Isuzu Trooper Owners Club UK™

[stig664]

HELP ! My trooper pressurises the coolant system forcing the water into and beyond the expansion tank, anti freeze mix is perfect, engine stays fine till I go up hill or put my foot down, no sludge in header tank etc, temp comes down when back off the throttle, could the water pump be sucking in air to pressurise the system ??? PS just fitted new rad cap an still same !

[Google]

[Topvaux]

In answer to your question, no, the pump can't suck in air.

If you release the rad cap when the engine is cold do you get a release of pressure? Does anything different to usual happen when you start up from cold - misfire, white smoke or whatever? If there's nothing like that you're hopefully not into headgasket territory.

These do apparently suffer from blocked rads which would show up in this sort of weather at higher speeds and higher loads.

Hopefully there'll be some brighter sparks along soon who know the 3.0 and its foibles who can maybe improve on my suggestions.

[stig664]

Thanks, but rad fins are clear, see daylight (inc between my ears !) small amount of smoke at start but goes after a couple of mins, small amount of pressure when been standing an hour or so, maybe thermostat not opening properly ?

[Topvaux]

No - the tendency for rads to block is internally and apparently backflushing doesn't seem to clear it. Why any of that should be I'm darned if I can fathom but it is nevertheless a known problem.

Thermostat is a possible as well, of course

If I remember rightly Tim Banham had a problem like this with his, but I don't recall now what the (eventual!) solution was.

"TIM! - WHERE ARE YOU!?"

[eithan h]

it's not mixing the antifreeze with diesel is it?

[stig664]

Nope, just took out thermostat and it still seems to pressurise, just gonna take it for a little drive without stat in an see !

[eithan h]

it could be rad still do you know if it has the thin type or the fatter type

[stig664]

I think it's the thin type, is this covered by any recall ? Also went for a mile drive and it still pressurises without stat in and shows warm on gauge !?!  

[TimBanham]

Hi mine overheated because I stuffed into a gypsum quarry and thought I had cleaned the rad out but actuall had only cleaned the air con rad.

Without stating the obvious check that you have cleaned the actual radiator.

it took an amazing amount of cleaning to get mine sorted
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3.0TD LWB Citation

[stig664]

Mines ultra clean, just confused it still gets hot and pressurises without stat ???  

[Grandad]

this problem is a common problem with the radiators on london type taxis  there rads are fine on short runs and low speeds but as soon as they are subject to any hard work they over heat the only remedy is a new rad
when taken apart 50-60% of the cores are usually blocked solid
this is often caused by filling with plain water with no antifreeze so causing a build up of rust deposits which often cannot be flushed out   as  Topvaux said

[eithan h]

if it's the thin type then you would need to change it anyway for the thicker type and i don't think the rad was part of a recall

[stig664]

Cool, where do I get the thicker one, Isuzu were'nt very helpful !

[AD]

If the coolant is pressurising without the temp guage going into the red, then it sounds to me like the head gasket

Ive had this prob on an engine, it only pressurised when you made the engine work hard, it was combustion gasses entering the water gallery's due to a faulty gasket, there was no water/oil mixing.
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2011 3.0l Hilux Invincible
94, 3.1 duty
95, 3.1 commercial, Agricultural licence
04, 3.0 citation

[Topvaux]

I'd still be interested to know if there is residual pressure in the system when the engine is cold. If there is then you've at least got a headgasket problem.

There is a very effective chemical test which detects combustion gases in the coolant which would settle that question one way or the other.