knocking noise,but not rod knock

mcammarn

matt
Feb 24, 2012
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olympia wa
so i have this knocking noise coming from my 7mgte. it only happens when revving 2k rpms in each gear.
does not knock at idle what so ever.
just had the timing done, and its spot on.
also did i hg job not to long ago. and had the head resurfaced. gave the shop the head with the cps still attached.
got the head back with the cps not attached.
friend told me something about the cps possibly not lined up correctly? but im not sure what he was talking about.
is this called spark knock?
im not getting any codes also.
and what could i do to figure out why it has this problem?
thanks
 

Turbo Habanero

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Apr 28, 2009
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I do not know what spark knock is but....

I'm just gonna say it... sounds like you have the start of classic rod knock after a bhg..
 

peste noire

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Jan 11, 2012
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my old motor used to do the same as yours and it was rod knock. didnt seem so bother the performance till some else blew (lol) like 5 months later, but still pulled great even with rdk.

they sell stethoscope for this sort of situation.
 

te72

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Mar 26, 2006
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BoostMonger;1853213 said:
is the knock rpm dependent?

mcammarn;1853229 said:
not sure what that means.

Meaning that as your rpms rise, does the sound get faster? It will likely smooth out eventually (probably by the 3000rpm mark), but it gets worst in the early-mid 2000rpm range in my experience.

I'll agree with the other posts, it sounds almost exactly like rod knock to me.
 

mcammarn

matt
Feb 24, 2012
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olympia wa
te72;1853413 said:
Meaning that as your rpms rise, does the sound get faster? It will likely smooth out eventually (probably by the 3000rpm mark), but it gets worst in the early-mid 2000rpm range in my experience.

I'll agree with the other posts, it sounds almost exactly like rod knock to me.

right, the sound smooths out around that rpm
 

sethron71

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Jul 19, 2005
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It is the start or rod knock....you will see it get progressively worse till it damages something. If you put some new bearings in it now you may get away without damage to the crank or rods. But the reason you only hear it at 2K is the the harmonics just because right to make the rod rattle, I have a customer car at my shop right now that has the exact same things, starts up and idles super nice and then knocks as it revs and goes away if you rev it higher. Needless to say it is coming out to get a rebuild!

Seth
 

Suprapowaz!(2)

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Apr 10, 2006
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Same thing happened to me back in the day. Hardly a peep at idle, got louder as it revved up to the upper 2000rpm range, smoothed out around 3000rpm. It was RK.
 

IJ.

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6a00e54f871a9c8833013484e42980970c-500wi
 

mk3_7m

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Jul 21, 2007
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Hmmmm well that sounds discouraging. I've been driving my car for 3 years with that same rattle noise you describe. I hope it's actually valve lash...
 

sethron71

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If you can't tell the difference between the sound of too much valve clearance and knock you are in big trouble. Those noises are at opposite ends of the engine and should be very very easily distinguished!

Seth
 

supraguy@aol

Well-Known Member
Dec 30, 2005
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Everybody has had rodknock at some time.
And those who havent, will. : )

I have rod nock right now in my 4 age MR2, but its mild, and i will be pulling it soon.
I have had rodknock in my Supra twice.
 

IJ.

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SideWinderGX;1853898 said:
Did once of those measures happen to be running 6-7 quarts of oil instead of the recommended 5?

What else did you do, out of curiosity?
Yep always +1 Qt, 3 Qt Moroso Accumulator and a decent Pan completes it, no more RK ever, 1st thing I did on the new project car as well, Baffled the pan and fitted an accumulator.

My RK happened on the return leg of an interstate trip when I forgot to check the oil level before heading home, I was at freeway speed and had to brake hard for an accident ahead, accelerated again and Tap tap TAPP... pulled in to a service station and bought a couple of litres of gear oil and made the rest of the trip back..