Bolt tightening KV6 - Page 3

Mr Toad · 9th May 2020, 16:40

Thanks Simon that is very kind of you. I think I will give Laser Tools a call on Monday morning to see whether or not I can persuade them to send me a replacement part after all I have only used the tools once before. I will let you know how I get on.

Martin

Fred Byrne · 9th May 2020, 21:58

Well done. It's easier the second time around

Fred

Mr Toad · 10th May 2020, 19:01

That's what you would have thought Fred but the reality is different. Last time I had no difficulty lining up the sprockets at the rear and although I had no problem with the front head this time I have had enormous difficulty with the rear one.

It is interesting that today I used the exhaust cam at the front to line up the rear sprockets to insert the locking tool. Upon putting the locking tool on I discovered that the timing marks at the front and the rear were in line which makes me think that once the primary belt is on it should all be ok as Simon indicated. What I find unusual is that I had no problem with the front head yet I could not get the sprockets at the rear to line up with the front tools on. There has not really been any explanation for this and I am curious why this should have happened as it most peculiar.

Martin

chris75 · 10th May 2020, 20:09

Quote:

Originally Posted by Mr Toad

It is interesting that today I used the exhaust cam at the front to line up the rear sprockets to insert the locking tool. Upon putting the locking tool on I discovered that the timing marks at the front and the rear were in line which makes me think that once the primary belt is on it should all be ok as Simon indicated. What I find unusual is that I had no problem with the front head yet I could not get the sprockets at the rear to line up with the front tools on. There has not really been any explanation for this and I am curious why this should have happened as it most peculiar.

Martin

Does my quote in post#14 and comments in #16 not help to explain this ? Fitting the primary belt secures the alignment of the inlet cams but the exhausts remain free to move , as you found when you rotated one to line up the rear sprockets , so they are not yet aligned . The movement required is very small , and could on occasion be zero if you are having a lucky turn

Fred Byrne · 11th May 2020, 15:23

In theory when the inlet camshaft on the front bank is correctly lined up then the rear bank's inlet cam should also be lined up correctly. Unfortunately, as in practically all things in life there is usually a very small discrepancy. I presume this is because there is stretch in the timing belt or free play somewhere. What you must do is remove the locking pinpin and all tools from the front of the engine. You cannot lose the timing whilst the timing belt is fitted. Then examine the rear slot on the inlet camshaft on the rear bank. It should be pointing directly at the centre of the exhaust camshaft. It is probably very very slightly out. Any adjustment as Simon says is tiny. Indeed it may be almost unnoticeable. I checked this by putting both camwheels back. Then engaged the spreading tool in the inlet camwheel. Then checked that the small end of the tool was sitting centrally on the exhaust cam wheel. The corrections are tiny. You have to move the crankshaft by using a socket on the crankshaft pinion bolt with a very long lever. Then you can adjust the amount of rotation of the crankshaft with very gentle taps on the end of the lever. The adjustments are tiny. An assistant is helpful if they are reasonably patient and understand what you are trying to do, I am convinced that Haynes never did this operation or they were very lucky. I don't know which engine you have but in the case of the 2.5l engine the crankshaft has to be rotated 8 degrees beyond the safe setting marks on the crankshaft before the slots line up.This isn't mentioned in haynes or even in the Rover workshop manual. The reason is because the inlet valve opens 8 degrees later on the 2.5 than it does on the 2.0. Incidentally you may have notice small nicks on the edges of both camwheels. These should line up when everything is correct. however, your eyesight is not accurate enough to use these at setting marks.
I am sorry you are having such difficulty. I had the same difficulties until I twigged the omissions in the haynes book.

Fred

Mr Toad · 11th May 2020, 16:29

Simon I am pleased to say that I spoke to Laser Tools today and they agreed to send me a replacement part by courier which I have to say restored my faith! I hope to fit the primary belt tomorrow then I will see what the position is and I will keep you all posted.

Martin

SD1too · 12th May 2020, 09:33

Quote:

Originally Posted by Fred Byrne

... in the case of the 2.5l engine the crankshaft has to be rotated 8 degrees beyond the safe setting marks on the crankshaft before the slots line up ... The reason is because the inlet valve opens 8 degrees later on the 2.5 than it does on the 2.0.

