White smoke after RB26 rebuild

[yamaha227]

definately points to valve stem seals, how can i narrow it down to this before i look at getting them redone?

[Sydneykid]

definately points to valve stem seals, how can i narrow it down to this before i look at getting them redone?

Got that leak down test done yet?

[wombatau]

sounds exactly like an over-pressurised crank case - blowing oil past the turbo seals and piston rings. i bet after you've let the engine gear down running down a large hill and then pulled away, white smoke just plooms...

just make sure your crankcase can vent correctly, check your pcv and rocker breather valve are connected and free of any major restrictions and that your pollution gear (carbon canister) is connected and not leaking.

only a handful of things can cause that kind of smoke and almost all of them are ruled out because you have just rebuilt your engine. white smoke in your situation is indicitive of oil being spilled out post-combustion and smouldering (white) on hot pipes. the only thing i can think of that wouldn't be a pressurized crankcase (and isn't exempt due to the fresh rebuild) would be your turbo seals. unless your hks aftermarket turbo has done more than 100,000kms or has been run at more than 20psi for prolonged periods, i would first be checking all your emissions equipment and making sure it was all in order. first thing i suggest is connecting ALL hoses as per factory specifications. then, if it solves your problem, recconect it all one-by-one until you find the smoke-causing culprit.

all the best mate.

-wombat

[vspecv]

Hoping someone can give me some advice on what maybe causing my GTR to blow smoke after a full rebuild. Its done about 300km's since rebuild, so i might be jumping to conclusions but it seems to be a fair bit.  

Hear's what i had done, bore and hone to suit 20' over JE pistons, total seal ring set, forged Argo rods, new standard nissan crank and bearings throughout.

Head has been rebuilt with new valves Todda bronze valve guides and new seats cut. Also had my sump modified with a Trust sump extension kit and a N1 oil pump. had all this work done by a engine shop up here and put the rest of the gear back on myself.

Built the engine keeping in mind i wanted it to be able to make about 400kw at the wheels in the future. I have HKS 2530 turbo's on now with ces racing dump pipes and apexi exhaust, plus upgrade injectors, fuel pump and Apexi power fc, mines airflow meters and huge intercooler and a HKS remote oil filter/cooler kit to help keep things under control.

Bit of a run down on what ive done, hope this will help in sorting my problem out.

It seems to blow nice thick white smoke after it has been idling at the traffic lights when i take off and after i have been decelerating into corners and then accelarating out. but if i cruise at say 110 on the highway for a little while then change down and go round some tighter corners and accelerate and take it to 5000 with boost it doesnt blow any smoke at all.

The car was off the road for about 6 weeks with no battery sometimes, is there a chance the power fc needs retuning?

oil catch can doesnt seem to be getting any oil mist in it, i have the pvc valve blocked off and the line into the rear turbo intake boot is also blocked of, would this effect my crankcase venting at all, and having total seal rings would this add to the problem?

Before i had the engine rebuilt it was running fine, no smoke i had the HKS turbo's on it then to so it makes me think that i cant be the turbo's. or is there a chance that because they have been sitting for 6 weeks the seals me have dried up or something happened?

The engine was tuned with all the above mods down south in melb except for the pistons, rings and rods etc. i was hoping because i didnt change anything that would effect the mean effective pressure of the engine eg cams, boost level, CR etc that i would be fine with the existing tune on the power fc before my rebuild.

Im going to try and put as many k's on it over the next few days and load the thing up hills etc to see if it comes good, and will also keep an eye on oil consumption/oil level increse aswell. Have spent big bucks on this engine and hope the engine shop did the right job with bore and hone.

hopefuly somone has some good news for me on what to try, Thanks

how does your catch can vent,

does it plumb back or just vent through a hose, if it plumbs back to the rocker covers, make sure the catch can has sufficient venting, if its running a filter, remove it incase its blocked.

did it have the catch can fitted previously?

Dean

[B-Man]

Hmmm , Interesting.

