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Location:
Sydney
Registered:
January 2003
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 4AG is smokin.. What could it be.. Please help!
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Sun, 01 June 2003 12:28
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ive had the 4AG running in the sprinter for a few weeks and its been pumping a but of blue smoke out the exhaust and using quite a bit of oil, its getting quite bad now. most of the smoking occurs after decelerating for traffic lights or going down a long hill, actually its pretty much after i take my foot off the throttle while its still in gear.
i've tried go narrow down what it could be and i may be wrong with this but i'm pretty sure that the oil is getting in to the combustion chamber through the valve guides and not the rings coz the compression is all fine.
the engine was sitting around for about a year before i put it in, i've heard that the valve guide oil seals shrink and harden if left for a while, is this true?
is there anything else that i'm missing that it could be?
if it turns out to be the valve guides is there anyone here that could change them if i pulled the head off and took the cams out etc coz ive heard u need special tools or something, or any workshops that anyone recommends?
thanks for any help,
Richard
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Location:
bris
Registered:
February 2003
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Re: 4AG is smokin.. What could it be.. Please help!
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Sun, 01 June 2003 13:33
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smoke when you let off the throttle sounds like fucked valves,
it really could be lots of things tho, its often the smallest thing you've overlooked for ages:S
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Banned user
Location:
ADELAIDE - The Drift City
Registered:
July 2002
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Re: 4AG is smokin.. What could it be.. Please help!
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Sun, 01 June 2003 13:33
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Do a compression test... if one cym is down more then the other then it could be valve guides or something
but i'd put my money on the piston rings being worn out mate. sorry dude
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Location:
Wollongong
Registered:
July 2002
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Re: 4AG is smokin.. What could it be.. Please help!
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Mon, 02 June 2003 03:14
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yeah its really hard to just narrow down. Stem seals or oil rings maybe if the compressions fine. Stem seals will usually blow smoke when you back off, or its been sitting for while. Start it up and there smoke everywhere. If its oil rings it'll smoke more under acceleration. I think you've basically got it covered though, I can't think of anything else thats just going to make it smoke.
Where was it sitting before you put it in? and did you get some oil onto the cylinders before you started it? You can't really check the guides without puling it apart yourself. There are tools that allow you to remove the valve springs without taking off the head but not all workshops have them, and i don't know how good they are, i've only ever heard of them being used a could of times.
Don't suppose you know how many k's roughly the motors done?
with putting the seeals in, once you've got the head off, I can't see any reason why you wouldn't be able to do the rest. Just get a valve spring compressor.
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Location:
Perth
Registered:
September 2002
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Re: 4AG is smokin.. What could it be.. Please help!
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Mon, 02 June 2003 04:50
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yeah, mines the same
blows smoke upon startup, and after beeen idling for a few mins
compression is 170-165 across the board
valve stem seals were done 45k kms ago aswell
but doesnt blow smoke on acceleration no matter how hard i go
are we talking valve stem seals? guides? or oil rings?
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Location:
Cairns
Registered:
May 2002
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Re: 4AG is smokin.. What could it be.. Please help!
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Mon, 02 June 2003 06:36
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Before you crack the motor open, check the emissions system. Sometimes the P.C.V. valve jams closed when the engine has been sitting around for a while. when this happens your engine builds up internal crank case pressure and forces oil pass the rings and stem seals. I have seen a "professional" mechanic spend mega bucks on an engine rebuild because of this symptom only to find out later the PCV was shagged. I have seen some EGR systems hooked up by a one armed blind man that suck oil straight from the sump on decel (manifold vaccum skyrockets), so just check these to make sure.
p.s. the PCV valve is a one way valve that lets internal engine pressures vent into the inlet manifold or air cleaner, but wont let a backfire into the engine. The PCV valve is usually a small silver or black tube about 2" long and 1/2" round and can be found fitted into a grommet on the tappet cover with a 3/8" hose to the inlet manifold or base of the air cleaner.
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Location:
Sydney
Registered:
January 2003
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Re: 4AG is smokin.. What could it be.. Please help!
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Mon, 02 June 2003 13:04
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yeah it pretty much does what you said mr supra, smokes like hell when i start her up in the morning and when i back off, also after i leave it ideling for a while.
as far as i know it was just sitting on the ground in a shed. the guy i bought it off said that it was not blowing any smoke though, its done approx 90000k's ( what he told me)
the actual power of the seems to be ok, its quite a bit quicker than my mates ae92 sx.
all the little breather hoses seem to be working ok
i will probably pull the head off it in the uni break in a couple of weeks, i'm really hoping its not the rings coz i don't want to touch the bottom end just yet.
i once heard someone say that you need to heat the head and use special tools to get the guides out. has anybody here replaced them? do you need some weird tool or anything?
thanks for the help guys!
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Registered:
January 2003
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Re: 4AG is smokin.. What could it be.. Please help!
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Tue, 03 June 2003 15:15
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Hey Champ!
Well i thought the engine had done around 190000 kms!
Thats what tim told me!
Either way, the engine will end up fine, just TLC and a nice new start of life for the engine!
What ever happens, what ever the disease, youll be able to fix it!
If you need help with anything Dicky, call us!~
Even though iam not that much help 
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: 4AG is smokin.. What could it be.. Please help!
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Tue, 03 June 2003 17:30
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Going by the symptoms it sounds just like leaky stem seals. The stem seals won't affect the compression, as this is built up with the valves closed, & when you'r decelerating there's alot of vacuum while the intake valve is open, which would help suck the oil through & into the combustion chamber.
You don't have to worry about that PCV valve either, 4AGEs don't actually have them, although most other motors do.
If you wanna get the valve guides/seals out without removing the head you can weld up a fitting for a compressed air line out of an old spark plug hollowed out, then you can pressurise the cylinder with compressed air which will hold the valves in place while you remove the springs & then the guides/seals.
Or you might be able to buy a fitting already made....
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Location:
Sydney
Registered:
April 2003
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Re: 4AG is smokin.. What could it be.. Please help!
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Thu, 05 June 2003 11:19
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Another way to get the stem seals off while the head is on (although sounds bodgy) is to feed nylon rope through the spark plug hole while piston is down, then crank the piston up to hold the valves in place. I've only heard of this method though.
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Location:
Sydney, Australia
Registered:
May 2002
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Re: 4AG is smokin.. What could it be.. Please help!
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Thu, 05 June 2003 12:53
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Out of interest, what oil are you using?
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Location:
Sydney
Registered:
January 2003
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Re: 4AG is smokin.. What could it be.. Please help!
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Mon, 09 June 2003 01:18
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yeah, i think i'll just pull the head off, i might give it a slight head job while i'm at it. is there much power in head jobs?
i'm using that castrol formula r synthetic stuff, 5W-40 i think.
any recommendations on who i should get to do the job?
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