Jump to content
SAU Community

Recommended Posts

Hey guys,

I've noticed white smoke coming from my exhaust the last couple of times I've driven down Bulli pass when I stop to turn left on Lawrence Hargrave drive. It doesn't do it any other time except coming down that hill which is a pretty steep grade - 1 in 6 I think its posted as.

My car is a r32gtst with an rb25, 3071r turbo, injectors, power fc etc. The engine and mods have only seen about 40000km in three years since the conversion. It does not appear to be using more oil than usual, coolant levels are good also. I have checked most vacuum/boost lines and I don't their is any air leak.

Any idea what could be causing the smoke??

Thanks

Mick

Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/
Share on other sites

I had a problem with my gtr where it would blow smoke out of the exhaust on engine brake going down hill. It was a leaky rear turbo seal, leaking oil into the hot exhaust. You dont notice the oil level a it only needs a couple of drops in a hot exhaust to smoke like crazy.

Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/#findComment-7320605
Share on other sites

I dont think it was particularly cold outside, maybe low 20s, would that be considered low??

Also I know the turbo was brand new when I did the conversion and upgrade, well when the workshop did the upgrade and conversion, I also got them to replace all coolant hoses on the engine, rear main seal on the engine, new water pump, timing belt cam seals etc, basically everything was replaced with new while the engine was out and easy to get to, however the engine itself wasnt opened up. It was a low km 2nd hand series 2 rb25 so I was told. It was a known workshop, but has since closed down, but the owner now works at a powertune. Im sure the seals for the turbo to exhaust would have been new also if thats what you mean??

I will prob take it to powertune - where the owner now works as he knows the car, just trying to get an idea of what the problem could be, hence how much I am looking at to getting it fixed as money is kinda short at the moment.

Thanks for your help guys so far

Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/#findComment-7321120
Share on other sites

On over-run with throttle closed, the engine will pull max vacuum.

Worn valve stem seals will allow oil to be sucked down the valve stem into the combustion chamber.

Worn guides make the whole show even worse.

These engines are getting old and often the valve stem seals, if they're still there, have gone brittle.

You probably find under normal driving, you wouldn't see any smoke but a long downhill is a good test.

Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/#findComment-7321398
Share on other sites

Ah ok thanks for the explanation.......yeah if you know the road its a long steep downhill run. I rarely touch the accelerator pedal so what your saying makes sense to me. Expensive fix?, while the seals are getting replaced, what else should I be doing/replacing to keep the engine maintained?? would the car need a retune after??

Edited by mii11x
Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/#findComment-7321435
Share on other sites

Don't forget this is just an internet diagnosis, would pay to have a hands on inspection for verification.

Valve stem seals can be done in situ, but it's a fair old job.

Cams, lash adjusters and so on out which automatically means cam belt etc all off. (so it's the ideal time to do that service)

Don't mix up the lash adjusters, they go back exactly where they came from.

Then systematically work on each pair of TDC cylinders.

With the crank locked, spark plug out, adaptor fitted and pressurise the cylinder.

Using your Snap-On tool, remove the valve collets, spring and you'll be looking at the old valve stem seal.

Remove old seal and fit new one. (check inlet V's exhaust valve seal, they may differ)

Spring etc back on, collets in your Snap-On tool and whack……. that one's done.

Only 23-more to do.

You'll do 8-each time then rotate the crank to your next TDC, lock it and go again.

Very important, TDC and crank locked.

I think I could live with a bit of smoke on over-run, don't you?

Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/#findComment-7321472
Share on other sites

Won't need a retune.

It is possible to replace the seals woth b the head on. Which will seriously reduce the costs.

As for how much no idea. I would do it myself.

Obviously thing to do is ring a mechanic.

Edit..

Beaten

With way more info!

Edited by Ben C34
Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/#findComment-7321473
Share on other sites

Yeah, I couldnt attempt this myself. My mechanical abilities are limited to general servicing lol - the biggest thing ive done myself is replacing a water pump when I had the rb20 in it and swapped over the shocks/springs to coilovers twice. It just looks embarrasing really, like I dont look after my car. Looks like I will be waiting for my mates brother to return for a couple of months.

