Engine hard start.

[Rabbie Tewe]

Hi

I have this problem with my Nissan Navara D40. Its started some weeks ago to blow out black & white smoke and then last week Saturday i noticed that the engine oil was getting low too soon after topping up.
On that same day i was driving down hill on 4th gear and I heard rattling noise coming from the front of the engine bay. Then suddenly the engine revs up by itself without my foot on the accelerator.
I quickly switch off the engine and roll down hill and parked on the road side.
I tried starting it but it just cranked and didn't start.
Then I Opened the hood, look in the engine bay checking for anything broken of fired up.. nothing...then i checked the engine oil and no indication of oil presence in the engine. The dip stick was totally dry.
I called up a tow truck and towed it home.

Guys i have no mechanic experience. Please help me locate the problem.
Thanks.

 

[Old.Tony]

If it's not leaking oil underneath the engine, then the leak is going either into the engine (possibly the PCV) or the exhaust (probably the turbocharger). The run-on you experienced would seem to indicate it's the PCV more than the turbo.

PCV - Positive Crankcase Ventilation - is how the gas that slips past the piston rings (called "blow-by" ) gets out of the crankcase area. Without this, the pressure will pop your oil dipstick and vent the crankcase oil ...

The problem is the crankcase oil gets heated by this blow-by, turned into vapour and heads out of the PCV. Many people install catch cans to intercept the oil while still allowing the exhaust gas itself (which is what blow-by really is) to enter the combustion chamber. A diesel engine will happily run on its own oil and diesel runaway is caused by excessive blow-by vapourising large amounts of oil which is evacuated through the PCV into the intake, combusted (without any regulation of the speed) and creating even more blow-by - a vicious circle that can only be stopped by either disconnecting the PCV or shutting down the air intake. Just a word on that: do not EVER try to block the air intake with your hand. Our diesels draw 2.488 litres (at zero boost) every 2nd revolution, so at idle it's pulling about 2.5*375 = 937 litres of air per minute. Needless to say, during a runaway it's not idling - it's doing over 5,000rpm so it's breathing 6250 litres per minute. It will rip the skin from your hands, and a cloth isn't strong enough. You really only need to inhibit the airflow enough to inhibit combustion and putting a shoe or a book or something like that over the intake (if you have a snorkel, this is) is quite effective and safer than using your body!

So, step 1 - find out how much oil is coming out your PCV. Crack the hose that goes from your intercooler to the intake manifold and wipe your finger inside it. It should come away with a small amount of black liquid (oil + diesel soot). Clean this section of hose with a rag, reinstall, take the car for a brief drive (15 minutes tops). Crack the hose and check it again. Lots? Little?

If you're getting a lot of oil out the PCV, either you're got massive amounts of blow-by (stuck rings, worn bores) or the oil cooler in the top of the motor isn't working well. Let's see how much you have first, then we'll go from there.

If it's the turbocharger (so the PCV isn't gushing oil), the turbine-side bearings are probably cactus and oil is leaking past the seal into the exhaust stream. It will mostly burn there, but it does mean your turbo either wants a rebuild kit or a replacement. I suspect this is NOT it, because of the overrun.

 

[Rabbie Tewe]

Thanks mate.
I'll do that tomorrow and get back to you.

I just have 2 questions in mind, is it possible for the engine oil to burn out in the with fuel if there's a worn out seal on the injectors?
Is a failed fuel injector could cause the hard start?

 

[Rabbie Tewe]

Oil also leaking out here...out the rubber cone seal for the line in for injectors.

 

[Rabbie Tewe]

fairly some engine oil comes out here under the turbo.

 

[Old.Tony]

Replacing the seals around the injectors would be a good thing to do. Oil leaking from those seals won't make it inside the engine.

The oil leaking around the turbo might be caused by a couple of different things, thankfully not all expensive.

