Refitting cambelt after it's snapped...... Finding TDC

**Steve X16XE** · 26-01-2012 17:57

I need to know where TDC is for cylinder one.

Sounds easy, but it turns over 720*, so it has 2 TDC marks.

As the belt snapped, I am not relying that the closest TDC is the correct one.

How do I line it up all correctly?

**Vinci** · 26-01-2012 18:40

If it helps....

**jamin** · 26-01-2012 19:13

I dont understand why you need to worry about 720'. Align the marks, turn the crank through at least 720' by hand, I usually do 1440 (4 crank revs). check they all align.

**Paul** · 26-01-2012 19:17

X16xe?

I'm lost to your comments. How can it have two TDC marks?

**GTE 16v** · 26-01-2012 19:18

Please clarify what engine you have.

**Vinci** · 26-01-2012 19:32

LOL, I reckoned he was on about his X16XE engine, hence the handle... but you never know....

**jamied** · 26-01-2012 19:35

looking at what is put in the first post and thinking in a non-technical term, the TWO TDC marks are only ONE.....

as in he has all the marks lined up, Crank & Cams..
Turns the crank one turn (360) to the TDC mark and the cams don't line up..
Turns crank again (360+360=720) to the TDC mark and cams line up....hence him thinking two lots of TDC going by the crank marking.

**lee303** · 26-01-2012 20:04

lol, not this again, did no one read the turbo stevo incident thread?

it is impossible to get TDC wrong on a twin cam if you align the marks, the crank cannot be 360 degrees out!!

**Tathan** · 26-01-2012 20:05

Oh christ.

**Tathan** · 26-01-2012 20:16

Small point, but if you're just putting a cambelt on after one's snapped you're pissing in the wind really as it will be fubar.

**Vinci** · 26-01-2012 20:37

This is indeed an interference engine isn't it??

**lee303** · 26-01-2012 20:41

yep

**jamin** · 26-01-2012 20:59

oh dear....the lack of reply speaks volumes

**Steve X16XE** · 26-01-2012 22:26

The lack of reply is due to me being out cleaning the sump at my mates garage.

Oh and it's an X20XEV engine. I forgot to put that bit. My bad.!

4 valves were bent and had two valve guides fixed and had the head acid dipped. I didn't bother putting that bit in as it didn.t reallt matter.

So it doesn't matter were the crank is at aslong as it lines up to the marks?

I did mean, one full turn of the crank means half a turn of the cams. So can the crank ever be out or does it not matter? I'm just wondering on all the damn sensors on the engine.

Oh and no, i've not fitted the belt just yet as didn't want to get it wrong and have to take it off again.

**Steve X16XE** · 26-01-2012 22:32

Oh and Vinci, many thanks. I've found something like that but yours has got more detail in it.

**Tathan** · 26-01-2012 22:41

Set crank to mark and cams to marks, everything will go swimmingly

**lee303** · 27-01-2012 15:48

yeah, there will be a point once the belt is on where the cams will be 180 out and the crank on its mark, but this is normal, as tathan reiterated, if you align the crank and cams up and fit the belt, all will be well

**Steve X16XE** · 27-01-2012 16:34

HT lead order? Is this an inside joke that I don't know about?

I left mine all connected to the coil pack so there can't be any mix-up.

**Steve X16XE** · 27-01-2012 17:28

Already had it off, stripped it down (4 valves bent and 2 valve guides). I've even removed the sump and given it a clean out whilst i'm working on it.

Now i'm putting it all back together I just wanted to make sure that the belt can't be fitted wrong if it's all marked up.

**MSG** · 27-01-2012 17:52

Originally Posted by Steve X16XE

Oh and it's an X20XEV engine. I forgot to put that bit. My bad.!

So it doesn't matter were the crank is at aslong as it lines up to the marks?

Its an X20XEV
it is reccomended that on this engine you do not rely on the crankshaft pulley mark for timing purposes as the outer part of the pulley can slip as the pulley is rubber damped which means it is made of two seperate parts put together with a rubber stuffed between the two parts, and the outer part can often spin from the other part that is bolted to the carnk flange, so the timing mark can drift and you end up getting it timed wrong, and risk valves being bent.

Therefore it is best to not rely on the pulley mark but use the dot on the crank flange. So unbolt the 4 screws and remove the main pulley then use the timing mark (a dot) on the crankshaft flange, the dot should be pointing downwards or at 6' O clock position whilst the two camshaft marks should corresponds to the marks on rear cover of the timing belt. Just to confirm, when the dot on the crank flange is at 6' O clock position (bottom most) the pistons 1 & 4 should be at the top most
position (tdc) . (you can use molgrips to hold the two cam wheels together e.g. the left wheel grip at 3'O clok and the right wheel gripped at 9'Oclock to lock them from turning whilst fitting the belt.

**Joker** · 27-01-2012 18:15

Stick a screwdriver down cylinder 1 and turn crank until it reaches its highest point, find it, go clock wise and anti clock wise until highest point is exact thus being the TDC.

**vectra640** · 27-01-2012 22:18

This is the exact way it's done on the X20XEV mate

Late Type C20LET Engine Timing

**vectra640** · 27-01-2012 22:24

And here's a tip to lock cams to fit belts if you don't have the locking tool, cut 2 small pieces of p1200 wet & dry and remove the 2nd cap on each cam then put the paper in facing down then refit the caps and tighten down, this will hold the cams solid enough to fit the belt, remember to remove paper before turning over the engine or it will end in tears, this is a tried and tested method and works perfectly

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