TAP TAP TAP, whats up with that???

[slow GST bih]

The other night i was out with some buddies, and was doin some racing. I noticed after the second time i raced that my car was making a Tap sound. So im lookin around my car for something loose or something that could makin that tap sound, and i figured it was the plastic lining under my car hitting the tire again. So i just ignored it for the moment.

So when we get in our cars to leave, i pull onto the road and my turbo began to spool and my car began to pull then nothing, i was making hardly any boost. So me and my buddies pulled into a parking lot and poped the hood, we pulled the throttle cable and to my horror, there was a pretty loud tap from under the valve cover, but it doesnt do it at idle, just when we pulled the throttle cable, and when actually driven it starts to tap in 1st, 2nd, switching between third and fourth, and fourth and fifth gear i dont hear it. We check my oil level and it was pretty damn low, so we put some oil in it and brought it home. The next day i turn the car on and its still making the damn noise, i changed the oil, and it still making the noise, so i begin to pull spark plug wires, and when i get to the third one over from the left, the noise is gone, the tap completely dissapeared.

So what exactly changes when the spark plug wire is hooked up and when its not?? and does anyone have an idea about what the tapping is, I figure either a rod is knocking, or a lifter, or maybe a lash adjuster needs to be replaced, but i dont know, so any help would be appreciated.

 

[awd_terror]

What kind of plugs did you have in?

 

[slow GST bih]

The Spark Plugs that i just pulled out yesterday are NGK R BPR6EY. They were in the car when i bought it.

 

[awd_terror]

If Im not mistaken, those plugs are longer than the ones I use. Also, NGK offer a colder plug that will help the car run better, and they are the NGK BPR7ES they are shorter plugs, the pistons might have been hitting the plugs?

 

[slow GST bih]

But why would only one of the pistons be hitting only one of the spark plugs?

 

[awd_terror]

Im not 100% sure that they were or if it really can happen, i do know that those plugs are longer in length. Try the ones I suggested.

 

[slow GST bih]

The sound went away when i pulled the Spark Plug wire not the Spark Plug. and I really dont think the piston is hitting the spark plug, if thats even possible.

 

[slow GST bih]

Maybe my timing is off or something, i still may try changing my spark plugs, anyone else have any thoughts??

 

[thehyena]

what mods do you have? do you have an aftermarket boost guage?

 

[awd_terror]

AH! I misread the part about spark plug wires. Hmm, not real sure then. Not unless it was a sticking valve or something of that sort.

 

[slow GST bih]

Um Ya, so i took it to a local mechanic and as soon as he heard the sound he told me it was I had spun a Rod Bearing. He doesnt think ive damaged the Crankshaft yet, but he said if i continue to drive it then i will seariously mess it up or throw a rod. I guess my plan is to order the rod bearings and do it myself with the help of some friends. If anyones replaced these themselves and knows the easiest way to tackle the job then PLEASE TELL ME!!! I plan to leave the engine in the car, remove the cylinder head, remove the oil pan and go at it that way. I'm sure it will be a hell of a job, but i hope i can get this done myself, because the bearings are inexpensive (if you buy them yourself) and i was quoted $1,000 for labor. So i hope this may help somebody else out that is having the same problem.

 

[Defiant]

You no more replace a bad rod bearing in the car than you fix it with an oil change. The crank has to be pulled and (most likely at least) polished, and the rod will need to be trued. Which means you may as well rebuild the whole thing, as you don't do this on one rod. Unless you own a used car shop in Mexico.

And no, the plugs had nothing to do with it. You raced while out of oil.

 

[slow GST bih]

So far all the people I've talked to almost garunteed me that the crank would be fine and have minumal if any damage done to it, and that by replacing the bearing of the rod that is knocking now and taking a close look at the other ones to see if they need replacement too, would take care of my problem. And what is and how do I true a rod? and why whould I do an entire rebuild just from one spun rod bearing. I dont have the kind of money required for a rebuild kit, but I'm sure I could get it if you someone gave me a good reason to.

 

[90AWDRaleigh]

This is going to sound crazy, but my dad's '86 Toyota pickup truck with the 22R 4 cylinder was knocking pretty badly. It would quit knocking when we pulled one of the wires (forgot which one). We just assumed it was a bad bearing in the bottom end. We pull the motor and take the head off too find that the headgasket had blown between two cylinders. The bearings were perfectly fine! The blown headgasket was causing the knocking sound. Because we already had the motor out we proceeded to rebuild the entire thing. Do a compression check before you tear down your motor...

 

[slow GST bih]

But in your dad's truck, wouldn't it have been making the knocking sound at idle, and did it sound like a metal hitting metal kind of sound. Mine definitely sounds metal on metal and sounds like the rod is just hangin onto the crank. But we'll see what happenes when we take the head off and drop the oil pan. I just hope an entire rebuild is where this will end up. And I noticed that the time i drove it up to the mechanic that the sound was alot quiter, almost gone, and then later it came back, as if the bearing had rotated to were it was causing the rod to hit up against the crank, but then moved back to where it was. It just leads me to believe that theres not that much damage yet. I hope.

 

[slow GST bih]

Has anyone on this board attempt to fix a spun Rod Bearing by just replacing it, and have it come out successful and fix the problem???

