dougisaacs

I think I need to remove my inlet manifold on my MY2000 UK turbo as I've managed to snap the bolt holding the knock sensor, while trying to remove said sensor. The access to the bolt is poor so I'm guessing the manifold needs to come off.

I've never done one of these before, any tips anyone? Also any tips on removing the snapped bolt from the block!?

markjmd

iTrader: (11)

Were you taking the manifold off anyway to do some other work on it? If you weren't and you're just trying to figure out how to re-attach the knock sensor, there are probably other unused threaded mount points on top of the block which will serve just as well. It really doesn't need to go back on the exact same spot as before, so long as it's bolted down square and tightened to around 20Nm.

Minjeeta

depends. Wheres the bolt sheared? Access wasnt poor enough for ye no tae get into it and fck the bolt. (kiddin son)

Best puttin a picture on to get better help mate. Bolted anywhere at 20Nm isn't really helpful to ye. (24Nm)

Knock senors critical though, so i'd get it done right mate.

Splitpin

Grief, how on earth have you managed to snap the bolt while removing the old sensor? It should only be tightened to 24-odd Nm, as above.

There shouldn't be any need to remove the manifold under normal circumstances. You can get to the sensor without even removing the intercooler if you have a 3/8 socket on a long wobble extension (and some blu-tack to hold the bolt into the socket).

However, if you've managed to shear the bolt, it sounds as though it's corroded tight into the block which is going to cause you a problem, and you will need tidy access to remediate it. Removing the manifold isn't at all difficult - only things that might not be obvious at the outset are to drain the fuel rail (by disconnecting the fuel pump and running the engine til it dies) and part-draining the cooling system until the header tank is empty. Then battery out so you can get access to the bolt securing the bracket for the multi-connectors.

From there taking it off should be obvious, and straightforward. If there's enough of the sheared bolt still sticking clear of the block, you could try working some penetrant in and then welding a nut to the remains. Heat from the weld will hopefully help loosen it. If not, will need to be carefully drilled out and the hole helicoiled.

Markjmd - The sensor ideally does need to go back in the same place. The knock detection circuit and amplitude triggers in the ECU are tuned to work with it in that specific location. The only convenient alternative on the block within reach of the standard length cable is the M8 boss right at the back, which is further away from the cylinders and prone to picking up increased levels of transmission noise. Similarly using one of the M8 bolt holes on the inlet manifold causes similar problems. Given how arbitrary the knock detection system is, the last thing you should really be doing is making its life even harder.

dougisaacs

Thanks for your help guys. Looking at the half bolt that's come out the bottom is really corroded so I guess the remaining is gonna be a ba**ard to get out. Therefore, I suppose it's manifold out. Even with half the bolt out, the sensor still won't move by hand!

I agree with what splitpin said about putting in back in the same place, don't want to mess with a system that is on the limit of effectiveness anyway.

When I get a better view I'll maybe try and post some pictures, but I don't expect there's many other options than what you guys have already covered. Here's praying there's enough bolt to work with.

Anyone know how long that bolt is?

I'm assuming I'll need new manifold to head gaskets, anything else I need when removing manifold?