This 2005 Volvo XC70 was recently purchased by my cousin for his grandkids who just got their license. They bought it extremely cheap and although the body it is excellent shape for a 20-year old car with 309k miles, it had some issues. Upon talking to my cousin, the guy he bought the car from had it to two different shops and they couldn't figure it out and my cousin being a mechanic himself thought he'd buy it cheap and get it running. I had several phone conversations going over some "possible" causes based on the symptoms, but without having my hands on it and seeing what the data was telling me, I was merely guessing, plus, I know nothing about Volvo's, but there's still and internal combustion engine there and they all need the same things to run.
After several phone calls he was getting frustrated and just wanted me to look at it, and although I really don't have the time right now, I looked at it as a learning opportunity and agreed to take it in.
It ran pretty good when they dropped it off and had no DTC's present. I was informed that it mainly ran rough and occasionally stumbled and died at idle when cold. Once it got above idle speed if you could "nurse" it to about 1200 RPM, it ran pretty good and even idled well once it warmed up. Upon dropping it off Monday night I threw the scanner on it and watched some live data but it really wasn't revealing anything obvious to me. The idle control was moving a bit more than I thought it should, but it was in fact moving and compensating so I thought we could take the IAC out of the equation, but upon inspecting it looked like they had already replaced it with a new one. I also saw all new PCV hoses and valve as well as new injectors.
Last night with it being cold, I ran it and watched live data again and nothing really jumped out at me, but then again, it wasn't all that cold as I keep my shop at 50-degrees overnight and then bump it to about 62 when I get home to work in it. It stumbled a bit upon cold start, but not terrible.
No DTC's set nor pending and nothing in the live data jumped out at me.
One of the things I suggested he looked at were vacuum leaks, which is kind of where my mind was going, so I hooked up the smoke machine.
Just used an expanding bellow in the intake duct from the air box.
And the thing smoked liked a chimney. Smoke was pouring out of the bellows/flex joint just aft of the air box.
And was REALLY smoking down near the turbo inlet and where the PTC (Positive Temperature Coefficient) valve and hoses connect. WOW! There was a LOT of smoke, so much in fact that even with a mirror I couldn't identify all the areas smoke was emitting from.
With the intake duct removed, I double checked to see what the turbo impeller looked like to ensure it wasn't damaged or appear to have had any foreign material hit the blades and it seems fine. Spins freely as well.
I noticed a couple of wires that have the poly loom destroyed from the heat, and >300k miles, so I will address those while I'm in there.
The intake duct was not the easiest to gain access to the that lower clamp on the turbo. I nearly racked it to see if access from underneath would be better, but I ended up being able to get a flex head 1/4" ratched on it and slowly backed the tension on the clamp off.
There's the culprit.
My initial thinking was that to try to save them some money I'd see if I could melt the leaks back together in the bellows and see if I could seal up the area leaking around the PTC assembly, but my fear is that although I could more than likely repair the leaks on this one that are present now, upon reinstalling or just the next couple hundred miles, who could say that another one or more could potentially develop and we'd be right back here. I figured a 20+ year old car the part would be an unobtanium, but upon a quick search I found several available online so it appears they must still be in demand enough to be manufactured. I guess I have to give Volvo credit there.
I called my cousin to see how far he wants me to go and explained my thinking about replacing vs. repairing this one and he agreed, especially if they are still available. I doubt I can find one locally, but I'll give it a try.
I'll keep you posted on what I determine, but I think I'm on the right track so far.
Thanks for looking.