A3 Cambelt broken, doh!

[Sly]

Okay, first winge, my service schedule says 115k for cambelt replacement on 20v petrol engines and mine snapped at 114944miles. I see now that everyone on here recommend it earlier. Well so do I now!

The car is a 2001 1.8T AUM engine with auto box and LHD, not that that should make any difference.

Moving on then, when it went about 40mph, no big bang, just loss of power, pulled over straight away and only tried turning it over a few times before diagnosing cambelt not turning with engine.

I'm happy to do the work myself but wouldn't mind a few answers and advice along the way. Will the valves and head always suffer damage? Is there an easy way to check without removing the head or is it worth just trying it with a new belt first and see how it goes? Could this make things worse or if the edges of the valves are just a bit bent would it just run rough if it all?

Any ideas on cheapest place for parts would be appreciated too, Audi ******** quote £700 for the lot which includes:


Cambelt, damper, tensioner
Water pump
20x valves
Headgasket + bolts
rocker cover gasket
coolant
inlet + exhaust manifold gaskets
turbo-exhaust gasket + 3x screws

Anything I've missed out that I may need?

Cheers in advance and looking forward to a big job but not the expense!

[Sly]

...added the poll for a laugh but it cropped the text.

Meant to say, "...so it's worth more to me than it would be to anyone else."

[zollaf]

get a head gasket set, including all the gaskets you will need and valve stem oil seals. also get the head skimmed. check the deck height of all 4 pistons as well. (piston on tdc, check height, any that are different and suspect bent con rod). you will need to grind the new valves in so a twizzle stick and paste will be needed, or get the engine shop that does the skim to cut the seats. the hydraulic tappets will have taken a hammering as well, but will probably be ok, but you might replace them to be safe. all the bits can be found at gsf etc, or try the site sponsors.

[Sly]

cheers, that doesn't make it sound any cheaper! Is it likely the head needs skimming or might I get away with it?! Is there a decent workshop manual I can follow or will Haynes do?

[zollaf]

its best to always skim a head regardless. it should cost about £30, but comes back with a nice shiny surface ready to fit. if you dont, you have to spend ages cleaning all the old bits of gasket off, and if it is slightly out (4 thou ), it will cause the new gasket to blow eventually.

[zollaf]

there you go, 100% of voters say fix it.:D

[Sly]

Sounds well worth it then, I'll do that. (Hate cleaning off old gasket!)

Would it be worth just trying with a new belt first or is damage inevitable on these engines? I got away with it about 10 years back with my 2l Carlton.

[kenney]

There is no harm in trying a new belt,although the chances are small that there is no valve damage.

[Sly]

There is no harm in trying a new belt,although the chances are small that there is no valve damage.

Then that's what I will do first. Optimism optimism optimism!

Will let you know how I get on...

[Sly]

So the belt is out, teeth sheared around the crank gear. The hydraulic damper is easy to push in by hand and the water pump only has half the plastic parts it originally had! Wife is picking up parts for me later.

Turning the engine by hand feels smooth with no unusual noise or resistance. Turning the cam on the other hand? Even with the plugs out is quite hard to overcome the valve springs (i imagine that's what the springiness is caused by?) Doesn't feel like there's anything grinding or otherwise though.

So if the new kit arrives early enough I'll line the cam and crank marks up and slap a new belt on. Turn it by hand a couple of times then start her up, just for a second! Who's feeling lucky?! :confused:

[kenney]

You could remove the rocker cover and inspect the valves

[Sly]

You could remove the rocker cover and inspect the valves

What would I be looking for from that side? I assumed that any damage would be caused to the valve face, unless the valve stem itself is bent of course.

[S18KER]

Im think you should be able to see if the valves are bend or not, you should be able to see the valves go in and out as you turn the cam.

Good Luck.

[kenney]

If the valve heads are bent there will be clearance between the cam follower and the camshaft lobe

[Sly]

Okay, I'll have a gander at that tomorrow before sticking the new belt on.

