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Rb25Det Exhaust Smoke

rb25debt

By rb25debt,
in Engines & Forced Induction

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rb25debt Contributor

rb25debt

Posted
Posted

So two days back i started my car first thing in the morning to warm up. I went inside and came back out after 5 minutes and noticed smoke lingering from my exhaust, it looks blue so im assuming its oil. I gave it a little revs and it stopped smoking, i drove to work, no smoke. On acceleration there is no smoke, it only happens first start of the day. There is no oil in my catch can nor is there any really in my intercooler piping. I am going to check the turbine housing for oil tonight. Does this sound like rings, valves or turbo? thanks guys

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rb25debt Contributor

rb25debt

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  • Author
Posted

Im replacing my turbo now but the nuts that hold it to the manifold are very weak and are starting to round, i can't fit a socket or a spanner completely around them because the nuts are placed so close to the inlet and there is not quite enough room to fit around them. I don't want to use a crescent spanner as im sure that will just round it

chiksluvit Experienced

chiksluvit

Posted
Posted (edited)

From memory they were 17mm? I didn't find it hard to undo them, just used a 17mm spanner

They're made by some special material so doesn't rust and stick to the studs. Pretty sure I used the ring end to crack them and just undid it with finger

Have done that on 3 r33s and they've all been the same

Edited by chiksluvit
Kinks Grand Master

Kinks

Posted
Posted

So two days back i started my car first thing in the morning to warm up. I went inside and came back out after 5 minutes

You really hate your car don't you.. letting a cold engine idle for several minutes is one of the WORST things you can do for engine wear.

Start it, wait for oil pressure (5-10 seconds), then drive it gently until warmed up.

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SargeRX8 Grand Master

SargeRX8

Posted
Posted

You really hate your car don't you.. letting a cold engine idle for several minutes is one of the WORST things you can do for engine wear.

Start it, wait for oil pressure (5-10 seconds), then drive it gently until warmed up.

Can you elaborate on this?

Kinks Grand Master

Kinks

Posted
Posted

Can you elaborate on this?

The best thing for an engine, no matter what, is to be at operating temperature. With the engine, coolant and oil at operating temperature there is virtually no wear because everything is working as it should. That's why taxis commonly do 500,000km on the original engine - they are never stopped for long enough to cool down. Our skylines also have water/oil heat exchangers - effectively the coolant is used to heat the oil and get the oil up to operating temperature as soon as possible.

When your engine is cold, the components (pistons, rings etc) have larger clearances. This lets more of the cylinder mixture bypass the rings and contaminate the oil. Cold cylinder walls also condense the fuel mixture which makes this effect even more pronounced.. Oil that is diluted by fuel does not lubricate well, and in any case oil that is below its operating temperature is not an optimal lubricant either.

If you idle an engine, the engine is producing the minimum amount of combustion necessary to maintain a stable idle. There is no load on the engine whatsoever, you may think that this is better because no load = no wear right? Well.. everything in the engine is constantly moving and sliding past each other so the longer this goes on in a non-optimal state the higher your wear. In fact, many diesel motors produce so little waste heat on idle that you could idle them for an hour before they warm up. Obviously this is not good!

The best way of treating your engine is therefore to start it, let oil circulate to all the components (oil pressure light goes out) and then drive it off in a gentle manner keeping the revs below 3000RPM and avoiding loading it heavily. High RPM and heavy load will cause additional wear but lightly loading the engine produces MUCH more waste heat, gets the temperature up to operating point and everything works as it should. Letting a cold engine sit there idling for 5-10 minutes is absolutely pointless.

GTSBoy Grand Master

GTSBoy

Posted
Posted

i'm not sure i agree with it....isn't this why they have multi-grade oil...this may be true if you run single weight oil.

It has less to do with the oil viscosity than it does with the engine running cold with big clearances and the blowby/condensation problems. It is perfectly valid.

Nevertheless, my behaviour in this respect is varied. In the morning I start my car and push it out of its spot so I can access the other side to load up my laptop bag and lunch and so on. Walk back inside, kiss the ruggies, pat the dog, kiss the wife. Go to the back end of the house and pick up whatever I forgot to bring to the front (lunch, coffee beans, whatever). Go back to the front, remember I forgot something else, go back to the back. So the car ends up running for 2 or 3 minutes before I drive away. The downsides of that are elaborated in posts above. The upside is that the car comes to full operating temperature a lot closer to home than if I drive it away from cold, and seeing as I get to an 80km/h merge after only 1 minute from the driveway, it's nice that the car's not stone cold.

On the drive home from work, I start it, back it out, drive it away cold and gently.

GTSBoy Grand Master

GTSBoy

Posted
Posted

so cold start fuel enrichment is the solution for what kinks was saying about minimal fuel injected at idle?

Um what now?

If what you're asking is if the enrichment is there to make more heat to overcome the lack of heat....then no. It is there because the engine won't run when dead cold without it (or rather, won't run nicely, will stumble and hesitate and carry on). Running rich actually ends up generating less heat anyway, as the excess fuel is dead mass that has to be evaporated and heated up to flame temperature, thus reducing the flame temperature.

Badgaz Experienced

Badgaz

Posted
Posted

no i guess what i'm saying is that its not a minimal amount of fuel at idle its actually more than when the engine is warm and idling which when sitting in gridlock e.g. i guess i can't see what difference it makes in terms of how long you take to get your car to temperature...but my opinion is that moving from cold to hot too fast is bad for anything.

Kinks Grand Master

Kinks

Posted
Posted

no i guess what i'm saying is that its not a minimal amount of fuel at idle its actually more than when the engine is warm and idling which when sitting in gridlock e.g. i guess i can't see what difference it makes in terms of how long you take to get your car to temperature...but my opinion is that moving from cold to hot too fast is bad for anything.

Cold start enrichment is only a few percent and just enough to compensate for fuel condensing on cold cylinder walls.

There is a MASSIVE difference in the fuel requirement for actually moving a ~1500kg lump of metal compared with making the engine continue spinning of its own accord with no load on it.

Engine temperature changes from 20C to 85C over the course of 3-5 minutes. This is slower than boiling some water in a kettle so I don't know why you're hung up on things warming "too fast". When petrol burns, the cylinder temperature shoots up a few hundred degrees in milliseconds, if you're that worried about things going from cold to hot perhaps you should drive an electric car?

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