Suddenly Knocking Engine

Hi!

I'm not exactly sure I'm in the right place, so please excuse me if my post is inappropriate - but I am desperate. I own a '94 Plymouth Sundance, 2.2L, automatic, non-turbo, with 130K miles. Engine was running fine, until one day a knock (more like a very loud 'ticking') suddenly manifest from under the valve cover (or so I think).

- There is no change in engine performance - it's just very loud.

- The ticks frequency is approx. 300-350 bpm. at idle (about 5 ticks per second).

- It's loudness decreases when making right turns, such as on a highway off-ramp with a tight radius.

- The loudness is also lessened during acceleration, or when releasing the gas while traveling at highway speeds.

- While in motion, if the gas pedal is depressed just enough so that the engine is not under any substantial load, the ticks loudness increases dramatically. It is also louder while idling in park or neutral, than when idling in gear... interesting.

- Under the valve cover, the camshaft show no signs of excessive wear, or other damage. I did not remove the camshaft to check the bearing caps or journals, but noticed nothing unusual. It seems like there is plenty of lubrication there.

- After running the engine breifly without the valve cover (about 5 seconds) and sutting it off, a little smoke appeared, concentrated on the right side of the valve trail (standing in front of the car, facing it).

- When it first started, I'd have sworn that the noise was coming from the valve train, but after listening to it without the valve cover, I'm not so sure - it could be a bit lower - but just a bit.

One mechanic said I needed a new engine based on the sound alone - he didn't even pop the hood. The guy at Speedee who changes my oil said it sounds like rod knock and is not worth fixing - just run it until it dies. The guy at AutoZone said his car had a similar knock, and all he had to do was re-torque the camshaft bearing caps to solve the problem. I did not try this due to lack of a torque wrench, but is it possible?

The problem did not develop over time. It was running quiet when I parked it for the night, then the very next morning it was knocking loudly - with no change in performance - only the smptoms listed above.

I would be most grateful for any opinions you might have to offer - should I put the money into fixing this problem, or is my engine really on its last leg?

Many thanks in advance for any help you can give me.

Sincerely, Jason W.

(If you wish to e-mail me, please remove the "x" from the address)

Reply to
JWit
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Might be a rod knock. The "overnight" scenario can go like this. You are driving your car that day and everything is just fine. You park it and the next day when you come back, and as soon as you start the car it starts knocking. If it is a rod knock, here is the most likely explanation. You have a small leak into one of the cylinders from the coolant thru the head gasket. That day when everything was fine, while you were driving your car the crack in the head gasket developed, it is small enough you can't even tell you are burning coolant outta the tail-pipe; and while you are driving the coolant simply just gets burned and assimilated into the combustion process. You let the car sit overnight, and the leak starts flooding one of the cylinders, next day you try to start your car and the flooded piston gets hydrolocked, since it can't compress the water, but all other pistons work fine and produce enough power to get rod on the hydrolocked piston to bend and the crankshaft to keep turning. Next thing you know your car starts up and the water gets pushed out of the cylinder in the stroke. You now have an engine with a bent rod that runs normally otherwise. In your case I am not sure if it is a rod-knock. Get a compression test done. If one of the cylinders is below normal and adding oil doesn't help it, I would suspect a rod-knock. Of course if it is a rod knock at 600RPM (idle) you should hear the noise about 10 times per second. In your case you are hearing it 5 times a second, it seems this would be caused by a valve; since, the valve will open every two revolutions in a four-stroke otto cycle engine. Seems to me the most likely cause for the noise is a bent or worn valve (exhaust or intake I don't know). I hope any of this advice helps, keep us posted with whatever you find out.

- JR

"JWit" wrote in message news:QUfZb.59774$ snipped-for-privacy@nwrdny03.gnilink.net...

Reply to
JR Lomas

This probably sounds like the eminent failures of the crankshaft bearing. Based on your very clear description above, I feel I can hear it. Re-torque the camshaft might not help. These knocks are fairly common.

