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shaggydog

Member Since: 12 Aug 2012
Location: Kent
Posts: 3347

1991 Defender 110 200 Tdi USW Arles Blue

Positive turbo pressure intake side

Hi guys,

Was setting up to do my timing belt today but events overtook themselves and I ended up doing some errands and then changing my oil.

After changing the oil I checked out what had been a bit of a booming noise occasional which I managed to trace to the induction pipework.

I suspected one of my piston rings had stuck or gapped or something and was causing pressure in the crankcase to be emitted into the rocker cover and air intake but i found very little if any to be present.

What i did find however was that the turbo intake is pushing air out and in at the same time.

Yes, weird.

With the intake pipework intact, I removed the engine breather to the air filter body and found it to be pulsing.

I removed the air intake pipework from the nose of the turbo (exposing the compressor) and with the engine running felt a positive pressure coming out of the compressor.

So. why?

Surely the intake side of the turbo should only suck?

Any thoughts? Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197

Self confessed mileage hunter

22nd Nov 2016 7:55pm

g-mack

Member Since: 07 Jan 2014
Location: northumberland
Posts: 1967

oh shaggy, welcome to my world

i have had this issue for ages! motor runs fine so never really got to bottom of it. i suspect cam timing! i think the inlet is opening slightly too soon on the exhaust stroke!
of course this is just a guess! My 109 thread

my youtube channel

22nd Nov 2016 9:01pm

shaggydog

Member Since: 12 Aug 2012
Location: Kent
Posts: 3347

I must admit I thought of you when I noticed it.

Just seems counter intuitive, there should be no positive pressure there so its ether something blocking the pipework downwind of the turbo, the turbo centre seal is letting by (but no oil present?) or as you say its a timing issue but that would have more of an effect when removing the oil cap which it didnt. Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197

Self confessed mileage hunter

22nd Nov 2016 9:41pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2732

Does it push air out of the turbo intake when it is off idle?

22nd Nov 2016 9:48pm

shaggydog

Member Since: 12 Aug 2012
Location: Kent
Posts: 3347

Yes. Seems to find equilibrium with some revs added and then just sucks in from then onwards. Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197

Self confessed mileage hunter

22nd Nov 2016 9:51pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2732

I wouldn't worry about it then, even if it is a problem how often do you sit at those revs when driving?

I have noticed that my 200Tdi appears to 'chuff' air out of the air box drain hole at idle. No idea why, nor have I any idea why yours would do the same from the turbo, however moving air can do very weird things so there may be a simple explanation for it that someone cleverer than I could give us. For all I know mine might do the same as yours, next time I have the turbo pipe off I will give it a try.

Could be engine wear - mine has 274k on the clock so the rings are probably not in their original state, however it runs fine and returns good MPG so as long as that continues I'll not worry too much about it. I don't go chasing problems that might not even be there, I get enough real ones to keep me busy!

22nd Nov 2016 9:59pm

shaggydog

Member Since: 12 Aug 2012
Location: Kent
Posts: 3347

Mine is only a nipper its only just clocked over 190k!

In that case I will apply steam engine fault finding to it.

"If you hear an unfamiliar noise, listen to it until it becomes familiar, the noise is no longer a worry"

Thanks guys!

Timing belt tomorrow.

Wish me luck

Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197

Self confessed mileage hunter

22nd Nov 2016 10:08pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2732

There's a very good pictorial guide on LR4x4 if you haven't seen it, worth a look.

23rd Nov 2016 9:52am

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