VN Engine - Signs of failed engine valves
Was wondering if anyone could tell if that the engine valves had failed or were starting to fail, would it cause the engine to have a rough idle and no power. The reason being is because we have had the car advertised for wrecking and we are getting a person constantly coming over and making stupid offers for the vehicle. I am looking at replacing the whole coil pack including EFI module but would like to know before hand so that I am not wasting money...
valves could cause loss of power,but there are symptons that are very noticable,like popping,rings also cause loss of power,if you think it's deeper than just the normal basic checks,get it compression tested,that will tell all.Originally Posted by nolim8ts
When the engine is stab revved to 4000RPM in neutral it will pop then the next will occur at just over 4000RPM after a couple of normal stabs. So a compression test would tell if the valves were stuffed?? How much would I be looking at for a pressure tester as it is pretty difficult to get it to the mechanics? I stared it up this arvo, and it started idling alot rougher than before...
If anyone has any more idea's on what could be causing this problem, that would be great as I do not want to start pulling the engine apart...Things I have checked / done:
replace fuel pressure regulator
new leads / plugs
cleaned IAC valve, TPS and throttle body
The next thing I will be looking at is changing the whole coil pack, oxygen sensor and earthing.
Last edited by nolim8ts; 02-04-2007 at 09:25 PM.
popping is a sign of crap valves?
Buggger
Mine pops all the time when i use gears to slow down.
Burbles almost.
When im driving around normally it never does...
Uh oh..
Dont like my driving? Get off the sidewalk!
1988 VN Calais: CAI, 2.5inch Catback, 18x8.5shadow chrome wheels, JVC DVD player + 7inch Screen.
Donating Member
if you got a modified exhaust system the exhaust will make a " popping " noise when u go down gears
We got rep back, yaaay!
phew.
Oh well still got **** idle.
Crappy old engines.
Thats ok, i'll keep saving till i can afford a Calais-V 6.0L
check your injectors. I just fixed the same kind of problem with mine. It sounded like it was running on 5 cylinders, idling fast (1000rpm) and had a popping from the exhaust and after replacing a heap of stuff took it to a mechanic who did a fuel pressure and flow check and the fuel flow was excessive so I changed the injectors over(20 bucks from self serve wreckers) and the problem is fixed.
Here is the link to the thread I started about the issue.
Running on 5 cylinders.
one easy test for a burnt out valve(s) is let it idle,as idle will be rough with a crook valve as well,use a rag,just place it over exhaust tail pipe(no pressure on it,just sit it freely so that exhaust will flap it away or see if it tries to suck it in),if it is sucked in,it's a sign a valve has gone
I did the rag test and came out fine.. didnt suck in, and it was blowing out which is a plus.
Im thinking maybe a dogy injector...
A few months ago I calibrated my flow rate so that my fuel used was within .5Litres of what went in the tank, but not its almost 2 litres out... if the car is getting a dodge injector, would that be a sign?
yeah a dodgy injector can cause all sorts of symptoms,especially rough idling...
wooo.
blooooooody!
Calais Comforts...OH Yeah
does your car it still start when its warmed up. Sounds like mine when crank angle sensor was stuffed.
My CAS is brand new.
I should check clearances... how do i do that?
Haha... I hate getting dirty under the bonnet... anything that needs more than 5 minutes and a spanner usually has me cursing.
Commodores dont have valve clearances. The hydraulic lifters take up the slack between the rockers and the valve stems.
EDIT:The only Commodore that might have valve clearances is the VL (dont know much about the RB30 engine) but I still dont think so as it is a fairly modern design and its only the older engines that dont have hydraulic lifters/tappets.
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