 

[90AWDRaleigh]

Originally posted by slow GST bih
But in your dad's truck, wouldn't it have been making the knocking sound at idle, and did it sound like a metal hitting metal kind of sound. Mine definitely sounds metal on metal and sounds like the rod is just hangin onto the crank. But we'll see what happenes when we take the head off and drop the oil pan. I just hope an entire rebuild is where this will end up. And I noticed that the time i drove it up to the mechanic that the sound was alot quiter, almost gone, and then later it came back, as if the bearing had rotated to were it was causing the rod to hit up against the crank, but then moved back to where it was. It just leads me to believe that theres not that much damage yet. I hope.

It did do it at idle...anyways, just do a compression check, its cheap, simple, and fast. More than likely you are right, but it would hurt to explore all other possibilities. Mike

 

[slow GST bih]

I'll do a compression test before i begin attempting to replace the rod bearing. Thanks for your help Mike.

 

[92redman]

Are you sure the sound is coming from the block and not from just under the valve cover? I think that if you were being oil starved, you would hear the lifters ticking real loud first and probably the camshafts making noise because the head would be starved long before the crankshaft, unless something is plugged. I wonder if it could be the spark plug wire shorting out because that could make a loud snapping sound that sounds like it is just under that valve cover... Just a thought, don't flame.

 

[slow GST bih]

The spark plug wires are pretty new, and based on sound files that ive downloaded today, im definitely sure its a rod knocking. And from what ive read from other sites when you have a very recently spun rod bearing, the sound won't be at idle and will be loudest between 2,000 and 3,000 RPM's and thats exactly what mines doing. So this weekend I guess I'll jack the car up and remove the oil pan, and see what i find. I'll post what I discover.

 

[95redeclipseGS]

where did you find these sound files...my car has been making a knocking noise for a few months now. It started one night that i was driving it really hard... but i checked my oil and i had plenty... and i took the oil pan off and there was'nt any metal shavings in it... it really sounds like metal hitting metal though, it seems like it gets worse after getting hot... i don't here it at idle at all, i start hearing it when the rpms get up higher and it is most profound when the car changes gear it kind of speeds up and gets louder ( its an automatic 95 eclipse gs ) my first guess was a rod... but if i can't hear it at idle, and there weren't metal shavings in the pan... i j/ dont know... what are the other possibilities, any opinions or ideas would be appreciated... thanx
-charlie

 

[slow GST bih]

So its been a couple days now, and i finally got my car jacked up and on jack stands, I drained the oil and removed all the nessacery parts to drop the oil pan. So today i droped the oil pan and found inside some metal shavings, which im assuming is what has been shaved off the rod bearings or the rod itself. I then cleaned the block with some brake/carb cleaner, rotated the crankshaft (using a 1/2" drive, w/ no socket- fits right into the crank) and inspected each rod, I found that only one rod had any freeplay (which i had expected), and all the rest i couldn't budge. I can actually see pieces of the rod bearing hanging out of the end of the rod. I've taken the bolts off the end cap but cant seem to get it off, is there some kind of trick??? maybe im just being a weakling. And Charlie I would recommend you doing the same thing, drop the oil pan and see if you can physicly move any of the rods, they shouldn't budge and if they move even slightly up and down or any direction for that matter I'm afraid you may also may have a spun rod bearing. I'll post what i find once i get this damn end cap off.

 

[95redeclipseGS]

if there weren't any metal shavings i cant understand it being the bearing but i might have to check it all again... but if it is the rod bearing.... tell me what has to be done to fix it... complete rebuild??? j/ replace the bearings? whats the worse case scenario driving w/ a spun rod bearing?
and is a knocking noise a symptom of a blown head gasket? because it would be great for me if that was the problem because i j/ had it replaced last christmas and it had a year warranty....
well... im gonna check into some other stuff... thanx alot guys... keep me posted
-charlie
ps
i pulled that thing w/ spark plug wires... pulling one then starting the car.. i went through all 4 plug wires and it knocked w/some gas, every time... so does that tell me anything??

 

[slow GST bih]

If there weren't any metal shavings in your oil pan, and when you removed the spark plug wire and the knock didnt stop then...

you most likely dont have a spun rod bearing. The reason a spun rod bearing causes the knock is because the rod isnt tight around the crank anymore and whent there is combustion (which is taken away when you pull the spark plug wire) the rod actual knocks against the crank, causing the knocking sound.

Yes, a blown or bad head gasket would cause a knock but it will be all the time.

Sounds like you problem is probly in the cyl. head, such as a lifter, lash adjuster, or the valve's, you should check those out, see what kind of shape there in. Get a Hane's manual and check the clearences out. Make sure to check you the PCV valve which can sometimes get clogged up and can cause some searious knocking in the head, do to low oil pressure.

Thats all i can think of right now, I hope i got all this stuff right, if i screwed something up here please correct it, and please put in your input if you think it may be something else.

 

[slow GST bih]

O ya, and I did spin a rod bearing, the thing looks like a potato chip now. So right now im in the process of removing the head, so i can get all the rods reconditioned, put in all new rod bearings in, getting the crank turned(feels a little rough), replacing the main bearing, putting in all new gastkets, and new piston rings. I think that should ensure a good run'n engine for awhile, anyone have any thoughts on other things that i should replace that wont cost me to much, im just looking to patch it up for now, but didnt want to just do the one rod and have another one knock once my car is up and runnin again. Thanks