Boost is anaemic - Am I too demanding or looking at rebuild

[Cody]

Vincent: My Bentley doesn't cover turbo.  The diesels it covers are the 1.6l N/A versions from back in the '80s. Is yours different from mine? Is there a Bentley for vans like mine that came from Europe?

Cody

[Cody]

With Respect to  the suggestion about leaks:

What's a good way to check? I was under the van with the engine running and could not feel a leak nor isolate a location of a sound that seemed likely to be a leak but then the engine was not revving under load.

Should I do like with a tire and bathe it in soapy water and the do a quick drive and then get back under it to see if some foam built up somewhere?

Seems like most of it won't work because the heat'll evaporate the liquids.

Just stay under it and have somebody rev the engine? Without load is  there going to be any boost to check for?

If the turbo were gonzo would there be a noise that would give it away.  Right now it just sounds like the turbo on a diesel truck a nice high pitched windiing up sort of whine -like sound.

[Cody]

Is there any chance that I'm just not throwing enough fuel at it?  When we put on the intercooler we adjusted the fuel screw a little but it is still not smoking at all.  I was hoping to  get  turbo to somethign like 12psi  and then I'd adjust the screw to just barely detectable smoke under heavy load.  Perhaps I  should adjust it to barely smoke now as it is and then see if more boost comes on??

[mud and diesel]

To your original question, Im running a tuned(ish) AAZ in a large square vehicle but have a k14 and boost is very quick,
but, when i first had the engine running i took it for a spin and boost hit 25psi as soon as i opened it up a bit, then dropped suddenly to 8psi and stayed there, it then took ages to build back up to 8psi if i eased off, at first i thought a hose had come loose, but what had happened was the wastegate was sticky! it took 25psi to open it then stayed open,
If i was you i would remove the wastegate and free it up, then as someone else noted make sure the seat is not cracked and seals well.
If this doesnt solve it then add more fuel  :twisted: (assuming all hoses and gaskets are sound!)

[Cody]

Does that require removing the entire turbo or is it possible to remove the Wastegate itself.  Unfortunately my Bentley doesn't cover the turbos.

[mud and diesel]

You shouldnt need to remove the turbo unless something in the engine bay is stopping you getting at the bolts, There are three bolts that hold the wastegate on, undo these and use the wastgate as a slide hammer to pop out the inner seal, once you have it on the bench, force it to move, then clean the shaft up with very fine sandpaper, aso dont lube it up as it will burn and turn to carbon making it stick again! (dont ask  :roll: )
http://www.vwdiesel.net/phpBB/viewtopic.php?t=13357&highlight=k24+rebuild

[vanbcguy]

Maybe I'm nuts, but my K24 seems to make way more boost low down than others around here...

I'm usually hitting 10 PSI just past 2K RPM in second... by 2.5K RPM getting 15 PSI is no problem whatsoever (that's where I have my wastegate set)...  I haven't done ANYTHING other than block off the BOV and put a 'tee' in to my wastegate line.

Highway cruising is usually in the 4-6 PSI range at 120 km/h or so on flat ground...

what kind of tranny do you have?

I THINK it's an ATH, I'll have to check again... That's the appropriate one for my chassis though and the gear ratios line up with reality...

3.67   3.45   1.94   1.29   0.91   0.75

not too bad!  fairly tall.  so in 2nd @ 2000 rpm you're doing roughly 30 km/h.  some oils help lubricate the turbo better too, so you get less lag that way.

Yeah, I actually noticed it start spinning up quicker after the first oil change I did...

Bingo on the 2000 RPM / 30 km/h thing.  The car doesn't really move much in first, but second is where it really gets the turbo spun up and has a good long pull...  Off the line I can't beat anyone but as soon as I'm in to second gear I'll catch 'em!

Some day I'll get an intercooler together and then see what this turbo can really do... Given that it has no problems with 15 PSI I'm sure it'll put out 20+ without working too hard.

[vanbcguy]

With Respect to  the suggestion about leaks:

What's a good way to check? I was under the van with the engine running and could not feel a leak nor isolate a location of a sound that seemed likely to be a leak but then the engine was not revving under load.

Should I do like with a tire and bathe it in soapy water and the do a quick drive and then get back under it to see if some foam built up somewhere?

Seems like most of it won't work because the heat'll evaporate the liquids.

Just stay under it and have somebody rev the engine? Without load is  there going to be any boost to check for?

If the turbo were gonzo would there be a noise that would give it away.  Right now it just sounds like the turbo on a diesel truck a nice high pitched windiing up sort of whine -like sound.

In my case I had an exhaust manifold leak at the head.  I ended up spotting it because there was a little soot cloud that would puff out when I hit the accelerator.  The other thing I had was a cut in my LDA line where it had been rubbing on one of the injector line clamps.  Those two things in combination stole a lot of the performance from the car!

I think the best thing to do is make sure everything is torqued up appropriately, that all the rubber parts are in good shape (intake hose, LDA line, etc), and that everything on your intake side is happy (clean air filter, no obstructions in your intake system, etc)... I like starting with these kinds of things because they're "low hanging fruit" - they're easy to check, they rule a lot of other stuff out and they're pretty much dirt cheap things to diagnose.  

[vanbcguy]

I THINK it's an ATH, I'll have to check again... That's the appropriate one for my chassis though and the gear ratios line up with reality...

3.67   3.45   1.94   1.29   0.91   0.75

not too bad!  fairly tall.  so in 2nd @ 2000 rpm you're doing roughly 30 km/h.  some oils help lubricate the turbo better too, so you get less lag that way.

