I've been reading a lot of the posts on this Forum and others about VVT, its failure modes of leaking, and /or causing rattling and bent valves from failure.

Unfortunately, it's because I got a call from my wife one night that our V40 wouldn't start, and there was a puddle of 'brown fluid' on the passenger side of the car.

A quick look and I saw the exhaust cam sprocket is MISSING! You can see the fractured metal of what remains bolted to the hub. Can't find the remains of the sprocket, the tow truck driver my have grabbed it as a souveneir!

So this was an extreme failure, and I'm trying to determine if I should fix this. I wish I'd read about the this issue earlier, the small oil leak ( probably for the last 4 months) and rattling sound ( for the last year or so) , which I thought was transmission( changed fluid, helped shifting immensely but rattle remained) or heat shield, are telltale enough that I would have changed the VVT sprocket with the belt.
And finding links to the reasonable cost cam tools makes this very doable.

So, my questions to the experience of the forum, is what is the likelihood I have bent valves? The engine never started, but did crank - could there be a cam position that is 'safe' angle the cams could have stopped at, or is that not possible?

I'm thinking of getting a sprocket from a junk yard ( $30) reassembling and doing a compression test. If it's the head the same junk yard will sell me a head for $200, tempting compared to changing some valves.

But it's got 170k miles, and two rusty fenders . . .

Advice please!

Thanks all,

Nero

 

You should post to the s40 forum as this one is pretty dead. My guess is that you have a few bent valves. If you are willing to do some work yourself though I would go for it! These things go forever.

 

You bent valves. There is no safe position when the engine is turning.

 

Here's an update:
I found some of the sprocket pieces, I've attached a photo showing the remains of the VVT hub and a sprocket fragment.

I wanted to see which cylinders had bent valves, so I carefully rotated to engine to get the pistons all at the midpoint, and use an adaptor to connect an air compressor to the spark plug openings. I then manually rotated the cams to seem If I could position the valves to a point where there's be no air flow.

I was expecting a bent valve to hardly block airflow at all - to seems like essentially an open valve. What I found was that I could get all the cylinders to resist airflow, and I was very surprised. Maybe cylinder # 3 leaked a little more than the other, by my adaptor could have been leaking instead. So seemed oddly promising.

Here's a weirder thing. I could rotate the exhaust cam as much as I wanted. I can only rotate the intake cam -90 deg or + 90 deg. It feels and sounds like it's hitting a solid metal piece, that really feels like the external sprocket is jamming on a fragment of metal. But I can't see any such thing.

I would have expected a bent valve to possibly jam the camshaft, but if it did, the value would have to be be partially open. I can't reconcile how I could have a jammed valve stopping the cam movement and not have it leak air like an open valve. Anyone have any thoughts?

I'll pull the valve cover / cams - nothing to lose.

I've also attached a nice chart showing expected valve openings for each cylinder. It's to see, as was ES6T pointed out and is pretty obvious after a little thought, that for a 4 cyl engine, there should be no safe spot for the cams to be stationary and the engine to rotate.

-Nero Lumos

 

It might be worth doing a real compression test before opening things up. Who knows maybe you got lucky somehow...

 

Hi Pierremcalpine,

Doing a compression test is what I want to do next.

I still have to figure out what's going on the the intake cam, so pulling the valve cover/ cams isn't a bad thing to do ( what is the right name for the top portion of the head that is both valve cover and cam bearing shell?).

This will leave all the valves closed ( if they are not bent, but this is what i'm looking to check). I read another post where someone bought a V40 with a snapped timing belt, and they installed a belt just to diagnose which valves got bent. For me to do that I'd have to buy a VVT sprocket ( ~ $200 new, and $30 at a junkyard). With the intake cam jammed, I might as well open thing more to do this test.

Nero Lumos

 

I wouldn't beat yourself up about that. I think the oil leak and rattling are unrelated to the outer sprocket failure.

The sprocket is an odd design, the toothed portion is supported on one side only and from your pic it looks like the toothed portion is manufactured from sintered metal. I think the cause of this failure was some kind of manufacturing defect combined with a weak design.

Edit: I just took another look at your pic and two of the mounting lugs for the toothed portion of your VVT sprocket are visible but there are no bolts or broken pieces of sprocket attached to those lugs. Looks like those three bolts actually worked loose and fell out causing the sprocket to fail catastrophically. I'd guess there might be one bolt still in the lug that can't be seen. This would be a very unusual failure which you could not be expected to find. Because I'm a cynic I'll also say this would be a good way for a malicious person to sabotage your vehicle.

Also, I'd take the intake cam sprocket off to see if there's a piece of shrapnel or a bolt behind it stopping its rotation.