Author Topic: Refitting the timing chain... (Read 13021 times)

anutz · « **on:** 23 April 2015, 11:18:05 am »

So I am putting my cylinder head back on....and have hit the first real issue...

The camshaft chain...

The issue is I cannot get the marks on the cams to line up 100% with the marks on the camshaft caps...

I tried several times last night and each time they were slightly off

I need to consider what is causing it - I don't have the pictures I initially took of them due to my phone failing....so having to assume the always were spot on...

As a warning as well I have had the timing chain drop off the crank sprocket initially as when I put in the Exhaust timing guide it knocked it off - that's sorted now!

My process is:

1. Set Piston #1 to TDC using Socket on the flywheel
2. Hold Exhaust side of Timing chain tight and place Exhaust Camshaft in place,
3. Seem to be able to always get it spot on BUT then the chain shifts it over as it engages with it about a 1mm
4. Keeping it tight I then feed the Intake Cam in - seems to be spot on

So I suppose I need to consider

1. Was it ever spot on
2. How much tolerance is ok - I assume non

3. Could it be the chain
4. The manual says take the sprockets OFF the cam slightly whilst adjusting and mesh them with the chain, issue is due to the way the fixings are graded i.e. distance between them I suspect this would make it worse

Adding pics so you can see what I am on about...

Jules-C · « **Reply #1 on:** 23 April 2015, 11:39:29 am »

If it's within 1mm you're OK. If you got it wrong you would be 1 tooth or more out which is a lot more than 1mm

anutz · « **Reply #2 on:** 23 April 2015, 12:05:41 pm »

here we are

Paulfzs · « **Reply #3 on:** 23 April 2015, 12:29:11 pm »

that looks fine to me, fill the hole make a new one in line with the arrow it wont bother you then

anutz · « **Reply #4 on:** 23 April 2015, 01:12:50 pm »

I will get my drill - you have seen how accurate I can be with that

rhinoeli · « **Reply #5 on:** 23 April 2015, 01:28:49 pm »

Correct chain pitch? You can check against the old one.

anutz · « **Reply #6 on:** 23 April 2015, 01:40:26 pm »

hi, sorry this is the original chain, I have not replaced it, just had the cylinder head off....so its in the process of being put back on...

rhinoeli · « **Reply #7 on:** 23 April 2015, 02:36:29 pm »

oh ok

On the photo you attached the camshaft cap bolts are not in place. I think they should be... (?)
If the chain is tensed between the two sprockets, the marks should align near perfectly.

Paulfzs · « **Reply #8 on:** 23 April 2015, 02:54:55 pm »

Quote from: anutz on 23 April 2015, 01:12:50 pm

I will get my drill - you have seen how accurate I can be with that

good point..

get a sharpie and a lazer level.

Jules-C · « **Reply #9 on:** 23 April 2015, 04:05:09 pm »

The exhaust one does look a bit out. Have you tried moving it round by one tooth and see if it looks any better?

anutz · « **Reply #10 on:** 23 April 2015, 04:18:51 pm »

just re-done them both, looks a little better, will add a photo....but now I have slack in between the sprockets, but there is no way I can avoid that - tried all sorts...

might end up taking the cam sprockets off whilst the cams are in and rotating them around....Its the only other variable I have...

BBROWN1664 · « **Reply #11 on:** 23 April 2015, 04:28:36 pm »

Check to see if you are 360 degrees out.

TDC on each cylinder appears twice for each time the valves operate.

anutz · « **Reply #12 on:** 23 April 2015, 05:04:20 pm »

So alignment is good...but look at the chain lol

I cannot keep it any thighter when I install the Intake cam, issue is that piston 2 cam lobes are pushing down on the valves so once its bolted down there is slack available...

if I pop my finger on to the tensioner at the back of the engine it does take up this slack...will rotate 360 and see what happens, might be the wrong part of the chain

paulchucky · « **Reply #13 on:** 23 April 2015, 06:09:49 pm »

i know it sounds obvious but have you taken the chain adjuster out completely
then tried to set the timing

then re-install the adjuster

anutz · « **Reply #14 on:** 23 April 2015, 06:26:50 pm »

its out and I have not put it back in yet....

looking at the manual I do that once I have things set up to - I figured with all the slack In between the sprockets there was an issue there first to fix...?

greenman · « **Reply #15 on:** 24 April 2015, 12:49:41 am »

How Many miles has it done? Just thinking, high mileage, stretched can chain, maybe, would set things slightly off.

anutz · « **Reply #16 on:** 24 April 2015, 07:14:09 am »

18,000

Will have another go a little later over the weekend, not go much free time coming up so its going to be stood for a while....

Issue I keep having is simple dealing with the lobes that will be tightened down on to open valves, changes the tension on the chain no matter how taught I keep it...

Most likely needs the sprockets mobilising whilst on the shafts so I can rotate either component and position the marks ok else rotate the sprockets to take up slack...

thunderpantz · « **Reply #17 on:** 24 April 2015, 07:18:43 am »

I had this problem. What you'll find is that because of the slack in the middle of the two cams, when you wind the crank round one/or both or the cams will go out of time. Took me bloody yonks!

anutz · « **Reply #18 on:** 24 April 2015, 07:26:17 am »

was it just trial and error or was the are process you could use to sort it - do you think the idea about the sprockets would work?

It always was a rattily engine to be honest, even @18000 miles always had rattles

thunderpantz · « **Reply #19 on:** 24 April 2015, 07:32:55 am »

I can't remember exactly but i know it involved a lot of bloody swearing. I think i ended up having to set both cams to "1 o'clock", wound the crank a couple of times and the were spot on. Its all about getting rid of that slack in the middle though first before winding.

Where abouts are you based chap?

Jules-C · « **Reply #20 on:** 24 April 2015, 08:03:28 am »

It is tricky since the lobes try to push the can put of position. It looks like the intake cam needs to be rotated one tooth to the left. It will be out of alignment when the chain slack but everything should line up again when the tension taken up

anutz · « **Reply #21 on:** 24 April 2015, 08:15:23 am »

that's another thing I was thinking - when I torqued it down it was ALWAYS off, so as you say, line it up OFF and then when torqued it should line up - might take a few goes!

anutz · « **Reply #22 on:** 25 April 2015, 12:38:03 pm »

Progress - bang on with correct tension now

Has been cranked through many revolutions with a socket and no movement of the timing marks

Onward with the rest of the rebuild...measuring clearances....this is going to be fun

red98 · « **Reply #23 on:** 25 April 2015, 01:49:38 pm »

Good work anutz......got to take your time with timing

.......check and double check and check again, making good progress well done.....clearences and shims and things are a bit easier...........but , if you need to change any shims its a cams out jobbie....but you are foc-u's timing expert now so no problems there

.........I did mine last year at 40,000 miles and they were within tolerances, on the limit , but just inside , I did change 5 shims to get them spot on but did'nt really need too......let us watchers know how you get on, iam sure you will, with pics as well

unfazed · « **Reply #24 on:** 25 April 2015, 03:34:25 pm »

Now exhaust is right,

The slack in the centre will not disappear until the tensioner is fully installed and you rotate the crank and allow the tensioner takes up the slack.
Then check the marks again.