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Discussion Starter #1 (Edited)
New videos further down \/ \/ \/
YouTube - Alfa twinspark sounding rough

Here is a poor video of the sound(s) my engine makes. The engine had over heated and did the headgasket, it's all been apart, had the head skimmed and put it all back together.

I know the whine is going to be a few things, not worried about that (belt too tight, tensioner worn, etc)

More concerned of the general rough sound the engine has. It sounds the same hot or cold. Was thinking a few things, exhaust manifold gasket blowing, sticking tappet (they were removed and I didn't fill them with oil which perhaps I should have), worn variator (have a recipt for one fitted less than a year ago so unlikely)

Just wondering for some input before I tear it all apart again.

Other than the noises, it runs absolutely sweet, pulls hard, runs smooth as silk.
 

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Discussion Starter #4
YouTube - MOV02416.MPG

Here is a video shot with another camera. The noise is coming from the belt side of the engine. This video was taken when it was stone cold, it does seem to get quieter as the engine warms up.

I am having trouble starting the car also, it turns over fine but will only catch if I have my foot fully down on the throttle. When it does start, it takes a while for the engine to idle, you need to rev it for a minute or so and then it'll idle perfectly.

I'm thinking sticking tappet or variator. Wondering what others think?
 

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How much did they skim off of the head?

It sounds like something knocking against it.
 

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Discussion Starter #6
I'm not sure how much he took off but he did tell me he had to remove the valves as it was going to just nick a couple. There is a indicator on the head for how much can be taken off so doubt he over skimmed it.

I did hydraulic lock it. I put some oil in the bores (with a syringe and over did it on piston 1) to increase compression to fire it up the 1st time. The engine locked solid on the starter motor, didn't think that was enough force to bend a valve or anything. Maybe I need to do a compression test.
 

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I'm not sure how much he took off but he did tell me he had to remove the valves as it was going to just nick a couple. There is a indicator on the head for how much can be taken off so doubt he over skimmed it.

I did hydraulic lock it. I put some oil in the bores (with a syringe and over did it on piston 1) to increase compression to fire it up the 1st time. The engine locked solid on the starter motor, didn't think that was enough force to bend a valve or anything. Maybe I need to do a compression test.
If it locked on the starter I reckon you may have bent a conrod. :(

There is a hell of a lot of torque in a starter motor (they draw hundreds of amps), plus it is geared down due to the size of the ring gear and starter pinions.


You may be able to fix it by dropping the sump and removing it from the bottom, without removing the head if you are lucky.
 

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Discussion Starter #8
I've just disconnected the coil packs and turned it over again, it turns over nice, no knocks, etc.

That is something I was thinking about after a similar thread on here. Maybe I need to take the sump off and check (done it on a 156, horrible job)

If the conrod was bent, what would make that sound, little end?
 

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Well if the conrod is bent, the part below the piston can hit the lower edge of the bore as it goes up and down, that will cause a knocking.

It may be a good sign that it doesn't knock with the coil disconnected though.

I would also assume that if it has hydralocked it will also flat spot the big end shell on that rod, plus it will cause it to wear unevenly if the rod is bent.
 

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Discussion Starter #11
That sound is the big end bearings on yours isn't it (caused by the conrod)? My knock is at half speed compared to yours.
 

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That sound is the big end bearings on yours isn't it (caused by the conrod)? My knock is at half speed compared to yours.
Your absolutely right. This sounds camshaft/valve related. Could be the following, worn cam lobe/follower, buggered hydraulic tappet, broken valve spring, burnt or cracked valve. ...or any combination of the above. Have you done a compression test? You may find one cylinder is down. A leak down test (a good mechanic will be able to do this) can determine bad sealing at the valves and help pin point the poblem.

You'll have to look at the cam lobes for abnormal wear. The lobes should be 'plate glass' smooth. Any scoring of heavy scuffing means the hardening on the lobe has been breached and the wear will be rapid. the matching follower/tappet is probably had it too. The problem hopefully should be fairly obvious...
 

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You say that it is difficult to start it really should start when you turn the key you should'nt need to have your foot down on the accelerator pedal. When you timed her up did you use the locking tools and also make sure that the bottom end stayed put on the mark, I recently purchased a car that would'nt start cleanly and i found the timing was out, i automatically did a belt change and it starts spot on now! keep us all posted on what you find, hope it's not too serious. good luck
 

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Discussion Starter #14
I do have all the propper tools for timing, I could have maybe made an oversight when doing the belt, will check. I think i'll remove the belts and camshafts and check all the tappets.
 

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Discussion Starter #15
I took the belts off, no problem with them, all timed up correctly. I took the tappets out and dipped them all in oil. Put it all back together and it still sounds the same. The condition of the camshaft seems fine, no obvious wear over cylinder 1 which is where the noise is coming from.

I've taken 2 new videos of it. This one when its cold YouTube - Alfa Twinspark Knock 1 and this one when it's warm YouTube - Alfa Twinspark Knock 2

When it's warm, the noise is quite faint, don't think you'd spot it unless your looking for it.

The noise sounds like it's coming from the variator area to me. (cylinder 1 inlet side)
 

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I still reckon you have bent conrod.
 

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Did the lifters/tappets all lift evenly when you removed the cams to dip them in oil?

Dropping the sump is pretty quick, if you have a long thin ribe to get at the gearbox end studs.
You will soon know if it is a conrod.
 

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Discussion Starter #19
They all lifted evenly, a few seemed a bit tight once lubed up they all slipped in and out easily.

I'm in the process of dropping the sump, everything is done except for the 2 tricky ribe bits inbetween the the engine and gearbox. My extension bars are too thick to get in there properly.

Once I do remove the sump, if it turns out the conrod is bent, can you remove the piston and rod from below or is it head off?
 
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