over filled oil now i got a clunk pls help

I think i over filled my oil because just after i got this clunk\knock (not a tick) in what seems to be the bottom of the engine but it is hard for me to tell. When the jimmys cold it purrs perfectly but as soon as the engine heats up the oil pressure drops and the clunk kicks in. This looks like a failed part or something is screwing up as soon as the oil heats up. This truck has no horse power loss and it does not burn or use any more oil than it did before this problem. Ive been driving around like this for 5 months and mechanics keep telling me they dont no whats wrong with it and i dont have lots of money to spend to diagnose it.

1990 s-15 jimmy
4.3L fuel inj.
360478 km

Drain the oil and refill it to the proper level. Excessive oil can allow the crank to dip into the oil, creating foaming, and prevent the oil pump from moving liquid oil through the engine. Operation in this condition can destroy bearings, crank main and rod journals, cam lobes and journals, rings, rockers, and about anything else which requires lubrication.

You didn't say how much over the mark you filled the crankcase. was it slightly over the "FULL" mark like 1/4 inch or was it an inch or more?

Do like Blue Bowtie says, get the oil level back were it belongs. If the problem still persists, tell us what the knock sounds like. Does it get faster as you rev up the engine?

The knock kicked in while i was driving so i stoped and checked the level and yes it was over the mark by 1/2 inch to an 1 inch. So after work came home drained oil filled to proper level but the noise was still there. Ive been driving it this way for months and i also 4x4 it hard to see if the engine would die but it keeps on going. There is no oil leaks and it runs/sounds perfect when engine is cold including reving the engine. The knock starts when the engine is hot and yes the knock does increase with rpm. This is a loud knock but i dont think it has anything to do with the cylinders. The oil pressure reads fine when engine is cold and it even moves up and down with rpm but as soon as it gets warm it starts to drop until no pressure and a knock. The knock is a low sound fairly deep and definately sounds like a metal arm swinging around at higher rpms.

thanks for any help

nick

It sure sounds like a Bearing that is on its way out, but I would think something would have gone completely out after months of driving it like this. It could be a bad lifter knock like the one I had in my 2000 Jimmy, but I remember my lifter knock would go away when it warmed up. I would suggest that you do a crankcase flush using Gunk Brand 5 Minute Engine Flush to see if that takes care of the knock. If it is still knocking after a crankcase flush, I'm thinking bearing knock. If you do decide to do a Flush, there are some important things to know. Read the first 20 or posts on this thread.

http://www.automotiveforums.com/vbulletin/showthread.php?t=361285

I had an old Astro van that developed a knock (rod knock) and I ran it like this for another 100,000kms. If your not sure what the sound is, get it looked at by someone to see what it is.

Also, I am not trying to be a smartass in any way, but this is why it is important not to overfill your engine, because engine damage could/does occur.

My 82 Olds started a rod knock and 3 days later it destroyed itself by pulling the connecting rod and wrist pin out of the #5 piston and punching a 6 inch hole in the block. I would not wait to get this knock looked at by a reputable mechanic.

Definitely need to get it checked but the low/no oil pressure @ idle and a knock is pretty much a sure sign you spun a rod bearing.

I went to school with a guy that had a Duster with a slant 6, drove it to school and work everyday for 9 months with a rod knock, last day of school put a brick on the gas pedal and the sucker ran for 1/2 hour before it punched a hole in the block.

A family friend let his kid drive his 383 Cuda, came home with a rod knock (could never prove it but the kid was probably drag racing it and over reved it). Motor spilled it's guts on the way to the shop to get checked out.

So... you never know how long it's going to last, but if you keep driving it you know what will happen.

You may want to drain the oil into a pan and filter it through coffee filter to look for metal. You can also pull the oil filter and cut the sealing surface off and pull out the paper element and look for metal, if it is a bearing odds are you will find a bunch of metal in the pan or filter.

If your hard up you can try STP or Marvel Mystery Oil (I think those are pints) along with 4 and 1/2 quarts of 80 weight gear oil. But your just delaying the inevitable sooner or later that won't help anymore.

Good Luck

Sparky

If your hard up you can try STP or Marvel Mystery Oil (I think those are pints) along with 4 and 1/2 quarts of 80 weight gear oil. But your just delaying the inevitable sooner or later that won't help anymore.

Sparky
:eek:
80 weight gear oil...in the crankcase...?
I'll gaurentee you you'll have an engine problem way earlier than later.

If it was a spun rod bearing would my oil pressure read ok when cold and when hot drop and start to knock. I just dont understand how it could run and sound so perfect when cold but its a good place to start. Ill check the oil for metal and for sure there should be because this beast makes so much dam noise. What would be a reasonable price to get this work done and or get the engine rebult.

Thanks for the replys and keep them coming, somebody out there should no the exact problem because of these symptoms.

:eek:
80 weight gear oil...in the crankcase...?
I'll gaurentee you you'll have an engine problem way earlier than later.

Yeah, might as well throw cement into it and get it over with.

If it was a spun rod bearing would my oil pressure read ok when cold and when hot drop and start to knock. I just dont understand how it could run and sound so perfect when cold but its a good place to start. Ill check the oil for metal and for sure there should be because this beast makes so much dam noise. What would be a reasonable price to get this work done and or get the engine rebult.

Thanks for the replys and keep them coming, somebody out there should no the exact problem because of these symptoms.

Stranger things have happened. I would have to guess that you have a bearing going out that is worn just barely enough to clank after it is warmed up. Unless Detroit has changed bearing designs in the past few years, Rod and Main bearings usually don't "SPIN" the crankshaft journal usually galls deep into the bearing, throwing metal flakes everywhere . These bearings are half circles, one half fits into the connecting rod or the Block, the other half fits into the respective bearing cap. Each half of the bearing has some sort of a tang or key to keep it from spinning. Now Cam Bearings are different, they are usually full circle bearings and they will spin. When a Rod bearing starts to wear, the oil clearances become greater and greater until there is so much slop between the Crankshaft and the bearing that when the rod reverses direction during its stroke, it ticks, knocks, clanks etc. becoming louder and louder. Before too long, if you keep driving it, it will clank when cold too.

Simply put, if this is the problem my friend, you're on borrowed time.

To answer your question about cost, the last time I swapped an engine, I bought a newly rebuilt Long Block Engine and it ran me almost $2000 USD by the time I was done. I did the labor myself, but I replaced everything with new parts (waterpump, plugs, wires Dist Cap etc.).

I'm not sure the overfilled oil has anything to do with the knock, but in any case maybe some further testing can pinpoint it better.

The low oil pressure is causing knock, not other way around right?
What is pressure when cold idle, cold revved, hot idle, hot revved?

I see that it gets faster the more rpm you have. How does loading the engine change knock? Is it worse at idle, or crusing, or when WOT?

How warm does it have to be to start to hear knock? Does it gradually get worse as it gets warmer? IE if you were to run WOT or pull load with it would it be a lot worse? Is it starting when water temp gets to ???deg?

What happened right before the oil level was too high? was it an oil change, did no one add oil, if not then maybe water got in oil? to bring up level.

Without hearing it, it sounds like something in the piston/pin area , but that usually won't affect or be affected by the pressure. Perhaps it is a main bearing or cam bearing/gear related.