Thread: 1994 4BD1T Garrett Turbo questions

Originally Posted by Svengali0

I just gave it a bit of flogging up the Princes Highway. It'll still reach 130km+ with relative ease but dies on the hills. There is Nil boost discernible- only that warbling noise. On dark, exhaust plume can't be easily discerned through the rear view- as one would expect on full acceleration.
I'm thinking one of the turbine wheels is touching the housing somewhere. I'm guessing exhaust side. Might be the axial play that I've heard others say is terminal (shaft worn+turbine clipped).
I'll take it to a local tradesman tomorrow to see what he thinks. The rest of the engine/trans is damn fine.

You should be getting 10psi minimum boost at those revs Stue. You need to get the turbo looked at, probably needs that rebuild kit. You don't want to experience a runaway engine from leaking turbo oil. The later "T" engine pumps don't have a boost compensator like the earlier ones with the IHI RHB6A turbo. I have the TB2518 on my 6X6 and by tweaking the fuel rack screw by 1 turn can get up to 15psi now.

Originally Posted by Bearman

You should be getting 10psi minimum boost at those revs Stue. You need to get the turbo looked at, probably needs that rebuild kit. You don't want to experience a runaway engine from leaking turbo oil. The later "T" engine pumps don't have a boost compensator like the earlier ones with the IHI RHB6A turbo. I have the TB2518 on my 6X6 and by tweaking the fuel rack screw by 1 turn can get up to 15psi now.

Thanks Brian. Did you notice any difference in fuel economy on adjusting the fuel rack screw?

Originally Posted by Svengali0

Thanks Brian. Did you notice any difference in fuel economy on adjusting the fuel rack screw?

Very slight difference, from 16.5 to 18l/100 on a 6X6 with 4.7 diffs. But it is well worth it for the extra boost and acceleration.

Very interested to hear the diagnosis.
Noise aside, the lack of smoke seems strange as I'd have expected there to be more smoke with same fuel and lack of air (boost) - but hey - I've got more hammers than turbo qualifications so maybe its not an issue

Stuffed turbine isn't necessarily terminal, but may make it uneconomic to repair.
I neglected to say earlier that I replaced mine when I did the seal kit, as it was badly eroded and had also worn into the thin washer between the wheel and center housing. Turbine/shaft came from ebay and was a standard T25/T28 for < $100

Steve

Originally Posted by steveG

Very interested to hear the diagnosis.
Noise aside, the lack of smoke seems strange as I'd have expected there to be more smoke with same fuel and lack of air (boost) - but hey - I've got more hammers than turbo qualifications so maybe its not an issue

Stuffed turbine isn't necessarily terminal, but may make it uneconomic to repair.
I neglected to say earlier that I replaced mine when I did the seal kit, as it was badly eroded and had also worn into the thin washer between the wheel and center housing. Turbine/shaft came from ebay and was a standard T25/T28 for < $100

Steve

Thanks Steve. I'm now wondering if the dodgy air-cleaner to intake pipe I cobbled together may be restricting flow in some way- perhaps causing the symptoms. This might explain why there is nil observable smoke of any colour emanating from the exhaust pipe and bugger-all boost. I might pull that and see what it happens....

Atleast fit a boost gauge. Then start looking for problems

I'd also check some other basics like are you getting full throttle travel at the pump when foot is to to floor. Wouldn't be the first time power has been low due to a floor mat under the pedal, or the bracket on the engine has come loose.
Dodgy inlet hose collapsing under vacuum, clogged fuel filter or inlet screen at the pump banjo.
A couple of turns out on the max load (fuel) screw on the pump should at least give you some more visible smoke if the fuel supply to the pump is ok.

As Vern says, having a boost gauge would give useful info. Even if it's just a cheap mechanical one with a flex hose running out the side of the bonnet.

Steve

And for a third time, we need gauges and figures, otherwise its all speculation.