RB30 Nikki carby rebuilding help!!!

[dom14]

Hi Guys,
Please have a look at the photos that I've attached. Carby is upside down in the photos. First one is inlet manifold. There's photo of the carby kit as well.

I pulled out the carby to rebuild with a kit.

The problem with the carby is that it won't idle on petrol, but fine on LPG.
I have to hold the RPM above 2000RPM or so, or the engine dies and it won't start for another fifteen minutes or so.

The bottom of the carby and the top of the manifold doesn't seem to have a gasket that seals it like other parts. The orange/brown bit is a gasket I believe. But, it looks like some bits are burnt, doesn't it?! I'm not sure it seals properly.
Do I need to scrape it off(the orage/brown gasket like layer) before placing a new gasket?!

Are you guys familiar with this problem(no idling on petrol)?
What usually causes it? Will the rebuilt kit fix it?! Or do I need more parts?

I don't have a carby diagram, ,manual or instructions for this.
Can you help me with a one?

I would really appreciate any help.

Thanks

[GQ TANK]

The orange bits in the second last photo is the gasket.

While you have it apart, do the carby heater mod as it will give you a little bit better power. - See the honey comb in the second to last photo - break it off. Also some guys remove the metal can or file wilder to try and give a better fuel spread

Before you rebuild the carby with the kit - I would try this.

1. Get some carb cleaner and give the carby a good clean.

2. On the second to last photo - the BLACK bit is a spacer, remove it and the gaskett. - You will see three screws. Maker sure they are tight, as I had these come loose on my RB30 and it affected idle. The gasket kit has 2 replacement gaskets - one for each side of the block. If the screws where tight - you probally need to put the kit though it. - I just done my tb42 (it uses the same kit)

If you do put the kit in it - lay out some news paper on a clean serfice - take photos of each step - it will help with assembly.

The "burnt" look is oil from the pvc valve setup. - Are you blowing smoke? - als make sure the pvc valvele and pipes are ok.

[dom14]

The orange bits in the second last photo is the gasket.

While you have it apart, do the carby heater mod as it will give you a little bit better power. - See the honey comb in the second to last photo - break it off. Also some guys remove the metal can or file wilder to try and give a better fuel spread

Before you rebuild the carby with the kit - I would try this.

1. Get some carb cleaner and give the carby a good clean.

2. On the second to last photo - the BLACK bit is a spacer, remove it and the gaskett. - You will see three screws. Maker sure they are tight, as I had these come loose on my RB30 and it affected idle. The gasket kit has 2 replacement gaskets - one for each side of the block. If the screws where tight - you probally need to put the kit though it. - I just done my tb42 (it uses the same kit)

If you do put the kit in it - lay out some news paper on a clean serfice - take photos of each step - it will help with assembly.

The "burnt" look is oil from the pvc valve setup. - Are you blowing smoke? - als make sure the pvc valvele and pipes are ok.

Hi GQ,
Thanks for the reply. The car is not blowing smoke. It's a bit sluggish to start on LPG(even with the cold start solenoid). it's idling RPM is pretty low(500ish), when cold on LPG.
The real problem is it won't idle at all on petrol. I have to keep the RPM around 2000 or engine stops and won't start for another ten-fifteen minutes either in petrol or lpg.

I forgot to mention, I have removed the EGR valve and pipe and blocked the openings from exhaust and inlet manifolds. It was not related to this problem. I did it because EGR pipe broke open during last head gasket job and I kept putting maniseal to keep it going. Finally I decided it's lot easier to remove the EGR assembly than having to weld the copper pipe.

BTW, what is the honey comb bit and metal can bit are for?
Are they there for the same reason as for EGR system(fuel emission control)?

I didn't understand what you meant by "If the screws where tight - you probally need to put the kit though it".

I checked the PCV system earlier. It seems to be working fine. I felt a strong vacuum when I disconnected the hose and put my palm against the end. That's enough test, right?!

Thanks

[GQ TANK]

I pulled the egr off the rb30 I had in my mk - I had to - to make the motor fit. it did not affect idle.

The honey comb is a fuel heater - guys have found that it restricts air flow - less power. You dont need it unless you live in a very cold climate. I had a an idle problem with my rb30 - it was due to the 3 screws that hold the butter fly assembly to the carby being loose. The screws are hidden by the gasket at the bottom of the carby (near the black spacer.

