tom7 Posted May 21, 2003 Share Posted May 21, 2003 Whilst undoing the crank pulley bolt on my K series, the car was in gear with handbrake on, using cam locking tool, big screwdriver in ring gear and an extension bar, there was a loud crack ❗ The bolt was still tight but... the crank pulley was no longer lined up with the 90 BTDC mark. I gave it another go which loosened the bolt but appeared to move the pulley closer to the BTDC mark. I've since removed the belt etc and moved the crank assembly back to 90 BTDC in anticipation of re-assembly. What did I break Did I slip a tooth on the belt at the crank pulley, should I be concerned? Any suggestions please Tom Link to comment Share on other sites More sharing options...
Tight fart Posted May 21, 2003 Share Posted May 21, 2003 Sounds like the keyway in the pulley. SLR for sale T.F@O.F. www.griptv.com Link to comment Share on other sites More sharing options...
oilyhands Posted May 21, 2003 Share Posted May 21, 2003 Sounds like the small dowel/keyway protrusion on the crank sprocket, I usually drill these out and replace with a steel pin to avoid that happening. You may be able to repair it by doing just that. Remove the crank sprocket and drill it from behind where there is an indent directly behind the dowel into which the drill bit will slot nicely, drill straight through and then replace with a 6mm(I think its 6mm from memory) dowel which you can make from the shaft of a 6mm bolt. Oily Link to comment Share on other sites More sharing options...
Peter Carmichael Posted May 21, 2003 Share Posted May 21, 2003 For all those reading this at home... DO NOT ATTEMPT TO LOCK THE CRANKSHAFT USING A CAM LOCKING TOOL. Link to comment Share on other sites More sharing options...
Dave McCulloch Posted May 21, 2003 Share Posted May 21, 2003 As I'm about to do a cambelt change, this concerns me slightly... I realise you should not use the cam locking tool to lock the crankshaft, but reading Tom's post he was only following the Rover engine manual - ie lock flywheel, insert cam locking tool and undo crank pulley. Should (or can) you loosen the crank pulley bolt before locking the cam sprockets - presumably if the engine is "timed" first and is in gear with the handbrake on and the wheels chocked, the crank "shouldn't" turn while the bolt is undone (or loosened at least). The cam locking tool can then be inserted and the bolt and pulley removed. Assuming the pulley locating dowel shears (sods law and all), I presume my friendly local Rover dealer can provide a replacement (do I remember circa £8 mentioned on another thread?) Dave Link to comment Share on other sites More sharing options...
Peter Carmichael Posted May 21, 2003 Share Posted May 21, 2003 The consequence of locking the cams when there is the likelihood that the crank will turn is that you risk bending valves. It isn't worth it and you should pursue all other methods of locking the crank (screwdriver in flywheel/handbrake/helper on brakes with car in top gear). Once loose, the cam locking tool can be readily inserted with the assurance that the timing belt will not have slipped. Link to comment Share on other sites More sharing options...
oilyhands Posted May 22, 2003 Share Posted May 22, 2003 I'd agree with Peter, lock the crank, crack the pulley, *then* align the crank and lock the cams, otherwise you risk bendy bendy valves and knackered cambelt if the crank slips. If you can be 100% certain the crank wont move while undoing the bolt , I.E. you have a stonewall method for ensuring it cannot then inserting the cam locking tool wont hurt. I have recently heard of two instances where a cam locking tool was used on its own to prevent the crank from turning while attempting to undo the crank pulley bolt. The results were predictable with the cambelt jumping teeth and the crank turning out of sync. with the cams. This is potentially a disaster in the making. Any of you who are contemplating changing bottom pulleys should be *very* careful. Dave, if the pin shears just drill out the old 'pin' and replace with a proper steel dowel, it will be much better. Oily Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted May 22, 2003 Leadership Team Share Posted May 22, 2003 I agree entirely with Oily (usually a good idea!) - do not lock the cams, lock the crank and "break" the lock on the crank bolt. Then re-align the whole timing setup to the "safe" position and start again. Crank bolt should now unscrew in a normal manner. Tom - you were just unlucky that the friction between the bolt and the front pulley was greater than the strength of the small key - it's nothing more than a lump in the timing pulley. I've found in practice that unless you have a proper crank locking tool, it's easier to remove the engine (honestly!) then lock the crank across the back with a bar bolted on. Then you can be sure that you get the correct 205Nm torque on the crank bolt when you put it all back together. How you get the full torque with the engine in beats me! May be possible to make a locking tool that fits in the starter opening? Stu. Link to comment Share on other sites More sharing options...
