What's making the noise ? - Alfa Romeo Bulletin Board & Forums

 
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post #1 of 11 (permalink) Old 11-28-2016, 08:53 AM Thread Starter
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What's making the noise ?

My 2 ltr Giulia Ti Super Replica is nearing being finished. When I bought the car there was so much wrong with it it was untrue, however, the worst problem, was that I'd found that the guy who'd previously "built" the engine, had no idea, and had run it for around 700 miles with the distributor inserted the wrong way round. He'd also used a different exhaust front cam cap, so the cam timing was impossible to get right, I re-marked the cap with the correct timing mark, using the Spruell template and it timed up perfectly first time. I think he may have tweaked a valve very slightly messing about trying to get it right, as there's less compression on number 3 cylinder than the others, but that's for later.
I've now finally got round to having a look, and took the sump and oil pump off the car, (engine in situ), last week, and got the front cover off today (cylinder head left in situ as the gasket hadn't had time to get stuck, it came off ok).

The problem was, that although it is an instant starter (now that I'd timed both the cams and the ignition correctly), and it revs freely, and goes very well, there is an unholy row from the timing cover.
I bought a new chain, as the tensioner was so far out, it was in danger of departing the front cover, and this brought the tensioner back to being about 5mm out, so thought I'd cracked it. No difference.
Having got the cover off today, I'd expected to find maybe the bush for the idler gear in the block goosed, and maybe the one in the cover too. maybe he'd forgot the oil slinger ?
No such luck. Whilst there's a minimal amount of movement noticeable in the block / timing cover bushes when the cover is off, , when I trial fit the cover there's almost no movement when it's supported at both ends, and spins freely. The front and rear idler gear oil bushes are good too. Sprockets all good.
The only part I can discern any excess movement in now, is the tensioner sprocket bush, but not so bad that it's nearly falling out, probably about 15 thou "wobble" as I rock it with my fingers, (chain off).
So what else can be making this noise ? The noise at idle is louder than anything else .
Valve clearances are good and quiet, water pump is new and quiet, bottom timing chain isn't too worn, oil pump has no real end to end play on the shaft, the bronze gear and it's mating part on the crank are undamaged and yet the noise is definitely coming from inside the front cover.
It's not big end or mains bearing play, as I checked a couple of both when I took the sump off, and they're almost unmarked.

I've checked the oil pump shaft for straightness as best I can, and can't see that it's bent. I put it back in the cover today with the distributor, and fastened it up. it spins freely .

Any more ideas anyone ? Have I missed something ?

Steve

GTA R
Giulia Ti Super Rep yet to finish. BMW 2000 NK to Ti spec

Last edited by GTA R; 11-28-2016 at 02:30 PM.
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post #2 of 11 (permalink) Old 11-28-2016, 01:01 PM
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Hi Steve,

Is there any evidence of the timing chain having been running against the inside of the cam cover? (as if the chain was loose)

I had this recently on a Duetto (just bought by a 'high profile car guru' in the UK!), the classic timing chain rattle at about 2500 rpm, so re-tensioned it and it disappeared..... until I revved it again!
I noticed that the 14mm bolt that clamps the tensioner was not protruding enough from the head which led me to think that the wedge was probably missing that the pin on the end of the bolt locates into - without this the bolt keeps going and ends up between 2 coils of the tensioner spring & doesn't clamp the tensioner properly. On removing the tensioner, this was found to be the case - the wedge was missing & the spring was damaged by the bolt. Could be what's happened to yours....?

Ian

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post #3 of 11 (permalink) Old 11-28-2016, 01:36 PM
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Are you certain that it is from the front of the motor? I had similar loud rattling noises when my flywheel got loose.

Ed Prytherch
79 Spider
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post #4 of 11 (permalink) Old 11-28-2016, 01:44 PM
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Good call Ed - I've had that too & it sounds like the ends are hanging out! Also worth checking the front pulley - they make a similarly awful noise if the nut comes loose & I've found about 30% of them are cracked where the keyway locates.....

Ian

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post #5 of 11 (permalink) Old 11-28-2016, 02:28 PM Thread Starter
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Quote:
Originally Posted by ianellisalfa View Post
Hi Steve,

Is there any evidence of the timing chain having been running against the inside of the cam cover? (as if the chain was loose)

I had this recently on a Duetto (just bought by a 'high profile car guru' in the UK!), the classic timing chain rattle at about 2500 rpm, so re-tensioned it and it disappeared..... until I revved it again!
I noticed that the 14mm bolt that clamps the tensioner was not protruding enough from the head which led me to think that the wedge was probably missing that the pin on the end of the bolt locates into - without this the bolt keeps going and ends up between 2 coils of the tensioner spring & doesn't clamp the tensioner properly. On removing the tensioner, this was found to be the case - the wedge was missing & the spring was damaged by the bolt. Could be what's happened to yours....?
Ian, no, that was one of the first things I checked, the wedge is in place and it holds the tensioner well. At some time in the past, it has touched the inside of the cover, as it is lightly marked, but must have been a long time ago.The new chain is nice & tight, I've run it maybe a dozen times since I replaced the chain, and it's remained where I tightened it to.
Checked the flywheel too and it's not loose.