I just put a kit though the carby on my gq 4.2. , the rb30 is bascally the same as I had a rb30 carby that I used as a comparison. My truck had a idle issue - then stopped working on petrol. plus I was leaking fuel by the accorator pump & the rubber boot had perished.

The kit fixed it. I now have an issue that Im trying to sort out - the idle is around 1200 rpm on both fuels.,

[dom14]

I pulled the egr off the rb30 I had in my mk - I had to - to make the motor fit. it did not affect idle.

The honey comb is a fuel heater - guys have found that it restricts air flow - less power. You dont need it unless you live in a very cold climate. I had a an idle problem with my rb30 - it was due to the 3 screws that hold the butter fly assembly to the carby being loose. The screws are hidden by the gasket at the bottom of the carby (near the black spacer.

I just put a kit though the carby on my gq 4.2. , the rb30 is bascally the same as I had a rb30 carby that I used as a comparison. My truck had a idle issue - then stopped working on petrol. plus I was leaking fuel by the accorator pump & the rubber boot had perished.

The kit fixed it. I now have an issue that Im trying to sort out - the idle is around 1200 rpm on both fuels.,

Hi mate,
I was able to change the idling by playing with the idle adjustment screw. The screw sticking out of the inlet manifold side of the carby. Try that.
I'm not sure about the TD42, in RB30 the ideal idling suppose to be 850ish. I'm guessing it's lower in TD42. I've added a photo with an arrow. You can try turning it half a turn either way while the motor is running, start with ant-clockwise. I've been told to remember the original position of the screw, in case the adjustment doesn't work. Mine at the moment idles around 500ish when cold on lpg, which doesn't bother me. It's bit slack to start, even with the newly installed cold start solenoid. I'm thinking it's a carby issue as I couldn't find any vacuum leaks. So, I'm trying to fix it now.
If your on gas, you might be able to play with idling on the converter. some converters have idle adjustment screw on it, mine doesn't. My previous car, the Jackaroo did. It won't do anything with the idle adjustment of petrol of course. correct me if I'm wrong, idling suppose to be different on petrol and gas. I think in gas it suppose be lower. of course, the turning all around are suppose to be different on lpg and petrol. I think in carby motors, it's quite a challenge. Mine has a compromised tune up setting at the moment while I'm waiting to purchase a certain unit to fix that issue. It' around $130.

I'm in Melbourne. The winter get close to zero on some days. Do you think it's ok to remove the fuel heater thing in this case?!

Thanks

[dom14]

BTW mate,
How easy was it to put an RB30 on an MQ? Did it bolt straight in?
Or did you have to modify the mounts and the gearbox?
Thanks

[GQ TANK]

Im in melbourne (melton) as well - and had no cold start issues with the rb30 after I done the Idle mod. Interseting the TB42 carby does not have the heater set up. The tb42 & RB30 carbys avery very simalar (they use the same carby kit)

It was a lot of work to fit the rb30 to the mk - I had to make gear box & motor mounts to take the angle out. (The motor was touching the steering shaft when I first bolted it to the gear box (the top to holes on the box had to be sloted). Power wisit was a big improvement over the L28. I was also looking at going EFI ( I still have a complete VL EFI setup - minus fuel pump). The TB42 - is a better motor again (and I now have a EFI setup for it - muns fuel pump)

Im familar with adjusting the idle on the carby & the LPG convertor, The truck is running fine other then the high idle,

[dom14]

UPdate!!!

I was able to maintain the idling and even start the car by removing auto choke assembly(picture 8) and manually controlling it. I used a screwdriver to keep the choke butterfly closed, and there it goes, car starts and maintains the idling. There's spring inside it, which I believe a thermostat controlled spring. I'm guessing this is the culprit.
Is this part replaceable?! Where can I source it from?!

Come on guys!!!

Somebody please give me a hand here with some information.


Thanks heaps

[Robo]

Get your hands on Nissan Fast computer program.
see home page for manuals etc.
and have a look at the schematics for what part maybe available for your carb.

sounds like the choke coil spring may not of been engaged properly or broken and check it's power supply.
also there's a alignment mark on the top of black choke cover and the alloy assembly, by default setting they align.
loosen retaining screws rotate black cover and re-tighten.