[yamaha227]

interesting thoughts , one of the first things i tried was mucking around with the venting system. when i got the car (before the rebuild) it had a small catch tank on it. the hose that originaly runs to the pcv valve was removed from the rocker cover end (still connected to the pcv valve) and had some sort of bung installed in it and was just dangling behind the rocker cover.

turns out on closer inspection the hose had split half way down anyway so was prob venting well still. the two pipes pointing forward on the rockers were interconnected and one of the other pipes heads off to a catch tank, then another pipe from the catch tank goes back to the rear turbo intake boot. the other pipe on the rocker was just vented to atmosphere with a pipe heading down the fire wall.... dodgy setup!

so with the rebuild i decided to get one of those simple catch tanks that sits on top of the rockers, i set it up correctly and had everything connected... so when i was first trying to sort out my probs i thought it was maybe the new catch tank setup.

turns out it wasnt cause i tried disconnecting things one at a time. ended up with putting the old catch tank on but on the advice of peter at advan, set it up differantly. he said to block the pcv off completely, block the rear turbo boot inlet line completely, interconnect the two forward rocker pipes and vent the other two to a catch tank with the catch tank venting with a filter on it.

Does this sound right or wrong??

Ive read on the total seal ring instructions that because they seal so well that they can cause pcv problems and they reccomend installing a bung with a 1/16 hole drilled in it into the fresh air side of the pcv. interesting??

May be oil/crankcase pressure related as it got worse after changing the oil again at 500k's. new oil = higher pressure and too much pressure is going to put more stress on turbo seals etc, along with too much crankcase pressure. checked the venting tubes at the rocker and no oil mist at all, so im guessing their is no blow by probs.

intereting, seems to be plenty of possibilities and hope fuly checking comps tomorrow it will cancel a few out??

[vspecv]

interesting thoughts , one of the first things i tried was mucking around with the venting system. when i got the car (before the rebuild) it had a small catch tank on it. the hose that originaly runs to the pcv valve was removed from the rocker cover end (still connected to the pcv valve) and had some sort of bung installed in it and was just dangling behind the rocker cover.

turns out on closer inspection the hose had split half way down anyway so was prob venting well still. the two pipes pointing forward on the rockers were interconnected and one of the other pipes heads off to a catch tank, then another pipe from the catch tank goes back to the rear turbo intake boot. the other pipe on the rocker was just vented to atmosphere with a pipe heading down the fire wall.... dodgy setup!

so with the rebuild i decided to get one of those simple catch tanks that sits on top of the rockers, i set it up correctly and had everything connected... so when i was first trying to sort out my probs i thought it was maybe the new catch tank setup.

turns out it wasnt cause i tried disconnecting things one at a time. ended up with putting the old catch tank on but on the advice of peter at advan, set it up differantly. he said to block the pcv off completely, block the rear turbo boot inlet line completely, interconnect the two forward rocker pipes and vent the other two to a catch tank with the catch tank venting with a filter on it.

Does this sound right or wrong??

Ive read on the total seal ring instructions that because they seal so well that they can cause pcv problems and they reccomend installing a bung with a 1/16 hole drilled in it into the fresh air side of the pcv. interesting??

May be oil/crankcase pressure related as it got worse after changing the oil again at 500k's. new oil = higher pressure and too much pressure is going to put more stress on turbo seals etc, along with too much crankcase pressure. checked the venting tubes at the rocker and no oil mist at all, so im guessing their is no blow by probs.

intereting, seems to be plenty of possibilities and hope fuly checking comps tomorrow it will cancel a few out??

sounds like ur catch tank is venting ok, but to be sure , leave the pcv blocked and the turbo piping pipe blocked and disconnect the catch can , so both rocker covers vent. then u will know for sure that the pressure is unlikely the crankcase.

i once fitted a catch tank to my gtr, but forgot to drill vent holes in the catch tank and i was leaving trails of white smoke down the street and pulling my hair out trying to work out what was going on, i also did lots of work, so was hard to pin point the reason, until someone pointed out that the catch tank wasnt venting.

did i feel like a butt head

[yamaha227]

yeah good point, definately good idea to try all the simple things before going rip tear bust again. any idea on how to pin point if its turbo seal problem? heard HKS 2530's are expensive to repair and not as efficent after the overhauls as no one can match the trims of the original HKS wheels?? dont want to pull them until ive tried everything.

[vspecv]

considering this is a new engine rebuild, i would be putting my effort in to determining if its an engine problem.

as others have stated, sounds like venting, ring or valve stem issue to me.

you could try dropping the engine pipe and looking for oil, but considering the smoke isnt that bad, i would think that any evidence of oil would get burnt away pretty quickly.

im assuming your car is the grey r32gtr with the leather, cant remember the previous owners name, but if it is those 2530s on your car,they have already been rebuilt.

