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Old 08-28-2008, 09:36 PM   #1
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Default F#$* Bad Engine Noises

So earlier this evening I was taking off from a stoplight, I took it up to 7.5-8k in 1-3. When I got into 4th and the engine noise was a little quieter I noticed a strange noise coming from the engine. I pulled off the road to a gas station. The noise is very noticeable at idle, but the engine still runs. I was able to turn it off, let it cool down and it still started. The noise is still there though. It sounds like two clicks or knocks for each engine revolution.

I pulled the valve cover and everything looked in order. I peered down through the plug holes and none of my pistons are sideways. There are no holes in the block or oil pan. The oil pump is supposed to be a weak point yes? Could I have shredded that?

Any ideas or thoughts (besides me being a fucktard) would be great.

Last edited by yertnamreg1218; 08-28-2008 at 09:53 PM.
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Old 08-28-2008, 09:51 PM   #2
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A. you shouldn't be revving much past 7000 (7250 is rev limiter)

B. the noise is most likely a con rod or crank bearing

C. you're a fucktard
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Old 08-28-2008, 09:53 PM   #3
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well played
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Old 08-28-2008, 10:22 PM   #4
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Quote:
Originally Posted by curly View Post
A. you shouldn't be revving much past 7000 (7250 is rev limiter)

B. the noise is most likely a con rod or crank bearing

C. you're a fucktard
A.
1) The OP has a Megasquirt ECU and can choose his own rev limit or none at all.
2) The stock rev limit is 6900.
B. Who knows. More info is needed and a video would help.

C. Spot on.

Do you have oil pressure? Crank the engine and make note of the reading on your oil pressure guage.

Why are you reving so high? I doubt your motor is making power at those RPMs without some serious headwork.
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Old 08-28-2008, 10:29 PM   #5
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That was amusing but one other thing to check is your crank pulley (see if it's wobbling) you could have a keyway issue - I had a very similar sound when I had that issue, may just be coincidental to your high rpm start. But yeah I agree with Curley :-P also.
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Old 08-29-2008, 10:49 AM   #6
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Nascar mechanics will usually swap the motor, or in the least replace the entire valvetrain if it's been overreved during a practice session.
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Old 08-29-2008, 10:59 AM   #7
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Does it sound like a lifter knock in the low end, or a guerilla with a sleg hammer? If it is a slight knock. It could be a wrist pin etc etc. You might can pull your motor down now and save alot. If it is Bang bang bang. It is probably a rod.

If you had a video it would help.
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Old 08-29-2008, 06:02 PM   #8
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Revving it that hard really isn't healthy. Tear it down now to save yourself some money.
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Old 09-11-2008, 11:11 AM   #9
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Well the engine is out of the car and in pieces. When I pulled the clutch off I found that the flywheel bolts were loose. The bearings all looked good, and there wasn't any play on the crank or rods. Right now my theory is that the flywheel was causing the noise.

While I have the engine apart I'm replacing the seals, bearings, rings, timing belt, head gasket, and motor mounts. Should run better than new when I get done with it (fingers crossed), and be ready for boost. Part should be in toward the end of next week, so hopefully I'll have the miata tearing around turns again in 2-3 weeks.
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Old 09-12-2008, 09:22 AM   #10
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Sweet.
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Old 09-12-2008, 07:00 PM   #11
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This time keep it below 7200.
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Old 09-26-2008, 12:28 PM   #12
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Well the project is nearing completion. This past weekend I cleaned and rebuilt the head. I finally got in the last couple parts I needed today. Rings from Total Seal, mounts from CorkSport, and a new wideband cable from DIY.

I'm planning on getting the engine built today after school, and tomorrow putting it in the car.

I miss it so much, it will be nice to have a car again.
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Old 09-28-2008, 02:53 PM   #13
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SUCCESS!!!!

I ended up working through Friday night until 4am on Saturday. Got the engine in and started it the first time at 4am. Cranked right over and started. It was the most glorious engine noise I've ever heard. Yesterday I finished getting the car ready to drive and finally drove it last night. I've been taking it pretty easy on the engine for now, but it seems like its not going to blow up (fingers crossed).
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Old 09-29-2008, 06:46 PM   #14
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I had a 1969 Chevy Blazer a few years back, and I pulled my friends Ford out of the mud one night. The whole drive home it made a rattling noise near the oil pan. Ended up being loose torq-converter bolts. Simple fix, but it rattled so loud, I thought it was gonna be expensive.
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Old 09-29-2008, 07:10 PM   #15
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Haha, seen that before thirdgen. Dunnu why chevy only puts 3 bolts on the torque converter.
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Old 09-29-2008, 10:35 PM   #16
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Great, what where the dollar signs, and parts list, from where?
I have a spare motor, and with me and my brother both having boost we need to get the spare spiced up.

Great JOB!
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