TD5 "Blow Back"

**DiscoJakes** · 17th November 2008, 07:25 AM

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** · 17th November 2008, 08:00 AM

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 $$$$$$$$$$$$$$$$$$$$$$.

**Graeme** · 17th November 2008, 11:49 AM

How is the cooling system and coolant condition?

**Rosco** · 17th November 2008, 11:57 AM

Originally Posted by Graeme

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** · 17th November 2008, 07:16 PM

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** · 17th November 2008, 07:48 PM

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** · 18th November 2008, 01:55 AM

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** · 18th November 2008, 05:35 AM

Originally Posted by DiscoJakes

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** · 18th November 2008, 04:59 PM

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** · 18th November 2008, 06:15 PM

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

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