cant get timing belt back on

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martin droptop
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cant get timing belt back on

Post by martin droptop » Fri Feb 24, 2012 5:01 pm

I have just changed my head gasket and now find the timing belt will not go back on properly .Ive used the cam sprocket locking tool,and Im sure all timing marks are correct but find the belt is either a bit slack between crank pulley and exhaust cam when fitted ,or just to tight to go on at all, Has anyone had this problem?

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Mykel
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Re: cant get timing belt back on

Post by Mykel » Fri Feb 24, 2012 5:32 pm

Auto or manual tensioner?
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Re: cant get timing belt back on

Post by Reckless Rat » Fri Feb 24, 2012 6:54 pm

I had a similar problem when I was refitting the new belt on mine. It turned out that the crank shaft was ever so slightly out - you will see that the timing mark on the crankcase should line up between the two dots on the crankshaft belt pulley. However, it's not an exact science and a couple of "thou" might mean the difference between getting the belt on & not. The long run of the belt should be tight on the exhaust cam to crank side. With a screwdriver on the starter ring gear, ease the crank shaft ever so slightly slightly so the mark is still between the dots but you can slide the cam-belt onto the pulleys without there being any slack. The tensioner will then adjust everything correctly so that you can 'just' twist the exhaust run through 90° at its mid point with your fingers. If it's slack when you put it on it'll be a tooth out.

This is of course assuming you've bought the correct belt because they are different dependant on the tensioner... the manual tensioner belt has 143 teeth and the automatic one 145.

Good luck.

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Re: cant get timing belt back on

Post by Bogbrush » Sun Mar 04, 2012 2:33 pm

I know my comment is too late and along the lines of "Hmmm... wouldnt have done it that way" but Ive just done the same job and found no problems. I was using the recommended flywheel locking tool though and suspect having everything locked up at the time of belt removal meant refitting was a breeze. On the other hand I have done the job on twin-cam Vauxhalls without using proper flywheel locks and Reckless Rat's advice above mirrors my experience perfectly. This is why you turn the engine using the crankshaft pulley bolt a few times after reassembly - to check everything is exactly aligned.
The definition of futility is doing the same thing over & over again, each time expecting a different result.

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Re: cant get timing belt back on

Post by RobboMC » Fri Jun 22, 2012 6:13 am

I'm about to attack a head gasket/water pump and timing belt replacement and I spotted Bogbrush's little picture here.
Is it worth the time to remove the hood completely before starting such major engine work?
Looks like a sensible option to me; I'm an experienced DIY mechanic but new to the MGF.

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Re: cant get timing belt back on

Post by Mykel » Fri Jun 22, 2012 7:19 am

No, that's not necessary. Simply undo the five latches on the rear of the hood and flip the rear end up. I then use a modified key lanyard to keep the thing open.
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Bandit
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Re: cant get timing belt back on

Post by Bandit » Fri Jun 22, 2012 11:57 am

No, it's not necessary, although it does have some merit - it can be helpful in opening up angles of attack that are a bit restricted with the hood in place, i.e. being able to kneel on the seats and lean into the engine over the T bar, which can make some of the spannering a little less uncomfortable...

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Rich in Vancouver
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Re: cant get timing belt back on

Post by Rich in Vancouver » Sat Jun 23, 2012 7:13 am

I installed a new timing bely two days ago as part of a head gasket change.
I had a terrible time getting the timing belt on. The first attempt ended up one tooth out
which was very frustrating. :rant:
On the second attempt I slacked off the mounting bolt on the
(manual) tensioner which gave just enough slack to slide the belt on, then tightened the bolt
and adjusted the tensioner. :thumbsu:
One other thing that really helped was removing the R/H shock absorber to give enough room to get my arm
in to get the belt on and tighten up the tensioner lock bolt.
Make sure you confirm the timing by rotating the engine two revs and observing the marks before putting the
covers on..

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Re: cant get timing belt back on

Post by S67SOK » Sun Jun 24, 2012 11:05 am

Im struggling too.

My boj cam locking tool hasnt worked........ any ideas out there for an emergency 'work around' please. Sunday afternoons not a good time to find a special tool shop!

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RobboMC
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Re: cant get timing belt back on

Post by RobboMC » Mon Jun 25, 2012 3:28 am

Mate I'm new to MGF's but I've been reading a lot of posts that basically say that the job is almost impossible without the locking tool. Descretion could be the better part here. The damage you may do will exceed the cost of a proper tool.

I have a fractured starter motor body in the dead car I just started fixing. I can't understand how the damage has happened but one theory is that someone tried to jam something in there to 'lock' the motor and instead of snapping open the pulley bolt they have destroyed the starter motor housing.

Any other theories, I can't see how the electrical torque could do such damage. Jump staring and hitting the starter together maybe? Or just hitting the starter on a running engine???

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Re: cant get timing belt back on

Post by RobboMC » Mon Jun 25, 2012 3:36 am

Bandit wrote:No, it's not necessary, although it does have some merit - it can be helpful in opening up angles of attack that are a bit restricted with the hood in place, i.e. being able to kneel on the seats and lean into the engine over the T bar, which can make some of the spannering a little less uncomfortable...

A lot of my DIY experience was with a '84 Lotus Esprit Turbo. In the end after a number of years I found that if something was in the way it was always better to just remove it and get clearer access. Even if it wasn't necessary it was usually rewarded with an easier job in the end and less skinned knuckles and swearing.

