shortly after replacing manifold.
In light of this exact senario, GM issued the tsb to help people keep from destroying their motors due to improper intake manifold installation. It would be exteremly foolish to make the problem worse by using a flush at this point.
Beware of the "Bolt-on, Pour-in "Mechanics"" that live on the internet. Stop driving it until you read the TSB and talk to a knowledgeable mechanic.

here is the link showing the tsb.
http://www.automotiveforums.com/vbulletin/showthread.php?t=526911

The key fact is that the problem appeared shortly after replacing manifold.
In light of this exact senario, GM issued the tsb to help people keep from destroying their motors due to improper intake manifold installation. It would be exteremly foolish to make the problem worse by using a flush at this point.
Beware of the "Bolt-on, Pour-in "Mechanics"" that live on the internet. Stop driving it until you read the TSB and talk to a knowledgeable mechanic.


That did help i have talked to a dealership about what some options are with it. For the most part we came to the conclusion if i wanna keep the car for a long time, rebuild the motor. the stress from a possible spun bearing from possible overtourqed manifold and the stresses on the heads from overheating a few months back. it would be cheaper to rebuild the motor while it still runs and the knock isnt that bad then to wait and try to bandaid by flushing it and put a rod though the block and really be up steam with out a paddle. i do have accesess to full garage at home(300 miles) I feel confident if i really baby it on the way home i should be able to make it. im still not sure what im going to do but untill i do the car will not move