12V V6 Cam Replacement. . . ? - Alfa Romeo Forum
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Help 12V V6 Cam Replacement. . . ?

Hi there,
I’m in desperate need of some help / advice from you Alfa experts.
I have a 2000 916 Spider 12V 3.0 V6 with ~125k kms on the clock.
There was a ticking sound coming from the under the cam covers when I bought the car, but it wasn’t too loud so I lived with it for a few months. I assumed that it was tappet adjustment that was required. Once it started getting louder, I had my local Dutch Alfa Specialist take a look at it and he confirmed that it was indeed the valve clearances that needed adjusting. He quoted me €400 for the work and I agreed that it was worth it to be rid of the noise.
He then called me and said that the wear on the cam lobes was bad enough that he couldn’t adjust the clearances enough to get rid of the ticking sound, and at that point he recommended replacing the cams at a total cost of ~€2,000 for parts and labor.
He replaced the cams and the buckets and I picked up the car. When I drove away, the ticking sound was every bit as loud as when I had dropped the car off 3 weeks earlier. Of course I called him right away and we booked another appointment so that he could fix it.
After another week with my car in his shop I picked it up. He said that he had to adjust the clearances to be much tighter than the Alfa specs to quiet the ticking sound. It worked, as the engine is now very quiet, but the performance is now crap. It idols very rough, the low-end power is awful, and the engine only smooths out when the RPMs get above ~3,500.
He told me that noisy tappets in the 12V V6 are ‘normal’. So I assume now that the cams didn’t need replacing and that I just blew the additional €1,600 for nothing.
Any advice on what the actual problem might be would be greatly appreciated.
Cheers.

Last edited by Woodyholland; 18-06-13 at 09:30.
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The 12v V6 engines always tick away merrily at idle, but it's the injectors making the noise. I guess you're sure it was the tappets?

400euro to adjust the tappet clearances? Now you do have to remove the cam to adjust the inlet valve clearances, but still.... Exhaust valve clearances are adjusted by little set screws - very quick and easy.
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As well as severe cam lobe and follower wear on the exhaust lobes, (inlets usually fine), you can also get bad wear on the ends of the rockers at the valve tips, which makes setting the tappets awkward. I used to adjust at the valve rather than the cam anyway (multiply spec by 1.4 to get clearance at valve) as I found it more accurate, but it's quite possible the engine also wants the rockers refacing. To set inlet and exhaust clearances can be quite time consuming and shims are hard to come by these days, so €400 maybe isn't as bad as it seems at first. Just setting exhaust clearances shouldn't take more than a few hours including strip and reassemble I don't think.

If it had new cams and a full set of 12 followers, then €2000 isn't too far off the mark as that's a lot of expensive parts. Work wise, it's not actually much more than simply setting the gaps, as you need to remove the cams to change inlet shims anyway.

One other potential issue is if the exhaust followers and lobes were really bad, the bores that the followers run in can go out of round.

Rocker shafts can wear too, again, making proper setting almost impossible. Same deal with cam bearings too if its bad.

The symptoms now sound like the gaps are too small and it's blowing past the valves. Do a compassion check to make sure this isn't happening or it'll burn the valves in short order.

Injectors do tick, but with stock cams and all as it should be, the valve gear shouldn't be too noisy, although it'll never be silent. Best case and you get a gentle mechanical purr. Worst case and it sounds like a bag of spanner s in a tumble dryer. I've had both sorts!

Hope that helps a bit.

Last edited by ChrisS; 02-07-13 at 05:35. Reason: Corrected myself about where to set gaps
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Forgot to mention, not that I saw that many, perhaps 7, but every 12v motor I ever owned had cam lobe wear to some extent on the exhaust lobes and followers, plus tip wear on the rockers. It is a poor design and prone to failure as the lubrication is so poor. Inlets never normally any trouble at all. The original engine in my 155 v6 was truly shocking.
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Quote:
Originally Posted by ChrisS View Post
Forgot to mention, not that I saw that many, perhaps 7, but every 12v motor I ever owned had cam lobe wear to some extent on the exhaust lobes and followers, plus tip wear on the rockers. It is a poor design and prone to failure as the lubrication is so poor. Inlets never normally any trouble at all. The original engine in my 155 v6 was truly shocking.
Issa not so bad. My v6 has hardly any cam wear at all - my mechanic even thought I must have swapped the engine. 220,000 miles on the clock and 12,000 mile oil change intervals, though the beast has only rarely seen the wrong side of 4000rpm, which is probably what does it.

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I put 100,000 miles on my 164 v6 and never adjusted clearances - checked them once and they were spot on. Valvetrain was always lovely and quiet, cam lobes like new. Oil change every 6000 miles though...
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There are always a lucky few, or perhaps it isn't luck, just good servicing, but by the time I saw the engines, they were already done for. The 75 crowd regard cams as a service item. I know I'm not alone in this! I've heard many clattery 12V v6 engines over the years, not all of them mine.

I know Ralf has a good one - he tells me every time I post anything up about cam wear issues on the 12V! I don't have a downer on the engine, I'm just posting my own personal experiences and the OPs problem seems to bear them out as well. Now, the 24V motors are another kettle of fish - never seen nor heard of valve train wear on those myself, although I don;t doubt there are folk out there who have. Other issues, yes, but not knackered cams.
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