Timing issue

Kman · Post by **Kman** » 25 Apr 2009, 23:37

After changing the head gasket on a 2.0 8 v engine, there have been some problems. The engine won't start and exhaust (it fires once or twice) is coming out of the inlet manifold, indicating a timing problem. During dismantling the position of the cam was disturbed, so I used the holes in the cam- and crank sprocket to do the timing. When checking TDC of cyl. 1 (screwdriver through sparkplug hole), the hole in the crank sprocket is NOT aligned with the "hole" in the block. I've heard that the crank sprocket may loose alignment because of the rubber "layer" in it. It is this true, and if yes, which other marks can be used to pin-point TDC.

PS. After fitting the time belt, I rotated the crankshaft for at least two revolutions with a socket, so there should be no collision between pistons and valves. Is a valve collision even possible on this engine?

Any help would be muck appreciated!

Regards

Kristian

Deanxm · Post by **Deanxm** » 25 Apr 2009, 23:46

Hi Kman

Yes they do suffer with the pulley's slipping, they should never be used for timing because of this fault, remove the starter motor and behind it you will see a hole to take, from memory, an 8mm locking pin/ drill bit which locates in the flywheel.
You will also get valve and piston love if the timing is out just the right amount.

Good luck
D

Kman · Post by **Kman** » 26 Apr 2009, 01:01

Thank you for quick answering:P .

I assume the hole in the cam sprocket marks TDC for cyl.1, so that timing is OK when a peg is in place here and in the hole behind the starter motor? The car has automatic transmission btw.

Could you please clearify your last sentence? Should I be worried about valve collision, or would it in this case require a lot of bad luck?

Kristian

Post by **CitroJim** » 26 Apr 2009, 06:00

A good tip here is to visit a scrapyard and take a solid pulley from an older XU engine as the timing hole is in the same place.

I have such a pulley from a scrap 205GTi (XU5) engine and I keep this pully as a tool for timing later XU engines with the notorious two-part pulley.

I have never found one of these pulley that has not slipped!

Deanxm · Post by **Deanxm** » 26 Apr 2009, 09:53

Sorry it was late and i was rushing

Yes the valves can contact the pistons but because they are recessed in the head slightly they would contact over a much smaller area of crank rotation than most!

The car has automatic transmission btw

Thats going to be a pain, there is no timing hole in the flywheel of an auto

i dont know if its because there are so many holes in it where the flexplate mounts, who knows. your only real chance to get it right is follow Jims advise and get an older pug or cit one without the rubber bonding or dare i say buy a new one

D

Post by **CitroJim** » 26 Apr 2009, 11:30

I was going to say, Kman, if you were local to me, I'd lend you mine but I see you're in Norway...

Not very local that

Post by **CitroJim** » 26 Apr 2009, 19:03

I don't know if this will help get you in the right place but the photo below shows a solid pulley. The timing hole is the middle of the three small ones and from the picture you can see the relationship between the timing hole and keyway.

The angle between the keyway and hole is (as near as I can measure it) 75 degrees.

Kman · Post by **Kman** » 27 Apr 2009, 21:43

Thank you for good advice!

I found a pulley from a 405 which looks exactly like yours, so I guess I will be able to sort out the timing.

Regarding valve/piston collision, I measured valve clearance this afternoon, and found all valves to be no more (and perhaps less) than 0.1 mm from spec. (0.2 and 0.4 mm). Can I safely assume that the valves are OK, or can they still be bent or otherwise damaged? Once I get the timing right I will also do a compression check.

Regards

Kristian

Deanxm · Post by **Deanxm** » 27 Apr 2009, 22:09

It should be fine if you turned it over by hand several times before trying to start, get the timing sorted with the new pulley and then turn by hand again to make sure all is well, looking at the followers to see that they are all following the camshaft lobes and then just bite the bullet and start it

D

Post by **CitroJim** » 27 Apr 2009, 22:13

Hi Kristian,

Yes, I think if the clearances are that close to the specification I think you can assume they're OK. Any bending is very likely to increase the clearances measured I would have thought.

Also, in the 8V engine, the valves are at right-angles to the pistons so if they do contact the pistons they are unlikely to bend. In fact, the camshaft is more likely to break!

I've seen an 8V XUD diesel engine where the cambelt slipped and the valves contacted the pistons sufficiently to leave perfect impressions of them on the piston crowns but they did not bend. The camshaft broke though!

Still, a compression test is a good idea but I'm confident you'll be OK.

Let us know how you get on please.

Kman · Post by **Kman** » 01 May 2009, 20:28

I fitted the 405 pulley a few days ago. However, when I put a peg in the hole, cyl. 1 was not at TDC, but half-ways or so through its progress down the bore. Rechecking (with a screwdriver through the plug hole), now with the pulley off, I found that cyl. 1 TDC corresponds to a point where the woodruff(?) key is at top (in relation to the engine vertical centerline). Comparing with the pulley, this suggests that the hole is 90 deg. or so off.

So either have I misunderstood and the hole is not supposed to correspond to cyl. 1 TDC (neither on the cam pulley), OR this particular crankshaft has the key rotated 90 deg (exactly or approximately).

I can use the woodruff key to do the timing, so can you confirm that the cam is locked in place by the peg at cyl. 1 TDC?

Regarding valve bending, the depression in the piston head makes the valves hit at an angle, so they will definitly bend if they make contact. Check this 2.0 turbo engine: http://activa.portbb.com/viewtopic.php?id=230

Regards

Kristian

Deanxm · Post by **Deanxm** » 01 May 2009, 23:10

Hi Kman

Dont forget the turbo pistons have the cut out in the crown's to lower the compression ratio so may not be the same as yours, N/A's have different pistons. That Turbo has the same head as yours and the valves are directly above the pistons its just the one in the picture half hit the edge of the recces in the piston crown, anything will bend though hit hard enough, square on or not.
I can double check for you tomorrow but im sure with the crank pinned all four pistons crown's sit halfway down the bore, so they are effectivly all level rather than having no 1 at TDC.
Im a bit fuzzy, its been a year since i done an 8v head but i will double check for you.

D

Kman · Post by **Kman** » 01 May 2009, 23:59

Thank you Deanxm

The NA has depressions too, although they may be more shallow.

All pistons level corresponds to a 90 deg rotation from cyl 1 TDC, which makes sense looking at the pulley. I hope I can confirm this from the camshaft position when locked in place.

I'm off to do the timing tomorrow morning (already made an appointment with an helper/actual owner of the car), which is a pity as the information would be very helpful. So don't go out of your way to check the piston position. I'm very greatful for all feedback from you and CitroJim!

Kristian

Deanxm · Post by **Deanxm** » 02 May 2009, 18:33

Hi Kman

Just to confirm, all piston crowns should be level halfway down the bore with the locking pins in place so the 405 pulley is correct.

D

Kman · Post by **Kman** » 04 May 2009, 08:31

You were of course right, with the pulleys locked in place all pistons are level and halfway down the bore, and the camshaft has the no.1 exhaust valve at max opening (which clearly isn't TDC

). The 405 pulley was right, I will certainly keep it for future work.

The car is up and running again, and all is well. Thank you.

Regards

Kristian