engine noise: HELP!

[bigshot82]

engine makes a knocking sound under load(good when idling). Occurs at about 30-40 mph, 2000-3000 rpm (when I hold the gas pedal steady). I let go of the gas pedal, noise is gone.

tried using premium fuel, did no good.

no engine light coming on

It's a protege 2001 standard transmission

[mmspeed3]

Unfortunately a knocking noise could be from anywhere. Have you used a stethescope (sp?), or long handled screwdriver / metal rod to pin point which side of the engine the noise is loudest on? Front, back, intake or exhaust side? Upper or lower end? Near transmission bell housing area?

Are you always in the same gear at 30-40 mph? Could it be trans / clutch / pressure plate issue at that speed/RPM combo?

"...knocking under load..." tends to make me believe it is a lower end / rod bearing noise, but we clearly don't have enough info yet to be sure.

Have you run a compression test? Leak down test? Are you getting any codes on the PCM? Autozone / Murray's (whatever 'good' parts store you have near by) can pull these for free in about 10 minutes or less.

What's your oil & filter change record? How many miles on the car? Have you checked the timing? Spark plug gap?

You should be able to unplug the fuel injectors 1 at a time and then see if the noise changes. The cylinder that stops making the noise or stops making as loud of a noise, when the injector is unplugged, would help pin point which bearing / cylinder is the culprit.

Maybe it's a bad motor mount / worn rubber isolator that is rattling at that speed / RPM (doubtful).

[martispeed]

well sorry to say it, but i have had this happen 3 times in the last 6 months(horrible shop). And to me it sounds like lower rod bearings.
The most likely # for this to happen is #4 cylinder (closest to the drivers side) due to mazdas poor design!!!!!

Also, have you checked your oil, are you low??

And the reason he/she would only be able to hear it between 30 and 40 is probably because of road/engine noise. I know each and every time this happened, there were no codes or CEL for that matter.

One easy way i know of to determin if its rod bearing failure is to disconnect the plug for injector No. 4. The engine will run rough but by reving the engine up to desired rpm (your case 3000rpm) you can see if the sound is still there. From what i know if the sound goes away, it is the lower rod bearing in that cylinder.


Hope this helps...

[Silver Streaker]

Good god, I stumbled across this here page and was happy to here that I'm not the only one with this issue. I have searched and searched for info on this problem and this is the only thread that I could find.

What kind of mileage do you have on your car? When did it start doin it?

I've got a 03p5 with BARELY 62k on it. It pisses me off because I have done nothing but treat and give this car the best there is to put into it. This is how it rewards me? What would cause such problem to occur? Is it a defect that should be replaced on mazdas dime or what? I've never heard of an engine having that type of an issue with just over 60k! (gun)(ripped):wtf: Sounds retarded if you ask me.(screwy) How hard and how much would you estimate it would take to fix? Any response would be greatly appreciated!

[jjkftw1]

same problem here. I'm a desiel man but my old lady has a 02 protege 5 that has grown on me until today. Great car with abosutley no problems besides the annoying valve train noise upon start up until now. 2.0l, manual tran, bone stock. The old lady called me up on her way to work stating that the motor was making a knock @ 2500 rpm and worse the higher the rpm. she stopped and checked the oil with no oil on the stick. She then procceded to the nearest gas station for oil only to recheck the stick before adding oil to find the oil level returned to normal the operating level. ???? My old lady comes out to the shop with me when im doing any work on her car so her knowledge of gettin around under the hood is not an issue here. so after she limped the car home and i let it sit for 20 mins to let the oil run down out of the heads and no oil on dipstick again. so i added 1/2 a quart and waited 10 mins. now oil level is above full mark. WTF? I'm wondering if these motors have any kind of pressure check valves or regulating valves in the oiling system or oil pump. Like i said earlier im a desiel guy and my knowlege of this motor is limited. any help or suggestions would be greatly appericated. also the car has 110,000 miles and most of the maintence has been done by myself. On an v8 I would be suspecting the knock to be coming from a crank bushing or piston wrist pin, but after showing concern about the noisy valve train and being told that its normal on several occasians, i've pretty much kept my mouth shut and been waiting to see what happens. Another thing that just boggles my mind is that no check engine lights, no rise in coolant temps, nothing. once again any ideas or knowledge will be followed up on.

[shanep5]

im getting a chatter up front to it sound like the cams arn't getting enuff oil on them. i was think it was happening do to low oil pressure but mazda had to be dumb and not put a oil pressure gauge in.

[jjkftw1]

well after going through 10 to 20 threads on this forum and trying to find out some pertant info i found none so i will leave some for the next person who looks at this thread for info. if you own a protege 5 with a 2.0 and it even begins to sound like a knock, shut it down and put it on the trailer. dont think that your going to just drop the oil pan to change the rod bearings either because this engine is built with an upper pan that supports the crank and unless you have the hands of a three year old girl your not changing the rod bearings unless you yank the engine. unfortanally i found this info the hard way as my old lady is the owner of the above stated vehicle and after dropping the pan to find what was left of a rod bearing in the bottom of the pan i wa even more pissed off that you can barley get a finger on the rod let alone try disassembley to replace the bearings with out jacking the motor only after loosing the motor from the tranny. i currently going through the options of either having original motor rebuilt or buying a reman.

[P-Funk!]

^ dude.

I am sorry to hear that. Thank you for reporting an update.