I'd also get your hands on the genuine repair manual and start testing various parts of the carb and vacum system.
as for the idle I'd also do a through maintance check on ign system incase it's contributing to the problems.

replace fuel filter and air filter.
carby inlet pipe fitting should also have a gauze filter inside it, check that to.
let us know how you go.
cheers

[dom14]

Get your hands on Nissan Fast computer program.
see home page for manuals etc.
and have a look at the schematics for what part maybe available for your carb.

sounds like the choke coil spring may not of been engaged properly or broken and check it's power supply.
also there's a alignment mark on the top of black choke cover and the alloy assembly, by default setting they align.
loosen retaining screws rotate black cover and re-tighten.

I'd also get your hands on the genuine repair manual and start testing various parts of the carb and vacum system.
as for the idle I'd also do a through maintance check on ign system incase it's contributing to the problems.

replace fuel filter and air filter.
carby inlet pipe fitting should also have a gauze filter inside it, check that to.
let us know how you go.
cheers


Hi mate,
I checked the power to the choke and the relay as well. Yes, there's power. Choke spring is not broken. There's a thermostat behind the spring inside the round black assembly, am I right?
When I was manually manipulating idling after opening the choke thermostat thingy, I couldn't see the spring moving at all(affected by the thermostat heat?). That's why I thought it may be faulty.

I have Haynes manual and I did few checks following that. I haven't actually checked the dizzy yet. I will have a look at it. Since, it's been ok with LPG, i thought dizzy may be ok.

I checked the gauze filter, it's part of the bolt that attached the petrol pipe to the carby. I couldn't see it's clogged.
So, I reckon it's ok.

I checked vaccum leaks, except inside the dizzy. I will check the dizzy now.

carby float chamber doesn't seem to be flooding, I can see through the glass, either half or less full when running on petrol.

Thanks

[dom14]

Get your hands on Nissan Fast computer program.
see home page for manuals etc.
and have a look at the schematics for what part maybe available for your carb.

sounds like the choke coil spring may not of been engaged properly or broken and check it's power supply.
also there's a alignment mark on the top of black choke cover and the alloy assembly, by default setting they align.
loosen retaining screws rotate black cover and re-tighten.

I'd also get your hands on the genuine repair manual and start testing various parts of the carb and vacum system.
as for the idle I'd also do a through maintance check on ign system incase it's contributing to the problems.

replace fuel filter and air filter.
carby inlet pipe fitting should also have a gauze filter inside it, check that to.
let us know how you go.
cheers

Hi Robo,
I have added two photos of the thermostat spring and what I think are the index marks.
Can you please have a look at it. Are they the index marks?
Does the spring look ok(by the looks of it)?
Thanks mate.

[Robo]

Yep,
they are the alignment marks you have highlighted.
when you place together ensure you engage the choke butterfly link with the coil spring
spring looks ok from here
haven't had your carby in my hand but
you may also notice on the face of black choke cover,
rich & lean , & arrows denoting which ways which.

so if you feel the need to play, you can be sure whats doing.

[dom14]

Any idea what this piece is? It's metal and kind of cylindrical with rough appearance(and it looks like aluminium as i could scrape off pieces of it with my finger nails) but not that hard for a metal piece though. It fell out of the carby when I started separating the float chamber part and top part. I have no idea exactly where it dropped from. I couldn't find a single place it would fit in.
Any idea guys?!
Thanks

[dom14]

Hi Guys,
Can I use silicone sealant between the gaskets for the carby to help with gaskets sealing better?!
I mean particularly the between the manifold and the lower carby?!
Thanks

[dom14]

Carby bottom plate gasket nightmare!!!

It's been absolute nightmare to remove it. it has turned rock solid from the heat over the time.
I had to dip in hot water with detergent over a day, and still wasn't easy to scrape it off.

Anybody know a better way to do it any quicker, please post some instructions here for future reference.

[Robo]

Hi Guys,
Can I use silicone sealant between the gaskets for the carby to help with gaskets sealing better?!
I mean particularly the between the manifold and the lower carby?!
Thanks

HYLOMER gasket spray.
its a sealer for the gaskets .
kinda like a spray rubber stuff that soakes into the gasket some-what.
also leaves the rubbery texture on the gasket surface to improve the seal.
auto shop around $20 a can.

