04 xc70. intake leak CBV Topic is solved

awizarddresden · Post by **awizarddresden** » 30 Aug 2025, 02:27

Hello! I've got a strange issue. On my 220k mile xc70 I'm having some cold start issues. On the first start of the day my xc70 will hesitate to start. She cranks. Catches. And then idles really poorly for about 10 seconds and dies. I assumed it was a fuel issue. I replaced the fuel pump. I've ran it with vida and the only codes I have are for an intake leak. And I have ecm-400a large fuel leak. I don't really smell any gas or anything. I ran across another post on here that mentioned their "large leak" was the evap purge valve going bad and plan to test that later

However. Ive been trying to nail down this intake leak code. I did a smoke test on the vacuum system. And smoke is pouring out of my cbv cover. Idk if mines gone bad or what but that seems to be the only place the smoke is coming from. Could that be the issue? A tear in the diaphragm causing unmetered air to get in and muck with the fuel air ratio?

You guys are a dedicated bunch. This is my first Volvo and. I love the car. I don't so much love my first euro car experiences lol.

Post by **DavidE7** » 01 Sep 2025, 19:55

Is your coolant level dropping very slowly without any visible leaks?

Those symptoms also match a head gasket leaking coolant into one or more cylinders after the engine is turned off. The engine stumbles until the coolant is evaporated or pushed out into the exhaust. The easiest way I found to check for this problem is with a bohr scope looking through the spark plug hole inside the cylinders at the edge of the head gasket while pressurising the cooling system with a hand pump. Droplets of coolant will appear if the head gasket leaks as the cooling system pressure is increased. It is also possible to measure for exhaust gasses in the cooling system - I haven't had a chance to use an exhaust gas detection tool.

Post by **DavidE7** » 01 Sep 2025, 20:05

Also - My comments are in the wrong order. IPD sells a replacement Compressor Bypass Valve diaphragm:
https://www.ipdusa.com/products/11813/C ... =P0,P11804
It is possible to install without removing the turbo but it is very difficult to reach all three screws for removal and re-installation.

I put this replacement part into both of the 2007 S60s with 2.5T engines because both were leaking when I ran a smoke test. Both diaphragms were completely intact when I removed them for replacement and the leak was happening around the perimeter where the metal cover is supposed to seal off on the diaphragm. I don't know if they leaked with manifold vacuum.

awizarddresden · Post by **awizarddresden** » 02 Sep 2025, 09:44

I pulled the original CBV and holy crap it was not easy to get out, the edge of the diaphragm was all wobbly and stretched out and clearly was not sealing anymore. I picked up the IPD replacement CBV just waiting on shipping.
I don't have any coolant leaks to my knowledge haven't seen the reservoir go down even a tiny amount.

I may just end up accepting the fact that i have to start this car twice each morning if this doesn't fix it honestly lol

awizarddresden · Post by **awizarddresden** » 07 Sep 2025, 11:34

Just an update to this. After replacing my cbv with the ipd kit it cleared my hesitant start. Fires right to life now! If you've got an intake leak code give that a check. I used a "smoke machine" by unplugging the vacuum line attached to the intake and blowing vape smoke through it with my mouth lmao.

It was gross and I had to brush my teeth 3 or 4 times. But once I got enough smoke in there I was able to see it pouring out around the edge of my cbv cover. Pro tip, be sure to be careful when screwing the cover screws back in. One of mine feels dangerously close to stripping. I've cleared my codes and driven a few times now and the code has not returned. Now to work on this stuck moon roof!