Actually on the way home I paid a bit more attention... at 30 km/h I'm at about 1300 RPM.  2000 RPM puts me right around 40 km/h in second gear.

Cruising along around 65-70 km/h in 4th puts me at about 1400 RPM...

[Otis2]

1991 TD Syncro Transporter with the 1.6l swapped out for a 1.9l AAZ.
the manifolds, IP  and Turbo (K-24) are from the original engine.  A TDI Intercooler was plumbed in.

Does the following intake manifold pressure sound like a problem?

Turbo boost is pretty slow to come on (at least in my opinion) nothing until about 2500rpm and then it is about 2.5psi and then it'll peak around 5 unless I'm flooring it up a hill in which case I'll get about 7.5psi.

I was wanting more and so I turned the wastegate screw all the way in (it was almost there already or things were just seized - the screw is completely free-threading and then just stops completely I guess I was expecting to feel like it was pushing against something)

On the first run after that up the test hill it very briefly jumped up to about 10psi but immediately dropped back down to the usual 7.5 psi.

I plugged the BOV vent (3/4" coolant hose clamped onto vent and a blanked 3/4" steel pipe clamped into the othe rend of the hose)  and there is no improvement.

You can hear the turbo whine pretty good, so it's spinning just that the resulting boost seems anaemic.

Smoke screw has been adjusted a bit but there is no smoke whatsoever.

Any suggestions as to what to approach next.

Some have suggested a K-14. Would that spool faster?  How about a VNT?
Does a K-14 plumb right in with the 1.6l manifolds?

Cody,

I have a Westy 2wd converted to AAZ, running a T3 turbo.  Same size as your K24.  I have disconnected the manifold pressure hose from the wastegate, so the wastegate never opens, and peak boost pressure is controlled exclusively by fueling.

First question, are you sure you have a K24?  I don't think that ever came stock on an AAZ.  If it's stock, I suspect that you have a K14 or K03 turbo already.

My engine produces significantly more and faster boost than you describe, although my boost builds slower and to a lower peak than the car drivers here report.  I strongly suspect that there is something about putting these engines into the vans that retards boost development... whether it's different gearing, or the different weight of the vehicles, the car guys typically report faster and greater amount of boost than the van guys, when both are using the same engine & turbo combination.  There are people here who have hit 30 psi boost pressure with a disconnected wastegate-to-intake-manifold hose, but my rig will only peak about 16 or 17 psi.

If I were you, I would definitely try turning up the main fuel screw on the pump.  That mod has had the single greatest effect on my boost response.  You report no smoke whatsoever, which is typical for a stock AAZ.  But if you are trying to improve performance, there should be some very light haze at full throttle.  The stock AAZ injection pump is really underfueled.

Cut the anti-tamper collar and turn it clockwise by half a turn, and re-test.  I think you will be pleasantly surprised.  It's certainly the easiest option to try, before pulling the wastegate or exhaust manifold or doing anything else.

[Cody]

Thanks for the reply, the turbo is a KKK K-24 as that was original equipment for  a 1.6l TD JX engine which is what was originally in the van.  Only the block and head were changed to AAZ, all else is stock.

I turned up  the screw until thre was smoke coming out when hitting the pedal.  Still no increase in turbo.  

Now however I  really have to watch it wheh I  drive on the highway  because my EGTs get out of hand pretty easily (of course with more fuel I'm able ot  hold higher speeds when a bit of a hill comes on)

So, still thinking I'm gonna first I'll pull off the wastegate (or complete turbo if need be) and check that out.

WRT the EGTs can I help  that a bit by advancing the IP timing to give the fuel more tim eto burn?

[Otis2]

Sounds like you have quite a mixture of parts.

Re: high EGT

If you're not getting any higher boost with the additional fuel, then it makes sense that your EGTs are going up.  So I guess your problem is wastegate related after all.

When I play with that fuel screw, it's effectively a boost control.  With every 1/2 turn, I get about another 5 psi of peak boost.  My EGTs are more or less "automatically" kept in check this way.  My pump is AAZ.

Are you intercooled?  And what kind of exhaust are you running?

I think those two things will have more effect on EGT control than timing adjustment.

If you need to build an intercooler, search around this forum, there are several good photos of van intercooler options.  

Exhaust should be very low restriction, too.  I have 2.5" diameter exhaust, and that's ok.  If you're running stock exhaust, it's probably narrower and more restrictive.  Some of the car guys here have ditched the muffler, as the turbo quiets the exhaust to some degree by itself (not my bag, but you may want to experiment that way).

[Cody]

It is intercooled (homemade) and I would like to  open up  the exhaust some but  don't have the time/money for it right now.  I'd simply like to  get it going as good as I  can with what I've got, fixing what's broke and adjusting what I can.

Cheers,

Cody

[Cody]

I found a leak.

when I'm below the van and somebody works the fuel lever to rev the engine there is a bit of air noise / wind coming from the bolts on the hot side of the turbo housing.  I guess I was suuspecting more of a leak on the compressor side but any leak will do as a culprit I guess.

The bolts are darn rusty and I'm a bit anxious about just gettin' at 'er and tightening them up.

Has anybody experience with these?  How about I spend some decent pre-lube time with PB Blaster or such and then try to back one off and then thread it bak into torque settings?  Would any sort of thread dope be recommended for this application?

Is there a sealing gasket of some sort involved in that location?
Cody