Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: r.welfare on 01 February 2007, 19:25:28
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OK, having watched the excellent DVD several times I felt today was the right time to swap the belts on my '95 Elite 3.0.
Stripdown went fine (although I snapped what I think is the crank sensor), old belt came off fine (was quite disappointed to see it was OK, actually - the car has done 126k and has no history).
I assmbled the parts from Autovaux (including the all important locking kit) and away I went.
It took several attempts to get the markings on the new belt aligned on the crank and then on each cam, but eventually it all seemed to fit. Aligned the upper and lower pulley to 12 and 3 o'clock, tightened the torx bolts, set the tension, and cranked it round for the first time.
Bugger - both out half a tooth. So tried to time 3-4 bank, reset the tension and around again...
Then disaster struck - the belt was slipping on the crank pulley. Tried to get myself out of the mess, but it was getting dark at that stage (started at 9, 2 hours off in the middle of the day to get a 15mm socket to get at those fiendish bolts that hold the aux tensioner pulley in...).
So, I've stopped now as it's got dark - but essentially, the crank's now out of line with the cams, and banks 1 and 3 have gone awry whereas 2 and 4 are pretty much where they should be.
And now the car's blocking the garage and generally sitting there looking sorry for itself, with the belts off (I took the timing belt off again). Tried to turn the crank before I took the belt off, but it got stuck...
Consequently, I feel like an idiot. Any tips for getting myself out of this unholy mess? The DVD is excellent so this is entirely my fault, I obviously missed something...bloody annoying :'(
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Don't panic. It's fairly straight forward to recover the situation.
Just need to get the crank to TDC and the cam pulleys in the right place then start again with the belt fitting.
I'm sure someone will be along soon with the detail.
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Thanks Jason. Is it not possible to have the crank 180 degrees out though? I thought the cams going through 720 degrees for every full rotation of the cam...
You can tell I'm confused! :-[
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I'm impressed you had a go in the first place ;) All you have to do is type TB or The Boy in a thread and like the bloke from Rentaghost he'll pop up any time now with his words of wisdom......... :y
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The words you are looking for are probably Marks_DTM_Calib or Matchless.....
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However, I do know it is possibly to reset it all, but there are precautions such as having crank 60 degrees BTDC to stop pistons/valve collision. Thats why we need an expert to comment...
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The words you are looking for are probably Marks_DTM_Calib or Matchless.....
I agree but they don't have a filter that alerts them to TB references like you do ;D Now R.Welfare knows who to PM.. there sorted :y
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Had a simelar problem when I did Gwilyms cambelt. Turned the engine once, and everything one tooth out.
Ie just started again, off with the belt, and re-alight the cams/crank, hold cams in right place with locking tools, and refit belt.
regardless of the white marks on the belt, if the crank is locked in place and the cams are locked, and the belt is fitted/tensioned, then you can't go far wrong... something must have been amiss....
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I believe I screwed up on the initial rotation. The belt started slipping on the crank, hence where I am now :-[
Might be best to tow it to my local garage and ask them to sort the timing and refit the belt, then tow it home so I can refit the pulleys, aux belt and the rest - but if there's an easy fix I'd be all ears - here's hoping :-/ I assume it *can* be done, as I would have thought you'd need to if you were repairing a motor with a snapped belt...
How did you realign the cams with the crank again JamesV6CDX?
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I believe I screwed up on the initial rotation. The belt started slipping on the crank, hence where I am now :-[
Might be best to tow it to my local garage and ask them to sort the timing and refit the belt, then tow it home so I can refit the pulleys, aux belt and the rest - but if there's an easy fix I'd be all ears - here's hoping :-/ I assume it *can* be done, as I would have thought you'd need to if you were repairing a motor with a snapped belt...
How did you realign the cams with the crank again JamesV6CDX?
What I would suggest is:
1) Remove cambelt
2) put a rag over the cam pulleys' (do one cam at a time) gently twist camwheel clockwise and the cam will sit so all valves are shut...the twist will be a fast and hard hence rag over the camwheels to save your fingers
3)set the crank at tdc (the notch on the crank pulley will actually be at the bottom)
4)turn the crank back 60 degrees (will set all pistons about mid travel in the block and stop and piston/valve interface)
5)set the cams to there timing marks and lock in place
6)Put crank locking tool on crank...turn crank clockwise to TDC and lock locking tool to water pump
7)start belt install again
Did you forget the wedge to hold cambelt onto crank pully?
This is what I am going to do on saturday when I swap my cams over
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I'm pretty sure that it is a bad idea to turn the crank backwards. You should go all the way around.
I'm not an expert, but I'd come help if u were closer.
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I'm pretty sure that it is a bad idea to turn the crank backwards. You should go all the way around.
