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Discussion Starter · #1 ·
I need to know what the knocking noise is in my engine.
i took off the valve cover and the cams to get to the lifters. when i took the lifters out some of them were stuck so i took them apart and cleaned them. but when i put every thing back to gether and timed it again it still makes the same noise. It doesn't sound like a rod knocking though. I didn't check the back valve cover though ,but it sounds like it's coming from the front. any help would be appritiated.
 

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Is it a ticking sound? If so that would be the lifters clacking. Best thing to try is to run an engine flush through the car and then refill it with Mobil 1 5W30 synthetic oil. Most of the time this will get rid of it, unless the lifter has already collapsed. If it has then you need to replace them, which can get expensive. Also when you pulled the lifters for cleaning did you put them back in the same spot they came out of? They have to stay in the same spot because of the wear the cams put on them.
 

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Ticking noise could also mean a bad friction gear. Mazda changed mine and the ticking noise went away...except when it's really cold out.
 
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Discussion Starter · #4 ·
Well we did put the lifters back in the same place, but i don't know if you would call it a ticking sound. what is a friction gear and were is it. we also replased the cam on the top of the front valve cover.It all started when my altenator went out and the exauhst droped down for some reason. i replased all that though. I also punched out the cat. would this cause back pressure and cause something to tick or knock?
 

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Shawn,

Can you be more specific?

Can you localize the noise using, say, a stethoscope (screwdriver-to-the-ear will work fine too). Is it coming from the timing-belt end of the head? Center?

Is it a light, distinct metallic "tap"? Does it vary in intensity with engine load? How does it vary with engine speed (tapping changes with engine speed, does it get quieter after 2000RPM or ...?)

If you're sure it's coming from the front bank and is under the valve cover, remove the cover, start the engine (be ready for a hell of an oil mess) and localize the noise without the valve cover there. Watch out for moving parts :)
 
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Discussion Starter · #6 ·
We all ready took the valve cover off and listed to it but you couldn't really tell, The noise is coming from the timing belt side of the valve cover. So what is a friction gear?
 

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motor noise

If the noise is comming from the timing belt side or it sounds like its in the t-belt cover it might be a bad pully or your water pump? If u know how to remove and instal the t-belt remove the belt and hand spin all the free moving pullys! (Remember the cam and crank gears have to be alligned to specs and there might be a engine balancer in there so be careful and get a mazda manual of this procedure.)This might not be the problem but in my couple years of experiance ive seen timing pullys and water pumps make some weird ass noises.It couls also be the timing belt it self. ive also seen timing belts not properly installed and the belt is too loose and will hit the timing belt cover. Once again get all the scamatics on this procedure because u dont want to bend and valves!
 

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Hey shawn
Do u have any idea on how to make the white faced red indiglo gagues? if u do can u hook me up with the materials i will need to fo it and what to do at the bach of the spedo cluster?
 

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shawn said:
We all ready took the valve cover off and listed to it but you couldn't really tell, The noise is coming from the timing belt side of the valve cover. So what is a friction gear?
Each bank has two cams. Only one of the two cams on each bank is driven from the timing belt. On the front bank, the exhaust camshaft is driven by the timing belt. On the rear bank, it's the intake cam that's driven by the belt.

The "other" cam on each bank (i.e. intake on the front bank, exhaust on the rear) is driven by the first cam through helical gears (you can see them if you take the oil cap off and look inside the cam cover...)

The helical gears have backlash and can be quite noisy because of that. The "friction gear" is designed to pre-load the gears and take away noise-causing backlash.

The friction gear bolts to the "driven" cam on each bank. It looks like a skinny gear right beside the main gear. It's held in place by a large nut on the end of the cam and is preloaded by a large, springy shallow-cone shaped washer called the "friction gear spring". It rides right up against the driven gear.

So it rubs against the driven gear and meshes with the drive gear. Here's the thing: this gear has one more tooth than the driven & drive gears, so it turns at a slightly different rate than the driven gear. Because of this, the driven gear and the friction gear rub together (hence the term "friction"). Because both gears are driven from the same drive gear, but turn at different rates, the system is "loaded up" and the backlash is taken out.

Friction gear springs can wear out (relax) over time, causing the friction gear to free-wheel. (IIRC, there was also a design change for the 1995 year that addressed the friction gear spring itself. When I had my springs done, they installed an updated spring on each bank.) When this happens, the lash is not taken up and the drive gears get quite noisy and clattery, especially because the action of driving a camshaft is not a smooth one, with 6 springs & lobes all trying to stop the shaft at "uneven" times.

The clattering noise from bad friction gear springs generally quiets down after about 2000RPM, but as the engine RPM comes back down, it will re-appear again. Mine sometimes makes a clattery noise when it's cold out (damn Canadian winters) but it usually goes away after a few minutes. Oddly, most mornings I never hear it and others it's quite bad...inconsistent engine :D
 
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Discussion Starter · #12 ·
Thanx alot man i'll check it out. i just got done taking off the fuel injection and it sucked so now i have the front and back valve cover off!
 

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just a note as im going through the old posts to replace my noisy engine,

Mazda part codes :
Spring: KLY1-12-417A
Nut: KL01-12-412A

Ford part code: F721-6278-AA (WASHER/SPRING)
Unknown what the ford code is for the nut... but that should set the vendor in the right direction.
 

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ah very good. The ford part number that I had up was from an old post, the new ones you put above are the 'revised' parts. (especially the nut) where you dont need to grind your own grooves in to fit together.


good eye and good news for those doing the change!

now to find good documentation on replacing valves... hmm still hunting.

hopefully when this is all said and done I can put together a post for complete engine silencing.

included will be repairing/rebuilding/shimming:
-karosine engine oil and coolant flush
-power steering pump
-valves/HLA
-oil pump
-disty timing and cam reinstall (including instructions for aligning the friction gear and cams)


for those that have already done all of these with the top end open maybe u can help me along and i'll document the whole process.

oh, and hello again to all the mx6 ppl, its been a while since i got my new (older but not broken) mx6!
 

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yeah Chef ur right lol.

Thats what i love about this site, for everything i cant understand from the haynes manual i can come here and hear the trials and errors to sort my wrenching out.

So far things are becoming disasterous. I've removed and replaced both friction springs. (EDIT: shortened this crap)

1) Does anyone know if BOTH sets of cams should be perfectly 'factory paint marker' aligned and the engine at TDC or are they off set a little bit? I marked the rear bank the way i took them out in the event that they have to go back in 'out of sync' with the front set.

2) what else besides HLA's, FGS, Timing belt and pully bearings could cause a diesel like ticking that dissappears at 2k rpm?
 

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I realize this is a very old thread but did you find a cause other than HLA's, FGS, ect.? My car is a 96 with a engine from a 94 so I am fairly confidant it is the friction gear but want to be as prepared as possible.
 
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