[dom14]

HYLOMER gasket spray.
its a sealer for the gaskets .
kinda like a spray rubber stuff that soakes into the gasket some-what.
also leaves the rubbery texture on the gasket surface to improve the seal.
auto shop around $20 a can.

sorry mate, got your reply bit late. I went ahead with silicone sealant(high temp clear type tube). I think I used bit too much, I should've used it only towards the edge of the gaskets to avoid any cloging of the passages between carby compartments. But, came out ok in the end. Still bit of hasitation, but i think it's because i haven't adjusted the throttle and the idle yet. Also, spark plugs didn't look that great either. I'm going to replace them as well.

[dom14]

Thanks mate. I have finished the carby rebuild. I put it back as it was with new bits and pieces. I'm about to post quite a few photos of the rebuilding process, so somebody else may find it helpful as well. it will take some time as I have to edit and prepare the photos. :)
Cheers

[Alitis007]

Just seen this thread, firstly NEVER USE ANY SEALANTS ON CARBIES the petrol will eat away the sealer and block the jets, . That ball that fell out is probably led not alloy and it must have been stuck there after breaking off an accelerator cable. Window scrapers are good at removing gaskets but if you dig a groove in the manifold you will need to sand it smooth and flat!! That coil inside the choke heats up with the 12v from the battery, so when it gets hot the choke turns off.

[Robo]

"Hylomar gasket jointing compound".
Brand ACL.
the ACL bearing company
www.acl.com.au
Just read instruction again.
I've used this many times before no problems.
It makes no recommendations on how not to use.
I contacted them, ringing me back.

[dom14]

Just seen this thread, firstly NEVER USE ANY SEALANTS ON CARBIES the petrol will eat away the sealer and block the jets, . That ball that fell out is probably led not alloy and it must have been stuck there after breaking off an accelerator cable. Window scrapers are good at removing gaskets but if you dig a groove in the manifold you will need to sand it smooth and flat!! That coil inside the choke heats up with the 12v from the battery, so when it gets hot the choke turns off.

Hi mate,
Thanks for the good advice. It's little bit late, but probably not too late to reverse it?!
Would you pull the carburettor out and clean the sealant and fit it back without any sealant the second time?!
BTW, is it possible to apply the 12V to the thermostat coil while it's opened and see if it moves/expands to see if it works?!

Thanks in advance for your reply.

P.S. I've attached few photos to demonstrate the possible damage I may have done.

[Alitis007]

Hi mate,
Thanks for the good advice. It's little bit late, but probably not too late to reverse it?!
Would you pull the carburettor out and clean the sealant and fit it back without any sealant the second time?!
BTW, is it possible to apply the 12V to the thermostat coil while it's opened and see if it moves/expands to see if it works?!

Thanks in advance for your reply.

P.S. I've attached few photos to demonstrate the possible damage I may have done.

You could get away with it on that heater element on the base but i wouldn't have used silicon i would have used an aviation form a gasket type sealant called Permatex 3 because you only apply a thin film to both sides of the gaskets. If you removed it now you may possibly tear the gasket so you might need to replace the gasket if you do so its up to you what you do, and its good thing that you didn't use sealant on the float chamber gasket coz that would have given you the most hassle.

For the choke if you apply 12v whens off it wont do anything because it would have relaxed the coil in it, but how you test it is dead cold you flick the throttle so that closes the flap on the top of the carby then feel how much tension it has then start the car let it idle for a minute then flick the throttle again and it should open depending on how hot its. You adjust where that coil is accordingly, the only thing you should be testing is with a multimeter the power going in and how long it stays there for if that makes sense.

[dom14]

You could get away with it on that heater element on the base but i wouldn't have used silicon i would have used an aviation form a gasket type sealant called Permatex 3 because you only apply a thin film to both sides of the gaskets. If you removed it now you may possibly tear the gasket so you might need to replace the gasket if you do so its up to you what you do, and its good thing that you didn't use sealant on the float chamber gasket coz that would have given you the most hassle.

For the choke if you apply 12v whens off it wont do anything because it would have relaxed the coil in it, but how you test it is dead cold you flick the throttle so that closes the flap on the top of the carby then feel how much tension it has then start the car let it idle for a minute then flick the throttle again and it should open depending on how hot its. You adjust where that coil is accordingly, the only thing you should be testing is with a multimeter the power going in and how long it stays there for if that makes sense.

