boost lost???

[uninformed]

Hi all, well I was hoping this would be a post on what I found rather than please help me.

Truck: 98 110 CC with a 2.8tgv

last Friday night I did a quick run up to the shops. 2.5km round trip, I left the truck running whilst I ran in. On the way home, I felt a sudden reduction in power, with a noticble increase in turbo noise, mostly whistle. Not a bad turbo noise, no crunching etc.

Sat morning I looked over the various hoses I thought to be under pressure. I only found one with a little divet in it, the small short hose from turbo to waste gate, but on closer inspection it had not penetrated. I took the top hose off (I/C to plenum) looked inside and could not see any delaminating etc. I checked engine oil level, coolant level. Both 100%. As the truck was already booked in for Monday morning for a timing belt and service I figured not to much point digging deep beyond my capabilites.

The vehicle has been returned and the mechanic believes to be fine. It is not. It is definitely down on power, by the feel of my bum say 20% easy. The engine runs smoothly. starts first turn very easlily. The turbo whistle is still pronounced and louder than norm. The EGT's are higher than normal, as they also were Sat and Sunday on light small runs. Example: as I drove from mech's to truck supply store, I was sitting on 90km/h in 4th and 5th and EGT's were 400 degrees post turbo. This is no load on a light 110 ute (cut down flat bed alloy tray), normally I would expect about 200, 250 max....hell it only sits on 350 with my 1.8t trailer doing 105km/h

basicly it is still the same as Friday night after incident.

some of work done by mech:

new air cleaner
replace main serpentine drive belt
install new recored rad
replace timing belt
tensioner modified gear and idler bearing
replace crank seal and oring
replace a/c idler bearing.
cleaned I/C with kero

he did find a hole in the small hose/pipe that goes across to the injection pump. he has repaired this with a sleeve.

I was suprised that that one had a hole, as 1 it is metal and 2, to me it seem like the injection pump is getting the correct boost pressure but not the engine, thats why higher egt and less power (my guess)

I rang him when I got to the truck supplies and had the message relayed via assistant: he has asked me to bring it back in the morning, something about adjusting the timing???

now to me, its not timing. It starts very easy, runs smooth. Nothing has changed pre him working on it as regards to the incident on Friday night. Im not keen on him spending(wasting) time on the timing.

a little back history on a small issue: In the last 6-12 months something has changed in the turbo side of things: Sarting the truck first thing in the moring is normal, I usualy let idle for 30secs min, then slowly take off in 1st and low rev change into second. I go up hill a small ways to turn around then down my little hill to level ground out to a T section at main road. I just putt along to let everything get moving and oil. this is only 300m. Then when i do give it some, generally in 2nd gear that first revving of the day, you can really feel the turbo kick in, almost like a valve being half open then full open. Once it has done this the first time it doest really happen again during that first journey, yes you can still feel the turbo kick in (more than a 300tdi) but not like the initial. Now if I let the truck fully cool after the first run of the day, it is the same as described. But if I get back in it with heat, the sooner (ie hotter) the more pronounced the result is) the same "valve like" issue is happening, but it takes longer and more revs to do so...so the first 500m-1km it is underpowerd and then viola, "valve like" opening and full boost. Once agian, back to normal in said journey.....

all this was explained to mech on monday morning.


SO...What should I look for, and what should i be advising the Mech to look for. Is it maybe a stuck waste gate? or manifold gasket.

I need this sorted asap. This is my work truck and every day its down is cost me $$$$

[harro]

I thought the 2.8tgv had a VNT not a wastegate turbo.
Have a close look at the actuator on the turbo and hose(s) make sure everything is free and working with NO leaks.
It doesn't take much to upset these turbos.

Cheers,
Paul.

[Disco_owner]

Fuel Lift Pump ?

clogged Fuel Sedimenter ?

[uninformed]

Harro, yes this is a VNT turbo (i thought that was internal shape of fins or nozzel direction????) .... is the actuator the little (40mm or so) silver round cylinder attached to the side of the turbo? it has a small hose going from it to a alloy casting directly infront of the turbo...

disco owner, the sedimenter was cleaned very well by me, new orings and tap installed and a new fuel filter installed 8000km ago. when i drained it there was pretty much zero water in it.

[slug_burner]

The VNT may have clagged up with soot. Check that the mechamism controlling the vanes moves without binding. VNT turbo's with electronic controls usually have a full range of movement built into them either at start up ot shut down to make sure everything keeps moving and nothing builds up.

If it is not a VNT turbo then the wastegate might not be shutting properly and you are leaking boost. Do you have a boost gauge that can help the diagnosis?

[rick130]

A very good point someone above raised, make sure the actuator and nozzle on the turbo have a full range of movement and soot hasn't clogged up the works. (yours doesn't have a wastegate if it's the TGV)

That might explain the sudden changes you are experiencing in boost and the higher EGT's.
At a wild arsed guess the nozzle isn't opening and closing properly.

[uninformed]

I was sold the engine believing it was a tgv, hense a VNT. How do I check the controlling mech? what does it look like etc? There are NO electronics or computer stuff on this truck or engine

[Benny_IIA]

I was sold the engine believing it was a tgv, hense a VNT. How do I check the controlling mech? what does it look like etc? There are NO electronics or computer stuff on this truck or engine

I far as i know the vnt fitted to the tgv is a mech controlled vnt (presure).

There will be an actuator with a rod that conects on to an arm on the exhaust housing of the turbo.

Remove this arm from the actuator or the arm. then check the arm moves easily from the stop start screw to it maxium.

Also check the actuator is working just give the arm pull with a pair of vice grips attached.

also check for a small crack in the pipe running from the intake to the actuator

[rick130]

Here's some VW VNT pics.

[rick130]

bugger, didn't work.
Try this