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16v boxer timing belt question

 
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alfa per la vita
Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Mon Jun 02, 2014 6:58 pm    Post subject: 16v boxer timing belt question Reply with quote

Hello everyone,

I am a newcomer here and I am currently changing the timing belt on a 16v boxer engine.

I have some trouble with the timing of the camshaft pulleys on the driver side.
The workshop manual says that at TDC the "I" marking of the exhaust pulley should match the center of the "II" marking of the intake pulley.

However not matter how hard I try Evil or Very Mad I cannot find a perfect match between the 2 markings. In fact the "I" marking points inside the area delimited by the "II" marking but it is not really centered.

The strange thing is that there is no problem with the passenger side, as the following pictures will show.




I am using a Contitech timing belt kit with 121 teeth on both belts.

Could you please tell me if this inaccuracy is somewhat "normal" on this engine or if the timing has to be redone properly Question

Thank you very much in advance !

Best regards Wink
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john 33_16v
16 Valve


Joined: 27 May 2005
Posts: 1406
Location: herts, uk

PostPosted: Wed Jun 04, 2014 10:50 am    Post subject: Reply with quote

I think i've had that- i wouldn't worry.

If you move it one tooth it will be to the right of centre as opposed to the left Rolling Eyes

Slackening the tensioners, turning the engine over with a spanner and re-tightening the tensioners might pull it in line better?
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eagle3
Alfa 33


Joined: 11 Nov 2007
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Location: France

PostPosted: Wed Jun 04, 2014 12:26 pm    Post subject: Reply with quote

On the right bank you have to turn the pulley back from where it wants to go(camshaft is pushing against valves that side) and hold it on the spanner while fitting the belt.
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john 33_16v
16 Valve


Joined: 27 May 2005
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Location: herts, uk

PostPosted: Wed Jun 04, 2014 12:42 pm    Post subject: Reply with quote

Correct Eagle, but without a holding tool that cam sprocket turns about 1/4 turn out from memory so i'm guessing he's held it in place it's just hard to get it smack bang in the middle.

John
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93 33 16v Mirtle Met
08 Fiat Grande Punto Exotica Red
90 Yamaha FZR600 Genesis- Silky white/red/blue
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Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Wed Jun 04, 2014 5:10 pm    Post subject: Reply with quote

Thanks for your replies guys,

when putting the belt on the right bank I did turn the pulley against the valve springs pressure with a spanner. In fact what I meant is that although the timing marks are facing, they are definitely not perfectly centered... But then I guess I will follow your advice John and keep going on.

Actually I am a little extra cautious about this because when I bought the car (back in September...), the engine was running very poorly, the iddle was quite low and unstable (nearly 500 rpm) with occasional misfires (loud, metallic-sounding "bang" from time to time when pulling the gas pedal for example).

We checked with a friend the compressions (12 bars in each cylinder), the ignition (which was ok) and the fuel line (a new fuel pump was installed) but we were unable to find the origin of the problem... We also found that on the driver side, the head would get very very hot compared to the one on the passenger side ! The new spark plugs I put on the driver side head would also get very dark after a few minutes, as if there was too much fuel being injected in the cylinders... So the injectors were replaced too but this did not make any big change.

I then realized that the camshaft timing looked just like what I have right now (ie not perfectly centered) on the driver side. So I suspected that this could have been the origin of the problem... On the meantime some of the hydraulic tappets on that side were completely collapsed so I chose to remplace them too.

So now I hope that the problem actually came from the tappets (-or from something else - any suggestion welcome Wink ), but not from the timing belt as I really cannot get a better timing.

Anyway thank you again ! Any input welcome !
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alfa per la vita
Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Wed Jun 04, 2014 6:04 pm    Post subject: Reply with quote

By the way: I have slackened the tensioners according to the workshop manual, ie by facing the little triangular markings for each pulley on each bank. No visible change as the timing belt is already quite under tension when you put it on the pulleys.
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Thu Jun 05, 2014 12:16 pm    Post subject: Reply with quote

Hi,

I think I may have heard of you through a mutual friend.
I wouldn't worry about the timing, the marks are not off (i.e. within tolerance) and I've seen a lot of them 16Vs run perfectly with the same offset that you have.

In general terms, hot running problems most of the time indicate a lean burn condition rather than a rich burn condition but sometimes diagnosis can be tricky.

I would look in detail at your cams & tappets, if you had to replace some tappets your cams may be worn as well. I would get a good look as well at throttle balancing as this is a common pitfall of all 16Vs, and at the same time investigate the possibility of an intake air leak.

Let us know your findings.

