boost lost???

**harro** · 1st February 2012, 04:42 PM

Originally Posted by 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

The actuator will be controlled by either vacuum or pressure depending on where the small line coming from it runs to.

A vnt will have the actuator at right angles to the turbo, on a wastegated turbo it will be parallel (someone correct me if I am wrong).

Check the stop screw on the actauator rod hasn't moved (this controls max boost) and that the actuator arm can move with some encouragement

as you are pushing against a spring. Also that the end of the actuator arm is actually resting on the stop screw.

If everything seem fine it may be internal

.
A vacuum or pressure leak on the actuator may be the culprit but I would not expect that to affect initial spool up (boost).

Or, as you have suggested a leak in the inlet manifold or associated pipe work between turbo and inlet

There are a few tips around about cleaning out (removing the carbon buildup) a vnt with something caustic like oven cleaner but I haven't done it and I would hesitate to try it.

Cheers,
Paul.

The tip about a possible small crack in the hose to the actuator is a good one.
The same thing happened to my td5

**uninformed** · 1st February 2012, 04:48 PM

here are 2 pics of my turbo:

**rick130** · 1st February 2012, 04:48 PM

Bush65's pics showing the actuator and rod from this thread http://www.aulro.com/afvb/isuzu-land...urbo-info.html

**uninformed** · 1st February 2012, 05:43 PM

ok, I just checked the little hose going to the actuator...I removed it, had a good look and feel, roll in fingers etc, then blew in it, then hooked up my compressor and nozzel blower and put 25 psi in one end and blocked the other with my finger....all seems good.

next I tried the actuator....I couldnt get a good go at it insitu and im thinking how can I test this thing with out recking it........DOH! hook hose up to it one end and compressor nozzel to other end of hose...15psi and it moves.

I may have found the problem! I think the little pin that goes through the bottom of the actuator arm is not located in the other end of the vnt part of the turbo....

Im going to see if I can get it in there....very very little room and I dont know how it is located, ie what stops it from popping out?

see attached pic

**harro** · 1st February 2012, 05:59 PM

Originally Posted by uninformed

ok, I just checked the little hose going to the actuator...I removed it, had a good look and feel, roll in fingers etc, then blew in it, then hooked up my compressor and nozzel blower and put 25 psi in one end and blocked the other with my finger....all seems good.

next I tried the actuator....I couldnt get a good go at it insitu and im thinking how can I test this thing with out recking it........DOH! hook hose up to it one end and compressor nozzel to other end of hose...15psi and it moves.

I may have found the problem! I think the little pin that goes through the bottom of the actuator arm is not located in the other end of the vnt part of the turbo....

Im going to see if I can get it in there....very very little room and I dont know how it is located, ie what stops it from popping out?

see attached pic

Should be a groove for a circlip, or maybe a hole for a split pin but I doubt it

**uninformed** · 1st February 2012, 06:15 PM

just took it for a spin, that didnt work. It was definitly out though, just going to see if it popped out again??

would there be a reason the moving parts inside the turbo (variable nozzels like in Ricks motion pic) would be jambed?

turbo whistle still very pronouced, egts still high and power still down

**uninformed** · 1st February 2012, 06:28 PM

yep, the little pin had popped out of the flat plate again...I suspect fairly quickly.

looking at the below attached pic, should just the little plate rotate (yellow line) or should the cast face rotate also (where red lines touch)...not the alloy compressor housing

im trying to get an understanding of the moving parts...Ricks pic has helped but cant quite tell what I should see moving from the outside

**Blknight.aus** · 1st February 2012, 06:28 PM

actuator sticking
boost compensator not functioning
Timing/valve clearances wrong
clogged muffler
sticking turbo bearings
intercooler blocked/cracked
air cleaner failed/wrong air cleanerdisregard, I left this window open too long.

I can potentially free you a slot on sunday.

The black rod from the boost actuator should move back and forth rocking the little brass arm between the second red line and the yellow one in your pic nothing else should be visably moving outside the turbo.

**rick130** · 1st February 2012, 06:29 PM

I'm guessing that pin should be fixed (peened in) where it's come out and the actuator rod pivots on it ?

**uninformed** · 1st February 2012, 06:31 PM

Originally Posted by Blknight.aus

actuator sticking
boost compensator not functioning
Timing/valve clearances wrong
clogged muffler
sticking turbo bearings
intercooler blocked/cracked
air cleaner failed/wrong air cleaner

I can potentially free you a slot on sunday.

did you read the entire thread????

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