[yamaha227]

yeah thats the car... was told when i bought the car that one of the turbo's had been rebuilt not sure if it was both or not?

[vspecv]

the turbos were mine , aswell as the afms, i sold them to ben and we had 2 failures. i definately bought 1 new core and i think ben used some parts from another turbo to repair the other.

i bought these turbos, thinking they were fine and got rolled and i footed the bill to repair them.

[yamaha227]

damn... second hand turbo's are a bit like buying second hand gearboxes... time bombs waiting to go off? so your thinkin it hopefuly isnt turbo related then, do you know how long ago they were rebuilt? would be becomming very expensive turbo's if their in need of more attention!

[vspecv]

no idea how many kms ago, but probably a bit over a year from memory.

i doubt a turbo issue, a bit too much of a coincedence aswell i reckon.

[yamaha227]

hope so, not keen on pulling turbo's off and considering they were fine before the rebuild it would be very unlucky...

[DAN00H]

certainly a valve(s) stem seal problem, same thing used to happen in my 302. Old rule of thumb, smoke on acceleration = rings, smoke on deacceleration = valve stem seals.

[yamaha227]

well after a long day at the work shop still no closer but have atleast cancelled a few things out. did a dry comp test, compressions were good so didnt bother with a wet. did notice something interesting though with all the plugs out, plugs in number 3 and 4 were alot blacker than any of the others. all the rest were burning nice and clean. here are the comp results...

CYL COMP PLUG CONDITION

#1 = 160psi clean

#2 = 165psi clean

#3 = 166psi black/brown

#4 = 174psi black all over

#5 = 165psi clean

#6 = 175psi clean

comps are good, bit of variation between 1 and 6 but nothing to worry about at this stage i think. so pulled the front pipes of to cat and started the engine with a few small pushes of the throttle after it was warm and noticed that both turbo's seemed to be smoking similar amounts. which makes sense compared to plug condition. so im thinking either the fuel is not atomising well in those cylinders or the valve stem seals are leaking in those cylinders. will put a AFR meter on it tomorrow and hopefuly this will cancel out a fuel problem. any idea what sort of time is involved in doing valve stem seals with head on??

[Cubes]

Chances are you will have to by a VRS kit as the valve stem seals on their own are more expensive than the VRS kit.

For example the VRS kit I bought for my RB25head was $275.

Just for the valve stem seals they wanted $330.

[vspecv]

i think , it sounds like u have eliminated any ancilary problems.

comp test still wont 100% eliminate a ring problem, likely would pick up a broken ring or ring land, but if your problem relates to bedding in or faulty ring or rebore/hone the only way is to tear it apart.

what about a bore scope , you may see some scoring in one of the bores.

if u cant find the problem and decide to pull the head off, i would just pull the engine, u will spew if u go to all the work pulling the head off to find its the engine.

been there done that!

its starting to sound like its going to be coming out.

[vspecv]

well after a long day at the work shop still no closer but have atleast cancelled a few things out. did a dry comp test, compressions were good so didnt bother with a wet. did notice something interesting though with all the plugs out, plugs in number 3 and 4 were alot blacker than any of the others. all the rest were burning nice and clean. here are the comp results...

CYL COMP         PLUG CONDITION

#1 = 160psi           clean

#2 = 165psi           clean

#3 = 166psi           black/brown

#4 = 174psi           black all over

#5 = 165psi           clean

#6 = 175psi           clean

comps are good, bit of variation between 1 and 6 but nothing to worry about at this stage i think. so pulled the front pipes of to cat and started the engine with a few small pushes of the throttle after it was warm and noticed that both turbo's seemed to be smoking similar amounts. which makes sense compared to plug condition. so im thinking either the fuel is not atomising well in those cylinders or the valve stem seals are leaking in those cylinders. will put a AFR meter on it tomorrow and hopefuly this will cancel out a fuel problem. any idea what sort of time is involved in doing valve stem seals with head on??

doing valve stem seals with head on wouldnt be too time consuming, probably half a day at a guess.

ive still got my money on a ring problem.

(have u spoken to ben, he may be able to offer some advice)

[yamaha227]

havent spoken to ben yet but will try to call him today, one of the disadvantages of living up here... no one has any experience on these things. good idea with the boro scope, i have one at work i can use that we use to inspect gas turbine engine internals so it should do the trick. will go pick it up today and see what the bores and valve/pistons look like, hopefuly give me an idea...