Regards,
zp
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Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Thu Jun 05, 2014 9:43 pm    Post subject: Reply with quote

Hello Zenith,

Thanks for your answers.

En effet nous avons bien un ami commun - en fait nous nous sommes même déjà rencontrés une fois à Supélec, alors qu'on venait de changer le moteur d'une 145...

I'll continue in English as this may interest other people experiencing similar problems :

The heads that are now fitting the engine were offered by our mutual friend Antoine as the original ones showed some cracks near the coolant and oil passages... So the camshafts were also replaced during the swap although they are not definitely not new. They seemed however a bit better than the previous ones but I have to admit that I did not measure them. The tappets are all 100% brand new however.

Concerning the throttle balancing, how would you proceed ? Do I really need to buy the special vacuum pressure meter from the workshop manual or do you know some special technique that would do the trick ?

Thank you very much for your time and concern

best regards
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RFlower
Alfa 33


Joined: 17 Feb 2004
Posts: 432
Location: S of France

PostPosted: Fri Jun 06, 2014 8:32 am    Post subject: Reply with quote

For throttle balancing I have used a Sychro Test for many years.

It is relatively cheap, simple, and accurate, if a bit slower than multiple gauges.

I don't think they are made any longer, but come up on eBay from time to time. Google "buy synchro test" (don't forget the "h")

Edit: I most recently used it on my Ro80, which has twin SU carbs, but the throttle linkages I bought for the Sprint, when an original one broke, are plastic, and have no adjustment.
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Sun Jun 08, 2014 8:03 pm    Post subject: Reply with quote

Hi,

Good to know you are who I thought you were Smile

You can use any off-the shelf vacuum measurement / comparison tool. I have a Twinmax ( http://www.selectronic.fr/twinmax.html ) and have been using it for ten years now ; the device is good, and has only one flaw : no automatic shut-off (e.g. you can drain the battery if you leave the thing on)
Other devices may be fit for the job, too (any decent motorcycle carb balancer will do the job)

I suggest you start checking for air leaks before adjusting the balancing.
On 16Vs two weak points in the circuit : the thick black spacers under the throttle bodies, and the four individual small vacuum pipes.
Get acquainted with vacuum measurement, take multiple readings, at idle and part throttle, try to diagnose what's going on before you actually attempt to adjust.
If there's an air leak, you'll need to solve it before you do anything else.
To balance individual throttles you'll need to drill the cap which prevents access to the bypass screws. To adjust between left and right banks you'll need to adjust the throttle linkage.

Regards,
zp
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Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Tue Jun 10, 2014 12:20 pm    Post subject: Reply with quote

Many thanks for your quick answers again.

I did not know about the Synchro Test, I saw some videos of people using it, interesting stuff ! However I am not sure that I can use it on my car as it is fitted with an electronic injection system (ie if I want to put the Synchro Test on top of one of the throttle valve, I would have to disconnect both the airflow meter and the idle valve from the circuit!).

So I guess my best bet would be to use the TwinMax that can be used on the bypass screws.

Concerning the air leaks, I will replace the 4 gaskets of the black spacers.

For the small vacuum pipes, what can I do to ensure that their sealing is good ? They were pretty easy to take out during the disassembly so they probably are quite leaky. Can I use anaerobic glue or something like that ?

Also, on the idle valve, there is some sort of fat O-ring (ref. 60535034 if that matters) that has seen better days... I will see if one of the Alfa dealers still has one in stock but from my experience so far I am not very optimistic. What would be the best way to "restore" this kind of O-ring ? Do you guys know of any "magic" product for this job ?

Also, on another note, I have noticed that almost all of the bushes for the anti-roll bar are heavily cracked. Even worse, the front engine mount has been totally ripped apart throughout all its length. I was unable to find a new spare front engine mount, and the bushes, although available, are now sold by aftermarket companies at ridiculous prices (nearly 80e). Is it okay to fix them with polyurethane glue, like I read on some other forums ?

Best regards
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Tue Jun 10, 2014 1:18 pm    Post subject: Reply with quote

Hi,

The vacuum pipes you may as well renew, using correct diameter hose.
O-rings can be sourced without issue, in your case from any reputable Bosch dealer, or measure dimensions and source it from an O-ring dealer (many around)
Front engine mount is a little more tricky but you can find second-hand, sometimes NOS, and online search using the part number will yield a few results.
Sway bar bushes can be replaced with a number of variants, there are almost the same from one car to another, spend some time in a junkyard and find the correct ones. Alternative is to use powerflex/superflex or equivalent.

