engine bay tapping noise - its running now!!

[fla 9]

Are there only the two chains on the RHS of the engine (looking from the front) for the cams, or are there any others that would need to be looked at? Also, how do you remove the belt tensioner from the block? I'm planning to remove and replace with the spare i've got, but other than that i dont know where to proceed.

Where is the oil pick-up point as i want to rule this out as being blocked? How do i get to it? Also, where else should i check for poor oil flow? I just changed the oil and filter so they are fresh. I'm really not wanting to remove the head as this will be a mission i dont want to do, if possible.

[Roger Blassberg 0]

There are 2 chains; one comes up from the crankshaft to an intermediate gear, the other comes from there up to both camshafts. There are guide rails and tensioners for both chains. The only bit you can remove without taking off the gearbox is the top tensioner bolt which in turn bears against the top tensioner pad (which is the most likely area of wear, but with such low mileage is unlikely to be an issue). You can only see the top chain and the top tensioner with the gearbox still on.

 

The belt tensioner needs to be relieved of its tension before removal by screwing a bolt (M8 from memory) into the threaded hole provided, until the pulley is clear of the belt; then simply undo the three locating bolts and it will quite literally fall off. Be careful when you do these bolts back up!! It is very easy to over-torque them and strip the threads in the aluminium head casting, so use a torque wrench. About 15 Nm. (to be confirmed)

 

I can't answer your other questions, but I know several men who can; one of them will be along very shortly.

 

Looking back on all of this, you still need to eliminate the serpentine belt driven ancilliaries when looking for your tapping noise.

 

Best wishes

 

RB

[dr_mat 0]

There are 2 chains

 

Technically there's three chains .. Though the design is as you mention, the early 12v VR6s used a TWIN chain for the upper section. Later 12v engines used a single upper chain that was obviously a little wider.

[fla 9]

There are 2 chains; one comes up from the crankshaft to an intermediate gear, the other comes from there up to both camshafts. There are guide rails and tensioners for both chains. The only bit you can remove without taking off the gearbox is the top tensioner bolt which in turn bears against the top tensioner pad (which is the most likely area of wear, but with such low mileage is unlikely to be an issue). You can only see the top chain and the top tensioner with the gearbox still on.

 

The belt tensioner needs to be relieved of its tension before removal by screwing a bolt (M8 from memory) into the threaded hole provided, until the pulley is clear of the belt; then simply undo the three locating bolts and it will quite literally fall off. Be careful when you do these bolts back up!! It is very easy to over-torque them and strip the threads in the aluminium head casting, so use a torque wrench. About 15 Nm. (to be confirmed)

 

I can't answer your other questions, but I know several men who can; one of them will be along very shortly.

 

Looking back on all of this, you still need to eliminate the serpentine belt driven ancilliaries when looking for your tapping noise.

 

Best wishes

 

RB

 

Useful info as always RB. Where is the top tensioner bolt and top tensioner pad? Is this the same as the belt tensioner (may be an inane question)? I suspect that teh starter clutch is gone so until i replace that i wont really know the effect of removing the serp belt ancillaries from the equation. I hope my evening pics show something obvious. I'll try and take some of other areas of the bay too.

[fla 9]

pics added, but taken blind so they're not too great.

Anyway, its to the left of the engine bay (by the fuel pipes) that the tapping noise could be heard. Whereabouts are the tappets as Toad suggested that there could be one sticking?

Could someone please ring them in the picture?

[Roger Blassberg 0]

Top tensioner pad is to the back of the top (double row/duplex) chain; it is not the same thing as the belt tensioner which is on the other end of the engine by the fuel pipes. You'll see the chain tensioner by peering down the chain aperture.

 

The top chain tensioner bolt appears as a very large hexagon bolt head on the outside rear of the engine; lean over the engine where the top chain is seen in your picture and you can't miss it. This is the only bit of the chain tensioning apparatus you can remove without taking the gearbox off, but , frankly, don't bother at this stage because they don't go wrong as a rule. The only thing that can happen to it is for it to get blocked with dirt - it relies on oil pressure to develop its tensioning action.

 

Tappets, also known as cam followers, are immediately below the camshafts. There is one for each cam lobe and they appear as large circular shiny shapes. In fact they are inverted buckets; under each one is a valve stem. They also rely on oil presasure to keep their adjustment and can be blocked with dirt if it unfortunately gets into the system. More likely cause of failure is wear. To get them out you need to take off the camshafts.

 

It's all pointing to the belt end of the engine for the tapping noise, isn't it ? The starter failure seems coincidental. The only thing I haven't yet quite got my head around is why the engine stalled, unless one of the ancilliary components has completely siezed its bearings and that was enough to stop the engine via the belt.

 

We'll get there eventually.

 

By the way, where in Middx are you? You've got me hooked into finding out what's going on and I'm not a million miles away so might have a look for myself if you are in agreement. Send me a private message if you like.

 

Best wishes

RB

[Stan 24v 0]

By the way, where in Middx are you? You've got me hooked into finding out what's going on and I'm not a million miles away so might have a look for myself if you are in agreement. Send me a private message if you like.

