Have an 86 SE V6 that has developed a nock. What actions should I take to try and diagnose the problem? What information do you need to help me out? Let me know and I'll respond back.

What kind of knock? If it's audible at idle, unplug each spark plug wire in turn while listening. If the knock goes away on one cylinder then it's a rod knock on that cylinder.

JazzMan

It knocks at idle, and then gets severely worse as you give it gas. The knock also becomes louder and more rapid as you give it more gas. If you look in the hole where you add oil should it be relatively dry? Mine is. It also sounds like it is coming from the side of the engine that is facing the front of the car.

welp, if its a rod knock, it is usually quiet when the engine is cold. then after things warm up (the oil), the oil gets thinner and then starts knocking. if it knocks right away even when cold, then its BAD. (not that its ever good, but if it always knocks, its a really bad knock). is the knock a deep solid knock or more like a higher pitch, (ping)? there are a few things you can do, 1st ( if not real bad), you can put in thicker oil, sae 30 strait, or add some of that motor honey. this should at least help quiet things down some, but this is no real fix at all. 2nd is find the bad rod bearing(s) and replace them. your gunna need to get the oil pan off , then if the bad one is real bad, you should be able to wiggle the rods and the bad one will reveal it self. sometimes if it was bad and you ran it for a while like that, it will damage the rod as well, making it go our of round, in which case you will need another good one, or have it reconditioned. i made that mistake once, and put on new bearings, only to have it still knock . anyways, this gives you some info to get you started.. hope it helps.

Rob

It's the BAD one that he spoke of above. It always knocks. It is a deep knock.

While the engine is running...and knocking, using insulated spark plug pliers or having loosened the plug wires, but not disconnecting them, lift each one( with reg. pliers that have good insulated handles) to produce an "open" circuit. You can also use a non-powered test light and carefully slide it between the boot and the wire at either the cap or plug end. If the knock noticeably diminishes or goes away, that is the cylinder that has the bad bearing. If no difference is heard and it is a pretty heavy/deep knock, then it is more than likely a main bearing.
Hope this helps.

Jon

My dad checked it out today. He seems to think it is a valve train problem... possibly a stuck lifter. Any thoughts on where to go from there?

If it is a lifter problem you should use Marvel Mystery Oil in both the oil and gas (per MMO instructions) and it will free the stuck lifter. I have done this countless times. A knock is deeper than a lifter tap. Sounds like a deep thump or knock. A lifter tap sounds like a ballpeen hammer hitting a vise, high and clicky. Once you've heard a bearing knock you will never mistake it for a lifter tap IMHO. Hope it turns out to be a lifter as you might as well prepare yourself for a rebuild/swap if it is a bearing. Don't try to replace the bearing on the rod as that won't work for very long. The rod is probably ruined as is the crank journal, putting a new bearing in will only lead to more distruction.

Hard to tell without hearing it for myself. Why dont you hook up a vacuum guage and see if you have a steady needle and what the inches are.

If you think that its valvetrain related it could just be as simple as adjusting your lash. I know that there is a TSB on our 2.8s warning about worn valve guides creating a knocking noise as well (found in ALL-Data).

Either way - hook up a guage and let me know what its reading.

Easiest way to diagnose a knock is to have an experienced mechanic listen to it. Might cost a couple of bucks but it's worth it...

If it is a rod knock, it will go away under a load. like going up a grade. If it is a main knock it will knock going up a grade under load. If the knock stays going up a grade or going down a grade then it is possible you have a valve train problem. Good luck
Don

My dad got some of that stuff to put in my oil (he gave me some long explination as to why it would be pointless to put it in the gas, but I wasn't really paying attention to him). Well, It didn't do anything. So what's next. My dad told me the next step is to start taking things off until I can see what isn't working. Is there anything else to try before I start tearing into it?

Oh, after listening to it more, it sounds like a higher pitch rapping, rather than a rod knock. It is there when Idle, and becomes more frequent as you hit the gas (which makes sense to me because things are moving faster inside the engine, so I don't know if that helps any).

sounds like a valve lifter. I always used CD-2 lifter cleaner in the oil with good results.
Don

my dodge did this i drainded 1.5qts of oil and took off the valve covers then pored Valve-Medic directly on the valve train put the covers back on started let it run 45-60 secs turned it off and added lucus oil (1qt) after that give it like 5min and check oil level add reg oil to full line this got rid of my nioses

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its always the ones you dont suspect

[This message has been edited by 1987bluegt (edited 03-16-2005).]