Turbo help please

[20vT Dan]

I recently bought from auction a 51 Octavia Elegance Turbo 150 bhp I believe.Soon realised it had a blown turbo on the way home,no boost,exhaust full of oil etc.So I fitted a second hand one from ebay which is supposed to be good but still no boost.Sucks like hell from the intake pipe but blows nothing at all out,this one is not smoking and had little play in the shaft.Do I need yet another turbo?Any ideas appreciated.:(

[Tech1e]

Really need some propper diagnosis done.

Fault codes?

Boost pressure?

Why dd the first turbo go?

Have you replaced the oil feed pipes?

All questions that need answers.

[20vT Dan]

The engine light is not on,there is no boost pressure,I have no idea why the first turbo blew,its an ex plod car with 72000 on it,the oil feed pipes appeared ok.

[Tech1e]

Just because the engine light isnt on dosnt mean there isn't a fault code.

How do you know there is no boost?

How did you check the oil line?

[Babs]

I have no idea why the first turbo blew,its an ex plod car with 72000 on it

Answered your own question, there...

[20vT Dan]

Looks like I need to do some more investigating,oil feeds etc.The reason I think there is no boost is there is no pressure at all in the inlet pipes at any kind of rpm.The joys of buying at auction thankfully it was only £1275,I take it babs that all ex plod skodas blow up?

[20vT Dan]

Can anyone tell me what electrical fault could cause no boost pressure?

[Tech1e]

N75 solenoid fault, boost pressure sensor fault.

I take it you are feeling the boost pipe when revving to check the boost then?

[20vT Dan]

The boost pipes are collapsing when the engine is revved,I assumed they would expand.The turbo I bought was s/hand but suppossed to be ok.Might have to get another and check all oil lines etc before I fit it,I forgot to flush out the intercooler which was half full of oil which could well have knacked the new one.Can the n75 be replaced with a manual boost control?

[bengie]

don't replace the n75 with a manual device, just get it fixed properly. Sounds like you need an hour with a good mechanic to me not just a monkey that replaces parts at random.

[richm]

make sure the turbo spindle spins freely, there is minimal free-play in the spindle, the oil supply to the bearing housing is good, and clean out the intercooler and pipework.

If the boost hose(s) is collapsing when you open the throttle, there is either a restriction in the system (blocked intercooler, turbo not spinning freely) or the hose has gone soft and getting sucked in when the throttle is opened quickly.

If the hose collapses far enough to restrict airflow, the turbo will not be able to make enough boost to expand it again, so you have a viscious circle - the engine is creating vaccuum which collapses the pipe and continues to do so until the throttle is closed off again.

[bengie]

as he said really, which pipe is collapsing?

[20vT Dan]

I think ill have to take some bits back off and have a look at things,also do the gear selector cables fail on these as its rather stiff and reverse is almost impossible to find.Cheers

[richm]

the selector mechanism is quite fussy about adjustment precision to get clean selection of all gears.

[20vT Dan]

Thanks for your help guys,its safe to say ive destroyed the replacement turbo with my not very knowledgeable mechanical skills,it has as much play in the shaft as the one I took out,its obviously been starved of oil,will change the oil feed pipes for turbo no 3.Think I will end up keeping the car as a toy for a while,as it looks great in dark green with the window tints.

[Tech1e]

Ahhh if you said the pipes were collapsing I would have said dead turbo straight away, it happens when the air flow cant pass the knackered impellor and it acts as a restrictor.

[20vT Dan]

Well ill get another turbo and do the job right this time,is it common for the oil feeds to block as they seem quite a fair thickness to get blocked?

[Tech1e]

Yeah, why i asked.

Carbon builds up inside due to some people using the wrong type of oil, this blocks the flow to the turbo.

[20vT Dan]

Its obviously been neglected at some point then,is the oil fed in from the feed on top of the turbo as this is the one I didnt look at.