 

Best wishes

RB

 

Thats why this is still "THE" best forum around :thumb right:

[fla 9]

By the way, where in Middx are you? You've got me hooked into finding out what's going on and I'm not a million miles away so might have a look for myself if you are in agreement. Send me a private message if you like.

 

Best wishes

RB

 

Thats why this is still "THE" best forum around :thumb right:[/quote:nq62cfix]

 

Absolutely. :) I'm in Northwood, RB, about 4 miles from Watford. Very kind of you RB, btw. Whereabouts are you based? pm sent.

[fla 9]

Is there a special method to removing the cams or anything that needs to be checked or marked first? I want to have a look at the tappets under them, according to Bentley they should move about 5mm iirc and spring back when pressed.

[Roger Blassberg 0]

Oh dear!! I went to see Hasan's engine this morning and it's bad news, the crankshaft and the camshafts are no longer connected so it seems that the bottom chain has indeed broken (the top chain seems to be intact). Peering down into the innards it looks as though the intermediate sprocket teeth are mangled, so it's definitely a case of gearbox and head off to ascertain the extent of the carnage and to rebuild at least the timing gear. What a thing to happen to such a low mileage engine! (And, by ther way, to such a nice guy; thanks to Hasan and his family for their great hospitality.

 

Best wishes

 

RB

[fla 9]

Many thanks for your help Roger, it was a pleasure to have you over. Like you said it looks bad and the option looks like whipping the engine and gearbox out and stripping it all down. The only other option is, i guess, to find a block with verified low miles and drop that in. If the head is ok, it may be worth keeping that as a spare just in case... So now i'm on the lookout for a written off low miler VR :( - one has to die to keep another alive. Any other options welcomed.

 

What a dismal sunday.

[Jim 2]

Thats dreadful news. How could this have happened to such a low mileage engine?!

[zak 0]

Hassan bad news, seems like its not a good week for corrados!

 

I think you will only be able to make a decision on which way to go once you have the engine stripped down, you may be able to keep your head and block and salvage a few bits like the intemediary from another engine.

[fla 9]

Thats dreadful news. How could this have happened to such a low mileage engine?!

 

Jim, thanks for that. I cant understand either. Bizarre to say the least, plus a shed load of money on the wallet too. Ironically, i was offered a good price for the car over the summer, which i turned down, and the missus has been after me to get rid for a while.

 

Hassan bad news, seems like its not a good week for corrados!

 

I think you will only be able to make a decision on which way to go once you have the engine stripped down, you may be able to keep your head and block and salvage a few bits like the intemediary from another engine.

 

Zak, i think you're right, the simplest may be just to swop the blocks over and then i can strip teh old block down in my own time. The risk here again is, whilst the engine may show low mileage, the potential problems are unknown, as i found out to my cost. Having spoken with a mechanic friend, the engine swop will be the simplest to do, and probabyl teh cheapest. Right now, funds are extremely tight, to say the least, with, like many others, us trying to put down a payment for a new property. As I mentioned to Roger, i had throught of breaking it, but then it would be a crying shame, especially that everything else in it is pretty much spot on. even the auto box is great, believe it or not.

I think i'll risk getting a new block, to get the car up and running. I didnt want to be tinkering in the cold, but needs must ,and its parked outside at the moment, which is not ideal. TBH, even a higher mileage block that has had the chains, tensioners and stems done would be fine. Taking the engine itself apart is a bit beyond my realm of knowledge and i'd be far happier pulling the old one out and dropping the 'new' one in. If thats the case, Zak, I might need a few extra hands :).

 

Bummer.

[fla 9]

An interesting bit of advice received - apparently i will only need to have the head skimmed (prob £80-£100) replace the stems and seals and the chain can be replaced without removing the gearbox, with the engine in situ? Is that true (re the chains?) If so, tht would be ideal. Just a question of removing all the ancillaries around the coilpack side andfitting the new lower chain, tensioner and guides. Any comments on that?

[antonio_b12 0]

could be wrong here, but i didn't think you could fit new lower chains with out removing the gearbox.

 

As its hard to see the timing marks, as long as its timed properly then its ok, but you don't want to re-do the work again.

[Roger Blassberg 0]

Yes, quite a few comments.

 

You simply cannot get at the chains, tensioners and guide rails without removing the gearbox because the intermediate chain wheel and the bottom half of the chain cover are behind the flywheel housing. The engine can stay put but will need supporting when the gearbox is off; the gearbox mount holds up that end of the engine as well. I suggest that you look in the Knowledge Base - there is the most excellently documented procedure including photographs in there

 

Until you have removed the cylinder head you cannot ascertain the level of damage to the valves and/or pistons. If there are bent valves then the associated valve guides may also be damaged - easily replaced if you have the right equipment but would entail recutting the valve seats. I would advise replacing all valve guides, springs and stem seals at this stage because you are then certain to have no more problems in that area for the next several years. Certainly it would be worth stripping the head to give it a light skim and checking all valves for straightness, even those which are apparently undamaged. Any damaged pistons would obviously have to be assessed and replaced as necessary.

