Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: addy on 18 January 2019, 12:18:22

Title: Camshaft replacement
Post by: addy on 18 January 2019, 12:18:22
I am refitting the exhaust and inlet cams, Haynes manual says make sure No1 cylinder lobe is up, when I do that timing marks will be out The writeup off this Site for Headgasket replacement says put them at TDC, I cannot get them to stay at TDC. I never removed cam sprockets so they are correct. Also removed cams one at a time, along with carriers, and wrapped in seperate marked boxes, so not wrong way round. Here is a pic of exhaust Timing mark position now against rocker cover. Could it have something to do with me cleaning out the lifters, they do compress and spring, they also went back into the places they came from. Can anyone see anything I have missed or should it do this? Thanks for any help, it's driving me mad  :'(

Exhaust timing marks.
(https://i42.photobucket.com/albums/e331/Remingtonarmy/Omega/DSC_0107_1.jpg)

No1 lobe of Exhaust cam
(https://i42.photobucket.com/albums/e331/Remingtonarmy/Omega/DSC_0105_1.jpg)

exhaust cam
(https://i42.photobucket.com/albums/e331/Remingtonarmy/Omega/DSC_0102_1.jpg)
Title: Re: Camshaft replacement
Post by: Doctor Gollum on 18 January 2019, 12:20:57
Is the cam pulley correctly oriented?

I believe that it is possible to refit it 180 degrees out...  :-\
Title: Re: Camshaft replacement
Post by: Kevin Wood on 18 January 2019, 12:25:56
Firstly, make sure the crank is turned back to 90 degrees before the TDC timing mark to ensure you don't damage anything while fitting the cams.

You will need to turn them to the TDC mark and then lock them in place. Do you have the locking tool used for cam belt replacement. If not, I would get one before proceeding further.

Often there are flats on the camshafts that you can place a spanner on in order to hold them in place. The valve spring tension will act on the lobes and cause them to try to move, so maybe get an assistant to slip the locking key in while you hold the two cams in place with a pair of spanners?

If you haven't removed the sprockets, it strikes me that you won't be able to correctly reinstall the camshaft seals?

Once you have the cams locked at the TDC position, then carefully turn the crankshaft up from the 90 degree before TDC position until the TDC mark lines up, then proceed to install the cam belt as you would when changing the belt.
Title: Re: Camshaft replacement
Post by: Kevin Wood on 18 January 2019, 12:30:38
I should have said, regarding the Haynes advice regarding cam lobe position, it's best to ignore it.

The TDC markings are the correct reference, and these occur when no.1 cylinder is at TDC at the end of the compression stroke. This means that on No. 1 both cam lobes should be away from the followers (but neither will be straight up!), and, on No. 4, both lobes should be partially acting on the followers (inlet opening and exhaust closing).
Title: Re: Camshaft replacement
Post by: dave the builder on 18 January 2019, 12:36:35
Just to add....
when you had the lifters apart ,you just gave them a smear of oil or assembly lube right  :-\
not filled them with oil  :o
(they fill and adjust on he first start up) which always makes a horrific sound like you left half a socket set inside the engine .but once filled with oil (and you've changed your pants) all is good  :y
Title: Re: Camshaft replacement
Post by: addy on 18 January 2019, 12:58:21
Thanks for the quick replies.  No I didn't fill the lifters as I read it can cause them to lock solid, so let them fill naturally. Did lube them before fitting into head.

I did turn crank off TDC to prevent valves hitting pistons.

I do have the locking tool for the cams. I did not remove cogs as could not find the timing mark that is supposed to be on the first bearing carrier, so thought safer to leave them on. Have checked the seals and they are seated fully home.

Doctor Gollum,  how can you tell if out 180?
Title: Re: Camshaft replacement
Post by: Kevin Wood on 18 January 2019, 13:31:23
Doctor Gollum,  how can you tell if out 180?

By checking the positions of the cam lobes at the TDC position, as described in my post above.^  ;)
Title: Re: Camshaft replacement
Post by: addy on 19 January 2019, 15:11:06
I am sorting pics of the cams, with marks all set.
Title: Re: Camshaft replacement
Post by: addy on 19 January 2019, 15:39:22
Set the Timing marks up on the cams and locked them. Both No1 EXHAUST AND INLET Lobes look like this, almost level. (EXHAUST are the first two closest to you, inlet are in background)

Do they look OK?

(https://i.postimg.cc/Zqt7jkSv/DSC-0106.jpg)

Back two EXHAUST lobes on cam
(https://i.postimg.cc/VLhHrrZR/DSC-0104.jpg)

Timing marks locked in place
(https://i.postimg.cc/7PnF6nzr/106.jpg)
Title: Re: Camshaft replacement
Post by: Doctor Gollum on 19 January 2019, 16:48:30
What engine is this?

Should have been asked first :-[
Title: Re: Camshaft replacement
Post by: addy on 19 January 2019, 16:55:43
Sorry my bad. It is a 1995 2ltr 16V. (according to Gates catalogue X20XEV?)
Title: Re: Camshaft replacement
Post by: Doctor Gollum on 19 January 2019, 17:07:32
Re read the following in Haynes...

Page 2B.9 10, Camshafts and followers - removal, inspection and refitting, Refitting, Paragraphs 9 through 19.

Pay particular attention to the complete paragraphs 10 and 18 :y