I'm not an expert, but I'd come help if u were closer.
You are only turning the crank....nothing else...no belt..no water pump and if there is any piston travel on the pins/rings that will be 'reset' when the crank is wound to TDC AFTER the cams have been locked to there respective timing marks........only a 60 degrees twist...it is listed as the way to avoid piston and valve interface
I think there are 6 bolts on the crank so you can use the bolt holes to judge the 60 degrees
Providing the cams are set so no valves are open you could rotate the crank 300 degrees clockwise but I cant see the advantage
I think the reason for generally not rotating anti clockwise is allowing that the cambelt would usually be in situ and any flex in the belt may cause an adjustment in cam timing and may cause pistons and valves to hit each other?
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If you can't sort it yourself, and the garage want crazy money, then I'm not a million miles away
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NO....no.no.no.no.no.no....
What posotion is the crank in, report back before doing anything else....the most important thing to do is to get the crank to 60deg before TDC so that no valve interference can occur......then the belt can come off and the cams can be set correctly, crank moved back to TDC and then the belt can be re-fitted.
So what did you do....turn the crank the wrong way (this is the normal mistake!)......
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The crank has been turned backwards at one point, yes - when I realised the belt was slipping around the crank, one of those things you do without thinking! :'(
Currently the crank is at just before TDC (i.e. notch just before bottom cutout in oil pump). Can only be rotated (forwards!) about 180 degrees before it won't move any further. Presumably this is where valves are touching pistons? I took the belt off last night - cams 2 and 4 are in roughly the right position, cams 1 and 3 are a fair way out.
Is it possible to bend valves on pistons just by rotating the crank with a socket set? I have an awful feeling about this... :(
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Yes it is but, you have to apply a fair bit of force...
If you turn the crank the wrong way (easily done with a ratchet set wrong) then the tensioner unloads the belt and the 3-4 cam wheels fly round!
So the belt is off?
If so then turn the crank backwards to 60 deg before TDC.
Then rotate the cams to align the markings and fit the locking tools. Move the crank back to TDC with the locking tool fitted and start again......
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Thanks Mark. E45 Torx bit to rotate the cams then?
60deg before TDC - notch at 4 o'clock?
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Yep...4 Oclock is fine.......Thought it was a T50 torx....could be wrong though.
Dont use a ratchet to turn the cams, use a bar, as they will spring over...!
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Hmm, will have to nab a bar from my neighbour, all mine are ratcheted!
Presumably I will need to rotate each cam sprocket a couple of turns to make sure I feel resistance at all times, so none of the valves have bent?
I'm a bit worried about bent valves. When I cranked round the first time (the right way, with the belt on and everything aligned), there was a lot of resistance at certain points then it would just go smoothly for a bit. Is this normal, i.e. cams loading and unloading?
Sorry for all the dense questions!
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This is normal as the pistons go through the compression stroke...
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Phew!
Final question - when turning the cam sprockets, do I do 1, 2, 3 then 4, or 3-4 first then 1-2?
Thanks very much Mark - your knowledge of such matters is much appreciated!
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Phew!
Final question - when turning the cam sprockets, do I do 1, 2, 3 then 4, or 3-4 first then 1-2?
Thanks very much Mark - your knowledge of such matters is much appreciated!
Providing the crank is 60 degrees before TDC doesnt really matter what cam you turn first....but according to the DVD you must time/degree cams 3+4 BEFORE 1+2
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Its the crank that needs to be 60 deg before TDC......not the cams.
When re-setting the cmas....it doesn't matter which bank you do first but, do do them a bank at a time....
When resetting the timing its the 3/4 bank first and then the 1/2, as per the DVD
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Its the crank that needs to be 60 deg before TDC......not the cams.
When re-setting the cmas....it doesn't matter which bank you do first but, do do them a bank at a time....
When resetting the timing its the 3/4 bank first and then the 1/2, as per the DVD
type O ...no idea why I put cam when I was thinking crank...doh
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Right - I'll have a go at sorting it all out tomorrow. I'll get someone else to turn the key once it's all back together though! ::) Fingers crossed no valves bent - I'd be surprised, as I'm a 12-stone weakling - Mark makes turning the crank look effortless on the DVD!!!
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The car has just come back from the garage, all back together and running! They charged me 2hrs labour for putting the belt back on, tensioning it properly, refitting the pulleys and new aux belt, then reassembling all the connectors and pipes ;D
So many thanks to all and I'm happy I didn't bend any valves. Check engine light came on 500yds after pulling away though >:(, time for a paperclip test methinks.
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I must just add, then I'll shut up and listen, I'm doing mine soon! TDC = piston No1 is at the top, to prove this whip the plug out to comfirm if necessary...
Ok I've shut up now!!!
DC x