Crankshaft timing

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2001 - 2007 V70
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Ellyatts
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Crankshaft timing

Post by Ellyatts »

I have 2005 v70 2.5 I purchased where timing was done incorrectly. I usually lock up cams line up marks on crank and cams.
Can the crank be set on the marks but be 360 off? In other words we know crank does 2 rotations to line up the cams. What if someone made a full rotation on the bottom with timing belt off then set timing. Would that matter?

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SuperHerman
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Post by SuperHerman »

No. Crank if at its timing mark can only be in the correct place.

Where timing can be off 180 degrees is when the cams are upside down. So on a Volvo the cam ear that should be below the line is above the line and vice versa - with properly used timing tools it cannot happen as the tools will not fit.

If you have properly used the timing tools - and the cam/lines are correct and the lock tabs go in correctly that cam is correct relative to the crank. Same holds true with the other cam.

Three pieces to timing - Crank at correct mark - Exhaust cam at correct mark looking at rear of the cam - Intake cam at correct mark looking at the rear of the cam. Again - for the cams if the tools are properly used both will be set correctly. So you now have one piece to set for correct timing and that is the crank. If at the mark - engine is good for that portion of the timing.

I lied - there are four pieces to timing. The last piece of timing is the most difficult. Where most people mess up on Volvos is setting the VVT hub(s). This is what I would guess your issue is. Even though the crank and cam are correctly set - the cam gears and VVT hub(s) could be positioned incorrectly. Unlike the old days of keyed cams and cam gears or one piece cams - your Volvo has cam gears and a VVT hub that can be misaligned.

I don't know your expertise, but this is what I would do. Set crank to timing mark, install cam tools on to rear of cams and secure and look at where the cam gear marks are lined up on the plastic cover. These marks are on the front of the engine , right side or passenger side. If timing is correct the marks should all line up or be within 1 or 2 degrees from the marks on the plastic timing cover. My guess is you will be further off from this and your problem is the VVT hub(s) were not correctly set.

As I didn't do the original timing, I don't know if the VVT hubs were removed or they were left intact. To change the front cam seals the VVT hub has to be removed, but not for a timing belt change.

Ellyatts
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Post by Ellyatts »

Yes I have the correct timing tools and lock the cams. I have done both my v70r with 2 vvt hubs. Setting marks with hubs tight clockwise with cams locked.
I have never worked on a car where someone else has incorrectly done timing.
But you eased my question. The crankshaft was my concern. I was not sure if there was a sensor or something and it must be set on the correct rotation.
So if crank lines up and I line up cams and properly set the vvt we are good.
Thank you very much
I always appreciate professionals opinion.
Better to ask than be sorry later lol
Thanks a million
Paul

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SuperHerman
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Post by SuperHerman »

Great you are familiar with the process and should have no problems. I would proceed as follows - set crank - place cam tools and lock them down then look at where your front cam timing marks are in reference to the plastic cover. This will give you an idea of what the prior person did wrong.

It is possible they totally messed up the cam gear(s) and vvt hub(s) so this step is worthwhile.

Then I would remove the timing belt and start from the beginning. It is much easier than trying to work off prior mistakes. A clean slate.

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darrylrobert
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Post by darrylrobert »

My cars timing was off when i bought it also, only by two teeth. it ran fine.

there is a video where the guy sets the crank timing mark at around 3oclock, the car starts and runs fine according to the video and dozens of people thanked him for showing them how its done. I wrote a comment saying he done the timing wrong but he said its how it was and it worked, cant argue with that.

In regards to VVT, some people say you need to tension the hub when you remove the belt, im not sure why. If the hub doesnt move and its at the timing mark why move it?

As i understand it the VVT hub should only be tentioned when it has been removed from the shaft.

Did the car
run with the timing so badly off? do you have pics??
1981 260 GLE converted to 240 M46 after auto box failure
1987 740t auto converted to M47
1997 V70t5 auto converted to M56
1998 V70 factory M56 (parts car)
2001 XC70 factory M58
2002 XC70 auto (parts car)

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abscate
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Post by abscate »

The VVT hub moves with respect to the cam shaft, so aligning the hub mark to the cover mark does not necessarily make the cam timing correct. The good news is the range of motion on the VVT hub is not enough to make piston valv interference so you can’t toast -your engine if you don’t time it right. You will either pop a P0014 code or have reduced performance

Maybe this helps...

There is nothing :special “ about the timing marks. The crank and cams never interfere anywhere during the rotation of the belt.

In theory, you could take a correctly timed car, remove the belt, and restore the new belt in the same piston by making new marks wherever the belt happened to be.

Please don’t try this, the marks give you a fail safe if/when something slips or Skylab falls in the middle of the job, etc,

Simple on a non VVT car, complex on VVT
Empty Nester
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Ellyatts
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Post by Ellyatts »

The car would not even start. So my process would be to set up and re time as you suggested. Then I’m going to do the compression test. Most likely I will have bent valves
Fun fun lol
Thanks again for all the help

chrism
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Post by chrism »

darrylrobert wrote: Tue Apr 21, 2020 9:52 pm
In regards to VVT, some people say you need to tension the hub when you remove the belt, im not sure why. If the hub doesnt move and its at the timing mark why move it?

As i understand it the VVT hub should only be tentioned when it has been removed from the shaft.
Thank you for mentioning that. Too many people make a simple T-belt replacement a much bigger task than it needs to be by thinking they need to do all this cam locking and VVT clocking, etc.

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darrylrobert
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Post by darrylrobert »

I wouldnt jump to conclusions regards to bent valves, get the timing sorted first and get it running. I hope you got a good price, buying a non running car and all.
1981 260 GLE converted to 240 M46 after auto box failure
1987 740t auto converted to M47
1997 V70t5 auto converted to M56
1998 V70 factory M56 (parts car)
2001 XC70 factory M58
2002 XC70 auto (parts car)

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