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Adjustable Cam Gear Problem?

Drakey

By Drakey,
in Engines & Forced Induction

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Drakey

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Hi All,

Have a quick question for you.

I bought a skyline that has a few mods, like cooler, r34 turbo, all the usual and also has adjustable cam gears.

Now a couple of weeks since i bought the car i heard a squeaking from the cam gear cover, sounded almost like a pully.

Well i got the car serviced and about 2days later the noise went away so i didnt worry about it anymore.

But now my car seems to lack alot of power from what it used to have. It used to start breaking traction in 1st gear and when i changed to second the car would step out sideways. Now its the mildest churp. So i dont think its just me getting used the the car. The car also seems to have a flat spot now just above 4K and certainly does not pull how a car running properly should.

My question is could of something came lose or something gone out of adjustment with the cam gears, its all i can think of?

Any help peeps?

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**RB2530** Proficient

**RB2530**

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Mate I would get it checked out...If it is a cam pulley adjustment that has come loose there is a risk that it will shear or wear the adjustment bolts. That may then lead to loss of drive on the cam shaft and that is very very bad...Piston colliding with valve territory...equivalent to broken timing belt...Dont want to scare you but also dont want to see you stuff your engine...

You can easily check the cam pulley adjustment bolts on the exhaust cam by just removing the crank angle sensor but if you are not confident in doing this, get someone else to do it...You need to make sure it goes back on properly...

Drakey Collaborator

Drakey

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Awesome thanks rb

Ok Ill check it out to see.

Another question. Im not sure how adjustable cam gears work, well i have an idea. But if they are now out of whack will I have to take it to someone to get them set in the right place?

And need to be tuned up again?

**RB2530** Proficient

**RB2530**

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Unfortunately if it turns out they have moved, to get them perfect again, it will mean dyno work...

But you always can just have them set at zero (no dyno work required) and your car will be fine...Adjustable cam gears change the power curve characteristics of your engine...You can tune them to give more high end power but you lose mid range and vice versa...The gains you get will depend a lot on other engine mods as well..If you do a search you will find out heaps more info on this...

Main thing at the moment is to make sure they are not loose and jumping around everywhere which is a nightmare waiting to happen....Better to have them set at zero and tight rather than bent valves and a big bill....

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
Unfortunately if it turns out they have moved, to get them perfect again, it will mean dyno work...

But you always can just have them set at zero (no dyno work required) and your car will be fine...Adjustable cam gears change the power curve characteristics of your engine...You can tune them to give more high end power but you lose mid range and vice versa...The gains you get will depend a lot on other engine mods as well..If you do a search you will find out heaps more info on this...

Main thing at the moment is to make sure they are not loose and jumping around everywhere which is a nightmare waiting to happen....Better to have them set at zero and tight rather than bent valves and a big bill....

well not really fine, it would still require a tune potentially as the gears are no longer where they were

so the car wouldn't drive the same on the tune that's allowing for it

BAMR33 Mentor

BAMR33

Posted
Posted

Cam gears don't squeak when they're lose, they rattle and sound like your engine is going to blow up. I should know because I forgot to tighten my ex cam once. Probably just a belt squealing same area much more probable noise.

Tyre spin from 1st to 2nd? what a useless gauge of performance. Could be anything that has changed... road surface, air temp, slope, tyre pressure, road speed, clutch usage, driver control.

Have you even asked what the service involved? normally a service is just oil, filter/s change and a check up on everything thing else.

**RB2530** Proficient

**RB2530**

Posted
Posted
well not really fine, it would still require a tune potentially as the gears are no longer where they were

so the car wouldn't drive the same on the tune that's allowing for it

Depends on how radical the tune actually is...'a few mods to me means std ECU or aftermarket ECU with close to stock tune'...Good thing about Nissan platform is it uses afm over map sensor (as you know) and therefore any changes to the basic airflow characteristics of engine (due to cam adjusment) are acounted for by ECU...

And when I was thinking 'fine' I was thinking safe engine operation vs piston colliding into valve...

**RB2530** Proficient

**RB2530**

Posted
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I just remembered about a car I saw with a similar problem..What had happened was the guy fitted the CAS back to his car without the rubber grommet....The rubber grommet actually has brass spacers in it where the CAS bolts go through. If the grommet (and therefore spacers) are not used the end of the CAS shaft will bottom out in the end of the cam shaft...this puts a big load on the CAS bearing and it will stuff the bearing and CAS in no time..

Also as previosly mentioned check all of your belts are tight...Loose belts will squeak especially when they are cold...To diagnose sqeaking belts, start the car and spray the pulleys with something called belt dressing...You can get it from Repco...If it is the belts, as soon as you spray them they go quiet...Well they do for me anyway...

Drakey Collaborator

Drakey

Posted
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Cam gears don't squeak when they're lose, they rattle and sound like your engine is going to blow up. I should know because I forgot to tighten my ex cam once. Probably just a belt squealing same area much more probable noise.

Tyre spin from 1st to 2nd? what a useless gauge of performance. Could be anything that has changed... road surface, air temp, slope, tyre pressure, road speed, clutch usage, driver control.

Have you even asked what the service involved? normally a service is just oil, filter/s change and a check up on everything thing else.

Yeh i understand that and i know plenty of things can change and that is a terrible way to gauge performance. But the ones i did notice is major lack of power anything from 4K and above and i had trouble passing a au falcon that normally wouldnt have any worries.

I just remembered about a car I saw with a similar problem..What had happened was the guy fitted the CAS back to his car without the rubber grommet....The rubber grommet actually has brass spacers in it where the CAS bolts go through. If the grommet (and therefore spacers) are not used the end of the CAS shaft will bottom out in the end of the cam shaft...this puts a big load on the CAS bearing and it will stuff the bearing and CAS in no time..

Also as previosly mentioned check all of your belts are tight...Loose belts will squeak especially when they are cold...To diagnose sqeaking belts, start the car and spray the pulleys with something called belt dressing...You can get it from Repco...If it is the belts, as soon as you spray them they go quiet...Well they do for me anyway...

Yeh i used to work at a car servicing place and i took it back to them. i was there when it was service and it was usual filter + oil and general check over.

your idler bearing could be on the way out. Often these aren't changed when people diy thier cam belts at 100k.

Makes sense, but would it stop squeaking?

Ok so i have booked it in to get tuned. im not sure why it isnt making the power it used to but im taking it to get it tuned by the last people that tuned the car. Hopefully its something simple. but i did notice the car's fuel economy has gone down aswell all at the same time.

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