Hi Fred,

I was following your explanation and nodding in agreement until I reached this bit! According to MGR the difference is 6 degrees but this is surely achieved by fitting an inlet camshaft (yellow ident) specific to the 2.0 litre engine. This appears to be confirmed by shorter valve lift than the 2.5 and a greater 8 degree difference on inlet valve closure.

Quote:

Originally Posted by Mr Toad

Simon I am pleased to say that I spoke to Laser Tools today and they agreed to send me a replacement part by courier which I have to say restored my faith!

Now that's good customer service!

Simon

Mr Toad · 12th May 2020, 18:48

I am pleased to say that the part turned up from Laser Tools today, that really is exceptional customer service.

I had forgotten how difficult it was to fit the front tools with the air con pipes in the way. I really needed at least three hands to fit them, the wife was therefore press-ganged to assist. We still found it difficult but eventually managed it. I then fitted the primary belt and the tensioner. Tomorrow I shall remove the tools and the locking pin and then turn the engine over twice using the crankshaft bolt. Today the marks all lined up at the front but only the front head sprockets lined up the rear head sprockets were slightly out but according to Simon he says I shouldn't worry about that! I just hope he is right!

I will see how it all lines up tomorrow.

Martin

SD1too · 13th May 2020, 08:50

Quote:

Originally Posted by Mr Toad

... only the front head sprockets lined up, the rear head sprockets were slightly out but according to Simon he says I shouldn't worry about that! I just hope he is right!

When I was doing this job I was just as doubtful when other club members told me to expect this, but they were right!

It's an odd state of affairs I agree, and one which keeps us guessing how on earth this happened!

Simon

Fred Byrne · 13th May 2020, 09:53

I think that it must arise when you are tightening the bolts on the camwheels at the front of the engine. When you are tightening these bolts the camshafts are in the correct timing positions . Let's say that you tighten the front camshaft bolt first. While you are doing this the camwheel may turn very very slightly because the tensioner may allow the timing belt to move but the actual camshaft can't move because it is held by the locking tool. if the belt was held rigidly this would not occur but, effectively, it is held by the spring in the tensioner. The same thing happens when you tighten the other camwheel bolt. Then when you remove the locking tools the belt moves back to its original position rotating camshafts ever so slightly. The movements are tiny and that is why we can ignore it.
It's a theory anyway, but there has to be some explanation. Perhaps we should all go back to timing chains. They are noisy but much more reliable than belts.

Fred

9th May 2020, 16:40	#21
Mr Toad Avid contributor Rover 75 V8 tourer & MG ZTT & MG RV8 Join Date: Apr 2007 Location: London Posts: 138 Thanks: 41 Thanked 24 Times in 14 Posts	Thanks Simon that is very kind of you. I think I will give Laser Tools a call on Monday morning to see whether or not I can persuade them to send me a replacement part after all I have only used the tools once before. I will let you know how I get on. Martin

9th May 2020, 21:58	#22
Fred Byrne Avid contributor Rover 75 Saloon Join Date: Jun 2018 Location: Ballynahinch Posts: 194 Thanks: 69 Thanked 60 Times in 23 Posts	Well done. It's easier the second time around Fred

10th May 2020, 19:01	#23
Mr Toad Avid contributor Rover 75 V8 tourer & MG ZTT & MG RV8 Join Date: Apr 2007 Location: London Posts: 138 Thanks: 41 Thanked 24 Times in 14 Posts	That's what you would have thought Fred but the reality is different. Last time I had no difficulty lining up the sprockets at the rear and although I had no problem with the front head this time I have had enormous difficulty with the rear one. It is interesting that today I used the exhaust cam at the front to line up the rear sprockets to insert the locking tool. Upon putting the locking tool on I discovered that the timing marks at the front and the rear were in line which makes me think that once the primary belt is on it should all be ok as Simon indicated. What I find unusual is that I had no problem with the front head yet I could not get the sprockets at the rear to line up with the front tools on. There has not really been any explanation for this and I am curious why this should have happened as it most peculiar. Martin