Mrs Sly picked up parts for me from Unipart, cheapest I could find:

Cambelt kit (belt/tensioner/damper) £75.44
Water pump £22.94
Accessory belt £13.94

With the vat, just over £130. (Audi over £200)

Can't help thinking that's just the start of it though!
Remember, optimismoptimismoptimismoptimism!

[Sly]

So I went into work this morning (I know, it's a pain isn't it?!) and had a bit of a forum with the lads. We came to the conclusion that if a valve face is bent, it's only going to be bent upwards, then starting the engine would damage the valve seat. Also, if one of the valve stems is bent, turning the engine could damage the guide or worse. I have to admit I agree with the logic so I'm not gonna risk the new belt just yet.

I'm away for a couple of days but almost certainly gonna need some more advice over the weekend! Cheers. :confused:

[kenney]

if the valve is bent it will not return to the valve seat,you can check the height of the cam follower,and if the valve is bent,it will hit the piston,and you will notice this when turning the engine over by hand before starting it

[Sly]

if the valve is bent it will not return to the valve seat,you can check the height of the cam follower,and if the valve is bent,it will hit the piston,and you will notice this when turning the engine over by hand before starting it

Excellent advice, optimism is back again! Will have to wait till the weekend now to get the rocker cover off and have a shifty. (work work work...)

[Sly]

I'm back and who was I trying to kid?!

So I finally got the head off today, been waiting on delivery of a M10 Ribe bit to get the head bolts out. Didn't realise the head bolts had this special spline thing going on as the heads were full of oil and I though they were just hex keys. After sawing the mangled end off my ever shortening allen key twice I thought I should investigate further. Luckily didn't knacker the bolts (cheap allen keys!) Top tip for anyone else trying this at home, the M10 Ribe bit needs to be at least 100mm or so long, the Laser set from Halfords aren't long enough. Sealey do a head bolt tool kit with 8 various bits including a long M10 Ribe for £35. Oh, and Audi have their own tool but you can't just buy it, you have to fax Audi UK and apply for it?! That's when I hung up!

So let's look at some photos then...

As you can see, all my exhaust valves and four of my intake vales are open which isn't going to be good for compression!!! They is bent! The other 8 are gonna get changed whilst I'm at it. Taking it to an engineers tomorrow who's gonna charge 50+vat to skim it and some more again to lap the new valves in, Hopefully the guides are okay.

About those pistons? Should they really have that much crud on them? I don't think the marks made by the centre intake vales are gonna matter much but that crud is gonna get cleaned off.

Now to strip the head then, (it's in my kitchen so Mrs Sly isn't overly happy!) my Haynes book shows a home made tool to keep the chain tensioner compressed. I've made one exactly as instructed but can't work out how it fits in? Any one done this before? Is it just for taking the tensioner out on it's own so can I just take the cams and tensioner out all as one without it?

Apart from that, I'm feeling pretty good about things. Got some good prices for the new parts with a bit of phoning around. Luckily don't really need the car for a few weeks so can take my time and no stress, just hope engineers don't turn out too pricy, there's only the one place locally so no choice really. Would appreciate an answer about the tensioner so I can get it to the engineers tomorrow.

[Sly]

...and here's the problem! The notches align at the top and with a bit of manoeuvring of the camshaft pulley to make the chain tighter you can almost imagine 16 rollers between them! Ignore the cable ties, they're there to hold my ineffective as yet compression tool out the way.

By the way, as the valves are bent how would I go about releasing them. Wouldn't using the valve spring compressor push the bent rod back in and damage the sleeve? I was going to leave that to the engineer but the more I do myself, the cheaper.

[Sly]

Sorted it, you need a 6mm threaded rod to make your own chain tensioner compression tool and a fairly tough plate of metal ground an drilled to fit just right! I'm gonna leave the bent valves for the engineer to sort out.

Can't wait to put it all together again. Sure there's gonna be something left over!??

