After a fraying belt hopped a tooth on the exhaust cam on the horizontal cylinder on my ST4s, I was lucky to get away with just some bent exhaust valves. However, I got an independent Ducati guy to change the valves for me and he was checking clearances when he copped that the inlet rockers were badly worn. I have some new ones on order but I decided I might was well pull the vertical cylinder head too and check the rockers and clearances also. But, I can't get the shagging idler pulley off. The frame rail means that the allen key won't engage right and even a long, ball-ended key just won't seem to crack it. I know there is thread lock on these, but I feel I am putting way too much torque on it and the key is twisting with no joy. I have given it a few taps of a hammer to try to dislodge the thread lock, bit to no avail. Can anyone else recommend something or know a trick I'm missing? I don't want to brute force it as I reckon it will either strip the threads or bugger the allen head.
Socket with an allen bit, Impact driver with an allen bit. If the head rounds out smack a Torx/stardrive bit in there.
Condolences, not an eay fix. They do reckon that you should get the locktighted area up to around 100 deg to destroy the threadlock. I never attempt any of these beggars with anything other than an impact hammer, but you cant get one in ?? Yoy deffo have to remove the pulley ??
Allen bit held in a tap wrench? (Not the plumber's tool, but the two handled thing that holds the thing that cuts a thread)......and could you push a wooden wedge in there between the frame and the tool to keep it in the allen bolt......?? AL
Thanks for the suggestions. I do have blow lamp, and I reckon I'll have to change the bearings anyway, so it may be the only option. But I am loathe to just have indiscriminate heat on the area. Bastard thing!
i'm guessing that you have the standard shallow headed allen screws fitted? These often show signs of previous damage from slipping with allen key. Is poor access to these a known problem with ST4 or is it a case of getting just the right allen key/socket? You can use a flat ended drift to not only shock screw loose but to close up the allen slot ready for the next attempt at undoing (but you've tried this). if this fails to work you could try an oversize torx (as suggested) or a sharp punch or even a pair of soft jaw mole-grips if you can get access. Have used the last two methods with most success in the past.
I don't think he has the access to be able to hammer a bit into the head Chris, not that I know anything about how the frame is on an ST.... AL
Something like this I reckon.....if this is an ST4.........(but FFS, why do Ducati need two bl**dy circlips to hold it all together as well as a bolty thing?)
Im thinking the idler pulley would be the gold pulley on the left, the tensioner is the black one on the right? Surely you can release the belt tension with the tensioner pulley, get the belt & head off, then faff getting the idler off on the bench? Unless Im missing something obvious? :biggrin:
I think the head separates just below the three allen bolts and above the idler...........stiill, I know nuffink about them enjuns. But if the central circlip was removed, wouldn't it just slide off or have I got completely the wrong enjun and the wrong end of the stick? AL
it's worse than that.. me still dozy with some lurgy of 14 days read 'ST2' somehow.. (reference to shallow headed allen screw(s) is the giveaway). It's not that you can't get access to clout the end of the one bespoke allen screw, it's that you don't need to, as somebody said if you are merely removing the belt to take the head off as you just slacken the 'mobile' idler nut. Further to this, you would leave that blighter alone anyway as (as someone also quite rightly said) they are normally factory secured with high strength locking compound and there is a chance that same will partially strip the female alloy thread in the head on removal. As i'm sure all are aware - if pulley and/or bearing need changing then can be done with head off after removing circlip on the 'static' idler. EDIT - There's not enough room to slide pulley off because of the frame AL. 2nd EDIT '"Don't read technical threads when dozy" is my self advice here - I had assumed bent valves were on vertical cylinder still needing repair and hence head removal necessary.
