Boost / Vac
 

S80 T6 2000

I think I might have a bad TCV, but to do some testing before buying a new one I got an boost guage to check. I connected it to the small connector on the side of the double plastic pipe that feeds the intercooler. On the guage I'm getting some boost, but never any vac. I've read on alot of post about vac leaks etc, and wondered if I should be seeing vac, or if I need to connect it inline somewhere else on the car.

Can anyone give me some advise please? Should I see vac? or should I connect it up differently.

thanks

Stu

RE: Boost / Vac
 

In the pipe from the intercooler to the throttle body there is a valve with a small vacuum line tap in there. Yes you should see vacuum.

RE: Boost / Vac
 

you should be able to plumb a vacuum line to any port that comes from the manifold. on a warm engine you should be getting 20 inches of mercury with no load on the engine. i would check the source of your gauge. or the gauge itself. if you had no vacuum i would think at idle your car would be running like crap. what are your symtoms? or what is your issue, rather... do you not think that you are getting enough boost?

RE: Boost / Vac
 

Its ok, I was using the wrong pipe.

I get 15 inch's on a cold engine. I'm guessing thats still not very good?

I also had a report from volvo saying I have oil leaks around the turbo drain seals, camseal intercooler pipes and breather box.

And I also have a 'tappet' noise coming from the exhaust camshaft. On the top of the engine, there are two large disks, about3 inch's across. these look like they're designed to 'pop' out if the internal presure gets too high, the one over the exhaust has alot of oil around it. Does it sound like a oil channel could be blocked? If so, is there anything I can do without stripping the engine down to check?


thanks for all your help guys, much appreicated.

Stu

RE: Boost / Vac
 

15 inches on a cold engine is not bad.. a better way of checking is to look at it when it is warm. and then you want about 20 inches with no loads on and trans in park... and camseal intercooler pipes? there are camseals that leak and intercooler pipes are nowhere close to it... hrm..and the breather box or oil trap box or whatever it is officially called.. yeah.. they tend to leak a lot. tappet noise is probably hydraulic lifters in your engine with poor oil circulation due to neglect of oil changes and stuff...i dont think those three inch disks where meant to pop out.. i think they are just like freeze plugs, or maybe oil plugs...

RE: Boost / Vac
 

Is there anything I can do about the lack of oil to the exhaust camshaft? Any procedure's? or aditives I could use to free up some of the oil passages? I'm worried about driving the car obviously, but I need to get a steering wheel module replaces this weekend, and I need to drive about 500km's to the garage and then back again so it can pass its fitness check.

thanks

Stu

RE: Boost / Vac
 

You might have bad oil pan o-rings.

RE: Boost / Vac
 

Blimey, this is turning in to a bit of a pain in the ass. I think I bought a bit of a lemon. The service history isn't as good as I was led to beleive, but never mind.

ok, so, Oil pan O ring, breather box, turbo return seals, is there anything else on an engine with suspect service history you'd recommend with 150,000 kms on the clock please guys? I'll get the warrent done, then I think i'll take it off the road and strip it down and do all this at the same time.

Thanks for you help again with this, glad i'm gettings somewhere.

Stu

RE: Boost / Vac
 

I think thats about it just make sure you inspect everything else really good.

RE: Boost / Vac
 

Cheers Tech, I'll let you know how it goes.

Stu

RE: Boost / Vac
 

ok, 19.5 inch's on a warm engine :)

I'm getting about 6-8 PSI of boost, and it fluctuates as I accelerate. Also when I lift of the throttle, I sometime gets a sudden harsh jolt. I've heard of wastegate solinoids going bad, and something else on the turbo thats supposed to help releive excess pressure, could these be bad aswell?

I've got breatherbox seals on order to be done at the weekend. After that is turbo returns and oil sump o-rings in a month or two.

at least its keeping me out of trouble.

Stu

RE: Boost / Vac
 

i think you are supposed to get more boost then that.. if im not mistaken around 12psi at closed loop. the ecu may be limiting the boost for some reason. do you have a ses light on? and what kind of "jolt" are we experiencing?? do you get a jolt of electricity? or a jolt noise or jerk?? and the boost control solenoids do go bad like anyother solenoid would... but i think it would result in excessive boost ... they close and wastegates are acuated to relieve boost. seems as though the ecu sees something and limits the boost. im doing the best i can reading through your notes. it would be much easier if i was looking directly at the car...

RE: Boost / Vac
 

yeah, I know what you mean, I'm a sys admin, trying to troubleshoot over the phone is a PITA, but I can't afford your flight to New Zealand. :)

Its a mechanical jolt, like being hit up the rear. Its not vicious, but you can deffinately feel it, like a sudden surge in power.

I've got no lights on the dash, and no codes have been stored either (got volvo to check for me)

Stu

RE: Boost / Vac
 

new zealand?? im in kentucky..

RE: Boost / Vac
 

I'm jealous, some of the shops you guy shave overt here is great, and the prices kick the arse out of ourws :(

Anyway, I did the breather box clean this weekend which went well. After driving it for the first time, it seems like the turbo's aren't spinning up ( I think I might have missed a connector or something, but I'll work on it later), but what I did notice was that I wasn't getting the jolt any more.

So my question is,

What in the turbo system could cause a surge of power when you lift off the accelerator? Could it be whatever should release the pressure?

cheers

Stu

RE: Boost / Vac
 

You can try this additive to free up the oil passages. It gently dissolves sludge. I believe they ship internationally: http://www.auto-rx.com/

RE: Boost / Vac
 

You should be getting about 12 psi. I think maybe your TCV is out. When it goes the system defaults to the low pressure you are seeing. You can get a heavy duty one here for less than factory cost (the listing says S60 but it will work on your car): http://www.ipdusa.com/Volvo-S60/New-...p-74-815-4235/

RE: Boost / Vac
 

Check all the turbo hose clamps to make sure they're tight.

Have you inspected the engine mounts?

RE: Boost / Vac
 

i just had the bcv go bad on my car, and an aftermarket ipd unit is not too expensive and ive read it is far superior. so they probably go out a lot and would guess that yes, it could be very well your problem to be addressed. id get a new one from volvo or upgrade and see what happens then...

RE: Boost / Vac
 

Excellent, thanks for the advice guys, I'm going to get the IPD unit, love the fact you can take it apart and clean it.

Stu