Ok,Mike I will do that. I topped it off cold this morning and added water wetter. Will get back to you after the pressure test or before if coolant level drops.

 

Handy thread... I'm still in the process of finding out what has and hasn't been done on my disco - Love it, but a little scared (cos of the dollars to fix) of what I'm yet to find.

Had an issue today where it overheated about 1K from home - no coolant to be seen. Have done a top up to see how fast new stuff goes, hopefully nothing too sinister is going on. On cold start up though I did notice a lot of "steam" coming from the exhaust (got the V8), so took it for a lap around the block and once I got back the "steam" was no longer being made, so possibly just a normal cold start getting the system warmed up issue rather than a head gasket issue?

Have looked for any obvious big leaks on the pipework, found none. Some signs of super slow leaks on the throttle housing and thermostat, but nothing that indicates it would be leaking large amounts of coolant.

I've done lots of country miles lately in it, and its been reasonably warm mid 30's to low 40's (C) - been a little neglectful in not checking fluids as regularly as I should - but do these things tend to expand coolant out bit by bit particularly when the ambient temps high to the point where it doesn't have enough and then overcooks?

 

Inferno:

43 C is like 109 F.... Al Gore has pushed all the global warming toward you..

No they tend to leak coolant or convert it to steam, but the coolant reserve bottle usually stays at the 50% mark and use of coolant is not normal. The cap vents at 20 PSI. You can smear some mud around the base under the coolant cap to see if it stays "dry" or gets wet from venting.

Could be leaking into engine, check oil level and when you change oil look for milky look of coolant in oil. Some leaks are sneaky and only happen at speed. You can rent/borrow a coolant pressure tester and pump up the system to about 20 PSI and let it sit, coolant leaks will show up. Some times wate rpump leaks out the nose, or around rear gasket.

Could also be head gaskets, there is a chemical test for exhaust gas in coolant which is about $50 / US, it can do maybe 15 tests, and confirm head gasket small leak.

Attached is flow chart of the cooling paths from the RAVE shop manual set.

 

Cheers Savannah - I'll keep a close eye on whats going on and systematically get each test done to see what it might be. I downloaded the RAVE manual and have the 13 odd pages sitting on my desk for the V8 Cooling system... will post up what if anything I find.

Looking out my window today I think Al's taken all the global warming back, its cold, wet and really windy. While we've had a few hot days its looking like this could be the coolest summer we've had in over 12 years - not sure what the global warming guys can tell us about that one.

 

***Update***

Haven't been able to hook up a pressure test yet - the Clipsal 500 (V8 Supercars) is on here this weekend and all the mechanics around are off playing, will try another couple tomorrow and cant seem to find someone who'll hire a tester to me... BUT,

One Mechanic today and he'll be able to do a pressure test on Monday for me. He did give me a couple of other things to look for as well though to check and see if it is a head gasket problem.

First up was the pressure test, but then he said he also tests in the coolant bottle for CO, if there's a gasket leak to a cylinder you'll get CO in the coolant returning to the bottle, the other thing he does is fills the bottle right up to the top, then pulls the fuse on the ignition coil and turns if over watching the coolant. If it pulses then its likely to be getting pressure pulses from the cylinder.

So, being a combustion engineer I have a combustion analyser and was able to measure the CO coming back to the bottle from inside the bottle and it read upwards of 200ppm - immediately next to the bottle it was 0. So clearly getting some CO back in there from the coolant. Haven't done the fill it up and watch it bounce trick yet, but even without the other tests being done I've also noticed its running rough (like its missing a cylinder) cold, but coming good after a minute.

Seeing as (in my very amateur opinion) a head gaskets gone, how long is a head gasket change likely to take??

 

About 12 - 15 hours shop time. About 2 weekends DIY. $300 parts, $200 machine shop to skim the heads flat to within .002 inch. Around $1500 - $1700 shop (all inclusive), or $2500 plus at dealer. All price US dollars, which are worth less every day.

Because of the coolant flow design in the D2, not sure the pulses in coolant jug would be as reliable an indicator, and HG may not begin leak until a certain temp (same for cracked head or block), and there are multiple paths to the coolant jug and trapped gas pockets in the system to compress. The chemical CO tests you buy from the parts store do about 15 tests for $50. But sounds like you have that covered, and can also use that same gear to have proof of performance for any repairs.

Wonder what your test gear would show in another vehicle, as a control? Are these CO analyzers available in a compact and under $500 version?

Here's a flow chart of the cooling system. When repairs are done would suggest a new factory thermostat (not after market), and flush radiator, convert from Dexcool type coolant to something green in color, if this has not already been done. A sludged up radiator could have been a contributor to this problem.

 

I think I'll get a shop to at least do the diagnosis - then work out what I do from there. 3+ days of my time is worth heaps and I'd be better off paying someone to do it while I still make coin.. plus being my work "car" the spend is a tax write off. The motor itself is looking shabby, oil all over it etc and I'd want to give it a good clean too - been reading up on the seafoam and inlet cleaning. That said, I do like the idea outside of everything else of just having a play with the thing myself.

The analyser I have is about 5K from Testo. Awesome bit of kit but really not meant to be used on cars. The additional aldehydes in the exhaust on petrol motors tends to kill off the cells really fast. I will see if I can benchmark on another car though, makes sense.

I think its time to do all the fluid checks / changes I've been meaning to do for ever. I've noticed the coolant is still the red stuff, so I'll be changing that up regardless, do a cooling system flush as well. I need to do a complete oil change and would like to do the trans and diffs too. I've only had it 6 months, and I don't think it got too much love outside of basic servicing.

Will keep you posted !