can i get my timing off by putting a cam pulley on offset

[twooldvolvos]

I am in the process of changing a cam seal in my son's 2001 xc70. I'm not afraid to do it but I must admit that its a first for me. I noticed that the cam pulley has 3 bolts holding it on and that the bolt holes are not round but slightly slotted. This allows the pulley to be adjusted in relation to the shaft by a degree or so. I am wondering if I can throw the timing off by putting the pulley back on rotated slightly from where it came off? I took note to where the bolts were positioned as best I could when I took the pulley off (they where pretty much in center of the slot). Its confusing to me how anyone can time a car using only marks on the block if the pulleys are adjustable too. Can anyone set me straight? Thanks.

[Astro14]

Yes!

That's why you either buy or make a tool to LOCK THE CAMS IN POSITION from the rear of the engine. If you've already taken the pulleys off...well...too late...line the bolt holes up as best you can...but for the VVT...I think you're in deep trouble...I don't know how you would get that set, and keep the cam position from shifting, which would be disastrous for your timing...

IF you've not loosened the cam pulleys yet...STOP...get a good shop manual explanation and have Amazon FedEx you this:

http://www.amazon.com/gp/product/B00K0QRMHS/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Then, you can lock the cams and crankshaft in place to keep the relationship while you remove the pulleys...and they won't shift under the torque required to reinstall the pulleys...

[Astro14]

Further, if you've got an oil leak at one cam seal, you've got to ensure that the PCV system (AKA Flame Trap) is not plugged, or you will get leaks elsewhere on this engine...

[twooldvolvos]

Further, if you've got an oil leak at one cam seal, you've got to ensure that the PCV system (AKA Flame Trap) is not plugged, or you will get leaks elsewhere on this engine...

Astro14,

Thank you for your response to my question. I was successful in getting the car to run well today so I don't think I got the timing off by removing the timing gear to replace the blown seal. However, I was disappointed to see oil hissing out of the seal around the shaft almost immediately after i started the car. Upon examination of the 2 seals I purchased (one for each timing gear just in case), I noticed that the seals were different part numbers and that I had put the wrong one in. They were about the same size but the one I did not use definitely matched the original one better than the one I put in.

Putting the correct seal in is not a problem. I will do that.

But on to the more important question. I suspect that you are correct that my PCV system is not working correctly. Is it normal to have enough pressure behind the cam seal to blow oil out around the shaft?

I'm learning about my XC-70 but sometimes its painful. Thanks for your advice.

twooldvolvos

P.S. The cam seal I am working on is behind the plain gear and is toward the front of my wagon. I did not touch the other gear that has some type of sensor wired to it.

[JRL]

You're supposed to have NEGATIVE pressure which obviously doesn't blow anything out.
If you have over 100K miles and/or have used dino oil instead of synthetic, the breather system probably clogged or 90% clogged

[Astro14]

Astro14,

Thank you for your response to my question. I was successful in getting the car to run well today so I don't think I got the timing off by removing the timing gear to replace the blown seal. However, I was disappointed to see oil hissing out of the seal around the shaft almost immediately after i started the car. Upon examination of the 2 seals I purchased (one for each timing gear just in case), I noticed that the seals were different part numbers and that I had put the wrong one in. They were about the same size but the one I did not use definitely matched the original one better than the one I put in.

Putting the correct seal in is not a problem. I will do that.

But on to the more important question. I suspect that you are correct that my PCV system is not working correctly. Is it normal to have enough pressure behind the cam seal to blow oil out around the shaft?

I'm learning about my XC-70 but sometimes its painful. Thanks for your advice.

twooldvolvos

P.S. The cam seal I am working on is behind the plain gear and is toward the front of my wagon. I did not touch the other gear that has some type of sensor wired to it.

Briefly, you shouldn't have any pressure at idle, or under boost...

So, I suspect that this seal failed due to PCV system pressure...it was simply the weak point in the system...luckily...could've been the VVT cam seal...which is harder.

So, if you got this one done, and nothing else leaks, then count yourself lucky and change the entire PCV system ASAP...before you're back in doing another seal.

My intake (the one you describe, front of the engine) cam seal blew out of the head under pressure from a failed PCV system. Make certain that you replace all the components and that you clean out the passages to the block...

cheers,
Astro