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Possible camshaft issues...

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TurboZ.Dude
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Possible camshaft issues...

Post by TurboZ.Dude »

Hey there guys, long time no hear!

I ran into a bit of a trouble; the engine is doing chuff-chuff-chuff at idle (one cylinder clearly coughing but not misfiring) but running fine above 1100 rpm, apart from a couple of misfires here and there. The combustion is clean, the spark plugs stay clean and look like they should. No oil in the coolant, no coolant in the oil.

I decided to check and readjust the valve clearances because it may solve the problem. There wasn't much to readjust, everything was just about spot on. But what I noted was that my cam seems to be badly worn on cylinder #4, the exhaust lobe is worn down a quarter of a millimeter where the runner touches the cam, spanning one centimeter on either sides of the lobe too. I noted this while readjusting the valve clearances the day before yesterday.

And it's due for MOT by the end of this month... including obligatory emissions testing...

Anyway, I'm going to do a compression test before concluding it's the cam that's causing the chuff-chuff problem. May be piston rings just as well.

If it turns out to be the camshaft, is there enough room in the engine bay to replace the camshaft (including rocker shaft and arms of course) without taking the head off?

Thanks!
Jan
My N12:
http://forum.n12turbo.com/viewtopic.php?t=4926,
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in all honesty dude these cars are shit but they have so much character, are fun and go fairly well when running right. we still play around with these things because they are a fun addictive little shitbox! :D - Ash
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zoomzoom
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Post by zoomzoom »

off with her head

zoomzoom
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TurboZ.Dude
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Post by TurboZ.Dude »

Ok, thanks m8!

I replaced the head gasket a few months ago, looks like I can't avoid opening the engine up again...
My N12:
http://forum.n12turbo.com/viewtopic.php?t=4926,
http://www.zxoc.co.uk/forum/topic.asp?TOPIC_ID=6345
http://forums.mightycarmods.com/showthr ... Pulsar-N12
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in all honesty dude these cars are shit but they have so much character, are fun and go fairly well when running right. we still play around with these things because they are a fun addictive little shitbox! :D - Ash
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Damo
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Post by Damo »

Head can stay on!

Been there done that.

Undo the driverside engine mount, the front engine mount and jack the engine up to allow the cam to slide out over the guard. It is far easier with a second set of eyes and hands to make the whole thing work.



Damo
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TurboZ.Dude
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Post by TurboZ.Dude »

Oh! Sounds a bit brutal to me but I'll give it a shot, thanks m8! :D
My N12:
http://forum.n12turbo.com/viewtopic.php?t=4926,
http://www.zxoc.co.uk/forum/topic.asp?TOPIC_ID=6345
http://forums.mightycarmods.com/showthr ... Pulsar-N12
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in all honesty dude these cars are shit but they have so much character, are fun and go fairly well when running right. we still play around with these things because they are a fun addictive little shitbox! :D - Ash
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tassuperkart
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Post by tassuperkart »

Nagh, its easy m8, Youll see.
Once the pulleyt is off you only have to jack the motor enough for the cam to clear the top of the guard.

Oracle
Forcd4 wrote:Oh fuk no dude it's you a again, the oracle.
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TurboZ.Dude
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Post by TurboZ.Dude »

Ok E, I'll take your word for it!

Thanks for your input guys, I have a day off Monday next week. Going to swap out the cam at that time. :)
My N12:
http://forum.n12turbo.com/viewtopic.php?t=4926,
http://www.zxoc.co.uk/forum/topic.asp?TOPIC_ID=6345
http://forums.mightycarmods.com/showthr ... Pulsar-N12
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in all honesty dude these cars are shit but they have so much character, are fun and go fairly well when running right. we still play around with these things because they are a fun addictive little shitbox! :D - Ash
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TurboZ.Dude
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Post by TurboZ.Dude »

Thanks heaps guys, the engine runs perfectly, no "chuff chuff", and it passed MOT emissions tests like a charm!

Engine runs smooth and very easy, I don't even need to hold the throttle down as much on highways as I used to do! 8)

Here's the old cam (didn't bother to clean it up because it's not going into the engine again unless I have it reground at some point):

Exhaust lobe #4 is very very worn.
Image
Image
Image
Image

Old camshaft:
Image
New camshaft:
Image

New rocker shaft, rocker arms, and tensioner in place:
Image

Final lubrication prior to putting the valve cover back on:
Image

It's a bit tappy at the moment with the initial valve clearance adjustment I made home in the garage, I'll let the new setup bed in a bit before readjusting the valve clearances. It's already more silent on a couple of cylinders so it's soon time to do the readjustment.
Last edited by TurboZ.Dude on Wed Feb 13, 2013 9:43 am, edited 1 time in total.
My N12:
http://forum.n12turbo.com/viewtopic.php?t=4926,
http://www.zxoc.co.uk/forum/topic.asp?TOPIC_ID=6345
http://forums.mightycarmods.com/showthr ... Pulsar-N12
Image
in all honesty dude these cars are shit but they have so much character, are fun and go fairly well when running right. we still play around with these things because they are a fun addictive little shitbox! :D - Ash
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tassuperkart
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Post by tassuperkart »

Eeeeek, that cam lobe wear is very bad. I hope you changed the rockers as well.
Make sure to run the engine HOT and do your adjustments quickly.
You dont need to let "bed" in or anything.
have fun
E
Forcd4 wrote:Oh fuk no dude it's you a again, the oracle.
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TurboZ.Dude
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Post by TurboZ.Dude »

tassuperkart wrote:Eeeeek, that cam lobe wear is very bad. I hope you changed the rockers as well.
Make sure to run the engine HOT and do your adjustments quickly.
You dont need to let "bed" in or anything.
have fun
E
Yup, I replaced the rocker shaft and the rocker arms along with the camshaft! :)

Thanks for the advice, I'll do the adjustments as soon as I have time!
My N12:
http://forum.n12turbo.com/viewtopic.php?t=4926,
http://www.zxoc.co.uk/forum/topic.asp?TOPIC_ID=6345
http://forums.mightycarmods.com/showthr ... Pulsar-N12
Image
in all honesty dude these cars are shit but they have so much character, are fun and go fairly well when running right. we still play around with these things because they are a fun addictive little shitbox! :D - Ash
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