Hi folks, as you know Y25DT (opel only), as well as most of the BMW diesels around 2000-2003, is known for it's swirl flaps problem. after a while they tend to break and follow the route of the air manifold-valves-cylinder-valves-turbo and cause severe and $$ damage. they help making a turbulent air-flow at low loads and idle and therefore better combustion in these conditions, but the improvement is actually very small. so as a preventive maintenance the flaps can be removed or replaced with aftermarket "stronger" ones. today I removed mine:
the inlet manifold is held by 7 nuts (11mm) and 12 bolts (10mm). they can be seen here (i'm unscrewing the nut):
there is a sensor for the manifold pressure in the back, you can feel it and disconnect it. there is also a vacuum hose for the swirl flaps actuator. both can be disconnected after you unscrew and take out the manifold. also disconnect the injector wires and unscrew their cable holders from the manifold. there's also the EGR, i didn't remove it, but disconnect the inlet air and exhaust pipes from it:
the manifold with the flaps actuator and the flaps themselves:
removing the actuator here:
the flap removed with it's housing:
the flap broken off the housing. some of them broke pretty easy:
here you can see the manifold with the flaps removed. as you see on the pic below, the flap housing is left with a hole in it. we don't want to have a boost leak there and i screwed a screw with glue there, than I glued it properly from the outer side. you want to screw it from the outside in, because if it loosens up (which I doubt) it will not drop in the cylinder:
when done you must plug the vacuum hose for the actuator in order not to have a vacuum leak. again I used a screw and some glue.
You can then clean the rubber seals ( in orange on the manifold) and clean the places they fit on the engine side for better sealing.
You must be careful with the seals and the bushings for the nuts. they tend to fall off and 1. you can lose them in the jungle down there and 2. they can fall in the holes for the air intake on the engine. that will be pretty bad. when I assembled the whole thing and tested it there was a major boost leak from the first cyl. the seal was fallen off it's place and i had to disassemble again. doing this I lost a bushing from one of the nut holes. it was a disaster. I searched for it for 5 hours and didn't find it. i was sure it went in the inlet holes and to the intake valves. after a couple of hours the next day I found it hiding behind a rod in the suspension (thank god). the I used a drop of superglue to hold the bushings and rubber seals to the manifold so I can be sure they stay at their places during the fitting of the manifold back in place (a bit pain in the ass). so - be careful. after reconnecting the manifold pressure sensor, the injectors and the EGR pipes and it's vacuum control I was ready for a test. worked like a charm. I even sense some throttle response improvement in the low revs. I guess thats due to the missing flaps, they are simply not there to wait for them to open up (they are fully open on heavier load of the engine, but closed/semi closed at standstill and low loads).
as far as it goes for the tightening torques, I didn't check what they should be, be cause I don't think that's too important for the inlet manifold, but as soon as I go to the repair service I go I will ask them to tighten the nuts and bolt properly as I don't have a torque wrench. I tightened the pretty hard with my wrench and a half meter extension pipe
here are all the photos I've taken during the process:
http://img12.imageshack.us/g/photo5ue.jpg/Hope I've been comprehensive enough. I will be happy to try answer questions too
Cheers and drive "safe" [smiley=beer.gif]