[Sly]

I'll keep this post going just incase any one else is trying a head strip/rebuild for the first time. Got my head back from the engineer today, all 20 valves replaced and 8 exhaust guides + a skim for £380! And I supplied the valves and oil seals as well! Feel I got somegood prices on the parts though:

Head gasket set - Camberleys £55+vat (includes valve seals, chain tenstensioner, rocker cover, head, inlet , outlet gaskets and cam seals)

Valves - Camberleys £155+vat

Belt kit + tensioner + water pump + aux belt - Unipart £131

Head bolts - GSF £18

Turbo to manifold gasket - Audi £3
All comes in under £800 which isn't bad as the labour is free! (just a little slow!)

Gonna start rebuilding the jigsaw puzzle tomorrow...

[Sly]

One thing the engineer mentioned was to compress the tappets to squeeze any oild oil out of them. Mine are currently sat upside down submerged in fresh oil as Haynes suggest. Should I compress them with some soft jawed pliers or can I do it with thumb pressure? I would have thought they should be fitted with oil in them but if he's saying to squeeze the oil out I'm not sure now. Any ideas?!

[Sly]

Sorry, I forgot to keep you updated I was so pleased with myself. It all went together fine, first time. Turned it many times by hand and the timing marks were always spot on. Started with a quick clatter then ran fine. Cleared some fault codes on vag-com which never came back and it's now sweet as a nut. I'm no expert and I did this in front of my house on a couple of axle stands (some of it was done in the kitchen much to Mrs Sly's amusement) but it worked well with no disasters so feel free to ask me anything if you're trying this yourself.

Cheers for the help along the way.
:beerchug:

[kog]

Just read your adventure with the 20 valve head.
I'm in a similar situation but only (only!!!) the 8 exhaust valves have bent.
How did you get on with compressing the oil out of hydraulic lifters as I'll soon be at a stage were I'm, hopefully, going to re-assemble the cams back on to the head and would welcome any useful advice?

[Sly]

Well good luck firstly. My cam followers were really clean compared to some pics i'd seen on t'internet so I didn't try to dismantle them as some people suggest. I used a pair of soft jawed plug pliers to gently compress the follower using a socket on the internal plunger as a spacer. I'd been storing mine immersed in clean oil anyway and when I squeezed, it was just enough to see a small squirt of dirtier brown oil coming out. I kept them immersed to stop any air getting in or whatever? They only made a clatter for a second or two when I first started it, but not again on any subsequent starts.

Take lots of photos of where things go before you take it to bits, especially the timing marks and spacing on the timing chain!

Hope this helps

Sly

[kog]

Thanks for the reply Sly.
I cleaned my hydraulic lifters by soaking in brake cleaning fluid overnight, re-filled with clean engine oil, re-assembled them and left overnight again immersed in clean engine oil.
I eventually re-assembled the engine after a very careful re-build of the head. It started first time and ran like a dream...that is until I took it for a test drive, during which something has catastrophically gone again!
I suspect it's a valve stem (or several) snapped and I've had reports of batches of faulty valves out there as suppliers are now issuing disclaimers saying that any breakages are as a result of faulty fitting not faulty parts!! Even some garages I've spoken to have fallen foul of this.
Thanks for your help

kog

[Sly]

Tough break, can't imagine how p**sed off I would be in that situation. Well done for having a go yourself though. Who's to say you wouldn't be in the same place if a garage had done it for you then?! Good luck with the recovery...

[adamss24]

Federal Mogul valves are just rubbish and they shear clean at the cotter end- the manufacturer is trying to blame the builder for not setting the valve springs square in the bore- this is just bull crap as it's not really possible. I had a 1.8 T with bent valves at some point and fitted Federal Mogul valves. I was lucky i did spun the cams before fitting it to the engine (like i always do !) then i heard the ping and the valve just dropped ! I have took the rest of the valves off, and got a replacement from ECP with some swedish valves K Swiss or something. Never had a problem with those and i have rebuilt a few in my time !

[Sly]

Well I must have been lucky with mine then as I selected mine with price as the overriding factor! Phew!

[fanta]

Just before. Give up my aum engine im going to run through some of your steps.. The car starts and after a warm up cylinder 1 seems to work.. Before that it seems stuck and not firing causing a missfire.. I've ruled out electrical as the spark works on other cylinders and so does the coil and loom

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[Scott K]

This thread is 7 years old so you may not get many responses.