2001 V70 2.4T Rough growling when accelerating / Volvo code ECM-644A Topic is solved

[prwood]

OK. Time for an update. Also a massive entry into the bloops and blunders category.

My next diagnostic step was to recalibrate the camshaft sprockets and vvt hub. In the process of installing the rear cam locking tool to hold the camshafts while I removed the belt and timing gears, while tightening the screws into the camshafts, I snapped off the screw in the exhaust camshaft.

Considering my options, I knew I couldn't just leave it because a) I still needed to install the tool and b) Even if I just put things back together, I would still have needed to screw the camshaft position sensor aperture back on, which is a no-go with a snapped-off screw stuck in there. Next options were to try and remove the screw with the camshaft in place, to avoid having to crack the cam cover open again, or crack open the cover and try to remove it on the workbench. Hoping to avoid the camshaft cover job again, I tried using a screw extractor to get the screw out. I thought I had gotten a pretty good bite on the screw and that I would be able to pull it out, but it wouldn't budge... and to make matters worse, the screw extractor broke off inside the screw.

At that point, I knew the camshaft was going to have to come out no matter what. So, I reluctantly and with much cursing removed the cam cover again and removed the exhaust camshaft. Couldn't get the screw out even on the workbench. At that point I went to plan C. Found a matching exhaust camshaft at a junkyard, reinstalled it, did the whole cam cover reseal procedure, recalibrated the timing gear and reinstalled the timing belt.

So, as of this morning, all of the camshaft angle values are in the valid range:

All readings within +/- 7 degrees, and all within +/- 2 degrees of each other, as per spec.

camshaft_position.jpg (105.21 KiB) Viewed 1433 times

That means the timing gears are properly adjusted, and the VVT hub and VVT solenoid are not defective.

That being said... ye olde growling sound is still there.

Not sure where to look next.

[abscate]

Shinola - that is a lot of work. Well done.

I got a fair warning about the cheap bolts on the aftermarket cam lock tool so I bought some real ones form McMaster.

Maybe turn the stereo up until spring and drive it until you remember why you love it again - and it did give you a cross country trip of a lifetime, with SWMBO to boot.

[prwood]

Update: I fixed it! The culprit? One hideously-busted right engine mount:

Old engine mount. BOTH screws should be above the rubber mount if the mount is in good shape.

New mount installed (notice how much higher the bottom screw is compared to the original mount).

Old Mount (cleaned up and repositioned) vs New Mount. Apart from being in new condition, the new one also appears to have a beefier design.

Engine sound and vibration are now extremely minimal. Everything is extremely smooth.

I'm thinking I should have fixed this a lot sooner. Who knows how many side effects could be traced back to the engine riding down an inch too low on the passenger side, or the vibration/movement caused by the engine essentially touching the subframe.

Here's a link to a video showing the difference in motion between the old and new mounts: https://photos.app.goo.gl/UtM1RFSQrJZCXx4EA

[abscate]

Thats a nasty, nasty engine mount. Yeah, the engine sitting on the pads is not good and lots of things can go wrong. Check all those hard lines for rub points and chafe damage.

[hethaerto]

Nice work!

[jonesg]

Update: I fixed it! The culprit? One hideously-busted right engine mount:

IMG_5545.JPG

IMG_5547.JPG

IMG_5551.JPG

Engine sound and vibration are now extremely minimal. Everything is extremely smooth.

I'm thinking I should have fixed this a lot sooner. Who knows how many side effects could be traced back to the engine riding down an inch too low on the passenger side, or the vibration/movement caused by the engine essentially touching the subframe.

Here's a link to a video showing the difference in motion between the old and new mounts: https://photos.app.goo.gl/UtM1RFSQrJZCXx4EA

Have to wonder if that collapsed lower mount damaged the upper mount.

[abscate]

Our 2001 V70 2.4T is making a rough growling noise when I accelerate. Not the "wow, what a great sounding engine" kind of growl, but more of an angry "grr, I don't want to do this" kind of noise. No unusual noise when idling or cruising at highway speed.

It's actually happening under the same conditions as the issue we had earlier this summer, where the whole car was violently shuddering when we accelerated. In that case, we had the right CV axle replaced and the problem went away. This time it is just a rough growling noise, accompanied by a very slight vibration. I haven't yet been able to pinpoint the source of the noise other than being in the front of the car.

My research on this forum and elsewhere thus far has indicated the following two possibilities:

* Bad CV Axle
* Bad wheel bearing

I did just finish up a camshaft seal replacement job that involved jacking up the right side of the car to remove the wheel, and then jacking up the engine another inch further to access the VVT hub torx bolt. This left the right CV axle hanging at a pretty sharp angle, which in hindsight I probably should have had some support underneath. The boot doesn't appear to be damaged, but I'm wondering if this put too much strain on the CV joint and now the new axle is damaged again?

My other thought is that at the same time as this job, I also replaced the floppy old top engine mount with a new Hutchinson OE mount. Maybe the tighter mount is leading to increased noise?

I don't think it's related to the cam seal replacement itself, otherwise I think I'd be hearing the noise whenever the engine was running.

Any thoughts on how I could isolate whether this is a CV axle or wheel bearing issue, engine mount problem, or whether it is something else?

[abscate]

From your First post you had motor mounts on your radar- that’s good mechanical intuition !

I’m still a bit curious as to what the four ‘ flanks’ of camshaft adaptation are. One tooth of cam gear doesn’t seem like a lot for timing either, I think you get a 10% HP boost with CVVT ?

I think I’m going to go check my front / right motor mount this morning. ( do you reference a motor mount to Car or motor ?)

[prwood]

From your First post you had motor mounts on your radar- that’s good mechanical intuition !

I’m still a bit curious as to what the four ‘ flanks’ of camshaft adaptation are. One tooth of cam gear doesn’t seem like a lot for timing either, I think you get a 10% HP boost with CVVT ?

I think I’m going to go check my front / right motor mount this morning. ( do you reference a motor mount to Car or motor ?)

The VIDA instructions say to tighten the bolts to the motor first, then tighten the bolts to the subframe. There is a torque spec plus angle tightening spec that is different for each pair of bolts.