TD5 "Blow Back"

[DiscoJakes]

Hi all - new here from SA

I'm concerned with the amount of "excessive breathing" on my TD5 Disco II. Both from the oil filler cap and dip stick. There is no evidence of water vapour or water loss.
What should the compression readings be if measured at the glow plugs ? Is there a way to establish if this is caused by compression rings or something like injector seals ?
The breathing is slightly diesel or oil like but more in the form of hot steamy air !!

Any suggestions before I take the head off ?

Many thanks.

[Rosco]

Maybe an ominous sign of a cracked head. Mine recently developed a crack in the No. 1 injector pot which resulted in excessive crankcase pressure, the engine running away frighteningly due to diesel in the sump with fuel coming back up the breather pipe. Many many $$$$$$$$$$$$$$$$$$$$$$. :(:BigCry:

[Graeme]

How is the cooling system and coolant condition?

[Rosco]

How is the cooling system and coolant condition?

Interestingly in my case, the location of the crack was such that the cooling system was unaffected. May not be the case here though of course.

[Graeme]

I've just spotted the "no" before "evidence of water vapour or water loss" - it was off to the right of the screen and out of sight, hence my question about cooling system.

Have you compared your engine with another TD5 to verify that the pressure is excessive? They do seem to breath more than a petrol engine, in my experiences anyway. Have you checked that the PCV valve isn't blocked?

[DiscoJakes]

Thanks for the replies...

Cooling system is running hot if I push her, but I've switched to electric fans and they keep her cool when you slow down.
Running temp of 106 'C at 120 km/h and head temp of 92 'C seems to be the norm now. This is way too hot for me.

I've now done about 4500 km's after a full rebuild. She performs well and I do plenty off road and point events. Just this that annoys me.

[DiscoJakes]

Where and what is the function of the PCV Valve Graeme ?

Thanks Rosco over here I could have bought another disco for the price of a rebuild engine !!!

[Graeme]

Where and what is the function of the PCV Valve Graeme ?
The TD5's Positive Crankcase Ventilation valve is that black, often slightly oily plastic device that connects to the end of the engine breather hose and plugs into the turbo inlet hose. It allows crankcase pressure to be vented into the inlet tract but prevents backwards flow.

[Frenchie]

Have a look at your oil. Mine also did the cracked head, diesel getting int oil running away thing. Very scary. It was also running a bit hot previously.

Hate to say it but if your head is cracked be prepared to spend a few $k :(

[DiscoJakes]

Graeme, I've since routed that pipe with the valve all the way to the back and into the silencer - too much hot air going into the intake !!

Frenchie - this engine is still under warranty with a brand new upgraded head !! It's booked for Thursday for pressure tests and I want them to take the head off. I want to see what's going on inside. They were suppose to do a full rebuild bottom up.

My question is what should the pressure readings be and would one find the fault from them readings. This engine performs really well, albeit large intercooler and custom maps with all EU crap removed. The garage measured 25 cold and 28 wet pressure readings at the glow plugs a while back ? According to me these should be in the deep 30's.

I've spend enough they need to fix it, But WHAT !

Thanks

[Graeme]

It seems that you must have a problem to consider re-routing the breather, which BTW surely has to be illegal but that's another matter. I assume you know that #5 cylinder doesn't have a glow plug so it can't be pressure tested.

Taking it back to the rebuilders certainly seems appropriate as they should have a reasonable idea of how to find out what's going on. Good luck with it.

[DiscoJakes]

Sure, thanks Graeme, here in ZA we can still get away with a fair bit. If it doesn't need to be tested for road worthiness, nobody will know that it is there. But yes that is allot of air coming out there, hence my mod.

I lost around 50'C on my EGT's doing so.

Will post after the tests.

Some more pixs.

[Hartley]

I imagine you have eliminated the possibility of exhaust gas going backwards from the silencer into the crankcase.

[DiscoJakes]

Yes Harley I have, the pcv valve does operate one way and I've retained it. That said, it started as a quick test and see mod with my current problem, but I would consider leaving it as is to reduce the inlet temp and cleanliness.

As soon as I can find something like a provent here, I will fit one for the oil but the gasses and air can still go outside....

[DiscoJakes]

OK - did the compression at the glow plugs.

Dry Wet
1 16 20
2 17 21
3 16 20
4 16 18

16 Bars = 232 psi
20 Bars = 260 psi

I had 260 psi (Dry) 2 weeks ago. So compression is going down.

I've since found out the lr spec is around 360 psi or 25 Bars.

Tomorrow the head comes off....

[abaddonxi]

Continued here -

http://www.aulro.com/afvb/technical-chatter/67588-td5-cylinder-glazing.html

http://www.aulro.com/afvb/technical-chatter/67975-td5-blow-remains.html