If the person who installed the turbocharger put too much gasket sealant on the oil evacuation face (where the pipe goes back down to the motor), the turbo will fill with oil. It's fed to the turbo under pressure, but returned to the sump by gravity. Excess gasket sealant on the interface causes a lip which holds oil and impedes flow, and with crankcase pressure pushing up from below, creates dramas with oil forcing it out the bearings (usually the turbine bearing, which means it will enter the exhaust and not be visible to you).

You might also try and see if there's oil coming out of the oil inlet side of the turbo (underneath, in between the turbo halves, it's not easy to get to). It might just be that join has a problem (loose, worn gasket etc).

 

[Rabbie Tewe]

Good morning mate.

Thanks so much for the info. I will do what you mentioned above and also take some photos and revert.

 

[Rabbie Tewe]

See what I've found in the intercooler hose that connects to the intake manifold

 

[Rabbie Tewe]

That's inside the intake manifold.

Is that normal?

 

[peter robbo]

View attachment 36009
That's inside the intake manifold.

Is that normal?

fit a catch can

 

[MANNING]

View attachment 36008
See what I've found in the intercooler hose

would suggest a catch can too
but id be wondering how much oil is going in between changes.. its fairly easy to overfill

 

[Rabbie Tewe]

I took out all the hoses and and the intercooler, clean washed with petrol fuel, refitted and still it cranked but didn't start. I'm suspecting the fuel injectors..the first one in front is also leaking out oil and might gone bad.

 

[Rabbie Tewe]

fit a catch can

Where can i fit the catch can mate?

 

[MANNING]

Where can i fit the catch can mate?

run in inline with the pcv hose coming out from the top/back of the motor
run enough hose so you can install the can away enough from the heat of the turbo and hopefully where it will catch some cooling air.
sorry about my previous post.. i only really only saw oil in the intercooler and responded to that

 

[peter robbo]

i dont have one on my d22 yet, on list of things to do but i reckon you might find some posts on this forum re: catch cans. Its been recommended to steer clear of the el-cheapo ones.

 

[Old.Tony]

The oil in the intake lines is normal but as suggested, a catch can is a good upgrade.

There's a hose - about 25mm (1 inch) in diameter - that runs from the top of the motor at the rear, to the plastic air intake pipe that connects to the turbocharger (this is the PCV hose). This hose may have some foil-like insulation around it. To install the catch can, unplug this hose from the air intake side (not the engine side) and connect the hose to the intake of the catch can. Get another hose and connect it from the outlet of the catch can to the spigot that the original hose came off. Basically the catch can goes into the PCV hose. It's designed to catch the oil that you've discovered in the intake pipe.

Catch cans that are completely empty are not very efficient, because to catch the oil you need the oil to condense on the inner surface inside the can. The oil is coming through as a mist (vapour) and it must be cooled to return to liquid state. An "empty" catch can will still allow some oil to pass through the hosing and the intercooler. Adding stainless steel scourers to the inside of the catch can may assist here, reducing the amount of oil the catch can misses by providing more internal surface area, but this will reduce the capacity of the catch can.

 

[Rabbie Tewe]

Thanks everyone for your supportive feedback. I will install the catch can after i changed the fuel injectors.
After cleaning up the intercooler and the hoses, i put everything back but still it didn't start so i suspected that the fuel injectors might gone bad. As you can see the two on the side are totally burnt out.

Is it possible to just repair them and reinstall? Coz it's too expensive for me to buy new ones.

 

[Rabbie Tewe]

Can i just change the bottom part of the injectors?

 

[Old.Tony]

I don't know, I've never done it. General recommendation is to replace the injectors as they are precision components, withstanding significant pressures (up to 24,000 psi or 1700 BAR).

However, it can obviously be done. Here's a video I found on general Denso injector rebuilds, I hope it helps. It is a bit dry, and my guess is that the voiceover is done by text-to-speech because it's quite robotic, but it might help you.

 

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test the compression... if it used that much oil ,,,if one injector is seal is leaking compression and its effecting the rail pressure then the computor could be stopping the car from starting,, you can spend a lot of money by changing parts that are still working