Idle Problems When Clutch In In First

[simonthomasgoodwin]

as says ive been getting idle problems wen im coming to a stop and i hav the car in first.. it sometimes drops as low as 500 or less rpm then someetimes it stalls out aswell.. i recently took apart my throtle body and crossover pipe to paint rocker covers, could this have anything to do with it?

it doesnt happen if its in neutral though and once it felt almost as if it was stuck in first.. was very stiff to get out

any suggestions?

ta Simon G

[lachlanw]

do you have a big gay poofer valve ?

failing that yeah its something you played with

[simonthomasgoodwin]

haha nope bov is stock and plumbed back to the intake..

[defari]

leaks / aac valve needs a clean

[DVS JEZ]

Is it only when the clutch is in in 1sy and held in for a while?

If theres no airleaks causing the idle to drop like u say then the clutch hydraulics might be leaking intrrnally in the

master cylinder making it as if u are really slowly letting the clutch out.

Check the fluid in the clutch master cylinder. And then try starting the car puttin clutch in in 1st an hold it in 1st for a while and see if the engine revs slowly drop an trys to drive forward

[twinky]

Dont forget to check the slave cylinder.

Edited November 1, 2010 by twinky

[simonthomasgoodwin]

okay i cleaned aac valve i thort it had helped but it still does it more reg now.. dvs32r thanks for the input i will try that out tomorow

[simonthomasgoodwin]

Is it only when the clutch is in in 1sy and held in for a while?

If theres no airleaks causing the idle to drop like u say then the clutch hydraulics might be leaking intrrnally in the

master cylinder making it as if u are really slowly letting the clutch out.

Check the fluid in the clutch master cylinder. And then try starting the car puttin clutch in in 1st an hold it in 1st for a while and see if the engine revs slowly drop an trys to drive forward

oh also just to mention my clutch is a twin plate brass button.. and it doesnt do the on/off thing anymore -__- alot easier to drive but im wondering could this be apart of my problem or is this happening because of my problem?

and now when i come close to stalling i litterally have the rip it out of first.. wen rpm starts droping i can move it then it will hit 0, the 'grip' on the shifter will release and i can pull it out easily, then the rpm comes back up again.. it only stays on 0rpm for maybe half a second?

[Daleo]

oh also just to mention my clutch is a twin plate brass button.. and it doesnt do the on/off thing anymore -__- alot easier to drive but im wondering could this be apart of my problem or is this happening because of my problem?

and now when i come close to stalling i litterally have the rip it out of first.. wen rpm starts droping i can move it then it will hit 0, the 'grip' on the shifter will release and i can pull it out easily, then the rpm comes back up again.. it only stays on 0rpm for maybe half a second?

I'm with DVS32R, sounds like a Slave/ Master cylinder leak.

Check reservoir for low fluid level, then check under the car on the clutch slave cyl for weeping or a leak.

If you are losing fluid, but can't find the leak, you might be leaking out of the clutch master cyl & along the rod, running down the firewall behind the carpet/deadening.

If you are not losing fluid, you have a piston seal in either slave or master cyl that is slowly bypassing, but generally this will still lead to leakage down the rod.

Edited November 25, 2010 by Daleo

[simonthomasgoodwin]

I'm with DVS32R, sounds like a Slave/ Master cylinder leak.

Check reservoir for low fluid level, then check under the car on the clutch slave cyl for weeping or a leak.

If you are losing fluid, but can't find the leak, you might be leaking out of the clutch master cyl & along the rod, running down the firewall behind the carpet/deadening.

If you are not losing fluid, you have a piston seal in either slave or master cyl that is slowly bypassing, but generally this will still lead to leakage down the rod.

heya i checked the fluid resivour yesterday and its sitting on the full mark.. havent had a chance to check for leakage as yet and im down coast on holiday for the week so il have to hav a look then

if i havnt lost any fluid from master would it be safe to assume its not leaking any? if its a piston seal what does that mean? can i just order new seals and chuck em on or will it be a whole clutch rebuild sorta thing? ( im not very knowledgabe about clutch stuff! )

cheers! simon g

[Daleo]

heya i checked the fluid resivour yesterday and its sitting on the full mark.. havent had a chance to check for leakage as yet and im down coast on holiday for the week so il have to hav a look then

if i havnt lost any fluid from master would it be safe to assume its not leaking any? if its a piston seal what does that mean? can i just order new seals and chuck em on or will it be a whole clutch rebuild sorta thing? ( im not very knowledgabe about clutch stuff! )

cheers! simon g

Ok, sounds like you've isolated it to the master cylinder.

