slightly long reply [Diy_efi] blown engine...

[Rick McLeod]

The questions are:

1) Why did the engine stop if its not seized?
** First, understand what makes a dsl run, if mechanical injected and mechanical fuel pump'd (as the age suggests) it is totally self sustaining as long as then the fuel cutoff is powered, typical shutoff is that the fuel supply is interrupted to the injector pump, thereby starving the engine and it quits. Many heavy equipment dsl's like dozers, graders, etc. have a simple toggle switch for the fuel cutoff activated by the foot throttle, step on it and the switch enables the fuel, hit a push button on console to kick starter, and she starts! to stop, common practice is to lift the foot pedal with your toe, disabling the fuel cutoff valve, and she dies. Simplicity leads to reliability, don't want to have to tow a grader that is dead! As for dsl's they burn oil, and if the turbo seals blow, then there is a source of fuel entering the engine through the intake as opposed to the normal being injected at near TDC, so it would continue to run (and possibly run wildly out of
 control) until the injected source is cut, then possibly run on using the intake sucked turbo oil as it's fuel source. It would not run well, but would probabally run for some time until it finally starves itself and ceases.

2) I have another turbo. are there any special things I should take into 
cosideration when fitting it (like not using exhaust sealant prior to 
the turbine) ?
** Standard exhaust techniques are appropriate, gaskets need to fit tight, no leakage, and I've never herd of using 'sealant' but only high-temp gaskets. BTW, common practice is also to 'wrap' the turbo exhaust piping to reduce under-hood heat, critical in tight compartments on gas turbo but maybe not as important on dsl's.

3) Is it possible that putting a 'T' in the turbo oil feed to run an 
[electronic] oil pressure sensor has killed the turbo somehow? it hasnt 
got a long tail on it or anything - its an aluminium block with holes 
bored in it and the sensor screws straight into the block.
** As long as the flow is not impeded by the T or fittings, then this shouldn't be an issue. Bear in mind it may not be a 'true' indication of pressure, as there is not great restriction through the turbo for oil, it is a flow to create the float for the bearing and to cool it, critical that there is adequate retrun flow (meaning no restriction) to the sump, if there is restriction then the cooling and backpressure in the bearings could be a cause of blow-by in the turbo bearings and hence leakage into the intake, if this condition persists, it will deteriate the turbo oil seals and hence possibly the situation you encountered. I've seen this on cars that have a rubber hydraulic return line, they typically 'coke' or 'sludge' up and partly decompose the inner wall of the hose, thereby constricting the flow and eventually causing turbo failure in otherwise good condition cars. Pontiac 89-90 Turbo Grand Prix had this and the resolve it to regularly replace the return line,
 like every 20K to 30K, or replace the turbo every 50K, whichever suits you.

4) does it matter what the oil feed pipe is made of? (I used copper 
brake line)
** Shouldn't matter what the feed pipe is made of as long as it is metal, I've used copper, aluminum, & stainless materials with no apperant adverse affects. As long as the oil is not corrosive to the metal, and there are no fragments that could cause turbo bearing failure, go for it.