1999 S70 AWD -Did PCV, throttle won't seal & new oil leak

rodrigo67 · Post by **rodrigo67** » 09 Apr 2014, 12:27

Recently replaced PCV in my '99 S70 AWD turbo (engine B5254T). The PCV & tubing itself was not an issue, but I'm having a HECK of a time getting all the intakes/vacuums sealed up. Have had the intake manifold off three times now in search of my leak (I'm getting pretty good at it), and finally figured out I'm not getting a seal between the throttle body and intake manifold.

I'm a pretty accomplished DIY mechanic, but am new to Volvos. I reviewed lots of DIY videos & posts before tackling the PCV, so I felt really confident going into it. But when I opened the hood with wrench in hand I was surprised to see how differently my intake was configured. I carefully went about the job, dismantling what was in my way as I went. I first tried to remove the manifold with the throttle body installed, but when that went poorly I separated them. I confess that I did not make note of the throttle body's orientation when I took it apart.

So the really dumb question is whether it is possible to install the throttle body backward? Is this why I can't get a good seal? I did pick up a new OEM gasket from the dealer. I oriented the unit the way I did because it seemed a more comfortable fit for the wiring harness, but noted that the unit's label faces inward this way, toward the engine, which doesn't seem right.

The car will run, albeit poorly, sucking air madly and popping all the time.

After messing around for some time with the poorly running car I discovered a small puddle of oil beneath the area of the turbo. I haven't crawled under the car yet to verify, but there isn't much else back there from which oil could drip. This is a new, pretty significant leak. Is this caused by the PCV change? It does not seem intuitive to me that a freely breathing crankcase would force a new oil leak, so does this mean I did something wrong with the PCV?

All advice is appreciated.

Post by **jblackburn** » 09 Apr 2014, 13:21

Does your throttle body face the same way that it does in this write-up?

https://www.matthewsvolvosite.com/forums ... =1&t=55413

A significant oil leak from the turbo area makes me wonder if that rear cam seal (behind the cam position sensor) may have popped out. Otherwise, the drain, etc. shouldn't be leaking if it wasn't before.

rodrigo67 · Post by **rodrigo67** » 09 Apr 2014, 13:35

Sorry. I should have done a better job describing my set-up. My manifold/throttle setup are very different than in that write up. I wish I had a picture...

My manifold mostly extends straight toward the radiator (as opposed to turning downward in the photos included in the link), with the throttle body bolted on from beneath.

That was my first surprise when I started the job. I reviewed that very thread in preparation. My manifold/throttle are completely different.

Post by **jblackburn** » 09 Apr 2014, 13:37

Oh, okay. Yeah, I forgot the 1999 turbo setup had the TB underneath. Sorry - hopefully someone can help you there!

rodrigo67 · Post by **rodrigo67** » 09 Apr 2014, 14:13

Here is my intake/throttle setup. The throttle bore is a little off-center in the picture, and I arranged mine accordingly when reinstalling, but I can't get it to seal to save my life. I know how it feels when a bolt is nearing "too tight"... learned that the hard way many moons ago.

So what is the trick I'm missing?

: IntakeManifold.jpg (57.81 KiB) Viewed 928 times

Post by **burnout8488** » 09 Apr 2014, 16:58

You should be able to see the sticker looking at the throttle body straight on standing in front of the car. (Should be white or yellow)

There's really no trick, it's just four bolts holding the throttle body on… There was no need to remove it for the PCV system maintenance either.

rodrigo67 · Post by **rodrigo67** » 09 Apr 2014, 20:06

Wow... I sure wish I had checked the forum before I went out to mess with it again after dinner tonight. I removed the radiator fan and was enjoying all the extra room to work. Was gently snugging up the bolts alternately when I heard that sickening 'pop'.

: throttle body sm (1024x576).jpg (325.67 KiB) Viewed 913 times

On the bright side, I figured out conclusively that my throttle should be oriented exactly as burnout's photo indicates. Which seems to be exactly opposite the way the parts diagram indicates.

So my options, it seems, are to spring for a new throttle body (foregoing the core charge)... or try to get this to where it will hold air reliably. Wonder if this can be sealed up somehow? Can an aluminum casting like this be brazed? I'm open to ideas.

Post by **burnout8488** » 10 Apr 2014, 09:25

Yikes.

Well, has it ever been replaced before? Yellow label or white label? (White = original)

It's gonna fail eventually anyways, regardless. You might as well replace it now with a known good used (yellow) unit, or spring for a Xemodex that won't ever fail again.

Chances are you'd have to mess with this again at some point.

rodrigo67 · Post by **rodrigo67** » 10 Apr 2014, 20:42

The label on the side of the unit is white, but there is a yellow band around the wire harness. I think this means it's original?

The ETS light has come on & off over the last several months, though it is mostly off. I figured out some time ago that I was likely to have to pop for a new unit somewhere along the line.

But I have more to report.

So as I was sitting at my kitchen table staring forlornly at my throttle body I realized that the deformation is primarily outside the area where the throttle body contacts the manifold. I also realized that this really just needs to support fairly light pressures. It's not like this is a combustion chamber. So I decided I had nothing to lose by putting it in and starting the car.

And it works. The car is running beautifully.

I can't detect any kind of suction sound or vacuum leak from the area of the crack. I took it for a decent drive in town. It seems to be behaving perfectly. As far as I can tell, the throttle gets fairly warm, but not particularly hot -- so I'm wondering how big a part thermal movement may play in the longevity of this situation?

So the lesson from all this is that a lot of pain and suffering can be avoided when you make careful notes as you take stuff apart. I've learned this lesson many times over the years, and apparently needed a refresher.

Post by **burnout8488** » 10 Apr 2014, 21:16

I would keep it on if I were you too. That crack doesn't seem to be affecting anything at the moment.

Although if you saw an ETS light even once, it'll only get worse. If you have a junkyard nearby, go and get as many yellow-label TURBO ONLY ETMs as you can. It's always good to have a few as backup. Even one junkyard unit might outlast the car. $40 here and there rather than $500 upfront is a better investment.

(99+S80 T6, S70/V70 T5, GLT, C70…etc. will all work as long as they're the big Magnetti-Marelli style ETM)