This oil leak can be very difficult to pinpoint.

I took the photo above and redraw to show you why.

1. The Cam Seal prevents "low pressure" oil leak. Basically, any oil splattered at it while the engine is running.
Of course, if the PCV is clogged, the oil is pressurized here.

2. The VVT Hub Large O-ring (red dots in the diagram below) prevents high-pressure oil leak. As you know engine oil pressure is anywhere between 7 psi (idle) to all the way up to 50-60 psi.
- The VVT solenoid is only activated at certain rpm (? above 3500 rpm, I am not sure here), so at idle, there should be minimal amount of oil through the VVT Hub.

To add complexity to your issue of pinpointing the oil leak, the Cam Seal's lip is only a few mm from the VVT Hub Large O-ring. So when you see oil leak pooling at the bottom of the camshaft, it will be very difficult for you to pinpoint the source (Cam Seal vs VVT Hub O-ring leak)!!!

 

I took another random photo from the web to show you the proximity of the Cam Seal's Lip versus the VVT O-ring:

 

I have another theory that I can't prove: maybe pressurized oil (from the camshaft holes) ---> past the metal ring seal ---> Cam Seal area.

Anyway, just a theory, see RED arrow:

 

Thanks cn90 and ES6T

I used a small screwdriver, but was extremely careful. I am 100% certain I didn't even touch the side surface of the cam. Further, the camshaft seal's lip is actually on the VVT hub, as opposed to the cam itself, I drew the diagram below.



I will do some more wiping and cleaning as suggested, then idle the motor. So far (unless it is residual oil) it seems to show itself just under idle, no need to drive the car...

I think the next thing after that is to take off the rear timing belt cover, so I can see what is behind it. It sucks, because it means I have to undo/redo basically everything, again, but at this point - I'm getting pretty efficient at taking stuff on/off in that area.

I believe the rear timing cover cannot be taken off without also taking of the water pump - can someone confirm that please? And if I take off the water pump - would I need a new gasket, or can I re-use the one in there - it is only a few months old. I assume I would need a new one...

 

@jordank,

I don't have the VVT Hub with me, but you may be correct, i.e., the cam seal lip mates with the VVT Hub as in your latest diagram.

If your diagram is true, then the only way oil can get out is via the cam seal.
This is b/c even if the VVT hub O-ring is bad, oil will leak out of the VVT Hub but contained behind the cam seal lip.

Have you looked at the VVT Hub where it mates with the cam seal lip to be sure the surface is smooth?

 

The more I read on the web, the more I think it is your VVT Hub moving in and out too much. The answer may lie in the new VVT Hub:

VVT hub seal wear?

Exhaust Camshaft Front Seal Leak, 2005 2.5T

You may want to send these people a PM or post on these threads above to see what they say.

Check to be sure but I think the PN is 9497786, about $235:

OEM Volvo Part 9497786 | Pulley

 

@cn90 yes, I'm pretty confident on the seal rubbing against the VVT hub outer. Mine also has a tiny (but visible) groove in it, like the first post you linked. I agree the only way the oil can get out is via the seal, but I think there are two situations there. One - if there is a LOT of oil behind it (pressure is building up, due to bad o-ring, or worn out camshaft oil rings (as per your previous post), or a blockage on the drainage hole (which I didn't see on mine). Second - the seal is not sealing right (bad mating surface, bad seal, hub too far out, seal installed too deep, etc) and *some* small amount of oil is making it past. To me it feels like if it's the first - then the large oil pressure behind the seal would just push the seal out at some point, so I am leaning on the second.

Great point on the moving in/out though.. it definitely feels like it moves a LOT more than the intake, I had just thought it was by design, but maybe it has worn out. Also, with the motor running, the exhaust gear is visibly (by at least 1-2mm) more outwards. On the intake gear, the timing belt is basically centred when the motor is running, with around 1mm of the gear showing on each side of the timing belt. On the exhaust - the belt is butted up against the rear edge, and maybe even a little bit overhanging, and the rest of the gear width is showing at the front edge of the timing belt.

I just went in and measured the in/out play on the exhaust hub, and it is 2.6mm (though there is no easy way to fit the callipers on with the hub still on the car, so I'm probably up to a tenth of mm off). On the intake - it is under 1mm. When I push in/out, I can also feel the seal engage on the exhaust hub (or at least that's what I think it is - there is definitely a 'catch' as you push it in). No such 'catch' is felt on the intake.

I managed to take out the rear timing belt cover without taking out the water pump - managed to slide it down and out via the wheel well cover (though putting it back in there will be a horrible task, I'm sure of it). I have cleaned everything and am giving it the night to dry. Tomorrow I'll put it all back together, and run it. I also am planning on drawing some chalk marks under the cam gears, on the block, hopefully oil runs become more visible as they pass through the chalk.

I'll also post on those threads you linked - they sound EXACTLY like what I'm dealing with, thanks for those! Hopefully someone remembers how much in/out play is 'normal' on the VVT hub.

