2003 XC70 Turbo Overboost? Really?

Post by **hansenjg** » 02 Jun 2015, 17:56

OK. So this past weekend I took apart and cleaned my PCV system. Long job, found lots of blockages, the oil trap was a mess (so I replaced it with a nice clean one from the parts car) but I got it back together. Ran great for 45 minutes until it just died. Had it towed. Shop found the Turbo tube that runs from the turbo behind the engine to the intercooler had popped off. I figured I had failed to tighten the clamp when I put it back together. Picked up the car and it ran for half an hour and died. Same shop, same problem. Mechanic thinks maybe I'm getting too much boost which is blowing the tube off the turbo. I'm thinking not likely. Cleaning the PCV should not create that situation, right? He says there seems to be a lot of oil in the turbo line (I cleaned a fair amount of residual oil out of the turbo tube) and he is afraid to touch it. He wants me to take it to the dreaded dealer. I'm thinking, 1) maybe the turbo tube hose clamp is just not tightening up enough, as it's the original or 2) there is oil in the turbo itself and that is causing overboost? or 3) the turbo has been compensating for the dirty PCV and has been overboosting for some time (but I don't pretend to understand how that could actually happen). Any ideas? I am out of town until Friday when I'll go pick it up. I'm hoping this is an easy "non dealer" fix.

Post by **abscate** » 03 Jun 2015, 04:16

If the waste gate isn't functioning the turbo could overboost, but the turbos on these cars is pretty bullet proof. Are the turbo to intercooler hoses soft or spongy?

Post by **hansenjg** » 03 Jun 2015, 05:43

The hose that runs from the turbo tube to the intercooler seemed fine. Might be a little spongy, but certainly not significantly. Since I bought this car about a year and half ago I have noticed the turbo is pretty noisy. High pitched whine at any rate of acceleration. But it has always run fine and the mechanics who have looked at it (a couple of them are really good) have not mentioned it. Nothing I did to the PCV system would have affected the waste gate, right?

I'm putting my money on a bad hose clamp at the turbo/tube junction.

Post by **JDS60R** » 03 Jun 2015, 10:26

Check the junction and clamps. Clean everything up before you install new parts.
Clamps can fail also so be on the lookout for that as well.

A noisy turbo isn't a good sign.
Check the turbo, by removing the pipe between the turbo and MAF. Check the play on the compressor wheel and see if you can easily get it to touch the compressor housing. These turbos routinely fail, in my experience ( especially with average maintenance -especially non synth oil use) around or before 175K. The hotter the climate the sooner the failure.

But the good news is you can buy a rebuilt balanced center cartridge (CHRA) for under $400 and slip it into the housing in a weekend.

I would inspect your turbo so if it is rubbing then you can replace it before it grenades. I can walk you through it or there are write ups already available.

Lets put a boost gauge on the manifold and see how much boost we are making if we still suspect overboost.. To test I take a vacuum/boot gauge that can read up to 20-30 psi and run a vacuum line long enough to bring the gauge into the car - through window - or tape it to the windshield ( for test only - obviously) .

Let us know the readings and we will help diagnose the overboost - if it exists.

Good Luck,
John

Post by **hansenjg** » 03 Jun 2015, 10:57

Thanks John. I am picking it up on Friday when I get back home. I think I have a gauge to test the boost, so I'll try to do that this weekend. Where do you connect it to the manifold? I can't believe I am suddenly getting overboost, but it's worth looking at.

I will install a new clamp before I drive it away from the shop.

Thanks for the suggestion on checking out the Turbo. I'll do that soon as well. The car came to me 3rd hand last year and with the condition of the PCV trap, I'm quite certain the maintenance was marginal at best with previous owners. Still have a lot to do before it's where I want it.

Post by **JDS60R** » 03 Jun 2015, 12:26

connect to the manifold. On that car its on drivers side of manifold (rear of main ,crosswise runner,on right - not the big hose - the little one pointing towards back of car). Open the hood its on the right - there is a little port behind the main runner. - I think you should T into that line .

Post by **hansenjg** » 04 Jun 2015, 08:18

Thanks. I will post what I find out tomorrow.

Post by **hansenjg** » 16 Jun 2015, 06:48

Car is running fine. I put a new clamp on the intercooler line, no more problems. No overboost, as we figured. Turbo is still a little "whiney" but no more than it was before. Now that I have the PCV system cleaned up, it's time to get the camshaft seals replaced.