Thread: Cooling System Sanity Check

I am in the process of changing out the coolant in my GS 4x4, which as it happens is the first vehicle I've had with a cross flow radiator.
First step was to give the system a flush using a proprietary radiator flush & clean then back in the shed to cool down a little before dumping the coolant.
Then:-
- Coolant dumped using bottom hose and block drain with the brass filler plug out. Coolant was very clean; no evidence of rust or scale
- Top radiator hose inverted and distilled water poured down through the radiator till water ran clear
- Bottom hose inverted and distilled water poured through water pump and block till water ran clear
- Surge tank removed and flushed out
- Drain closed, hoses back on
System filled with distilled water to be run up to temperature and then drained and then whole sequence will be repeated with the plan being that any residual fluid in there will be either just distilled water or extremely dilute original coolant. The radiator will come out after the third flush to be taken to my local independent radiator guy for a check over for good measure.

The motor has always ran just under the 80 degree mark no matter what it's doing or how the ambient air temperature is. I filled the system after flushing using a proprietary coolant funnel set-up so that the air could bleed out during filling, and filling would be done with a positive head of water. All OK; top hose eventually gets hot as the thermostat opens and the motor idles away till usual operating temperature is reached. What surprises me though is that the bottom hose eventually only gets and stays barely warm. The top hose and thermostat housing get respectably hot, but the bottom hose gets nowhere near as warm.

I'm hoping there's nothing wrong in this, just that the cooling system is in good order and is working well, delivering cooler water water back to the block. The radiator core is not the original one - it appears to be a re-core - but is externally in good condition with no damaged fins etc. I will be installing a new genuine Isuzu thermostat as part of the final coolant fill so that I know it's benchmarked right, and I will then have a spare on hand for trips.

If anyone thinks there is anything untoward with the way the cooling system as described above is working advice would be appreciated.

Cheers, Dave

I suppose if you're just idling it wouldn't get there. If you're driving it, It should get to full temp, just take an extra few minutes.

That is just my personal opinion. I could very well be wrong.