No vacuum

[Capncoke]

Hey folks,

After reading lots of info on here I’ve had a play with my 09 pathy 2.5 to see if I can solve my issues - tons of black smoke from exhaust above 2k rpm, sod all power and terrible fuel economy.

I’ve replaced the fuel and air filters, and reset the ECU using the pedal method.

I suspect the SCV is toast as it has suffered a couple of times in the past 3 months whereby it won’t rev when just started but does when I restart the motor. Haven’t changed this yet however. That being said, currently I don’t have any sign of this behaviour.

The turbo actuator doesn’t move at idle or at 2500 rpm & the hose to the inter cooler doesn’t have any pressure - at least not to 2500 rpm as tested. When sucking on the actuator pipe, the arm that controls the turbo vanes moves about 10 to 15mm at a guess - not sure how much it should move or how hard I should suck...

The vacuum supply to the boost control gubbins near the air box is none existent - there is no vacuum supply (hence the actuator doesn’t move). I have replaced the vacuum hose for this, connecting it to the metal nipple on the drivers side of the engine. There is no vacuum in the new hose either, yet my brakes are definitely getting vacuum assistance as they feel very different when I cut the engine while rolling down my driveway.

Any ideas as to where to look next?

Thanks in advance.


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[ericcs]

read and try this, had the same problem!


ttp://www.navara.asia/showthread.php?t=35145

 

[Capncoke]

read and try this, had the same problem!





ttp://www.navara.asia/showthread.php?t=35145

I read your thread and see where you were losing vacuum. I have zero vacuum at that metal pipe where your broken vac hose was. It looks like there is another rubber hose that feeds the bottom of the metal tube but for the life of me I can’t quite get to look at it properly. Any idea where the bottom vac hose goes to - vacuum pump? How do I get to it without removing the engine?


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[ericcs]

ill have a look at mine in the daylight.
do your brakes feel ok, they get vacuum from the same place!

 

[Capncoke]

ill have a look at mine in the daylight.
do your brakes feel ok, they get vacuum from the same place!

The brakes are definitely vacuum assisted. However, if I pump and hold the brake pedal it does slowly sink to the floor with the engine running. I haven’t tried with the engine off. I thought that was more of a master cylinder issue than a vacuum boost issue though. With the engine off, the pedal is hard to use to stop the truck.


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[jonney]

If the brake pedal slowly moves to the floor when pressure is applied it normally is a fault in either the master cylinder or slave cylinder. it looks like you need to replace your small vacumn hoses as no doubt there is a slit / crack somewhere thats hard to find. work out the length you need and go to Supercheap Autos for this hose.

 

[Capncoke]

If the brake pedal slowly moves to the floor when pressure is applied it normally is a fault in either the master cylinder or slave cylinder. it looks like you need to replace your small vacumn hoses as no doubt there is a slit / crack somewhere thats hard to find. work out the length you need and go to Supercheap Autos for this hose.

Thanks for the info.

I have bought hose already.

I am struggling to find where the leak is so far.


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[ericcs]

see if you have vacuum at the steel tube on the drivers side, that will eliminate the passenger side. have you checked the boost control solenoid next to the air box, you can bypass it to test it, which will give max boost to the turbo

 

[Capncoke]

see if you have vacuum at the steel tube on the drivers side, that will eliminate the passenger side. have you checked the boost control solenoid next to the air box, you can bypass it to test it, which will give max boost to the turbo

There’s no vacuum at driver side steel tube (the one the vac hose to the boost control solenoid connects to).


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[Capncoke]

Here’s a photo...

There is no vacuum in either of the two metal pipes. I have tried swapping the hose and blanking plug over with no difference.

I can see what looks like rubber hoses attached to the bottom of these metal pipes - my hunch is that there is a leak in those. How do I get to them?


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[ericcs]

i didn't change any hose below what i showed in my picture, so can't help on that one!

 

[Old.Tony]

One of the hoses below (and I suspect the one in question here) should go to the vac pump. On the YD25 motor, this is driven by the primary timing chain and sits directly below the fuel pump on the right hand side of the vehicle. You will find easier access to it from below, after removing the "bash" plates.

This is where I'd be starting, given the description of the problem so far. The lack of vacuum at the top of the motor there is a giveaway. Vac to the turbo is controlled by the boost control solenoid (BCS) located on the hard pipe intercooler connector which sits roughly just below and forward of the alternator. If the BCS was at fault you'd have vacuum at the pipe pictured but no control of the turbo, and moving the vac pipe that comes across the motor from the BCS to the actuator will result in the turbo providing boost again.

If you DO try that last switcheroo though, be aware that it can overpressurise the intercooler and intake piping, so drive gently. I've had my intake hose pop off the back of the EGR when my Tillix valve (I replaced my BCS) lost its connection to the charge air pipe and the turbo decided to go well past the 24psi that my ECU could read.

 

[Capncoke]

Thanks @old.tony and @ericcs.

I found a rubber tube below the metal pipe that feeds the vacuum tubing to the BCS. I had a good feel of it with the engine idling and couldn’t feel any leaks. However the pipe felt like the rubber wasn’t in the best condition.

I didn’t replace the tubing, but went for a drive afterwards and I had boost! It lasted for about 10 minutes and then the car was back to black smoke and no boost. My theory is that the inside of that tube is disintegrating, and that my playing dislodged a blockage.

I will now replace the tube and see what happens. Will keep you posted.

Btw, I had to get to the tube from the top and my arm was really nicely wedged in amongst all the stuff in the engine bay. Not very pleasant.


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[Capncoke]

So I managed to get the hose off and put a new hose on the vacuum source. Started the car and had suction on the new hose. Then plugged it into the BCS and the turbo actuator started moving.

I was not able to put the new hose on the bottom of the metal pipe so ran it straight to the BCS.

I’ve just run a can of intake cleaner through the intake and about to go for a test drive. Hopefully I’ll have boost, brakes and much less black smoke. Will keep you posted.


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[Capncoke]

So just did a quick trip to Sydney and back. Car is pulling great and no or very little smoke once all the junk blew out of the exhaust after the cleaning spray.

I haven’t messed up the brakes with my new route for the vacuum tubing either so I’m still alive ;-)

Now I need to change the clutch - it’s slipping (again) now the power is back to normal.




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[Boogieboots]

Good news. Such pissy little things can be hard to diagnose

 

[Capncoke]

So just did a quick trip to Sydney and back. Car is pulling great and no or very little smoke once all the junk blew out of the exhaust after the cleaning spray.

I haven’t messed up the brakes with my new route for the vacuum tubing either so I’m still alive ;-)

Now I need to change the clutch - it’s slipping (again) now the power is back to normal.




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A quick update - got a new clutch fitted a couple of weeks ago. Went for SMF Exeedy and I’m very happy with it so far. I got every last bit of use from the original clutch - on way to the mechanics I couldn’t accelerate with more than about 10% throttle without it slipping. I’m not proud about it, just couldn’t afford to fix it before I did.


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