Help Me Diagnose Issues With My Rb25

[zebra]

Hey guys, Just after your opinions on what could be wrong with my engine.

pulling out of a servo on the F3 (just cruising) I noticed the knock warning going off its head >100. The car was still running on all 6 but was a little down on power, So I eased off and cruised slowly down the highway once I to my exit and let the car idle it had a miss (only at idle) with a rattle that sounded like sticking lifters, the car still drove ok. Still a little sluggish but running on all 6 with a cracked throttle (ie driving) got home, and pulled the breather hoses off and blocked the PCV to check for excess blow by, there was no more than normal (not much) with the car still on 5cyls at idle, so took it around the block to try and find out whats rattling and it was running fine again untill i was nearly back and it dropped onto 5cyls then 4. and hasnt come back.

Also checked to see if the CAS had slipped but it hasnt.

I havent had a chance to pull the plugs out yet (on holidays atm)

So my thinking is that the head gasket has gone. I thought it may have been ringlands untill it started running on 4cyls and no massive amounts of blow-by.

Anyone have any other ideas on what it could be. Once I get home I'm gonna pull the head off and have a look.

The car has ACL Forgies, Stock Rods, New oil pump and water pump, Genuine Nissan Gasket set and it was built ~2years ago

Also has Walbro Pump, PFC Pro, Std Injectors and AFM, Hi-flow turbo (tuned to 12psi but run day to day at 6psi)

Any help Appreaciated

Thanks

Andrew

[eeiko321]

Hey guys, Just after your opinions on what could be wrong with my engine.

pulling out of a servo on the F3 (just cruising) I noticed the knock warning going off its head >100. The car was still running on all 6 but was a little down on power, So I eased off and cruised slowly down the highway once I to my exit and let the car idle it had a miss (only at idle) with a rattle that sounded like sticking lifters, the car still drove ok. Still a little sluggish but running on all 6 with a cracked throttle (ie driving) got home, and pulled the breather hoses off and blocked the PCV to check for excess blow by, there was no more than normal (not much) with the car still on 5cyls at idle, so took it around the block to try and find out whats rattling and it was running fine again untill i was nearly back and it dropped onto 5cyls then 4. and hasnt come back.

Also checked to see if the CAS had slipped but it hasnt.

I havent had a chance to pull the plugs out yet (on holidays atm)

So my thinking is that the head gasket has gone. I thought it may have been ringlands untill it started running on 4cyls and no massive amounts of blow-by.

Anyone have any other ideas on what it could be. Once I get home I'm gonna pull the head off and have a look.

The car has ACL Forgies, Stock Rods, New oil pump and water pump, Genuine Nissan Gasket set and it was built ~2years ago

Also has Walbro Pump, PFC Pro, Std Injectors and AFM, Hi-flow turbo (tuned to 12psi but run day to day at 6psi)

Any help Appreaciated

Thanks

Andrew

ok this could be a no# of this

i guess you sound like the type thats willing to diagnose yourself than waste your money with mechanics ripping you off.

well i would check the plugs, but i have a feeling its not.

it could be injectors also.....either blocked or faulty...

but lets not point fingers yet.

what i would do, test the Ignition leads with a multi meter.....have you got one?

let me know coz there is a way to test the resistance.

OR

if you dont have a multi meter to test the lead....do it with a manual test

..the process BEFORE current to the plugs.......

by pulling out each lead off the plugs one by one with the engine running and earthing it on the earth bracket. hold then leads with a multigrip or pliers. do it one by one separate.......

this will tell you if the ignition system has a fault....including from ECU or Igniton coil.....or other sensors.

let us know how you go....

[eeiko321]

your probably best to have a Multimeter handy.

because come to think of it

if the ignition isnt the problem.......

you can test a few things in the next step with the meter

like O2 Sensor, Air Flow meter, Injectors etc.

but anyways, see how you go...

keep us posted or PM me if you need me to run you through steps in how to peform these tests.

cheers

[zebra]

Cheers for your help bud,

I dont think its anything electrical like o2, injectors etc.

just going off the rattling it makes its somthing physical thats causing the problem...I guess ill find out once i start pulling the head off...

[eeiko321]

Cheers for your help bud,

I dont think its anything electrical like o2, injectors etc.

just going off the rattling it makes its somthing physical thats causing the problem...I guess ill find out once i start pulling the head off...

well its really hard to tell withought seeing things......

i can only go by what your describing....

well have a look in the head if you wish..

but the thing is...does it have unusual smell of Fuel in the exhaust fumes?

becasuse cars that misfire or knock...a smell of unburnt fuel can be sensed at the exhaust.

but if the car is idling like it should but having rattling noises that doesnt affect the overal operation...then like you said, it could be more mechanical fault.

but so far it looks like you are seemed to be convinced it is a blown headgasket.

lets do some simple tests to see if this could be the case without major dissasembly.

first USUAL signs of damaged headgasket is...

the COOLANT!... check to see if you are losing coolant without any visable leakages any where else...

get someone to rev the car or even drive it.......watch the smoke of the vehicle....if its blowing white smoke......then it its the headgasket.

and when the engine running........ have the cap open at the radiator.... (make sure you do this on a cold engine)

see if there is any air bubbles coming up through to the cap.

these are the most obvious signs of blown headgaskets... check the underside of the radiator cap have white gunk or buld up/deposits underneath also

obviously signs of coolant in the oil or vice versa...

the reason why i dont really like to take off headgaskets just like that......it depends on how tight it has been tightened...

they are suppose to be tightened properly with a correct torque tensioner... but some people chose not to use it.....

and some use special sealing automotive sillicone to help seal the gasket that can cause it be a bitch to get off & at times when its taken off...it may never be the same

metal head gaskets can be the same...depending on how rough the installers are...

but mainly they are designed to improve durability and hold high compression for modified cars...as well as improved heat capacity. its not really designed for a reusable item.

anyhow.......check your coolant first

Edited March 18, 2009 by eeiko321

[zebra]

Well,

This could turn out to be a little more serious than I thought, pulled the exhaust manifold off earier and found lots of black oil sludge in the #3 exhaust port, ive nearly got the head off but it stated raining. so my guess is that its broken a piston (ACL forged) if it is, it will be that last time I buy anything from ACL again =\ so I dare say it will be time for another engine. Thinking about getting one of Lewis engines RB30 short motors and dropping my head on it. which i guess is a good thing lol...

to be continued

[zebra]

Well here is the damaged bore:

So my thoughts on a damged piston ring were right.

The new motor is nearly together just waiting on a headgasket to turn up so I can bolt the head down... then the fun begins of sorting out a whole new intake and turbo setup begins....as well as a new ECU.

Also does any one have pics on how theve done their oil drains? I'm thinking about making a hard pipe down between the manifold runners instead of using braided line. which is a) Bloody Expensive and b) Prone to melting

Cheers

Andrew