Zak1 Posted March 29, 2017 Share Posted March 29, 2017 Can someone help? I'm putting back the head on 12J engine and have replaced the cam belt. I've followed the instructions re timing to the letter a mixture of web advice and manual. Screwing the head down was fine until I noticed that one of the push rods appeared bent. Dismantling confirmed this and whilst waiting for a new day and new push rods I again attached the head minus one push rod (call me stupid). No problem until I manually attempted to turn the crank which came to juddering stop as one of the valves (exhaust over No. 4 piston) came into contact with piston. Easing it back and taking the slack off all the rocker arms, now giving the valve springs loads of room, only seemed to work until I hit another stop further in the crank cycle. Phone calls and visits to mechanics seemed to suggest that somehow the timing was out. Checked timing again No. 1 TDC, all notches where they should be. Spoke to nice guy at Dunsfold who suggested I try to turn it without the rocker assembly. Great it worked. Put the rocker on loosely, again with success. Now tightened the assembly and again can't damn well get the thing to turn, with audible clunk, even with the the arm adjustment at it's loosest! Please help as I'm about to do damage to myself. Many thanks ZAK Quote Link to comment Share on other sites More sharing options...
Puffernutter Posted March 30, 2017 Share Posted March 30, 2017 A long time since I played with a 12J (I used to have one in my 110), but doesn't one pulley have two revolutions w.r.t the other having just 1? Could you be 180 degrees out? Cheers Peter Quote Link to comment Share on other sites More sharing options...
neil110 Posted March 30, 2017 Share Posted March 30, 2017 The camshaft turns at half the speed of the engine. So as the post above suggests you might be 180 degrees out Quote Link to comment Share on other sites More sharing options...
monkie Posted March 30, 2017 Share Posted March 30, 2017 I think I might know what you have done. On the Crank pulley, there is a dot on one of the teeth (see the 1st pic below from my 19J). This is not TDC, but I think it corresponds to when all of the pistons are midway in the bore. It is easy to mistake this as TDC. For TDC, the woodruff key should be at the 12 o' clock position as in the second pic below. Quote Link to comment Share on other sites More sharing options...
Zak1 Posted March 30, 2017 Author Share Posted March 30, 2017 Thank you all. Monkie I have used the woodruff key and not the dot marking (made that mistake already), in order to set TDC and indeed No. 1 piston is at the top of it's cycle. Puffernutter and Neil 110 when you say 180 out which cog do I turn through 180 degrees? I'll try anything at this stage! A solution I've come up with, although a tad odd, would be to put some shims under all the rocker assembly pillars to elevate it and then get the necessary clearance but not sure if this is a tad too Heath Robinson for such a finely tuned piece of engineering. Does this ring any bells wth anyone as a way out? Thank you all for your suggestions. Zak1 Quote Link to comment Share on other sites More sharing options...
monkie Posted March 30, 2017 Share Posted March 30, 2017 If the timing marks on the crank, cam and FIP are all lined up correctly then nothing is 180 degrees out. The crank turns twice per revolution of the cam. As long as the crank is set to TDC and then you set the cam and FIP to their respective marks then all will be fine. As soon as you have tensioned the belt, are the marks still in alignment? Is the belt slipping at all when you move it? I wouldn't add any shims anywhere at this stage because thinking about it, the engine presumably ran fine before you did the timing belt. What head gasket are you using? Have you got part number STC1562 for the 2.5NA head gasket set? What other work have done on this engine since it last ran while you have changed the timing belt? Quote Link to comment Share on other sites More sharing options...
Ex Member Posted March 30, 2017 Share Posted March 30, 2017 (edited) You align the crank dot and not the woodruff key. It is more or less clear in the manual. There is also a notch in the flywheel, that should line up. Edited March 30, 2017 by Red90 Quote Link to comment Share on other sites More sharing options...
Ex Member Posted March 30, 2017 Share Posted March 30, 2017 FYI, it is also clear in the manual that the timing is NOT done at TDC... This is what it says. Quote The D.P.S. pump and valves are timed using the exhaust valve peak of number one cylinder. This is determined on later engines by the relationship of a slot in the flywheel periphery and a plugged hole in the flywheel housing through which a flywheel timing pin, special tool number LST 107, is inserted. Quote Link to comment Share on other sites More sharing options...
monkie Posted March 30, 2017 Share Posted March 30, 2017 3 hours ago, Red90 said: FYI, it is also clear in the manual that the timing is NOT done at TDC... This is what it says. Yes, this is right^^^ - apologies, I must have got confused with the Tdi I did a while ago where the woodruff is at 12 o'clock when timing the crank. But I think we are on the point here, you must be using the wrong reference marker as a timing point on the crank. When the woodruff key at 12'o clock the engine is at #1 TDC. If you have had the head off you will see piston 1 at TDC when the woodruff key is at 12 o'clock.When the dot is at 12 o'clock I'm sure the pistons are all half way down the bore. Follow the guide by Les. The only thing is - you have said that you have had piston valve contact with the crank in both positions, are you absolutely sure of that? Take the belt off, then set the crank to where you think it should be by the DOT and then see if you can lock the crank by putting a drill bit into the hole on the flywheel housing which should locate into the flywheel if the crank is in the right position. Quote Link to comment Share on other sites More sharing options...
Puffernutter Posted March 30, 2017 Share Posted March 30, 2017 Too late now but an Ed China trick! Leave the existing belt in place and then cut it in half lengthwise. When the cut is complete, remove the outer half. Then place the new belt so it is half way across the pulleys loosening the tensioner slightly to fit if needed. Then cut the remaining half of the old belt and remove. Push the new belt fully on. Cheers Peter Quote Link to comment Share on other sites More sharing options...
Zak1 Posted March 30, 2017 Author Share Posted March 30, 2017 Thank you all. I will have a go at using the dot instead of the woodruff key as a point of reference. Not sure how to hold the flywheel in place as I can't remember if the notch on it will be at the correct point (I seem to remember there might be two notches so the other may be visible at that point). As you may have noticed I'm somewhat of a beginner to this LR malarkey and I apologise for my lack of rudimentary understanding! I'll get back to you all tomorrow with I hope success. If I don't, then my wife can send the message after grieving for my self inflicted demise (if she grieves at all). Thanks again Zak1 Quote Link to comment Share on other sites More sharing options...
neil110 Posted March 31, 2017 Share Posted March 31, 2017 20 hours ago, Red90 said: You align the crank dot and not the woodruff key. It is more or less clear in the manual. There is also a notch in the flywheel, that should line up. When I attempted that method of unfastening the bolt on the crank pulley. It snapped the breaker bar, like a carrot. Quote Link to comment Share on other sites More sharing options...
monkie Posted April 9, 2017 Share Posted April 9, 2017 Have you managed to get your timing problem sorted? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.