V6 timing - here we go again!!

[ballymenaman]

I am in the process of re timing my 177hp V6 after a cam change (long story!).

I have been bombarded with all sorts of advice - some good, some not so good.

I have reached some conclusions that no doubt many of you will disagree with - but here you are........

1. Rover produced guidance on belt replacement and unless they are totally wrong this must surely be the definitive guidance. This advocates fitting the front timing belt using tools that determine the position of the inlet cam relative to the crankshaft at the engine 'safe' position. The cam end has a notch that keys it to the tool and there is no room for cam position variation. My conclusion here can only be that the inlet cam is intended to be fixed by the front timing tools and that any argument that the timing is determined by the rear sprocket tool is wrong.

2. The rear sprockets are keyed to the cam ends and can only be fitted in one position. If the rear tool is used to fit the rear belt there is no way that the timing of the rear sprockets can be wrong. The tool will only fit when the two sprockets are correctly aligned.

3. The timing notches on the rear sprockets do not align when the front timing tools are fitted and the car is in the 'safe' position. Hence - if rover meant the rear sprockets to be aligned when the safe position was selected - the rear tool would fit when the front tool was in place. This isn't the case.

I have read on a Land Rover forum that the rear tool is intended to do two things - to aid fitting the rear belts - and to hold the rear sprockets when tightening the bolts. This would explain a lot.

This all begs the question - are there loads of V6 cars knocking about out there with badly timed engines?

[SD1too]

It's good to hear from you again Andy. I have a few questions for you!

Originally Posted by ballymenaman

This advocates fitting the front timing belt using tools that determine the position of the inlet cam relative to the crankshaft at the engine 'safe' position. The cam end has a notch that keys it to the tool and there is no room for cam position variation.

I thought it was the exhaust camshaft which has the notch. Doesn't the inlet camshaft hub have the holes into which the pins on the tool locate?

My conclusion here can only be that the inlet cam is intended to be fixed by the front timing tools ...

As I understand it, each front tool can be fitted to both its camshafts only when the inlet camshaft is in a particular position. Am I correct Andy?

... and that any argument that the timing is determined by the rear sprocket tool is wrong.

I think that we need to consider your point number 2.

2. The rear sprockets are keyed to the cam ends and can only be fitted in one position ... The tool will only fit when the two sprockets are correctly aligned.

Doesn't that mean that the correct alignment determines the relative positions of the inlet and exhaust camshafts? If these can only be in one position, then isn't that the correct timing position (assuming that the crankshaft is locked in the safe position)?

3. The timing notches on the rear sprockets do not align when the front timing tools are fitted and the car is in the 'safe' position.

The primary belt is fitted and front tooling removed before renewing the rear belts, which is when the rear sprockets are fitted in the aligned position as you said in your point 2.

... if rover meant the rear sprockets to be aligned when the safe position was selected ..

Their official method seems to say exactly this.

... the rear tool would fit when the front tool was in place. This isn't the case.

This is the bit I don't understand.

I'll be doing mine in the coming months. It will be interesting to see if I find the same situation as you have. My valve train hasn't been touched since it left Cowley.

Thanks for your continued reports Andy.

Simon

[zefrench]

I timed my Freelander so that the rear sprockets notches are directly in a straight line and facing each other when the engine (cranshaft) is in a safe position.

[Mike Noc]

Originally Posted by ballymenaman

This all begs the question - are there loads of V6 cars knocking about out there with badly timed engines?

Probably a fair few that aren't timed spot on, but near enough so as not to be noticeable.

Originally Posted by SD1too

I'll be doing mine in the coming months. It will be interesting to see if I find the same situation as you have. My valve train hasn't been touched since it left Cowley.

Thanks for your continued reports Andy.

Simon

Simon before touching the belts can you let us know whether the timing marks on the rear camshaft sprockets accurately line up when the engine is in the safe position?

Can you also scribe a line across the outer edges of both pairs of the rear camshaft sprockets to check for any deviation with a straight edge after the job has been carried out?

Easier to see if you use a wide permanent marker first, then scribe through the middle of it.

Are you using the special tools?

[SD1too]

Mike,

Yes, yes, thanks for the tip and yes!

Don't hold your breath though. I'm currently renewing the 75's starter motor solenoid contacts, and that's just the tip of the iceberg as far as our fleet of vehicles is concerned at the moment!

Simon

[ballymenaman]

Simon - "I thought it was the exhaust camshaft which has the notch. Doesn't the inlet camshaft hub have the holes into which the pins on the tool locate?"