When you push in the clutch pedal, it levers a rod which then pushes the piston down the bore of the master cyl. This displaces the fluid in the bore, & forces it down the line toward the slave cyl.

This extends the rod of the slave cyl, which in turn levers the clutch fork. What it seems is happening, is the seal in the master cyl is leaking, allowing fluid to pass back around the edge of the seal. (remember, the diaphragm spring in the clutch assy is pushing back against the force you apply to the pedal)

This small amount of fluid will then return to the reservoir, thus you don't lose any fluid.

What will happen as this issue gets worse, is the rod seal in the master cyl will end up with too much fluid behind it as you release the clutch and it cannot escape to the reservoir. It is then forced down the rod and this is the fluid that can run down the firewall.

Hope this all makes sense. It sounds to me, like a new clutch master cyl, or a rekit is in order. Although, most of the time with nissans, it can cost more in labour & parts to overhaul your original, than to just buy a newie.

Edited November 28, 2010 by Daleo

[simonthomasgoodwin]

<br />Ok, sounds like you've isolated it to the master cylinder.<br /> <br />When you push in the clutch pedal, it levers a rod which then pushes the piston down the bore of the master cyl. This displaces the fluid in the bore, & forces it down the line toward the slave cyl. <br />This extends the rod of the slave cyl, which in turn levers the clutch fork. What it seems is happening, is the seal in the master cyl is leaking, allowing fluid to pass back around the edge of the seal. (remember, the diaphragm spring in the clutch assy is pushing back against the force you apply to the pedal) <br />This small amount of fluid will then return to the reservoir, thus you don't lose any fluid. <br />What will happen as this issue gets worse, is the rod seal in the master cyl will end up with too much fluid behind it as you release the clutch and it cannot escape to the reservoir. It is then forced down the rod and this is the fluid that can run down the firewall. <br /><br />Hope this all makes sense. It sounds to me, like a new clutch master cyl, or a rekit is in order. Although, most of the time with nissans, it can cost more in labour & parts to overhaul your original, than to just buy a newie.<br />

<br /><br /><br />

thanks for the help man, i might add wen i bought the car the slave cyl had a leak and i had a mechanic do it along with brake master but i think he mite hav just done brake mast and slave? any suggestions given this was in august/september

[russstuff]

Hey hows it going?

just wondering if you found the cause of your problem? just asking cause i had a similar problem with my r33.

i bought it with a big end knock, and sent it for repairs plus while they were at it i had them overhaul the gearbox. i had the nismo twin plate copper mix clutch.

before sending it away i had a similar issue with the revs dropping if i left it in gear at the lights for around 10 seconds.

after getting the car back it occasionally felt funny going into gear, sometimes, on a flat road if you didnt have your foot on the brake and you put the car into gear it would roll the car forward and quick gear changes were not an option. i bled the system several times, replaced the gearbox oil, replaced the slave cylinder and replaced the master cylinder but nothing fixed it.

hope you got it sorted before the xmas new year break!

[armoilers]

I wouldn't mind how you went with this too I got the same issues

Don't really want to send my mechanic out on a witch hunt (already done the AAC clean out/replacement path)

[Tony Brown]

Hope its not, but could be crankshaft end float, in other words the thrust surface on the main bearings could be worn, if they are worn, when you push the clutch in, the crankshaft is pushed forward and is trying to push the conrods/pistons on an angle towards the front of the engine.

As I said, hopefully not but a possibility.

It can be checked by measuring any movement at the crankshaft pulley, by using light leverage and a dial indicator, if you can try to push the pulleycrankshaft toward the back of the engine, set up dial gauge to zero on the pulley and then have someone else push in the clutch.

If there is any movement, its not good, but if movement is excessive then you have real problems.

I have had this problem in another car (not Skyline) in the past and if you can imagine the forces on the crank/conrods/pistons, then you can see why the engine is not happy at low revs when there is not enough power to keep it from stalling, it only happens with the clutch in but it also lessens the amount of travel that the clutch is getting because instead of pushing on the pressure plate, some of the travel is used to push it away before it starts to actually apply pressure.

It creates some really crazy wear patterns in the bore if honed.

I hope I have explained this clearly, but if not I can show you with some photos if my crappy photography will show it.

[Tony Brown]

Could be as simple as bleeding the clutch though.

Is the friction point close to the floor?

Does "pumping" the pedal before coming to a stop help?

Edited February 10, 2011 by Tony Brown