11th May 2020, 15:23	#25
Fred Byrne Avid contributor Rover 75 Saloon Join Date: Jun 2018 Location: Ballynahinch Posts: 194 Thanks: 69 Thanked 60 Times in 23 Posts	In theory when the inlet camshaft on the front bank is correctly lined up then the rear bank's inlet cam should also be lined up correctly. Unfortunately, as in practically all things in life there is usually a very small discrepancy. I presume this is because there is stretch in the timing belt or free play somewhere. What you must do is remove the locking pinpin and all tools from the front of the engine. You cannot lose the timing whilst the timing belt is fitted. Then examine the rear slot on the inlet camshaft on the rear bank. It should be pointing directly at the centre of the exhaust camshaft. It is probably very very slightly out. Any adjustment as Simon says is tiny. Indeed it may be almost unnoticeable. I checked this by putting both camwheels back. Then engaged the spreading tool in the inlet camwheel. Then checked that the small end of the tool was sitting centrally on the exhaust cam wheel. The corrections are tiny. You have to move the crankshaft by using a socket on the crankshaft pinion bolt with a very long lever. Then you can adjust the amount of rotation of the crankshaft with very gentle taps on the end of the lever. The adjustments are tiny. An assistant is helpful if they are reasonably patient and understand what you are trying to do, I am convinced that Haynes never did this operation or they were very lucky. I don't know which engine you have but in the case of the 2.5l engine the crankshaft has to be rotated 8 degrees beyond the safe setting marks on the crankshaft before the slots line up.This isn't mentioned in haynes or even in the Rover workshop manual. The reason is because the inlet valve opens 8 degrees later on the 2.5 than it does on the 2.0. Incidentally you may have notice small nicks on the edges of both camwheels. These should line up when everything is correct. however, your eyesight is not accurate enough to use these at setting marks. I am sorry you are having such difficulty. I had the same difficulties until I twigged the omissions in the haynes book. Fred

11th May 2020, 16:29	#26
Mr Toad Avid contributor Rover 75 V8 tourer & MG ZTT & MG RV8 Join Date: Apr 2007 Location: London Posts: 138 Thanks: 41 Thanked 24 Times in 14 Posts	Simon I am pleased to say that I spoke to Laser Tools today and they agreed to send me a replacement part by courier which I have to say restored my faith! I hope to fit the primary belt tomorrow then I will see what the position is and I will keep you all posted. Martin

12th May 2020, 18:48	#28
Mr Toad Avid contributor Rover 75 V8 tourer & MG ZTT & MG RV8 Join Date: Apr 2007 Location: London Posts: 138 Thanks: 41 Thanked 24 Times in 14 Posts	I am pleased to say that the part turned up from Laser Tools today, that really is exceptional customer service. I had forgotten how difficult it was to fit the front tools with the air con pipes in the way. I really needed at least three hands to fit them, the wife was therefore press-ganged to assist. We still found it difficult but eventually managed it. I then fitted the primary belt and the tensioner. Tomorrow I shall remove the tools and the locking pin and then turn the engine over twice using the crankshaft bolt. Today the marks all lined up at the front but only the front head sprockets lined up the rear head sprockets were slightly out but according to Simon he says I shouldn't worry about that! I just hope he is right! I will see how it all lines up tomorrow. Martin

13th May 2020, 09:53	#30
Fred Byrne Avid contributor Rover 75 Saloon Join Date: Jun 2018 Location: Ballynahinch Posts: 194 Thanks: 69 Thanked 60 Times in 23 Posts	I think that it must arise when you are tightening the bolts on the camwheels at the front of the engine. When you are tightening these bolts the camshafts are in the correct timing positions . Let's say that you tighten the front camshaft bolt first. While you are doing this the camwheel may turn very very slightly because the tensioner may allow the timing belt to move but the actual camshaft can't move because it is held by the locking tool. if the belt was held rigidly this would not occur but, effectively, it is held by the spring in the tensioner. The same thing happens when you tighten the other camwheel bolt. Then when you remove the locking tools the belt moves back to its original position rotating camshafts ever so slightly. The movements are tiny and that is why we can ignore it. It's a theory anyway, but there has to be some explanation. Perhaps we should all go back to timing chains. They are noisy but much more reliable than belts. Fred