One afterthought : since you have fiddled a bit with the camshaft and lifters, would it be possible by any chance that you have swapped the camshafts around? Intake and exhaust are different ones, and I never really attempted to purposedly swap between intake and exhaust, but since the seem roughly identical, I would guess the timing marks may line up. Worth checking anyway.

regards,
zp
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Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Sat Jun 14, 2014 4:52 pm    Post subject: Reply with quote

Hi Zenith,

Thanks for the tip concerning the camshafts, and yes I took extra care not to swap them during the rebuild of the heads; if my memory is right, the intake camshafts are a little bit "rounder" than the exhaust ones, which are more "pointy". I guess I will just try my luck now.

I have another question : I am changing the bushes linking the struts to the front crossrail. I could take the old ones out without any problem with a vise and a hammer. However, the new ones I ordered (original alfa romeo parts) are really too big and cannot fit the holes in the struts. If I try using the vise to force them inside they start bending Confused What is the proper way to deal with this problem ? Heating the strut ? Grinding the outside of the new bushes a little ?

Best regards
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Sun Jun 15, 2014 6:32 pm    Post subject: Reply with quote

Hi,

I know these can be hard to install. The OEM ones are fitted with an outer plastic sleeve which will shrink during install. You may need to make dedicated adapters to insert the bushes. Sometimes a vice is not enough and a cone-shaped mandrel and some grease will help.

regards,
zp

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Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Tue Jun 17, 2014 8:48 pm    Post subject: Reply with quote

Hi Zentih thanks again for all the help you provided.


Concerning the insertion of the bushes :

from your picture, i see that you have put a long threaded steel rod inside the bush to guide it, then put the bush inside a larger cylindrical piece (the brown one), then put two sockets of an adequate size (maybe the one on the left is a conical mandrel ?), two nuts, and then tightened ?

cheers
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Wed Jun 18, 2014 12:34 pm    Post subject: Reply with quote

Hi,

Yes that's the general idea. Get some lube in the area as well and you should be fine.

Regards,
zp
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Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Wed Jul 23, 2014 8:56 pm    Post subject: Reply with quote

Hello again,

I finally managed to put the bushes back in place ! Chamfering their outer grey plastic case a little (I used a belt sander) makes the process a little easier. Phew !

OK so I am now finally ready to put everything back... But I have one last problem Rolling Eyes... With the clutch ! I bought a brand new clutch kit (the Valeo one; its reference fits the one I got from Eper) BUT when I try to bolt it on the flywheel, one of the small bolts always snap ! By "snapping" I mean that I reach a point where I suddenly hear a metallic sound (like a small "clic") and the concerned bolt starts rotating freely. So I changed the bolts with new ones (M7x16mm... So easy to find, thank you Alfa!), since their threads looked a bit damaged.
And so I tried again today, but still no success ! It just keeps happening ! Each time I try I hear a bolt snapping away... I did bolt all of them very progressively and very gently at each try... The workshop manual does not say anything particular... Where could this problem come from ? Does anyone have used the Valeo clutch kit 801834 ?

Thanks in advance,

Best regards
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RFlower
Alfa 33


Joined: 17 Feb 2004
Posts: 432
Location: S of France

PostPosted: Thu Jul 24, 2014 11:04 am    Post subject: Reply with quote

Maybe there is something in the bottom of the threaded hole you are screwing the bolt into, or the threads are damaged.

Check the depth with thin rod and see if you can screw the bolts in all the way by hand without the clutch in place.

If necessary you can clean out the thread with a suitable plug tap.
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Dick Flower, Nr. Carcassonne. '94 Trofeo 1.4 ie (F), '93 Imola 1.3/1.4 ie (now for breaking) (F), '91 1.7 ie (GB)(spare car), '86 Sprint 1.5 QV (F). '87 VW Syncro camper (F), '73 NSU Ro80 (F), '99 Fiat Seicento (F)
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alfa per la vita
Alfasud


Joined: 02 Jun 2014
Posts: 32
Location: France

PostPosted: Thu Jul 24, 2014 8:25 pm    Post subject: Reply with quote

Thanks for your input RFlower,

Today I checked carefully the threaded holes of the flywheel and, big surprise, they actually have a diameter of 8 mm! This is why I had so much trouble fitting the clutch with the M7 bolts... I still wonder how the guy before me managed to tighten the clutch with this stuff Shocked

Best regards
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Fri Jul 25, 2014 8:25 am    Post subject: Reply with quote

Hi,

the six clutch bolts are M8 indeed
Be sure to center the clutch correctly otherwise you'll struggle to get the gearbox back in.

regards,
zp
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