dan

hi mate, you were bang on with the dawes valve. have it set to about 14psi now, and the boost curve is a lot smoother. still get the occasional spike of a few psi higher, but i think it is back to normal. when i originally started playing with the dawes valve the locking ring wasn't tight, so i am guessing that it had just came lose and readjusting/tightening it has fixed the issues. after having the dawes set incorrectly at a very high psi where it did nothing, i can now see why people install these!! thanks for all your help, if you are ever around brisbane i owe you a six pack. so now that the boost curve is smoother and the spikes are almost gone -- is there any consensus on what is a comfortably safe boost level on a CRD?? i am happy with the power at 14psi, but if i can reliably run it a bit higher then why not?? opinions would be welcome please mate.

hi mate, thanks for all your advice. i will adjust the dawes valve - hopefully that fixes it..!

yep it does seem a bit strange!! thanks for all your suggestions mate. dawes valve is definitely connected as you suggested. removing the vac line from the actuator causes the lever to drop as you suggested it should. i pulled the intercooler off today, gave it a clean and put it back on again tightly to look for any vacuum/boost leaks and think i may have found the problem - i can hear an air leak coming from around the cold/drivers side of the intercooler. not sure if it is the hose or cracked intercooler, couldn't really feel any air. took it for a short drive and could also hear a leak noise when boost gets up. would a cracked intercooler cause the boost curve to be uneven?? it sounds likely to me?? also - uneven boost curve aside, i would have thought the dawes valve would still stop the overboost problems?? it spiked up to 20psi after cleaning and reassembly. have i got the dawes setup right for low boost - to raise the boost pressure i thought you use the lock ring to extend the length of the valve?? so i have the valve adjusted so it is as short as possible, was expecting it to cutout at 5psi?? fwiw, there was a bit of liquid oil and black grime inside the intercooler and pipes. i would have thought the catch can would stop that?? but i am not sure how long its been since the intercooler was cleaned (if at all), or if it was ever cleaned after the catch can was installed.

thanks for the tip, i pulled the dawes apart and there didn't seem to be any obvious faults - no debris/oil/etc, lines clear, no jams. i couldn't hear any leaks from the vac/boost lines either, but the engine is fairly noisy so hard to entirely tell. the line between the intake and dawes is in poor condition but not cracking yet - i will try replacing it, but after that i am out of ideas - MAF maybe? i would have thought the dawes would keep things under control. i have it wound all the way out so i was expecting it'd limit me to 5-10psi, not the 20psi it is spiking to?? i share your sentiments on the catch can, but it was already in the vehicle when i bought it and i don't reckon it's worth the $$ to change over.

hi gents, i am having a similar problem so i figured i might reply to this original thread rather than start a new one. on my drive home from work today my CRD was boosting up rapidly to 15-16psi, then dropping down, and then up again, and basically boost all over the place. it used to boost up to 15psi, drop down to 12, and then gradually creep up to 14psi in a very controlled manner. it was making a weird noise so when i got home (10mins) i popped the bonnet and the hose from the catch can back to the intake had come loose. the hose clamps are pretty weak and the ends are not flared so it's not hard to pull them off, but still - strange. there was a fair bit of oily residue on/around the catch can so i pulled it off and gave it a clean - not sure if this is just from the hose clamps being useless, or some other thing. the catch can drains back to the sump and there wasn't much oil in it. i checked all the boost/intake connections for leaks and they all seemed ok. there is a bit of oily residue around the turbo, not sure if this from the turbo, is overspill from the catch can or poor aim filling up?? i have owned the vehicle for about 9months/5,000km and this is the first time it's played up. any ideas?? perhaps a dawes valve that has suddenly decided to crap out?? turbo seals?? some specs 2010 CRD manual, 59,000km 3" exhaust, EGR blanking plate, dawes valve, boost/egt guages, snorkel, cross country catch can std turbo, intercooler, turbo timer thanks for your help lads