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Discussion Starter #1
Hi guys

I have noisy valves and adjusted them according to spec when the engine was cold.
Exhaust 0,525mm - 0.550mm
Inlet 0.475mm - 0.500mm

They where all perfectly within these ranges (I threw my cold measurements away - so cant post them here now)

However - the valves are noisy when the engine is cold and gets a little bit more noisy when the engine is hot.

So I decided to measure clearances when the engine is hot :

Exhaust
1 = 0.63mm
2 = 0.59mm
3 = 0.65mm
4 = 0.59mm

Inlet
1 = 0.52mm
2 = 0.56mm
3 = 0.52mm
4 = 0.56mm

The manuals don't give a specification for a hot engine - but these gaps seem to large - and this explains my noisy valves.

Can I safely attempt to get my 'hot' readings within the manuals 'cold' spec to see if my valves run quiet ?

Or does the manuals cold measurements take the expansion and variance in consideration for when the engine is hot ?
 

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The 1750 engine in my (now former) Spider was rebuild by a German with a good reputation. They had set exhaust valves at 0,500 mm and inlet valves at 0,425 mm.
You could still here a little valve clatter cold, but at running temp nothing (probably drowned by normal engine noise).
 

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I've run my 2 litre like this for the last 25 years...
inlet 0.40mm to 0.45mm
exhaust 0.45mm to 0.50mm
...and there's no cold rattle. I wonder why the 1750 specifies wider clearances?

The trouble with trying to set valve clearances on a hot engine is - 'what is hot?' It's not a stable condition either, because you have to do it with the engine off...
 

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To the best of my knowledge both the 1750 and 2000 valve clearance is in 0,500 mm and ex 0,550.
I don't know what the 1300 and 1600 are sett at.
 

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Discussion Starter #5
I reduced my clearances and tested it this morning. It's quiet when cold and just a little noisy when warm. Standard clearances are very noisy. I will experiment some more but I reckon I will keep it like this for now.
 

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Discussion Starter #6 (Edited)
Alfa Romeo Bulletin Board & Forums - View Single Post - Cam journal wear

With my recent tapping noise and valve clearance adjustment I realised that I could possibly have worn cam journals.

I never thought about it - but the chain pulling on the front side of the cam could actually cause the front of the cams to start receding into the head and the rear of the cams to start eating into to cam caps over time - causing the cam journals to become 'oval' shaped.

This could possibly cause some noise when the engine is cold and the noise could become less as the engine heats up. I would like to do this plastigauge measurement on all my cam caps and see if they are worn.

Anyone have experience/opinion regarding this ?

Edit:
http://www.plastigaugeusa.com/how.html
 

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Discussion Starter #8
but as RJ says,worn cam journals are a source of poor oil pressure......do you have poor oil pressure?

have you listened with a mechanic's stethoscope to really pinpoint whether the valves, which cylinder, exh, inlet?... etc...
I am using 20W50 oil. Oil light goes out immediately after start. Oil pressure gauge drops low on idle and rises to about 30-35 bar on the gauge while driving. It does not rise and drop - so this means its not big end bearings. I also removed the plug wires one by one - but the noise does not go away which suggests top half of motor and not bottom.

Have not used a stethoscope to identify the noise yet - but it is definately at the rear on the exhaust valves side.
 

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I am using 20W50 oil. Oil light goes out immediately after start. Oil pressure gauge drops low on idle and rises to about 30-35 bar on the gauge while driving. It does not rise and drop - so this means its not big end bearings. I also removed the plug wires one by one - but the noise does not go away which suggests top half of motor and not bottom.

Have not used a stethoscope to identify the noise yet - but it is definately at the rear on the exhaust valves side.
I would definitely agree that it's worth listening carefully with a stethoscope - exploring the whole of the cam cover, head, etc - but watch out for moving parts!

I run 15W50 and - like you - have rock-steady oil pressure at everything but idle, although there is some temperature dependency. By the way, I don't think you have 35 Bar oil pressure: that would be over 500psi and would blow the engine apart...!
 

