Tapping Noise?

[battery]

hey my RB20DET has been making a tapping noise recently heres some facts

-always there hot or cold

-quicker with reving

-is silent when off the accelerator

-sometimes i get an ECU error on my consult screen (34) knock sensor usually only for the first 5 mins on very cold mornings but sometimes during normal conditions....

-i wired the fuel pump straight to the battery so its on full blast all the time, there was not much noise before this if any...

-revs are a bit strange sometimes at idle it will just go up and down between 1k-2k rpm sometimes will go down to 400rpm when stoping

-if i give it some just after it starts i will get a screeching noise for a few seconds sounds like fan belt but its a little different

-its not that loud if you rev at idle, heaps louder under load

-misses randomly sometimes

-i can't be sure but sometimes it feels like the engine is being held back, like the handbrake is being pulled... not sure about this though

basically trouble started after fuel pump relay died and i wired it straight to the battery this may not having anything to do with it, cause i was also doing some very hard thrashing at the time....

i have listened to it at idle with a screwdriver but i can only hear the fuel rail and injectors ticking which is normal i guess.

i was thinking that the increase in fuel pressure could be making them noisy but not sure...

could be lifters i guess but the sound should be there on and off the throttle which it is not?

any ideas?

[The Mafia]

sounds like you have spun a big end

[R31Nismoid]

Look it could be injectors and 2-3 other problems... as some of the things you've put down are not solely one thing or another

Like the miss, motor feeling like it held back etc.

My motor even with 2 blown piston rings still went alright if i made it, it was just a bit smokey.

But then it could be worst case as Jono said, and thats fairly likely.

Also - dont hard wire the fuel pump. Its dangerous.

[R34GTFOUR]

sounds more big endish than lifters.

Worn lifters wont get louder under load, but a spun big end will.

Check you oil for metal, if it looks metalic at all it'll be a big end bearing

[battery]

so if i have spun it how long will it last i mean i've been driving it for 400ks.... some of it has been hard driving too....

[R31Nismoid]

how long is a piece of string?

Stop driving it and get it checked before you do more damage

[battery]

whats it cost to replace a big end bearing with and without labour?

i think it might be better to drop a second hand one in with decent compression, cause last time i checked 40000ks ago it was around 110psi so fairly worn.....

apart from being dangerous in a crash situation why else is it bad to hard wire the pump?

[Duncan]

sounds like a big end bearing to me too. if it is worse with revs and when cold.

don't run the motor, get it towed and checked out. if it is a spun bearing it can get much more expensive very quickly.....

btw ash not sure why you think direct wiring the fuel pump is a bad idea, we do it all the time. the standard fuel computer often causes serious problems

[R31Nismoid]

btw ash not sure why you think direct wiring the fuel pump is a bad idea, we do it all the time. the standard fuel computer often causes serious problems

wait till you have an accident the the car keeps pumping fuel while its upside down

catches fire

doesnt end nicely

[Duncan]

sorry but the standard fuel computer doesn't have stall or rollover cut out either. obviously we add stall cut out on the race cars.

[R31Nismoid]

Race cars aren't road, its like comparing V8's and F1's.

I thought if the ignition etc controlled the pump then they stopped?

Im sure someone actually played with it... just gotta remember who

[R34GTFOUR]

whats it cost to replace a big end bearing with and without labour?

i think it might be better to drop a second hand one in with decent compression, cause last time i checked 40000ks ago it was around 110psi so fairly worn.....

apart from being dangerous in a crash situation why else is it bad to hard wire the pump?

if you catch it really early, you can get away with just slapping in a set off bearings. We did it to a mates car, 30,000km on and its still strong.

If you've done a bit of damage to the crank you may have to get it machined, so pretty much a full rebuild will get done if the motors tired.

or like you said just buy a 2nd hand motor, probably the cheapest option, but you may be buying someone elses problems

OR

slap a rb30 bottom end on your head

[R34GTFOUR]

opps just realised its an rb20, wont got the rb30 route then

get a 2nd hand engine, people practically throw out the rb20s these days

[skylinegtts]

if it was a big end bearing, wouldnt u still hear the tapping when ur off the accelerator (ie decelerating) ?

i would have thought there would be a constant tapping, either accelerating or decelerating?

when u start it cold, have a light sniff around the exhaust manifold/turbo area, if it smells of fuel, i think its the exhaust manifold gasket.

for me it explains most things, but doesnt explain the idle.

[mattymagoo22]

if you can stop the cylinder firing one at a time from 1 - 6 (you can do this by disconnecting the injector, coil or lead of the cylinder) you will be able to find out if it is actually a big end noise and exactly what cylinder its occuring. when the cylinder has no combustion most times if its a big end the noise will go away.

Hope this helps.

Cheers Matt.

Catch it early and you may get away cheaply.

[battery]

got someone to have a listen today they said it sounds like an exhaust manifold leak ill pull it down tomorrow and whack some new gaskets in on Monday

ill let you guys know how i go.

[mattymagoo22]

do yourself a fovour and go and spray some WD-40 or similar on the exhaust studs tonight, will save your so much drama tomorrow.

[The Mafia]

whew... haha lucky.

Sorry about the grim response, but tapping, and the leaking exhaust "tractor" sound is a little different haha.

[battery]

yeh i have one nut left on the manifold its a bitch im gonna have to take the rocker cover off to get to it....

the previous owner put one of those Chinese stainless manifolds on, its cracked where the pipes come together complete junk.

im gonna source a standard one and put that on.

thanks for all the help guys

[tom9999]

i recently spun a big end due to built incorrectly. its now cost me almost 9k but thats full forged engine