Usually resulting from lack of oil pressure due to either failure to check the engine oil level, a quick loss of oil due to a leak, or pump suction problem or other cause.

When the bearing fails, a knocking noise can be heard depending on the rpm, load, gear selection, etc. Soon, the engine seizes before the lower end of the connecting rod breaks off or breaks open, allowing the remaining section of the rod to sling out between the crank and the block, punching a hole in the block. The vehicle can be driven up to many miles, however, the oils will spray from the crankcase ignites, causing an engine compartment fire which will finally stop a vehicle from running.

It is possible for one or more of the pistons to have accumulated metal thrown off of the failing bearing which would be best to replace the engine block and clean out the camshaft bearing.

Keep your hopes up, somebody else can see this differently.

Milo Munira

Reply to
Indiån §ummer

Sounds a lot like a cracked flex plate to me.

Reply to
Steve

very well could be a bad flex plate. try to isolate it. pull the plug wires one at a time and see if it goes away. if it does it's a rod or wrist pin, if it stays it's likely a main bearing or elsewhere.\ Chip

Reply to
Chip Stein

Check the bolts holding the torque converter to the flex plate - I had a cavalier once that I swore was having a terminal engine failure - turned out to be loose bolts. tad

Reply to
ottertailfamily

Many thanks to all who responded to my problem! I couldn't have hoped for better information - who'd have though that you kind folk who merely read my description of the noise could give me more detailed information than those mechanics who *actually heard* the sound! :) It seems like there are a few possibilities to look at, and I will certainly check them all while I still can. On Wednesday, I'm taking the car to a mechanic recommended to me by a friend - and I'm bringing printouts of all your responses... I have no doubt that cause of the noise will be isolated then, and with your help. :) I will certainly keep you posted on any developments.

Speaking of "developments," I've more closely analyzed the sound and how it changes with engine load. While accellerating on the highway, the noise is like a "tick" as I've described (tickticktickticktick - definitely not a "ping," "clank," or "klunk" - like the parts that are making the noise are not hollow - it is almost the same sound as two *small* rocks, or pebbles, being banged to gether very fast). When I release the gas and the engine slows, the sound changes to more of a "rattle" than a tick or knock. Finally, when slowing to a stop and the engine is idling, the sound changes back to the "accellerating" tick - only louder. This change also happens if the car is idling in park - It ticks, but if I rev the engine a bit, it "rattles" for a few seconds, then changes back to a steady "ticking" when the RPMs settle back down.

Perhaps this new data changes some of your original diagnosis?

I am working on getting a recording of the sound and posting it on a website for those of you who are interested - I shoud have this up within the next few days.

Thank you again - and I'll keep you posted! :D

Jason W.

Reply to
JWit

UPDATE:

Thanks again to everyone who helped diagnose my problem... but it has suddenly become a moot point. :( Tonight, while driving home from work, the noise got REALLY loud, then something started rattling and pinging... then... CRACK! A dead cylinder... My oil light came on right away, and the temp started shooting up towards the red... fast. Seconds later, the engine seized and that was that. No smoke... no fire... just a faint smell of antifreeze. I guess it wasn't a lifter after all. :(

I got a good two years out of her... may she rest in piece(s). At least I have an excuse to buy my first "new" car... Probably go with a Kia... there's some good deals on them right now, plus you can't beat that

10 yr /100,000 mile warranty.

Thanks again, all! :)

J. Whittaker

Reply to
JWit

Surprised you only got 130k out of it - those engines are capable of

300k if properly maintained. Either it wasn't, or the clock was turned back, or it was a "lemon"! Why not consider a replacement engine? Lot's of these cars around, parts cheap and plentiful. They are good cars - I've taken parts from one in the wrecker's that had 430k on the odom. Main prob is folks who don't change the coolant every two years, and wind up with a leaky head gasket due to corrosion.

A Kia? Oh, gawd - read user reports on the web before you do!

Reply to
lemstraf

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