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Discussion Starter #10
By the way, I don't think you have 35 Bar oil pressure: that would be over 500psi and would blow the engine apart...!
Ha ha ! Yes 35 Bar would cause a couple of major oil leaks :biglaugh:

My oil pressure sits at around 30 psi? when driving - so basically the next line from the red area.

I drove the car to my mechanic yesterday for a listen. He is of the opinion that the issue is in the head and that the bottom end is fine (hope he is right).

He suggested I remove the cam cover when car is cold - and see if I can move the exhaust cam left or right at all. I must also see if it is at all possible to move the cam up or down at all - this will indicate worn cam journal.

I currently have Castrol 20W50 in the car and he suggested I replace this with something like Shell HX5 25W60 to see if this reduces the noise and if this will increase the pressure a little.

We also discussed using a mechanical oil pressure gauge to see what the actual pressure is.

I have two videos of the noise - one with cold engine and one with warm engine. Will upload this to youtube and post links here.

The cold noise is really really bad - but once warm the engine sounds pretty normal.
 

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He suggested I remove the cam cover when car is cold - and see if I can move the exhaust cam left or right at all. I must also see if it is at all possible to move the cam up or down at all
I very much doubt you will feel play with the camshaft all torqued down, cam chain on and some of the valve springs in full compression against the camshaft...

- this will indicate worn cam journal.
and some!

The cold noise is really really bad - but once warm the engine sounds pretty normal.
above you said:"It's quiet when cold and just a little noisy when warm"
 

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Discussion Starter #12
above you said:"It's quiet when cold and just a little noisy when warm"
Apologies - that info is not correct regarding the loud knock.

I had noisy valves all round and after I reduced the clearances the overall valve noise where quieter.

However - the big loud knock is still there - was hoping clearances would sort that out too.
 

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Quote: "My oil pressure sits at around 30 psi? when driving - so basically the next line from the red area."
30 psi equals circa 2 bars. My 1750 engine ran with 4 bars when up to running temp. Thy a mechanical oil gauge.
If that show 50+ psi your oil pressure sender is shot. If it shows 30 or lower your oil pump is shot.
With a new oil pump check for valve noise.
 

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Just be cautious making the cam clearances too tight, especially on the exhaust, you could burn a valve out.

I watched the video and the tap seems to coincide with the engine rock, almost like there is a slight missfire. Of course if the valve clearances are wrong its quite likely you will have a rough running engine, although yours does smooth out when warm. Before reducing cam clearances to remove the noise, I'd start out with everything to spec, then find out the problem, dont try masking it it could create greater expense. I'd rather have a noisy engine than a broken one.
 

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Sounds like the noise is at crank speed, are you running standard compression? We have had issues before with running with stroked conrods where the head had been skimmed too much and the chamfer was virtually missing on the combustion chambers, the noise we had was from the outside of the piston touching the head. Another thing it could be is a valve tapping the top of one of your pistons but if your cam timing was set properly it should be safe.
 

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Discussion Starter #18 (Edited)
Thanks guys.

This head has not been skimmed much at all - everything standard so running normal compression. The cam timing is also standard - both cam marks align when at TDC. I have checked with a torch down each cylinder while turning motor manually and no valves are touching any cylinders. I have done valve clearances so many times on this engine I can do it with my eyes closed now - but the noise just never goes away.

So my plan is to eliminate possible issues one by one.

First up is to get a mechanical oil pressure gauge and connect it. Where is the best place to connect it ? Sender underneath the carbs (big job) or sender on exhaust side - close to alternator (much easier task) ?

Another thing I remembered now is that the #4 exhaust valve head has been grinded - so the shim does not sit flat on the valve head. The shim does not ride on the cotters - I have confirmed this with engineering blue. Could this cause that much noise if the shim maybe wobbles on the valves head ? The clearance is small so in my mind I cant see this happening.

The noise really irritates me - i just wish I can pinpoint and resolve it.
 

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"First up is to get a mechanical oil pressure gauge and connect it. Where is the best place to connect it ? Sender underneath the carbs (big job) or sender on exhaust side - close to alternator (much easier task) ?"

The sender on the exhaust side is for "low oil pressure light", but can do, I suppose.
 
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