KA Problems

[Riceless]

Hello all, I recently posted this in the KA section and it was recomended that I also post it here.

I have a 91 240 with 142k on the engine. I don't know of any major rebuilds/etc, as I have only owned the car a few months. Last week something screwed up. I was testing my speed limiter and it cut at 113 and went down to about 95. Soon after that I tried to accelerate, but couldn't. BTW I did not exceed 5500 RPMs. The speed continued to go down until my car turned off (dash lights on, lost power steering). (I think my alternator may be going out too... and I didn't think to turn off the radio.) I parked on the side of the road and attempted to start the car again. After ten minutes of attempts and a rest it fianlly started again, only this time with a banging noise. Under any acceleration it sounds like a machine gun is firing within the engine. At any rate; the engine runs and the car drives, it just has that horrible noise. It doesn't even seem to run roughly. I've heard guesses ranging from a blown piston to a thrown rod, but nothing educated. I'm sure someone with more knowledge than me can pinpoint the problem instantly. Let me know if you have any ideas. Thanks.

[benemorius]

Diagnosing noises without hearing them can be tedious at best. Any chance you could try to determine the approximate location of the source of the noise?

Does it crank any slower than it used to before this occured, by chance? Low on oil, maybe? If there is any more input you can provide it certainly wouldn't hurt.

[Riceless]

No, as far as I can tell it still cranks normally. The oil was low, but not horribly so. The original thread is here: zerothread?id=109329 Check/confirm their ideas too. Thanks

[NISTECH]

I was thinking rod knock to. but its really hard to interpit a noise by your description as my discription of the noise could be different. do an oil change. When you do drain the oil into a clean pan. only drain a little oil at first like a half a quart. then slosh the oil around in the pan like your panning for gold. look to see if there is any shiny material in the oil like metal. this will help in determining if its a rod beating the hell out of the inside of your engine.

Another thing is the Db level of the noise is it low frequency or higher pitch. is this sound can you feel it when you place your hand on the valve cover or can you only hear it.

[Riceless]

I'll have to try "panning" tomorrow after work; thanks for the idea. You can only hear the sound, there's no abnormal vibration, and it is lower-pitched.

[NISTECH]

Try this, romove all your drive belts and fire it up, dont let it run for more then a couple mins as it will have no coolant flow or alt charge. see if the noise is still present. This will help isolate weather its an accesory making the noise or the actual engine/trans doing it.

[Riceless]

Hey, it took me until a sunday to find the time to touch the car. I tried "panning", and everything looks normal. I did not get to removing the drive belts, but I did look at the plugs and they look to have oil on them. I have read that this can mean worn bores or rings and possibly valve guides. Can you confirm this? What work would this require?
Modified by Riceless at 10:26 AM 4/3/2005

[NISTECH]

where is the oil at on the plug? do you have pics

[Riceless]

I don't have pics. It is on the exposed end, and a little up the threading.

[NISTECH]

as long as the oil is not built up on the electrode I dont think you have a ring problem. That is usually the indication oil is getting in the combustion chamber. If the oil was running down on the wire side of the plug ,when you pulled it out of the whole it could of got oil on it as you withdrew it.

[Riceless]

Here are a couple pics. I don't know if it's a big deal but I just want to make sure. Sorry about the poor quality - a camera phone is all that is around. Also keep in mind that these plugs were only used for a week or two.

[NISTECH]

guy you got internal problems going on. if you havent done a tear down before or know how to measure your bearing and piston to cyl clearances you may wanna get another engine for it. I suspect your gonna find quite a bit of damage to the inside of that engine. What ever is banging aint good. I am suprised you didnt find metal shavings in your oil and that the car otherwise seems to run fine. It should be chocking on the oil in the cyl. With the amount of oil on that plug you should be seeing blue smoke out the tail pipe as well.

[s13sr20chris]

if you have something else to drive, mechanical skills/tools, and time/roof over the cars head you can rebuild it yourself or swap a junkyard motor in.

[Riceless]

Yeah, I was pretty much expecting a rebuild or swap when the problem happened. I do have another car to drive, as well as a roof, tools and a lot of time. The thing I lack is experience. I know quite a bit "in theory" but nothing real. I would love to use all this as an opportuinity to learn since these engines are pretty cheap, but without resources or a mentor it's hard. I'm about to pick up a fsm, and I consider myself a fast learner. If you have any engine teardown/rebuild/swap links or books you can share, please do. Thanks for all the replies.

[s13sr20chris]

one thing that helps is to swap in another motor and rebuild the other on the side as a backup/hop up motor.