Hi mate,
I'm pretty sure, i can pull the gasket between the float chamber compartment and the bottom compartment without tearing it, Also I still have the old gasket which is still appears to be in good nick.
What I meant was, is this something that I have to rectify by removing the silicone sealant?!
What would you do? Would you leave a mistake like this as it is, or would you fix it up straightaway?
Thanks

[Alitis007]

Hi mate,
I'm pretty sure, i can pull the gasket between the float chamber compartment and the bottom compartment without tearing it, Also I still have the old gasket which is still appears to be in good nick.
What I meant was, is this something that I have to rectify by removing the silicone sealant?!
What would you do? Would you leave a mistake like this as it is, or would you fix it up straightaway?
Thanks

If you put sealant between the float chamber compartments then pull it down, if not leave that bit. On the base plate/ heater element i would on my car but if its ok so far you could leave it for now but eventually you will have to clean it up

[dom14]

Thanks mate. There are three parts to the carby one sitting on top of the other.
I left the top of the middle part(float chamber) without sealant.
But, I put sealant on bottom of middle part(float chamber) and bottom part.
There's a plastic plate between bottom part and middle part(float chamber)
The plastic plate has two gaskets on each side.
I put sealant on both sides of those gaskets.
Then the bottom part where it sits on manifold with the heater plate.
There are two gaskets on each side of that plate as well.
I put sealant on both sides of those gaskets.
So, overall, four gaskets with sealant on each side of them.
Only one I left out was the top of the float chamber gasket, which I thought too narrow to put sealant.
Following your advice, I think I may have stuffed it up by pasting silicone on them.
There's no drama so far. But, as you pointed out, petrol can eat into the silicone and clog up the internal passages over time, leaving my carby rebuild job useless.
I reckon, I will tear it apart again, remove the silicone and use the same gaskets or use old ones(or new ones)
Cheers

P.S. I wish I've heard from you earlier. ;)

Just added a picture showing the places I applied silicone which I shouldn't have. So, somebody can learn from it.

[Alitis007]

Thanks mate. There are three parts to the carby one sitting on top of the other.
I left the top of the middle part(float chamber) without sealant.
But, I put sealant on bottom of middle part(float chamber) and bottom part.
There's a plastic plate between bottom part and middle part(float chamber)
The plastic plate has two gaskets on each side.
I put sealant on both sides of those gaskets.
Then the bottom part where it sits on manifold with the heater plate.
There are two gaskets on each side of that plate as well.
I put sealant on both sides of those gaskets.
So, overall, four gaskets with sealant on each side of them.
Only one I left out was the top of the float chamber gasket, which I thought too narrow to put sealant.
Following your advice, I think I may have stuffed it up by pasting silicone on them.
There's no drama so far. But, as you pointed out, petrol can eat into the silicone and clog up the internal passages over time, leaving my carby rebuild job useless.
I reckon, I will tear it apart again, remove the silicone and use the same gaskets or use old ones(or new ones)
Cheers

P.S. I wish I've heard from you earlier. ;)

Just added a picture showing the places I applied silicone which I shouldn't have. So, somebody can learn from it.

You can only see so much but never mind you learn from your mistakes, and if you can help someone out it all pays for it self in the end but hey you should be able to do it with your eyes closed now lol
Trust me when i say, i've muffed a couple in my time haha

[dom14]

Yeah mate. I thought carby's are complicated piece of machines(they are). Now, at least I'm familiar with this Nikkiy carby. I think carby's are trickier than complicated. Can even drive an experienced mechanic insane at time. :))

BTW, I must have been upsetting fair number of 4WD mechanics out there with my posts and photos and my demands for answers. :))

[RB30 4X4 JUNKIE]

Thank-you for creating this thread I has helped

[dom14]

Thank-you for creating this thread I has helped

You're welcome mate. Thank George(Alitis007) as well. He helped me all the way with the job. A nice bloke who happens to be an RB30 specialist as well.

[dom14]

Thank-you for creating this thread I has helped

Hey mate,
Follow this thread as well. I've added bit more information with pictures.

http://www.nissanpatrol.com.au/forums/showthread.php?34948-RB30-Nikki-carby-float-level-problem&p=630257&posted=1#post630257

Cheers
Dom