 

Best wishes

 

RB

[fla 9]

OK, useful comments. Is there a method to the removal of the head? also the tranny - the auto is pretty heavy (circa 70 kg) so to yank it requires a crane i guess. The Knowledge Base guide is tremendous with super pics from 2cc, i wish he were local to me! Otherwise, any pointers on the head removal? If it is overly complex i may have to take it to a garage, which is not ideal right now.

[Roger Blassberg 0]

The Bentley manual is your best friend on the subject of cylinder head removal. As we discussed yesterday you will have to get the camshaft sprockets away from the top chain by releasing the top tensioner bolt and then disengaging the chain. Undo the head bolts in the correct order, starting from the ends and working towards the middle. Don't use the bolts again once removed - you must use new ones for re-assembly. The head is quite heavy too, especially at arms length.

 

You would be well advised to get a support bar for the engine to assist in the removal (and especially the replacement) of the transmission. The gearbox comes out from underneath so you need sufficient clearance. Support it on a trolley jack and gently lower it. I would suggest at least two pairs of hands.

 

Best wishes

 

RB

[fla 9]

Is it better to remove the gearbox and engine, or remove it with then engine in situ? The latter would be preferable.

 

Also, as a list of 'to buy' items i am lookkng at the following:

1. lower and upper chains

2. lower and upper chain tensioners

3. valves stems, springs and seals

4. head gasket and head bolts

5. Inlet manifold gasket

6. Throttle body gasket (already have)

7. Maybe a polish of the pistons

8. Head skimming

9. Lower sprocket (assuming its toast)

 

Anything else?

[fla 9]

AVS car spares do bits for the C, at comparatively good prices. They use Febi for the chains, tensioners and guides. Are these any good? Other recommendations?

[Roger Blassberg 0]

My personal view on such critical items, ones which will be catastrophic or a serious pain if they fail, is to go for genuine VW items. I am told that Febi Bilstein stuff now comes predominantly from China - not necessarily a bad thing , but for such items I want the security of a VW guarantee which I believe is 2 years on engine parts. In the grand scheme of things, you get what you pay for. I had to replace Febi Bilstein rear wheel bearings after about 6 months, they might just as well have been made out of chocolate for all the good they were. Fourseasons in California supplied my chains etc, all complete with VAG partnumbers on the boxes and moulded into the bits themselves.

 

Best wishes

 

RB

[Kevin Bacon 5]

Fla, sorry to hear the bad news mate.

 

I'va attached the VR6 head bolt tightening sequence for you.

 

As suggested I would remove the head to at least see if the block is salvageable. It would be a shame to lose a young engine. Granted it's bloody freezing at the moment but at least you'll know for sure.

 

It's easy removing the head. Drain the coolant off using the drain plug on the crack pipe (above and to the left of the oil filter). Don't need to worry about the oil just yet.

Remove all the ancilleries attached to the head exhaust downpipes (16mm nut x 6), undo the top alternator bolt, loosen the bottom bolt and swing it down out of the way, remove lower intake, remove chain side cover, coilpack, thermostat housing etc.

 

Regarding the cams, you can either remove the sprockets (15mm bolt, torqued to 100nm) by holding the cams with a 24mm spanner on the slotted sections and undo the sprocket bolts and leave the cams on the head and remove as a job lot......or you can remove the cams and sprockets as one peice.

 

It's not nice undoing the sprockets, often the rear cam needs doing in a vice with an airgun as the cam trigger wheel's washer compresses too much.

 

Remove the tensioner bolt (27mm bolt, torqued to 60nm)

 

Starting from the sprocket end, remove the cam caps (13mm nut, torqued to 20nm) and lay them out on a piece of card in the order you remove them as they have to go back in the same positions, but they are number stamped anyway and observe the direction arrow on the caps too, which points at the sprockets.

 

Then starting with the middle caps, slowly undo them being aware that some of the cam lobes will be under spring tension and therefore will be pushing against the caps. Once all undone, unhook the chain from the sprockets and remove the cams.

 

You are now ready to remove the head!

 

Don't be alarmed by any oil or water in the bores after you take it off. That's residual fluids seeping in after you break the head to block seal and perfectly normal.

 

If the pistons, bores and valves look OK, sigh a breath of relief and don't be tempted to remove the baked on carbon from the piston crowns and bores, leave them be! ;-)

 

Then we can go from there.

 

We need to find out why the crank chain snapped in the first place. It could be due to a siezed intermediate shaft. That sometimes happens when either the oil pump or intermediate shaft bearing seize.

[Kevin Bacon 5]

P.S. You will need a large spline bit to remove the head bolts. I think it's 12mm from memory. Halfords sell them. 12 sided rings a bell too.

[fla 9]

Thanks for the notes Kev. I'd rather remove the cams as one piece, as it appears to be a mission to refit them properly. What would cause the intermediate shaft bearing to seize? If i can isolate that, i would then need to address that to ensure after the rebuild the same does not happen again.

I'm slightly confident that the block will be fine as the engine had just been started and the car stopped almost immediately, at idle, so any damage i think (or hope!) would/should be limited.

Roger, i'll get in touch with Fourseasons and see what they can sort out. Deliveries at this time will be bad, but if i can get it all stripped down this weekend that would be a good start.