Isuzu Trooper Owners Club UK™

Browndoff · Posted: Sat Jun 22, 2013 18:41 Post subject: Rad-Flush comes out CLEAN?

Hi Guys,

My 3.0L has been overheating on hills etc. - so I plan to 'fix' the viscous-fan-clutch with a fluid of higher viscosity - but in the meantime, I replaced the Thermostat and the Radiator-Cap and ran a radiator-cleaning-fluid through the system for 2 weeks. This included a few longish runs - which also involved some overheating episodes!

Naturally, I expected this to produce a torrent of filthy sludge when I drained the coolant system today. Not a bit of it! The water + cleaning-fluid came out pale-green and looking pristine! Then I attached a garden-hose to the heater-matrix and flushed the whole system for 15 minutes. This, too, came out looking almost 'drinkable'! No sign of any rust or sludge.

You might think I should be delighted - but I'm a worrier! The Thermostat-Housing [for example] still looks brown and filthy inside - so the coolant-system is NOT perfect - it's just that NONE of the muck came out with the Radiator-Cleaning Compound!

I've refilled it with 50:50 coolant-mix [about 7.5L, including the Overflow-Bottle] - so it's ready to roll - but I don't feel I've made anything better! The Cleaning-Fluid used was one made for domestic central-heating systems - so it should have been capable of removing mountains of sludge - it certainly did in the house - but NOT in the car!

Can anyone offer any help in improving the cooling-system?

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Cam · Posted: Sat Jun 22, 2013 19:00 Post subject:

Take the Radiator out and check between the cooling fins, if you can't see through them then the wind and air can't get through them. If they are clear I would say from what I've read on here that the inside of the radiator has furred up.

My 3.0 was overheating on hills and it turned out to be the fins blocked with silt not allowing the radiator to cool, was easier to just replace the radiator
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2001 Trooper 3.0 Citation Lwb. 33" BFG's, Superwinch X9, 60mm lift, Monroe Adventure Shocks, Hid Spots and a Yaesu FT7900 2m/70cm's Radio
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Browndoff · Posted: Sat Jun 22, 2013 19:23 Post subject:

Yeah! I, too, thought the Rad must be 'furred-up' inside - that's why I put that stuff through it - but it didn't remove any gunge! The fins are clean enough but kinda 'battered', in places. I could NOT say it's got perfectly clear air-passages - but I'm REALLY hoping I don't have to replace the Radiator! They're NOT cheap!

adz1973 · Posted: Sat Jun 22, 2013 19:33 Post subject:

There's been a few posts regarding rads, a flush wont cure a blocked rad, Cams right in what he says. Maybe a rad change will sort you out.
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Cam · Posted: Sat Jun 22, 2013 20:04 Post subject:

Browndoff · Posted: Sat Jun 22, 2013 20:58 Post subject:

"[u]Maybe[/u] a rad change will sort you out."

God - I hate 'MAYBE'! That, however, is all one can expect in 'motor-maintenance'! There are so many things which go wrong - and yet share the same symptoms - that no one can ever be really sure that symptom 'A' definitely indicates problem 'B' and solution 'C'!!

The terrible thing is that, with cars, following the wrong 'trail', can be REALLY expensive! Look at the dozens of posts, on this Forum, where guys have pursued a symptom through several component-replacements - and STILL have not solved their problems!

Pardon the rant - I'll go and have a quiet lie down!

adz1973 · Posted: Sat Jun 22, 2013 21:34 Post subject:

eithan h · Posted: Sat Jun 22, 2013 22:27 Post subject:

won't be the viscous fan

eithan h · Posted: Sat Jun 22, 2013 22:28 Post subject:

won't be the viscous fan

TrooperDan · Posted: Sat Jun 22, 2013 22:34 Post subject:

take the rad out, empty it and see if it feels heavier than a mountain bike wheel and tyre (stop laughing) if so its f*****. New rads are really quite light
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Browndoff · Posted: Sat Jun 22, 2013 22:48 Post subject:

"feels heavier than a mountain bike wheel and tyre"

I'm NOT laughing! Of course, any deposit on the inside would increase the weight! That's a perfectly sound way to settle the issue --- if only I knew the 'proper' weight of a standard Isuzu Trooper Rad. Maybe I should try filling the rad with vinegar for a day, or two - to shift the lime coating...........?

BTW Eithan - Why are you so sure it COULD NOT be the Fan-Clutch? It must be faulty if it can't pass the 'cardboard in the Fan' test [i.e. very low torque at full operating temperature].

Cam · Posted: Sat Jun 22, 2013 22:57 Post subject:

eithan h · Posted: Sat Jun 22, 2013 23:03 Post subject:

i would happily hold the fan on a hot running 3.0l engine, it doesn't lock to the shaft at all and a "cardboard test" doesn't prove it, if you listen carefully when you start them up you will hear it roar and then die off thats the viscous working.
that and they are pretty bullet proof as well.
on a trooper i will always change the rad before a viscous coupling

eithan h · Posted: Sat Jun 22, 2013 23:06 Post subject:

i would happily hold the fan on a hot running 3.0l engine, it doesn't lock to the shaft at all and a "cardboard test" doesn't prove it, if you listen carefully when you start them up you will hear it roar and then die off thats the viscous working.
that and they are pretty bullet proof as well.
on a trooper i will always change the rad before a viscous coupling

Browndoff · Posted: Sat Jun 22, 2013 23:29 Post subject:

Cam Of course the fan turns when it's running - but if it doesn't have the TORQUE to drive the FAN at a decent SPEED to suck air through the radiator-grill, then there's no effective cooling. The whole point of a Viscous-Coupling is that it's supposed to run at much less than the ENGINE-speed - when it's COLD - but at almost the full engine-speed when it's HOT!

Eithan I don't have a strobe-light to check the speed of the fan - so I can't really be sure at what % of the engine-speed it's running [at any temperature] - but I've never heard any real ROAR - as one SHOULD with a fan running with enough TORQUE behind it to move the air with FORCE.

On another forum, someone suggested a 'sheet of A4 paper test' - i.e. when it's idling HOT, the fan should have enough 'suction-power' to hold a sheet of paper to the front of the rad - when COLD, the paper-sheet would fall to the ground - because the fan was not 'strongly-connected' to the drive-shaft.

Would such a test give a good indication of the 'state' of the fan-clutch?