Turbo - Setting-up the Wastegate
Wastegate mechanism setup Garret T2
|While the turbo is on bench, the wastegate poppet valve can be checked. Drop off the actuating arm from the solenoid and look under the circular valve in the exhaust outlet chamber. Are the seats of the valve and wastegate port it mates with in reasoanble condition. Does it look like it has been running open at all (heavy carbon on faces). Does it look like it would seal? This doesn't have to be the same standard as an exhaust or inlet valve seat, but a quick lapping with some medium valve grinding paste will take out a fair bit of damage quite quickly. Leave the poppet valve on the pivot arm and rotate back and forth manually (spinning valves with electric drills to lap them in is not a good practice).
If you have to change any of the wastegate's parts or alignment, you can re-check the initial boost pressure that triggers exhaust dumping (bypassing the turbine). First the actuating rod's length should be such that the valve is just held closed. Connect a foot pump with built-in gauge to the solenoid nozzle (barb), and watching the actuator for the first signs of opening, slowly press down on the pump. Note the pressure. By also allowing it to bleed down, you should find it closes at a similar point, but there will be a bit of overlap (intended by VW). These VW diesel wastegates are usually setup for 0.5 bar, about 7.5 psi.
This sets the maximum boost, or is intended to - of course can be modified using bleed valves in the line, or better still, Grainger style valves that actually allow an accurate max boost pressure to be set. 4 or 5 psi can be added without too much concern, above that the fuelling of a diesel would normally need to be looked at. Once you get to 15 psi an EGT and boost gauge to monitor for reliability is recommended. You will need to block off the BOV to get above about 10 psi (the safety Blow Off Valve in the inlet manifold) NB. Don't mess with petrol engine boosts unless you really do know what you are doing!
Make sure you fit the wastegate pressure feed line with good fittings, don't use small jubilee/hose clips to secure it, they distort at that size and create leaks, use the original light fittings or swaged fuel-pipe style clamps. Can test the solenoid end connection easily enough for leaks, but not inlet boost side connection.
NB. Lapping the wastegate valve and seat on a KKK 14 turbo is a different job altogether. More difficult, but can be done though (coming later)
KKK K14 – Waste gate valve seat repair
A big clean bench, preferably with a vice (unless you like wrestling turbos).
12mm Ring spanner for the banjo bolts of waste gate actuator pipe
An old 5mm allen key with 10mm cut off the short end
Possibly a slide hammer
Possibly gas torch or good heat source
Probably a sharp 5mm drill
Probably a centre punch
Probably an M6 tap
4 off - 6mm copper washers for banjo connectors on waste gate actuator pipe (compressor housing to waste gate actuator)
Gun gum exhaust paste – not sure this is necessary, but belt & braces!
3 off - M6 x15 cap head bolts (I imagine you’ll have at least one snap/round out)
New M8 nuts for exhaust flange – Mine were steel & rusted to bits, so now stainless steel.
Once you’ve removed your turbo, carefully plug the oil inlet & outlet holes, the compressor (aluminium side) inlet & outlet & the turbine (cast iron side) inlet & outlet. Degrease & wire brush all the loose rust off of it & inspect the cast iron side for cracks. It would be easier to remove the compressor housing 1st, but you’ll need a new o-ring if you do this (full turbo rebuild kits are available – even on Fleabay) and the rebuild guide here http://www.suzukituning.com/General/KKK%20K14%20Turbo/KKK14TurboRebuild.htm will help.
The hardest part is actually removing the waste gate actuator (the finned tube on the side with a steel pipe running from the aluminium compressor housing). I soaked the 3 cap head M6 screws in Plusgas (releasing fluid – WD40 will do nothing, so don’t bother) for a couple of days & then heated them up with a gas torch & still only freed one of the three. To get good access & be able to shift the bolts you’ll need to grind/cut an old 5mm allen key so it fits in under the swaged top. A ball ended allen key will just screw the head of the screw up, so I wouldn’t try to short cut it.
If they round out, then a sharp cold chisel will cut the bolt head off easily. Use a stud extractor & heat to pull them out or cut them off flush to the turbine housing, centre punch carefully, drill them out (5mm) & re-tap (M6).
My waste gate came out relatively easily, but they can stick (see thread & links below). They have two tin covers between the waste gate actuator & the turbine housing, these wriggled free fairly easily for me. There is also a washer on the mating face, be careful not to lose it. DON’T WIPE THE VALVE OR SEAT JUST YET – This will tell you how things are working!
Once this is free, have a look in at the state of the seat & the valve. On mine the valve was A1 & the seat pretty poor (two cracks in the housing & a visible chamfer on about ¾ of the seat. Generally, heavy carbon deposits on the seat itself is a sign it’s not closing properly.
I used a pillar drill with a 30mm drill bit on a slow speed to clean up the seat (Plugging the housing with rag to keep the swarf out), but you could make up anything to do the job (end of a broom handle & some grinding paste?!). You are just looking to re-instate the chamfer in the housing, ideally to match the chamfer on the valve, so have a look around your garage/shed for something & then gently twizzle until it’s shiny & even!
Give everything a good clean & blow out any swarf. You can check the diaphragm in the actuator works by connecting a foot pump with an airbed adapter & see if it ‘actuates’ mine moved at around 20-30psi (Anyone know what pressure this is supposed to move at?). The actuators aren’t really rebuildable – see 2nd post below. The fitting in the side of the actuator (13mm) is threaded & mine leaked. I used a wipe of Gungum to help seal this (PTFE would most likely burn out as turbos can get V.hot)
Clean the mating faces, the washer & it’s recess – I used a very thin wipe of Gungum on this, then bolt it back up (make sure you’ve got the inlet from the compressor in the right place!!
Bingo, all should be good.
andy2: From forum thread
I’ve had a couple of k14,k24 wastegates out from the housing and they are a bit of trouble to get off. There is two thin heatshield/gasket cups that are just usually stuck in the housing with rust. Basically you can only get them out by pulling on the wastegate which causes one of the shields to bend a little and then they will eventually pull out from the housing. The small bend in the one shield is nothing to worry about and they will be re-useable with out any issues. The slide hammer is definitely the tool of choice here Just keep doing what you were doing and it will come out without hurting anything
I’ve also had the wastegate's cover off too. Using two screwdrivers I just worked my way around the cover's crimp as if it were a tin can (just be careful as you will be reusing it).I had no problems putting it back together and it was in alot worse condition than the one you have. The reason I took mine a part in the first place was that it was seized open and was otherwise useless so I had nothing to loose by taking it apart. If you test it using regulated air and it works without sticking then just leave it alone. Dr diesel and I have played around with the screw on the cover to raise the opening pressure but it doesn't make much difference and if you screw it in far enough you can reduce the valve's opening travel as the screw also acts as a stop when the valve is fully open. This will raise boost by simply not allowing the wastegate to open all the way and will send EGT's way up. I would leave that adjustment alone Or put a bigger spring in the wastegate. So for anyone else looking to raise boost on the k14,k24 the best way is to just put a bleed in the line or use a boost controller, just leave the screw alone!
BTW just for reference the k14,k24 wastegates are not interchangeable, as I found out also