Engine noisy after waterpump/timing belt

marcellarius · Post by **marcellarius** » Mon Apr 07, 2014 2:59 pm

So, I finally got my car back together after doing the waterpump change, but upon starting it, there is a tapping, maybe like HLAs.

http://youtu.be/1gXR7n0PN6Q The cellphone mic doesn't do a great job of picking up the sound, it sounded more like HLA tick, with a hint of diesel engine.

Didn't go away after a couple of minutes of idling, and am now thinking I'm going to be pulling things apart again (joy). From some stuff I read on miata.net, it could be timing belt under-tensioned.

Any ideas?

WideOpenThrottle · Post by **WideOpenThrottle** » Mon Apr 07, 2014 3:50 pm

Cant see why it could be the HLA's unless your oil is really old?Did you take the camshafts out unnecessarily?
Did you set the tension at the correct mark?

Otherwise something could be rubbing if a belt has got a nick in it somehow?

broomfish · Post by **broomfish** » Mon Apr 07, 2014 7:24 pm

That doesnt sound good, if it wasnt there before you did the timing belt job, i would be pulling it apart again before running it any more

WideOpenThrottle · Post by **WideOpenThrottle** » Mon Apr 07, 2014 8:29 pm

Now that I have watched the video it could be incorrect timing...should be no engine damage as they are a non-interference motor.

marcellarius · Post by **marcellarius** » Mon Apr 07, 2014 11:26 pm

HLA tick went away. My theory for the rest of the noise is potentially under-tensioned cam belt.

I should have replaced the tensioner helper spring (free length slightly over spec), but I didn't fancy waiting on parts again so set tension, checked deflection which seemed okay and proceeded. Maybe I didn't set tight enough though.

I'm fairly sure the timing is okay. Double checked that because I didnt fancy repeating job. Aside from noise the engine seemed to run much like it used to.

marcellarius · Post by **marcellarius** » Thu Apr 10, 2014 5:39 pm

I'm having difficulty verifying if I've set the belt tension correctly. It seems all good at the tension set mark, but if I rotate the engine to #1 TDC for example, there is more slack than there was at the the tension mark. Is this to be expected (cam position causing load to be taken off belt between pulleys)?

GRUVBB · Post by **GRUVBB** » Thu Apr 10, 2014 6:18 pm

Maybe the belt has stretched in that segment. Im not a mechanic but have heard of this. Maybe try putting a new belt on???

WideOpenThrottle · Post by **WideOpenThrottle** » Thu Apr 10, 2014 8:51 pm

Are you rotating the engine clockwise?...the tension in other positions is bound to differ slightly just as you said regarding cam positions.

marcellarius · Post by **marcellarius** » Thu Apr 10, 2014 11:51 pm

It's alive! I suspect the tensioner shifted as I torqued it down.

It seems to be running well now... Feels like it gained 20kW in the process, although not sure if that's from the new water pump or from the bits I painted while I had them off... Or its just a bit more vigorous than the stock '90 vspec I have been driving

Cheers

4A-GE · Post by **4A-GE** » Fri Apr 11, 2014 8:47 am

Did you put stickers on it too?

Engine noisy after waterpump/timing belt

Engine noisy after waterpump/timing belt

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