Boost stops at 1.4bar - N75?

[UrS4boy]

I posted your one tooth story on my home forum, warning folks to check their cam-crank timing if they can't get a boost issue sorted. Then I posted my suggested correction procedure up for comment. One well known and respected long time UrS6 owner ( Tom G, aka scarman) provided the following comments:

"He will have to remove the lock carrier piece across the front of the engine to have enough room to work, and the serpentine belt tensioner and viscous fan. With these out of the way, there is room to remove the timing belt cover and access the tensioner to loosen the belt. It won't come off the lower sprocket teeth, so no problem there while he removes it from the upper sprocket and rotates the sprocket over one tooth and slips it back in place remembering to maintain the tension on the water pump side. If you aren't a total klutz, moving the sprocket teeth one space is a simple maneuver. No reason to mess with the sprocket bolt. Then re-tension the belt at the tensioner in the normal manner. Don't overtorque the small bolts for the tensioner adjustment. Add a little thread lock if concerned.

Then do the Bentley reverse of removal process to put things back together. The water pump could be changed while there, but I would not change it and continue to use the old belt."

I replied thanks and told him that you had previously done the G40 cam sensor using Nate P's (Imquattro's) procedure so you have a good idea what was what.

An additional comment came in from "UrSobessed" ("Dace"):

"If only needing to access the upper timing belt stuff(cam gear, tensioner) to adjust the gear forward one tooth, there is no need to remove the fan and viscous coupler. The serp belt tensioner is the only thing in the way of the cam cover coming off."

All moot if you really want to do the timing belt. Note: IMO the only acceptable way to do the timing belt is with the proper crank lock tools and the torque wrench extender and a 3/4" drive torque wrench and the appropriate 3/4" drive socket(s). Anything else is bush league/hack/dodgebodge.

[newsh]

Good plan.

This was the lower sprocket on my indigo Avant.

[hunker7]

I don't want to risk it, I'll do full timing belt job and i know it's 100%.

[newsh]

Well hopefully the crankshaft bolt was done up correctly and the "one tooth out" issue is not due to the lower sprocket slipping. I'm not sure how you can check this without actually removing the lower pulley which is essentially a complete timing belt job.

[hunker7]

Thanks for that. I need to take front bumper off anyways, and i need to change coolant too, so will be doing all that at the same time. And only changing water pump because there is no record of it being changed, just ttiming belt kit, £30 isn't much for peace of mind.

[UrS4boy]

Comment on my suggested 1 tooth correction

I posted your one tooth story on my home forum, warning folks to check their cam-crank timing if they can't get a boost issue sorted. Then I posted my suggested correction procedure up for comment. One well known and respected long time UrS6 owner ( Tom G, aka scarman) provided the following comments:

"He will have to remove the lock carrier piece across the front of the engine to have enough room to work, and the serpentine belt tensioner and viscous fan. With these out of the way, there is room to remove the timing belt cover and access the tensioner to loosen the belt. It won't come off the lower sprocket teeth, so no problem there while he removes it from the upper sprocket and rotates the sprocket over one tooth and slips it back in place remembering to maintain the tension on the water pump side. If you aren't a total klutz, moving the sprocket teeth one space is a simple maneuver. No reason to mess with the sprocket bolt. Then re-tension the belt at the tensioner in the normal manner. Don't overtorque the small bolts for the tensioner adjustment. Add a little thread lock if concerned.

Then do the Bentley reverse of removal process to put things back together. The water pump could be changed while there, but I would not change it and continue to use the old belt."

I replied thanks and told him that you had previously done the G40 cam sensor using Nate P's (Imquattro's) procedure so you have a good idea what was what.

[hunker7]

Thank mate, is the anything else that can be done/checked while it's all off?

[hunker7]

I think it is flying now I am well excited to sort timing out. I will take it all apart and do it again, as i need to change water pump, don't want to risk it.

[newsh]

When you take the sprocket off check the keyway carefully.

[newsh]

I thought it had to be the cam timing, it was really the only thing left to check that would reduce boost but not all the way to limp mode.
Dude your car is going to Fly!

[UrS4boy]

Just checked the timing, and it's out by a tooth. When I was removing cam pulley, I zip-tied it...it might have jumped a tooth, or when timing belt was changed not so long before I bought it. I will be taking the timing belt off next Sunday, I want to change water pump too, as there is no record of it being done when timing belt was done.

My guess is that it was like that when you bought the car. Regardless, IF you absolutely wanted to do the water pump, then you will be into the full monty. You might want to read this: http://12v.org/urs/FredMsTimingBeltR&RDIY.pdf

HOWEVER, if you just wanted to see if this is your issue first, and assuming that the timing belt is tensioned correctly, I would try to "adjust" the timing at the cam end, and not open up the whole timing belt/water pump can of worms just now.

To do this, I would mark the current position of the belt where it should be, i.e. at the notch on cam cover, with white out and then start into the G40 cam sensor procedure. However, when you get to the point where you would zip-tie the belt to the cam sprocket, you don't. You slip the cam sprocket off the cam, keeping the belt under a bit of tension (you might need an assistant for this). Then slip the belt off the sprocket (keeping a bit of tension on the belt. While your assistant holds the belt, return the cam sprocket to the cam shaft and with the bolt back on, rotate the cam the one required tooth (luckily is needs to rotate clockwise). With the cam now in the correct position, remove the sprocket and slip the belt back on with the mark on the belt you made. Now the mark should line up properly and the mark on the belt (which never actually moved) should line up with the mark on the cam sprocket. Finish off with the proper tightening of the cam sprocket bolt (holding the cam sprocket without damaging the G40 shutter wheel on the back of the sprocket).

All of this assumes that your timing belt is tensioned properly to begin with. If it is too loose, then you are probably into the Timing Belt procedure and you might as well do the water pump.

[Majorcina]

Hope it fix all the problems máte

[K Simmonds]

That's a pain but at least you've found your problem by the looks of things.

[hunker7]

Just checked the timing, and it's out by a tooth.

When I was removing cam pulley, I zip-tied it...it might have jumped a tooth, or when timing belt was changed not so long before I bought it.

I will be taking the timing belt off next Sunday, I want to change water pump too, as there is no record of it being done when timing belt was done.

[UrS4boy]

I did zip tie it, but i didn't have second pair of hands to help me, so it might have jumped a tooth. And thanks for the timing info

If you zip-tied it at the cam sprocket, it is very UNLIKELY to have skipped a tooth because the only other point where that could happen is at the crank cog and that is almost impossible. Nevertheless, you do need check the crank to cam timing as per that post.