 

On the issue of ebay O-rings for the VVT, by the time the VVT O-rings go bad, the gearing mechanism is probably loose too, causing sideways movement that exceeds the designed spec.

Relevant thread below:
VVT hub seal wear?

Looking at the ebay seller's listings, he sold quite a few O-rings.

But my thinking is: once the O-rings are bad, one is better off with a new Volvo VVT Hub. Does anyone know who makes the VVT Hub: is it Aisin or INA?

 

So... did this get resolved? What was the source of the leak?

 

The reason I haven't reported back is because.. I'm not 100% sure yet if it's resolved or not..

I replaced the exhaust CVVT hub. The in/out play on the new one was maybe 1mm, the old one - multiples of that. So what I believe was happening, is that the camshaft seal sits on the VERY end of the hub mating surface, and as the hub wore out and started moving in/out more - the seal was no longer sitting on it sufficiently to do it's job.

I have been driving the car with the timing belt covers off, and inspecting for leaks. I still have a (much smaller) oil drop collecting on the frame member underneath the motor, on that side, but for the life of me - I cannot figure out from where it is coming from. It is much less than what it used to be, so it is even possible it is just residual stuff that had collected either in the engine mount, or in the frame itself, and is coming out... I even went as far as to make a little 'L' shaped shelf of cardboard and stuck it underneath the two camshaft hubs, to see if there is any oil cast-off or dripping from there... nothing. The timing belt, however, still *looks* like it might have a small film of oil on it that I can't seem to wipe out - it comes back.

So, I'm just driving it more and I'll keep looking, and hopefully figure it out. however, yes - I believe that largely the leak has been fixed by me replacing the exhaust CVVT hub (and the seal behind it), and that the main failure was the hub wearing out, and having too much in/out play, which was causing it to go PAST the camshaft seal lip...

 

So after driving the car for almost 2 months without the timing belt covers on, I believe the issue has been resolved. I did have some pooling of oil drops on the car frame, but I believe that to be from oil collecting either inside the front subframe, or maybe inside the side engine mount. I had to wipe it clean a few times, and then there were no more drops.

Some of the lessons that I have learned from this:

- Make sure you MARK EVERYTHING, and check the markings multiple times, BEFORE YOU TAKE OFF THE TIMING BELT, and then again BEFORE YOU TAKE OFF THE HUBS. Follow the various DIYs. The important thing is to know exactly the position of the hub relative to the cam, and the only way to be certain of that is to have the cams locked, and then mark. Only ever take off the hubs with the cams locked, and everything marked.
- If you can - get the cam locking tool. I ended up making my own, but unless you have a welder, and are willing to waste 2 hours of your life - just buy (or borrow) the tool.
- The CVVT hubs wear out, and start moving in/out more than designed. That causes them to go past the lip of the oil seal, and results in an oil leak. I am pretty certain that I could have probably left my original oil seal in there, and just replaced the hub - and it would have been just as good. Not that I would recommend that, but just making a point that the issue was definitely the hub. If you have it off, I would still replace the seal.
- The seal must be installed WITHOUT bottoming out. This is unlike every other vehicle I have ever worked on, and resulted in my large oil leak after replacing it the first time. The links in the thread have info on how far to push it in - I did mine up to the chamfered edge, but no further.
- It is possible to take off the rear timing belt cover without taking off the water pump, but you have to break one of the little plastic bridges that keeps it together around the pump. The cover sits a little behind the pump, but with that small piece broken - you can make it go around it, and then take it out from below, inside the wheel well.

PS> If anyone is in the Phoenix area and wants to borrow my (self-made) cam locking tool - PM me. It worked great, and is probably at least 3x over-engineered.

 

There seems to be a large gap between the camshaft and the seal. Is that the right seal? The circumference seems wide. Shouldn't the seal squeeze between the housing and the shaft?

 

The surface of the VVT hub goes in between there (between the cam and the seal), with the seal rubbing against the VVT hub itself.

 

Please see diagram in post #24 above.

 

I looked into mine and found that it is like that with seal.
I am doing whole head and putting back together. When I posted to you I looked into my pulley etc. Shop removed pulleys without marking so I am going by all timing marks and vvt set up.
I can see an oring fortunately

 

Thanks for the note! Did you buy OEM or did you pick up aftermarket stuff? I'm reading so many posts of bad uro, pro parts, elring and others. I am so fearful of having to do the job 2x. Maybe fears are unfounded? Please let me know. Thanks!

 

Stick to Corteco seals, which are OEM!
Stay away from Elring etc. unless you want to do it again soon.

Search eeuroparts or rmeuropean dot com for details.

 

I should have heeded your advice. I made my own as well, but blew almost 3 hours on the construction. Total waste of time. I should have spent the $60 from ebay for one!

Thanks for your detailed description and follow up on your work. I'm in the same boat and it's looking like the exhaust hub is going to need a replacement!

 

Yeah... just took my T55 to the hub bolt and the cam shaft shifted! I stopped immediately... the tool did not hold it in place. I'm ordering one immediately. ughhh.... waste of time making my own.