Isuzu Trooper Owners Club UK™

Agpab · Posted: Mon Jun 04, 2012 8:40 Post subject: Curious Coolant Loss

Hi, I am a mechanic here in Tasmania, and so must swallow a degree of pride in posting here on what should be an easy diagnosis.

I have a Jackaroo (Trooper) with 4JX1 motor that is losing about 1 litre of coolant in 150km. It's not overheating and runs just fine. I picked up the vehicle as a non runner after the previous owner had spent several thousand and pulled the pin to cut losses.

I have talked with the previous owner's mechanic and it has had this issue for some time. He has had the head pressure tested and overhauled, new head gasket and bolts. The radiator has been recored, various hoses have been replaced, as have the injector and sleeve o-rings.

The radiator holds 15psi over night and when at operating temperature it held 15psi while I watched it over 20 mins, neither increasing in pressure nor decreasing. There is no oil or diesel in the coolant nor and coolant in the oil.

There are some small regular marble sized bubbles appearing maybe one every 30 secs when I watch with a sealed funnel but when a condom is placed over the radiator neck with the overflow clamped at operating temperature it does not inflate over a half hour of running.

This afternoon I ran the vehicle with the sealed funnel half full of coolant, I sealed the top of the funnel with kitchen cling film and tape and put the exhaust gas analyser in it to try and pick up HC's over a period of 10 mins through various engine revs. No HC's where present.

One curious thing is that the header bottle is neither losing coolant nor over flowing coolant, it appears not to be functioning properly at all. This is despite replacing and double checking correct radiator cap, checking the hose and bottle and breather integrity. This worries me and my next move is to set up a temporary replacement for this whole set up just to prove this isn't causing the loss by not returning coolant during cooling.

I can run the vehicle at 2500-3000 rpm in the workshop for half hour and lose no coolant, do a 30km drive and it looses 300-400ml. (but header tank remains unchanged)

When the vehicle is parked on dry concrete after a drive there are no signs of coolant so I suspect the loss is internal. I don't really want to go pulling the head off without a clear and definite diagnosis. Especially as it has just been done.

Any tips for a stumped tradie from the collective knowledge on this forum. Any peculiarities with the 4JX1 on this issue.

Thanks in advance.

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Gribble · Posted: Mon Jun 04, 2012 11:03 Post subject:

Robbo had a leak like this on his 3.0 , I dont remember the actual cause but he will when he's back on .
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Agpab · Posted: Mon Jul 09, 2012 12:57 Post subject:

On the off chance anybody else has experienced this, I'll report that since the last post the vehicle has done 3500km. It has at times done up to 600km with no coolant loss at all. Then it will lose 1.5litres in 30km. Then it might use a litre in 150km.
It is without doubt the most bizarre coolant loss problem I've ever encountered. Not going to rip it apart till I can find whats wrong with it so in the meantime I'll keep topping it up?
Has Robbie surfaced with any ideas yet?
cheers.

Gribble · Posted: Mon Jul 09, 2012 19:55 Post subject:

Send him a PM he will think he has new mate !
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TrooperDan · Posted: Mon Jul 09, 2012 21:27 Post subject:

just above the alternator adjuster mount is an L shaped pipe. It has a gasket on bottom and an O ring on tube into head. It could be leaking at the O ring and be evaporating on hot engine and or soaking into sound deadening. Last one I took out had a rock hard O ring and had been leaking.

or

is your carpet wet inside.

Agpab · Posted: Sat Jul 14, 2012 13:05 Post subject:

Thanks TrooperDan, will check that. Carpet is not wet. One other curious thing is if I check the coolant level on a Monday morning after it has been undriven all weekend there is pressure in the radiator even though it is stone cold and has sat for days and the coolant level is good.

Agpab · Posted: Sat Jul 14, 2012 13:12 Post subject:

montifub · **** Joined: 12 Nov 2009 Posts: 330 Location: Linton KENT

Redrobbo. I do know he changed the head, but speak to him first. Mine had a pinhole leak in the water return pipe from the oilcooler. Tucked down behind the turbo. Only found it when pressure testing the coolant system. Never left any water anywhere but hissed out under pressure
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montifub · **** Joined: 12 Nov 2009 Posts: 330 Location: Linton KENT

Sorry. Red Robbo
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Red Robbo · Posted: Sat Jul 14, 2012 17:22 Post subject:

Oy Oy

Aqpab....sounds very very similar to mine,if you've checked for all external signs,then its looking like a cracked head Crying or Very sad

Only sure way to tell is head off and pressure test.....Check the vent pipe that goes from cam cover to turbo inlet pipe,if you have antifreeze in the system,you may well get a "taster" of it int the breather Wink

Hope this helps.... Very Happy

Gribble....Behave Rolling Eyes

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Khotso...........

Agpab · Posted: Thu Sep 06, 2012 0:10 Post subject:

Just to update this thread, the curious coolant loss had continued.... that is except the last three weeks during which time it hasn't used a drop. Not ready to pull a head off yet.

nicerass · Posted: Thu Sep 06, 2012 9:37 Post subject:

Agpab · Posted: Tue Oct 02, 2012 6:25 Post subject: SOLVED!

The Jackaroo, split a shaft in the turbo and dumped all the oil through the engine. Put a new centre cartridge in it and hasn't used a drop of water since. Took me a while to put two and two together and still can't locate any crack in the old housing but it hasn't used a drop now in over 3000km.
Conclusion.... some sort of hairline crack, porous hole or other defect in water cooled turbo housing. I'm assuming that the erratic and curious coolant loss depended on hings like heat and boost on any particular dive.

dh0n · Newbie Joined: 30 Sep 2011 Posts: 2 Location: philippines

been loosing water lately around 120km and the reservoir is almost empty....can you pin point to me the shaft you are reffering?

thanks and regards

dh0n

uktotty · Posted: Wed Jun 05, 2013 16:53 Post subject:

This sounds like my problem, I lose 2 litres of water in a trip, engine overheats, chucks a load of stuff out of the expansion bottle.
I have replaced the thermostat, there is no water n the ground.
Like the toher guys said, nice dark oil, no sludge, no white smoke etc etc.