OK, should have started with a pic really. The vertical head needs to come off to facilitate the fitting of the new inlet rockers. To get at the cylinder head bolts, you need to remove both the adjuster and the idler pulleys as the pins that they run on mount the belt housing backing plate to the cylinder. The adjuster pulley mounting pin came out of the head OK, as did the pair on the horizontal cylinder. The problem this time, as you can see from the pick is that a normal allen key does not have the clearance between the frame rail and head. Hence the long, ball-ended key. However, I can't seem to break the tension due to the thread lock. Also, the blow lamp that I have is fairly big, so it would not be easy to direct the heat accurately. I know this area would get fairly hot in normal running anyway, but still I'd be wary. A
You don't need the head off to replace the opening rockers, but......... If you want the head off, use a 8mm bit from an impact driver set then use a spanner on that, usually 10mm. They are tight, but I've never had to use heat and never stripped one using this method. The ball end won't do it. It'll snap more than likely...
Tricky A blow lamp isn't really the best tool for this application, too wide a spread of flame. What would be better is an oxy-acetylene torch with a plumbers heat -shield pad draped over the frame to protect it. Failing that how about one of those cooking blow lamps seen on cooking programs, or I have even seen cigarette lighters that have a fierce flame on them, like a mini oxy-acetylene torch. How about a Allen key with the short leg of the 'L' smaller than standard, I have a couple of Allen keys where the shorter leg of the 'L' is barely a stub, but sufficient for doing the job, you could get one modified possibly? Just realized that what Chris has mentioned already is the deciding factor: "EDIT - There's not enough room to slide pulley off because of the frame"
There is absolutely no need to take the head off to change the rockers, especially openers. With the head insitu, remove the belts, remove the valve covers, remove the rocker spindle covers. Then, working on one side, inlet or exhaust, at a time, with a slide hammer or an M4 drawbolt and a socket, pull the opener rocker spindles out by about 25mm. The opener rockers can now be slid outwards clear of the cams. Remove the retaining screws from camshaft bearing caps and withdraw the camshaft out towards the pulley side, turning it slightly to clear the rockers as you do so. Remove the opposite bearing cap. You will now have plenty of access to inspect the rockers with the camshaft removed and while the camshaft is out you can have a look at it too. The opener rockers can be easily removed by pulling the spindles out a little further. The closers are removed by pulling the spindles out, but you will have the spring to contend with when replacing them, not an easy job on the dropped cam engines but you can deal with that task if and when necessary.
I take it its a bit late to let the engine run for a while and get some heat into it that way? :biggrin: Have you dosed the back of the idler bolt with any penetrating fluid? If the threadlock is the same stuff they use for their head studs you may have a struggle... Would agree with all said above - cut down the short end of an allen key with a cutting wheel on an angle grinder to fit between the frame & idler - also try tightening the bolt & see if this frees up the threadlock? Chop a length off the end of an allen key & use a spanner on it, could also try heating the bare alloy next to the idler with a torch, being careful to shield the idler & other paintwork with a piece of sheet metal?
See? I told you I didn't know nuffink about ST4s.......but at least I got the right pic. OK, as mentioned above, shorten the short length of an allen key of the right size......and use a tough ring spanner for extra leverage on the long end of the key......it will become obvious how the spanner will fit as you try to position it........failing that find a tough bit of pipe that is close fitting or get a solid bar and drill a hole in the end to take the allen key.... AL
** How difficult would it be to remove all necessaries to allow removal of the front engine mount bolt? Then you could raise/lower the engine up or down with a trolley jack & piece of wood under the engine, pivoting on the back mount bolt to drop or raise the idler pulley clear of the frame to allow fitting of a ratchet & allen socket? :smile: Apologies of my ignorance not knowing if this is doable on a 4V frame? :biggrin:
Have just found a suitable allen key to cut and got a decent hacksaw blade, so I'll try that. I will use a good adjustable spanner on the end of the shortened allen key and there should be enough clearance to get decent leverage on it. Will post my progress. Thanks all! Just to follow up on the comments earlier, I do realise it would be possible to do this without removing the heads, but the other head and all the stuff necessary to complete the repairs are in the workshop of the mechanic and so, doing it in situ would be a pain in the ass. Anyway, it will give me a good opportunity to clean up the crown of the piston and the combustion chamber, as it was pretty cruddy on the other one, so I’d not hold out much hope for this one.
