Viscous or Kenlowe

[topchef]

James.... Rad not blocked and all water ways appear to be clear. Cleaned and drained the whole system last year and refilled with the red coolant so that side of things should be ok. Fitted new stat and cap at the same time too, although the old stat turned out to be working perfectly anyway.

Popuptoaster... Good point, have thought about a small rad with its own thermostatically controlled fan to 'pre-cool' autobox fluid prior to hitting the main rad. Don't want to start making too much work if possible but this looks like a need rather than a want.

[Jameswallace]

You could always bypass the rad for the autobox just to test it to see if that helps

It does sound like something small and silly though as you have all the 'complicated' things sorted

How hot is the cab heater going? I assume the temperature gauge and sender are working accurately?

[popuptoaster]

I've got one similar to this, have used them on various motors in the past, simple and not much to go wrong, flow through the rad is regulated by oil temp without the need for a separate thermostat.

http://www.amazon.com/70264-SuperCoo.../dp/B000CIIDZE

[floatingkiwi]

are you sure you haven't got a knackered water pump or blocked/stuffed thermostat? You shouldn't overheat that quickly unless something else is wrong.

[topchef]

Would love to know what else could be wrong! Cooling system flushed and cleaned, water pump seems ok although not taken it off, but it does pump round. Thermostat replaced and cap (as mentioned earlier) so down to an aux rad for auto box fluid (as a pre cooler) so as to keep it running through rad as well, rather than totally separate. Also looking to re-site the intercooler and free up more of the main rad surface area. Maybe just a small electric fan on front of intercooler might solve a bit of the problem.

I'll keep trying all sorts of 'remedies' till one, or a combination of, works. Just waiting to see if anyone on here can come up with a definitive cure all, hopefully before I start something that becomes something I wish I hadn't started!!!

[floatingkiwi]

1) waterpump - take it off and get another one. Its unlikely its bad but they are cheap. Or just take it off and replace the gasket.

2) radiator - are you SURE it isn't blocked. It may well be if you've just done a flush - how much crap came out with the flush? Is it blocked? Have you removed it from the truck to make sure??
Get a prado replacement item. Twin core and thicker.

3) is your shroud still in place and complete?

4) is your fan hard to turn when cold then gets easier as you turn it by hand? It should.

5) Are you SURE the new thermostat isn't bad?

[Vagrant No2]

Cooling fans mechanical or electric only cool upto 30 mph, after that speed it is down to pure air flow being forced through. If you overheat then its blocked rad, pipes, air locks, water pump impellor loose on shaft (have seen this), air flow to rad restricted (spot lights etc in front of grille). And the usual Surf problem, head gasket/cracked head.

[topchef]

1) waterpump - take it off and get another one. Its unlikely its bad but they are cheap. Or just take it off and replace the gasket.

Will take it off and have a look first ~ see if all seems ok.

2) radiator - are you SURE it isn't blocked. It may well be if you've just done a flush - how much crap came out with the flush? Is it blocked? Have you removed it from the truck to make sure??
Get a prado replacement item. Twin core and thicker.

Not much crap came out but the guy who had it before me was fairly particular with the surf and kept on top of everything so assume it was fairly well looked after. Havent removed it but have had a hose in the top and ran water through ~ clear and unrestricted flow! Will consider a replacement if rad proves to be at fault but not chasing a fault by throwing money all over it unless necessary.

3) is your shroud still in place and complete?

Yes, all there and tight to rad.

4) is your fan hard to turn when cold then gets easier as you turn it by hand? It should.

It does.

5) Are you SURE the new thermostat isn't bad?

No, not SURE, but how sure is sure, it was bought as a direct replacement as I wasn't absolutely sure the old one was ok but was sure it was new and sure it should have been ok. Not buying another one on the off chance ~ I will assume it is ok. BTW the old one was OK too.

When weather warms a bit I'll do another flush, get pump off, test the stat etc and see what happens.

[topchef]

Cooling fans mechanical or electric only cool upto 30 mph, after that speed it is down to pure air flow being forced through. If you overheat then its blocked rad, pipes, air locks, water pump impellor loose on shaft (have seen this), air flow to rad restricted (spot lights etc in front of grille). And the usual Surf problem, head gasket/cracked head.

Hi, I would have thought that at 30 mph the air flow would still be less than a viscous fan running at 90%? As suggested earlier, I will remove rad after a flush to see if all is ok, as far as I am concerned at the moment tho I believe it to be ok. As mentioned, I did remove spots but it made no difference.
Will be dropping in to my mechanic soon so will have another test done to see if there is any gases in rad to suggest a cracked head.

[Vagrant No2]

Hi, I would have thought that at 30 mph the air flow would still be less than a viscous fan running at 90%? As suggested earlier, I will remove rad after a flush to see if all is ok, as far as I am concerned at the moment tho I believe it to be ok. As mentioned, I did remove spots but it made no difference.
Will be dropping in to my mechanic soon so will have another test done to see if there is any gases in rad to suggest a cracked head.

I did cover this subject many years ago at college when doing my apprenticeship. Air flow is a major factor in many ways, for example wind tunnels for air flow over the body and under, how the hot air leaves the engine bay. It is also how a carburettor works, by using a venture. I have helped cooling on kit cars etc, using small electric cooling fans and air guides to increase the flow to and trough the radiator. The same needs to be behind the rad when using a viscous fan. If the cowling or part of it is missing the air is not drawn through it will not work.

[topchef]

TFFT.....finally!!

After a good day running the beast, I saw a bit of steam coming from the bonnet, flipped the lid and found a few pin hole leaks around the top welds. Decided that a new rad was on the cards, ordered from Roughtrax and duly fitted. Took her for a test run and......no overheating....at all. Yeehaa!!

All that work and effort (mostly fun tho) and head scratching and it all boiled (sic) down to a blocked rad. Even after two flushes I assumed it was clear.

Happy motoring again without spending half my time looking at the temp gauge.

[Jonthefish]

Good news : )

Am wondering whether that might be my problem too - I get slight overheating on steep hills. Which Roughtrax radiator did you go for - the low price or the more expensive brass/copper?

[Lewd Lux Lover]

Always worth remembering that the OE temp gauge is really awful at telling you anything from about 82c to 100c as it has a resistor in the back of it making it 'dumb' to that whole temp range. If your needle is moving up its because the engine is already in trouble. They did this to prevent overly worried customers pitching their truck in because of 'overheating' every 5 mins but it does make it hard to work out what temp you are actually showing. Couple that with the odd place the thermostat is and it makes for difficult diagnosis.
http://www.toyotasurf.asn.au/techsite/tempgauge.htm

[topchef]

Good news : )

Am wondering whether that might be my problem too - I get slight overheating on steep hills. Which Roughtrax radiator did you go for - the low price or the more expensive brass/copper?

Hi Jon, I opted for the expensive version as long term I hope to get more out of it in terms of VFM. Also, an extra £100 seemed cheap for what has now become complete peace of mind. I carry a lot of heavy tools in the truck during the week and also tow a couple of horses in a 1300kg box at weekends, so a breakdown is not an option. As in earlier posts, have a look at stat, give it a flush through, check fins are mostly clear etc before going for a rad change. I went to give mine a quick flush and fill with red A/F on Sunday gone as only filled with water when I replaced the rad. Emptied the system into a bucket...almost clean enough to drink!! Now filled up with red and just debating what to have a go at next on the old girl lol. Good luck with yours tho, all the best.