Link to comment
https://www.sau.com.au/forums/topic/444833-smokey-exhaust/#findComment-7321482
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • First up, I wouldn't use PID straight up for boost control. There's also other control techniques that can be implemented. And as I said, and you keep missing the point. It's not the ONE thing, it's the wrapping it up together with everything else in the one system that starts to unravel the problem. It's why there are people who can work in a certain field as a generalist, IE a IT person, and then there are specialists. IE, an SQL database specialist. Sure the IT person can build and run a database, and it'll work, however theyll likely never be as good as a specialist.   So, as said, it's not as simple as you're thinking. And yes, there's a limit to the number of everything's in MCUs, and they run out far to freaking fast when you're designing a complex system, which means you have to make compromises. Add to that, you'll have a limited team working on it, so fixing / tweaking some features means some features are a higher priority than others. Add to that, someone might fix a problem around a certain unrelated feature, and that change due to other complexities in the system design, can now cause a new, unforseen bug in something else.   The whole thing is, as said, sometimes split systems can work as good, and if not better. Plus when there's no need to spend $4k on an all in one solution, to meet the needs of a $200 system, maybe don't just spout off things others have said / you've read. There's a lot of misinformation on the internet, including in translated service manuals, and data sheets. Going and doing, so that you know, is better than stating something you read. Stating something that has been read, is about as useful as an engineering graduate, as all they know is what they've read. And trust me, nearly every engineering graduate is useless in the real world. And add to that, if you don't know this stuff, and just have an opinion, maybe accept what people with experience are telling you as information, and don't keep reciting the exact same thing over and over in response.
    • How complicated is PID boost control? To me it really doesn't seem that difficult. I'm not disputing the core assertion (specialization can be better than general purpose solutions), I'm just saying we're 30+ years removed from the days when transistor budgets were in the thousands and we had to hem and haw about whether there's enough ECC DRAM or enough clock cycles or the interrupt handler can respond fast enough to handle another task. I really struggle to see how a Greddy Profec or an HKS EVC7 or whatever else is somehow a far superior solution to what you get in a Haltech Nexus/Elite ECU. I don't see OEMs spending time on dedicated boost control modules in any car I've ever touched. Is there value to separating out a motor controller or engine controller vs an infotainment module? Of course, those are two completely different tasks with highly divergent requirements. The reason why I cite data sheets, service manuals, etc is because as you have clearly suggested I don't know what I'm doing, can't learn how to do anything correctly, and have never actually done anything myself. So when I do offer advice to people I like to use sources that are not just based off of taking my word for it and can be independently verified by others so it's not just my misinterpretation of a primary source.
    • That's awesome, well done! Love all these older Datsun / Nissans so rare now
    • As I said, there's trade offs to jamming EVERYTHING in. Timing, resources etc, being the huge ones. Calling out the factory ECU has nothing to do with it, as it doesn't do any form of fancy boost control. It's all open loop boost control. You mention the Haltech Nexus, that's effectively two separate devices jammed into one box. What you quote about it, is proof for that. So now you've lost flexibility as a product too...   A product designed to do one thing really well, will always beat other products doing multiple things. Also, I wouldn't knock COTS stuff, you'd be surprised how many things are using it, that you're probably totally in love with As for the SpaceX comment that we're working directly with them, it's about the type of stuff we're doing. We're doing design work, and breaking world firsts. If you can't understand that I have real world hands on experience, including in very modern tech, and actually understand this stuff, then to avoid useless debates where you just won't accept fact and experience, from here on, it seems you'd be be happy I (and possibly anyone with knowledge really) not reply to your questions, or input, no matter how much help you could be given to help you, or let you learn. It seems you're happy reading your data sheets, factory service manuals, and only want people to reinforce your thoughts and points of view. 
    • I don't really understand because clearly it's possible. The factory ECU is running on like a 4 MHz 16-bit processor. Modern GDI ECUs have like 200 MHz superscalar cores with floating point units too. The Haltech Nexus has two 240 MHz CPU cores. The Elite 2500 is a single 80 MHz core. Surely 20x the compute means adding some PID boost control logic isn't that complicated. I'm not saying clock speed is everything, but the requirements to add boost control to a port injection 6 cylinder ECU are really not that difficult. More I/O, more interrupt handlers, more working memory, etc isn't that crazy to figure out. SpaceX if anything shows just how far you can get arguably doing things the "wrong" way, ie x86 COTS running C++ on Linux. That is about as far away from the "correct" architecture as it gets for a real time system, but it works anyways. 
×
×
  • Create New...