Knock, Knock

[Tutype]

I. I have a 2000 Blazer 4X4 LT with a knocking motor (it sounds like a little man is in the motor with a sledge hammer). Can anyone let me know if there is anyway to tell what's the problem simply by listening to the car run? There are no fluids leaking on the ground and the oil is ok (full and not gummy).

II. If I can't tell just by listening, what do I need to do to make sure what the problem is?

III. Would my 1996 4X4 LT motor simply swap places with the 2000 LT Blazer?

Thanks in advance,


-TuType

[Rick Norwood]

It could simply be a number of things. Lifters, Thrown Rod, bad mains. The lifters caused my Knocking noise and was a pretty easy fix.

Read this thread, it is a bit long but in it you will find the quick and easy way to fix lifter noise:

http://www.automotiveforums.com/vbul...d.php?t=361285

If it is a Rod or Main bearing, it is a very expensive fix.

[Jerry80871852]

One time I had something similar, a very bad knocking on a 75 Cutlass Supreme Olds while still under warranty. It scared me to death and I would not drive it another inch. It sounded like it was coming to pieces.

Thankfully it was a weekday morning and the place I bought it new from was open. Their service manager came down, said it was carbon on to of a piston.

He had me to drive it on to their shop. While running at a high idle he poured water through the carburetor, the water got rid of the carbon and I never had that problem again.

Hope yours turns out to be simple.

[Tutype]

Last question. I understand the engine flush process & will try it. However, my concerns are:
I'm in the Chi-Town area and it's been averaging around 20 to Zero degrees, so...

(1) Can I make the problem worst?

(2) Can I through a rod or something, and it puts a hole in my engine, or even worst like coming throuth the hood of the truck, or the dash?

(3) Get the picture, or am I just being foolish?

Thanks again for all the replies and help.

May everyone have a Blessed CHRISTmas!

[Rick Norwood]

Yes there is a possibility that things can break like connecting rods etc. and do more damage. Allowing the engine to continue to knock (assuming it is a thrown Rod) will only trash an already trashed bearing and crank journal. DO NOT UNDER ANY CIRCUMSTANCE REV OR GUN THE ENGINE. Idle it only.

If you start the truck and let it idle while you pour in the cleaner, it is not likely. If your problem is lifter knock, the flush technique should solve the problem fairly quickly. If your problem is a thrown Rod or Main bearing, the engine flush won't help and the few minutes it will run probably won't make a whole lot of difference.

Does the knock go away when the engine gets warm? Mine went away after a few minutes of warm up.

[Jerry80871852]

Can you tell if its at the top or bottom of your motor?

It its at the top it could be a lifter trying to stick & or stuck, and many times if a lifter is stuck the engine will not run smoothly. I had a problem with a stuck lifter in my 92 S10 Blazer a while back. Here is a topic about it.

92 S-10 lifters


When I would 1st start my engine the lifter would be stuck, them in about 3 or 4 miles it would come unstuck and my engine would run fine. I change my oil replacing one quart of oil with Rislone. That solved my stuck lifter.

As Rick said, if its a rod knocking, I would be hesitant about even starting it up and letting it idle once I was sure its a rod except for long enough to diagnose it.

[Constant Problem]

Check to make sure the transmission is bolted up tightly. If it is not you may be hearing the flex plate knocking. If it is tight take off the dust cover and inspect the flex plate for cracks. Check the small stuff first.

[Tutype]

Thanks everyone, it's done (toast). It appears the motor will not turn over anymore. Anyway, I am swapping my 1996 Blazer Motor & Tranny into the 2000 Blazer.

Thanks again to everyone.

Peace,

-TuType