I've been working on the engine with a specialy prepared reverse hood support ( otherwise known technically as a STICK ) but the idea of completely taking the hood off does appeal to me. Trouble is I've got nowhere safe to store it, maybe hanging from the ceiling??

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S67SOK
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Re: cant get timing belt back on

Post by S67SOK » Mon Jun 25, 2012 8:01 am

Tool on way from Amazon, should be here tomorrow !

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Rich in Vancouver
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Re: cant get timing belt back on

Post by Rich in Vancouver » Tue Jun 26, 2012 3:39 am

Agreed, The cam locking tool really is essential and for the price it's not worth trying to do the job without it.
The point where the timing gears have to sit is right on the edge where the cams cause them to sproing about 20 degrees.
You just have to look at them and away they go!
I used an electric impact gun on the crank bolt with a strap wrench to hold the pully steady and didn't have to use a crank tool.

I found the hood didn't get in my way. I hooked a bungee cord between the front and rear bars of the hood and that held it out of the way.

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S67SOK
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Re: cant get timing belt back on

Post by S67SOK » Tue Jun 26, 2012 7:53 am

Crank pully bolt whizzed out with my air gun, just in gear with the handbrake on.

Scary thing I found last evening........ Whilst waiting for my sprocket locking tool to arrive I have just been 'fiddling' and noticed that one of the bolts holding the aluminium casting of the lower engine mounting beam to the rear cross member / suspension mounting was in the bracket at about 30degrees. I thought 'bother' when the head gasket was done 7 years ago it must have been driven in cross threaded and I thought 'deep joy' if that ever has to come out.
So I thought , with a little sore time, lets see if I can get it out and put in through bolt. As I scrambled about to get a socket on to the head i found the bolt was completely loose and just sitting in the counterbore in the casting eeek!
Took it out and wire brushed the crap of it and it was quite OK, not even sure if had ever been screwed in as it was all covered in an even lager of dust and rust. Cleaned out the captive nut, good squirt of threadlock and back in it went - on the end of a yard long extension.
I checked the tourque of the other one and surprise surprise - that was only half way down its thread.

Needless to say i have now started a campaign to check all tourque settings - garages eh, who would trust them.

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Mykel
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Re: cant get timing belt back on

Post by Mykel » Tue Jun 26, 2012 7:39 pm

Garages and torque wrenches often don't make a "très bon ensemble", I'm afraid. Either loose nuts and bolts or the quite opposite.

On the last car I changed the cam belts (a VVC), some moron had tightened the two 18mm engine mounting screws to an extent we couldn't get them off with a professional tyre shop airgun set to full torque. In the end we used a high impact nut on two 10" extensions, a fixed t-bar with a one metre steel tube slid onto. Two people of more than reasonable body mass managed to get them off. Must have been in the 600 Nm range ... instead of 155.
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S67SOK
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Re: cant get timing belt back on

Post by S67SOK » Tue Jun 26, 2012 8:01 pm

Blimey - snap !
I cut a slot in the 'flange' around the engine bay to allow straight access to them. Odd that those two were massivly overtightened and the others were loose !

Anyway, job done and I am chuffed to bits, she even seems quieter now ?? Must be subjective but I am in the post- spannering afterglow at the moment , must have a cigarette

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Rich in Vancouver
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Re: cant get timing belt back on

Post by Rich in Vancouver » Tue Jun 26, 2012 8:29 pm

Any steel bolts that fit into alloy threads are subject to galvanic corrosion and can sieze into place.
Do the next guy a favour and put a smear of anti-sieze on the bolts before reinstalling them. :thumbsu:

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Re: cant get timing belt back on

Post by Bandit » Tue Jun 26, 2012 9:18 pm

Factories aren't immune to the torque anomalies either - those two bolts were regularly over-tightened in the assembly line, and add a few years of galvanic corrosion between the two metals and the chances of getting them to let go are only slightly higher than the chances of them snapping... Still, they're well worth undoing, wire brushing and re-torquing, as that will prevent them snapping when you least expect it, which will be when you've asked for every last bit of power the engine can deliver. Feeling the THUMP as a suddenly unrestrained engine smacks against the walls of the engine bay, and the flailing of driveshafts that have been ripped apart, is not my preferred way to end a track day :o

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S67SOK
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Re: cant get timing belt back on

Post by S67SOK » Wed Jun 27, 2012 7:27 am

Hmm,

Thats a thought, though correctly retorqued I wonder how much they were stretched by the previous overtightening and then my efforts with the trolley jack handle to un do. Perhaps I should replace them ?

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Mykel
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Re: cant get timing belt back on

Post by Mykel » Wed Jun 27, 2012 8:10 am

From what I saw on the threads of those bolts, they are not the part to worry about. There were lots of alloy remains in there, which had to be cleaned out with a small screwdriver.

I was actually prepared to have the whole threading in the alloy bracket come apart on retightening, but being well cleaned and lubricated with some ball bearing grease they went in smoothly and I had no problem torquing them up to the correct point. Fortunately that particular car is not used for track days ...

This can't have been a factory issue, as the cam belts obviously had been changed before. But not the tensioner, which had quite some play in its bearing, but that's another story. :lol:
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2004 TF 135 in Monogram Spectre, black leather, RHD
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2001 ZR 160 in Solar Red, LHD, LPG conv
Classic:
1972 MG Midget MkIII RWA in Blaze Red
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