Twang when turning over engine with new heads-expalantion

MilesnMiles · Post by **MilesnMiles** » Tue Mar 24, 15 7:19 pm

Ok, bear with me here

Heads now fitted to motor and tonight I installed the rocker gear.
I then turned the motor over manually. Motor rotated fine and then I felt a touch of resistance followed by only what can be described as a twanging noise. Not grinding or course, sounded like something was caught in the fan, but nothing was.
This happened twice. Called wife out to listen and observe for me. The noise did not repeat itself. Engine rotated fine, could hear compression come up subside and so on. All good.

The noise explanation. Is it just possible that a couple of the valve spring retaining collets were not quite seated on the new heads and as I rotated the motor, they seated hence the 'twang' noise I heard??

Pete · Post by **Pete** » Tue Mar 24, 15 7:26 pm

Pushrod seating? You would have noticed the colletts when you checked the rocker alignment....

Dave-R · Post by **Dave-R** » Tue Mar 24, 15 7:27 pm

Sounds like something wasn't seated correctly yes.

MilesnMiles · Post by **MilesnMiles** » Tue Mar 24, 15 7:29 pm

Heads came ready assembled and ready to fit, but they were built by humans.
Just haven't had it before. Could be a push rod too as you say. Could not get the noise to repeat after turning the motor a number of times so hope all is good.

Pete · Post by **Pete** » Tue Mar 24, 15 7:35 pm

I had that on the hot 360 - ended up bending a pushrod - I would have sworn it was in correctly but the pushrod had sat on a slight "ledge" on the lifter. Sick as a parrot............

MilesnMiles · Post by **MilesnMiles** » Tue Mar 24, 15 7:38 pm

Right Pete, will check everything again to be sure, cheers.

Blue · Post by **Blue** » Tue Mar 24, 15 7:46 pm

Agree with the above, misaligned pushrod pinging into place.

GeneralWee · Post by **GeneralWee** » Fri Mar 27, 15 6:08 pm

"built by humans" lol, I had a new door for a Punto once and the robot had forgotten to weld the hinges on

Cannonball · Post by **Cannonball** » Fri Mar 27, 15 8:59 pm

It is an absolute twat, when you get that with a or the push rods you think all is well check check check again then that noise as it jumps in to place i f u cki n hate it your paranoid for a while after

MilesnMiles · Post by **MilesnMiles** » Fri Mar 27, 15 10:21 pm

Paranoid is a good word, Dunc. I've checked it all gain, everything looks correct. All I can do is fire it up and see. It's only a cylinder head change. What could go wrong...."......?

Carl · Post by **Carl** » Sat Mar 28, 15 11:34 am

I had that happen too, like Dunc said your Paranoid for ages after, I kept thinking the retainer clip had pinged out and was working its way round the engine. Had a lifter tapping away too, so I took the manifold off to check, all clips in place but had a collapsed lifter, possibly the same lifter that pinged as it was on the same cylinder. I mentioned it on my rebuild thread. Don't assume you have the same problem though, yours is most likely due to the push rod seating, mine was probably coincidence.

latil · Post by **latil** » Sat Mar 28, 15 12:46 pm

Had this with new valve springs settling in too,could be colletts settling in or pushrods aligning.

MilesnMiles · Post by **MilesnMiles** » Sat Mar 28, 15 5:25 pm

Thanks chaps, let's hope it's good. I won't post entirely how it took me two hours to just fit a manifold and down pipe today cos some twat welded a captive nut to the manifold on the pixx. One hammer and chisel later and it's bolted up.
Unbelievable things that should be minutes to sort that crap out

Pete · Post by **Pete** » Sat Mar 28, 15 6:08 pm

Sorry to sound like the harbinger of doom, but if it were mine I would lift the rocker shafts and take out all the pushrods and roll them on glass to ensure they were not bent. You may find nothing but at least you will have peace of mind for the sake of a couple of hours work..............

John · Post by **John** » Sat Mar 28, 15 6:15 pm

Pete wrote:Sorry to sound like the harbinger of doom, but if it were mine I would lift the rocker shafts and take out all the pushrods and roll them on glass to ensure they were not bent. You may find nothing but at least you will have peace of mind for the sake of a couple of hours work..............

And the possibility of lots more twanging to boot