My reply - Both cams have notches. The plate on the front of the inlet cam, into which the tool fits, is keyed into the notch.

Simon - "As I understand it, each front tool can be fitted to both its camshafts only when the inlet camshaft is in a particular position. Am I correct Andy?"

My reply - That is correct.

Simon - "Doesn't that mean that the correct alignment determines the relative positions of the inlet and exhaust camshafts? If these can only be in one position, then isn't that the correct timing position (assuming that the crankshaft is locked in the safe position)?"

My reply - The inlet and exhaust cams are connected only by the rear belts. The rear pulleys are keyed into notches in the two cam ends. The rear timing tool will only fit when the two pulleys are correctly aligned.

Simon - "The primary belt is fitted and front tooling removed before renewing the rear belts, which is when the rear sprockets are fitted in the aligned position as you said in your point 2. Their official method seems to say exactly this."

My reply - I agree


I have based my conclusions on pure logic and the use of the tools. Those who claim the rear pulleys should be aligned when the engine is in safe mode cannot have been using the front and rear tools. I have tried it and the front and rear tools simply do not fit at the same time.

Having said all this, I am extremely nervous about relying on the front tool to time everything, given all the conflicting advice that I have been given. I don't intend to reassemble and start my engine until I'm absolutely sure I'm right!!!

[Ennine]

I did final checking with a laser. Found it a very good method

Nige

[Mike Noc]

Originally Posted by ballymenaman

I have based my conclusions on pure logic and the use of the tools. Those who claim the rear pulleys should be aligned when the engine is in safe mode cannot have been using the front and rear tools. I have tried it and the front and rear tools simply do not fit at the same time.

That really does tell you all you need to know about why the pulley marks won't align when the timing is correct.

Having said all this, I am extremely nervous about relying on the front tool to time everything, given all the conflicting advice that I have been given. I don't intend to reassemble and start my engine until I'm absolutely sure I'm right!!!

If you are at all worried then, with the spark plugs removed, turn the engine over a few times by hand - if anything catches you'll feel it and it won't do any damage.

[SD1too]

Thanks for your reply Andy. My further thoughts:

Originally Posted by ballymenaman

Simon - "As I understand it, each front tool can be fitted to both its camshafts only when the inlet camshaft is in a particular position. Am I correct Andy?"

Andy - That is correct.

OK, so with the front tools fitted, we have the inlet camshaft in a particular position and the crankshaft in a particular position. Both these positions constitute correct timing, yes?

Now if I looked at the rear sprockets, I would expect the marks on those to be aligned but you say that they are not. Can you confirm that you're using the appropriate version of the front tools for your engine (colour coded silver I believe)?

Andy - The inlet and exhaust cams are connected only by the rear belts. The rear pulleys are keyed into notches in the two cam ends. The rear timing tool will only fit when the two pulleys are correctly aligned.

That's very clear. So we know that the inlet camshaft is in the correct, timed position because the front tool fits. If the rear marks don't align then has the exhaust camshaft moved?
Is the mark on the inlet camshaft rear sprocket in the position shown in Ennine's photograph (nine o'clock)?

Simon - "The primary belt is fitted and front tooling removed before renewing the rear belts, which is when the rear sprockets are fitted in the aligned position as you said in your point 2. Their official method seems to say exactly this."

Andy - I agree

Good! So at what stage are you now, with reference to the above summary?

I have tried it and the front and rear tools simply do not fit at the same time.

The point I was trying to make in your last quote is that they're not supposed to be fitted at the same time! Once you've renewed the primary belt, you do not fit the front tool again.

I am extremely nervous about relying on the front tool to time everything ..

It doesn't time everything. It sets the inlet camshaft in the correct position to allow the primary belt to be fitted. The exhaust camshaft is 'timed' by aligning its mark to that on the inlet camshaft. Do you agree with me here?

I don't intend to reassemble and start my engine until I'm absolutely sure I'm right!!!

Indeed Andy. As Mike recommends, turn it over by hand first. Earlier this year I renewed the single timing belt on our very straightforward 4 cylinder 8 valve OHC daily driver. I made my own paint marks for security and turned everything over by hand several times to check that they still aligned. They did, so I started the engine and watched carefully. The belt seemed too sloppy. I hadn't set the tensioner quite right so I went back to the beginning and laced the whole thing up again and was rewarded with success. Slowly does it, and keep thinking all the time (as Bruce Forsyth used to say a long time ago).

Simon

[COLVERT]

All of these posts make very interesting reading.

Can't wait for the various outcomes.---





PS. It makes me realise just how lucky I am to have a DIESEL.--