Ed, no, had the home made stethoscope all over the engine, the noise is definitely from inside the cover.
The "ace" builder had missed the tab washer off the crank nut, but it was (very) tight. Checked the pulley and no cracks. It fits very snugly on the keyway.
I'm ordering a new idler bush for the block tomorrow, decided to change it anyway, even though there's little slop. Anyone have the best solution for getting the old one out ?
My first thought is to slit it as much as I can with a worn cutting wheel on the Dremel, then try and lever it inwards to reduce the diameter, and pull it out.

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Giulia Ti Super Rep yet to finish. BMW 2000 NK to Ti spec
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post #6 of 11 (permalink) Old 12-31-2016, 02:50 PM
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I just removed all my bushes. The timing cover one was a bear. I used a dremmel on the face and then a hacksaw blade in my hand to slowly slit the inside. When I had it close I was able to collapse it a bit and then use a slide hammer. It took a while but I didn't want to cut or crack the case. As was noted to me, once replaced the two bushings need to be carefully reamed together to fit the gear. See my 1750 s2 rebuild post for the tech manual page another bb member shared.

All the others came out easily with a slide hammer

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post #7 of 11 (permalink) Old 01-01-2017, 03:16 PM Thread Starter
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Ok, replaced the cover and block bushes and reamed them. Replaced bottom timing chain, and changed the idler sprocket for a better one. Replaced the timing chain tensioner for one with a sprocket with zero play. Fitted a pair of mint C & B 109280S cams, all new followers, had the head off, and found 2 broken exhaust valves, no valve damage and no piston damage. Fitted 2 new inlet valves too, as they were pitted, seats cleaned up well. With the head off I could see that it has been beautifully ported at some time in it's life to Jim K specs (I measured the ports as best as I could to the drawings in Jim's book and they're very similar), but the valves remain standard size. It now feels very wick.
Fired it up at the end of last week, and the clatter in the timing cover is eliminated, however, that's highlighted another, lighter noise at the back of the engine, only noticeable at idle. Over 1200-ish rpm, it disappears.
Sound appears to becoming from the starter, and after an initial glance, it doesn't appear to have the shouldered bolt in the middle hole, just a standard bolt. Starter has become noisy in operation too. Looks like he may have b*ggered up what was a pretty new CA lightweight unit. The noise sounds like the pinion catching / occasionally being spun by the flywheel.
Ah well, carbs off again in a couple of days to investigate. Noise doesn't go away when clutch depressed, so eliminating clutch / loose flywheel. Already tried to move the flywheel when sump was off, and no joy.

Steve

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post #8 of 11 (permalink) Old 01-01-2017, 03:52 PM
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Quote:
Originally Posted by GTA R View Post
Sound appears to becoming from the starter, and after an initial glance, it doesn't appear to have the shouldered bolt in the middle hole, just a standard bolt. Starter has become noisy in operation too. Looks like he may have b*ggered up what was a pretty new CA lightweight unit. The noise sounds like the pinion catching / occasionally being spun by the flywheel.

Steve:

You should read the thread at: Starter motor spins but does not engage engine

WA-Alfa, the originator of that thread, was also using an aftermarket, gear-reduction starter (his came from Alfaholics) and also experienced starter pinion-to-ring gear clashing. He posted this photo of his chewed-up ring gear:


Jay Mackro
San Juan Capistrano, CA

'63 Guilia spider
'65 Guilia Sprint GT
'67 Duetto
'91 164L

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post #9 of 11 (permalink) Old 01-01-2017, 04:15 PM
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A slight twist in a connecting rod...had it happen on anF3 Cosworth MAE... same symptom .. just a guess.
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post #10 of 11 (permalink) Old 01-02-2017, 12:43 AM Thread Starter
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Quote:
Originally Posted by Alfajay View Post
Steve:

You should read the thread at: Starter motor spins but does not engage engine

WA-Alfa, the originator of that thread, was also using an aftermarket, gear-reduction starter (his came from Alfaholics) and also experienced starter pinion-to-ring gear clashing. He posted this photo of his chewed-up ring gear:

Yes, read that, but my lightweight starter isn't that type, it's the Spider S4 late type, that does use a shoulder bolt :-

EL013 LIGHTWEIGHT STARTER MOTOR - 3 BOLT MOUNT - 9 TOOTH - Classic Alfa

Will have the carbs off, have a look sometime this week,

Steve

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post #11 of 11 (permalink) Old 01-02-2017, 07:44 AM
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Yes, read that, but my lightweight starter isn't that type, it's the Spider S4 late type, that does use a shoulder bolt
OK, got it. Then yes, adding the shoulder bolt may help. What about the bellhousing-starter shim - is that installed?

Jay Mackro
San Juan Capistrano, CA

'63 Guilia spider
'65 Guilia Sprint GT
'67 Duetto
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