Dave McCulloch Posted May 22, 2003 Share Posted May 22, 2003 Thanks all - followed Stu's method. Lined up timing marks initially, put car in top gear with handbrake on and wheels chocked and "cracked" the crank bolt - actually undid quite easily with a 24" breaker bar. Then used a smaller ratchet to realign timing marks, inserted cam lock tool and undid crank bolt and removed pulley. Interestingly, mine (1998 1600) didn't have a locating dowel - there was a very small key machined into the crank and a corresponding "notch" machined out of the crank pulley, so thankfully no dowel to break. Just got new cambelt this morning, so will reassemble everything tonight hopefully. Not sure why you can't get 205Nm torque using top gear / handbrake / wheels chocked method? - will soon find out! Should I use locktite on the crank bolt? Dave Link to comment Share on other sites More sharing options...
Peter Carmichael Posted May 22, 2003 Share Posted May 22, 2003 Yes. Definitely use loctite. You can have problems with the springing in the clutch plates, so the crank moves as you torque up. It is touch and go whether you can get the correct torque within the range of motion you have. Link to comment Share on other sites More sharing options...
Rob Walker Posted May 22, 2003 Share Posted May 22, 2003 Dave It is difficult to reach the correct torque by holding the engine in gear and with all the brakes on because the springs in the clutch friction plate compress and also the clutch plate can slip. The correct method is to use a flywheel locking tool, easy to make out of a bit of 5mm thick steel plate. Link to comment Share on other sites More sharing options...
tom7 Posted May 22, 2003 Author Share Posted May 22, 2003 Well the crank sprocket and pulleys all all OK, I can only conclude that I may have slipped a tooth on the belt. There was definitely no feeling of contact between pistons and valves (I won't be reusing the head anyway) so I may have got away without doing any damage to the pistons. Will inspect pistons closely (without turning crank) when I lift the head. Before I do, is there an *accurate* method of achieving 90 BTDC, the line up with the timing marks seems approximate, or is this good enough? Tom Link to comment Share on other sites More sharing options...
oilyhands Posted May 22, 2003 Share Posted May 22, 2003 Tom, Just remove the plugs from number one and number two cylinders, then use some welding wire to assess when both pistons are level, this will be 90BTDC, make sure number one is on the rise (at this point the 90BTDC marker will be close. Dave, The little locating pling on the sprocket *is* the 'dowel' that we have been referring to, it is very vulnerable and prone to wiping out. To lock the crank via the flywheel ring gear you can use the small hole found underneath the starter motor or the gap at the top of the bellhousing above the clutch cable, a length of 12mm silver steel round bar with an inverse tooth profile ground on is ideal to lock the flywheel against the bellhousing. Oily Edited by - oilyhands on 22 May 2003 10:25:03 Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted May 22, 2003 Leadership Team Share Posted May 22, 2003 Tom - on the crankshaft timing pulley you should find two small marks / circles at the front of one of the teeth. If I recall, with the pulley fitted these will line up at the top with a line cast into the oil pump when at 90 deg before tdc. Stu. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted May 22, 2003 Share Posted May 22, 2003 More accurate is to shove a steel rule down the plugholes and compare across cylinders #1 and #2. This is very accurate because at 90BTDC the pistons are moving at close to their fastest in relation to small crank movements. Link to comment Share on other sites More sharing options...
Dave McCulloch Posted May 22, 2003 Share Posted May 22, 2003 Just fitted the new cambelt. Managed to torque crank pulley bolt up to 205Nm just with the car in top gear, handbrake on and wheels chocked. It was slightly fiddly for the reasons Peter pointed out - the combination of the clutch springs, the car creeping forward slightly and the limited arc available to turn the torque wrench . A couple of quick questions (sorry this has gone a bit off topic, but might also help Tom!): 1) the original (ie from new - though as refitted by Caterham after they'd fitted the supersport kit) cambelt was right on the front edge of the pulleys and judging by the shiny state of the front edge of the belt it had been touching the front cover. The new belt has "walked" almost to the back of the pulleys and seems to have settled about 2mm from the rear edge of the cam pulleys. I assume this is normal / ok. 2) When setting the cambelt tensioner (manual tensioner) the manual says to use finger pressure on tensioner backplate and tighten locknut, then rotate crank 2 turns, slacken backplate bolt, check tensioner is tensioning belt on its spring, then retighten backplate bolt. To check tensioner was tensioning belt, I pulled backplate downwards slightly and made sure spring pulled it back up against belt (which it did). However, this left backplate some way below where it had been when set with "added finger pressure" - application of gentle finger pressure to backplate resulted in it moving a further 5mm or so at bolt slot (conincidentally to a position pretty close to where it had been tightened for the original belt). I've therefore finally set it at the "with slight finger pressure" position. Is this right? Thanks Dave Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now