Bolt tightening KV6

[Mr Toad]

I was rebuilding the heads and when it came to putting the sprockets for the secondary belts back on torquing the bolts up to 27Nm was okay but to try to tighten the bolts a further 90 degrees was impossible as in these times I had no-one to help hold the heads in place.What is the general consensus of opinion about using an impact wrench to tighten the bolts the further 90 degrees, one could mark the bolt head and the sprocket so that you would know how far the bolt had moved. Obviously you would have to be very careful not to over tighten it but this seems to me to be a way around the problem. Could this also be applied to the head bolts I wonder.

Incidentally I have found the special tool that holds the secondary belt sprockets to be rather useless as it keeps falling off as you are tightening the bolts, have others encountered this problem?

Martin

[SD1too]

Originally Posted by Mr Toad

... to try to tighten the bolts a further 90 degrees was impossible as in these times I had no-one to help hold the heads in place.

Hi Martin,

You say that you're rebuilding the heads. Are you attempting this with the head on the bench? If so, wait until they're refitted to the engine.

Originally Posted by Mr Toad

I have found the special tool .... keeps falling off as you are tightening the bolts, have others encountered this problem?

I found that the rear sprockets holding tool (12-175) slips off earlier in the process; when the assembly is refitted to the camshafts. The answer is to leave the spreader tool (18G 1747-1) in place.

I hope that helps.

Simon

[trikey]

Don’t use an impact wrench on these bolts.

[bsafly]

Definitely do not use an impact on the camshaft sprocket bolts or cylinder head fixings!

[Mr Toad]

Thanks for the responses guys. I was attempting to tighten the bolts on the bench but I will torque them up to 27Nms and carry out the 90 degree tightening once the heads are back in the car.

However I am having considerable difficulty in getting the rear sprockets to line up. I put 18G 1747-2 on the front of the engine and I would have thought that the inlet camshafts should be in the correct position but they seem to be slightly out so that if you attach tool 12-175 it won't fit over the sprockets. Anyone know what I could be doing wrong as when I did this work before I didn't have this problem.

I have noted what some of you say about using an impact wrench but none of you have provided a reason as to why not. I spoke to the impact wrench manufacturer and the person I spoke to seemed to think it was okay to use an impact wrench provided I was very careful and not apply too much pressure and mark the bolt head etc. as mentioned.

Martin

[SD1too]

Originally Posted by Mr Toad

I put 18G 1747-2 on the front of the engine and I would have thought that the inlet camshafts should be in the correct position but they seem to be slightly out so that if you attach tool 12-175 it won't fit over the sprockets. Anyone know what I could be doing wrong ...

You're not doing anything wrong Martin, I discovered this too! With the front tool (18G 1747-2) removed and the flywheel/drive plate locking pin removed, rotate the engine very slightly until the notches on the rear sprockets line up. The inlet timing won't be lost because the camshafts and crankshaft are kept in sync by the tensioned belt.

I'm not the only one to have experienced this.

Simon

[trikey]

Originally Posted by Mr Toad

Thanks for the responses guys. I was attempting to tighten the bolts on the bench but I will torque them up to 27Nms and carry out the 90 degree tightening once the heads are back in the car.

However I am having considerable difficulty in getting the rear sprockets to line up. I put 18G 1747-2 on the front of the engine and I would have thought that the inlet camshafts should be in the correct position but they seem to be slightly out so that if you attach tool 12-175 it won't fit over the sprockets. Anyone know what I could be doing wrong as when I did this work before I didn't have this problem.

I have noted what some of you say about using an impact wrench but none of you have provided a reason as to why not. I spoke to the impact wrench manufacturer and the person I spoke to seemed to think it was okay to use an impact wrench provided I was very careful and not apply too much pressure and mark the bolt head etc. as mentioned.

Martin

Personally I wouldn’t use the impact wrench on a cam bolt as I’ve seen a few kv6 camshafts break, I wouldn’t want to chance stressing an already suspect area.


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[Rich in Vancouver]

I also found that the tool to hold the rear sprockets tends to slip off.
My solution was to use a wire tie (Zap-strap) to tie it to the little spreader between the two cam wheels. That secured the wheels as one assembly which made it easier to install the wheels. This can be challenging when working alone and turning the exhaust cam to get the second pulley to line up.
I agree about not using an impact on the cams. The (sintered?) metal used is very brittle.

[Mr Toad]

Phew what a pain in the neck that was. One of the heads was ok but the other was a nuisance. I had the timing tool 18G 1747-2 on the front of the engine. I could not get 12-175 to fit over the sprockets. After much swearing and cursing I decided to remove 18G1747-2 and the sprocket and then insert part of both 18g 1747-2 into the end of both the inlet and exhaust camshafts. I then attached a socket to the end of each tool so that both camshafts could be moved into line with the secondary belt sprockets at the rear. I was then able to fit both sprockets which lined up, put the sprocket back on the front with tool no 18G 1747-2 with some difficulty and tool 12-175 fitted ok and was able to do up the bolts 27Nm then 90 degrees. You really need two pairs of hands at least.

I really do not understand why this was so difficult I thought that the special tools were supposed to make this foolproof, neither Haynes or the official manual mentions any problems they just leave you to find out for yourself, typical!!

Martin

Now I just have to put the heads back with everything else!!

Martin

[chris75]

Originally Posted by Mr Toad

Incidentally I have found the special tool that holds the secondary belt sprockets to be rather useless as it keeps falling off as you are tightening the bolts, have others encountered this problem?

Martin

You do need 3 hands , especially if the tool has seen a lot of use and the edges are no longer pristine !
I clamped it in place with a wood clamp from one end of the head to the other ; didn't need to be very tight but then it was a doddle
I certainly found it harder to do with the heads off the car than it is with them on it !