Offroad-Express

I’ve recently started towing a 1.5 ton caravan with a 1KZTE manual, non-intercooled Surf. This truck has had the entire cooling system maintained (new radiator, viscous clutch etc.). Now most would think that this truck tows the caravan easily due to the amount of power these things have, plus the fact that the temperature gauge doesn’t move (as we know these gauges don’t move until some form of nuclear fusion has occurred under the bonnet). Now, knowing the factory gauge doesn’t work I put on an aftermarket water temperature gauge with the sender on the water outlet flange and off we go on holiday. Driving into Cheviot with a head wind, 90kMH, water temperature 100°C or on the final hills leading into Blenheim, have to crawl up in 2nd gear to keep the temperature below 100°C. Something wrong with the cooling system right? Without the caravan the temperature never gets above 84°C. Following advice I’ve now had fitted a pre turbo EGT gauge and here’s the thing, it basically takes nothing to get the EGT over 700°C with the caravan on. I now think these things just aren’t capable of maintaining these high outputs and most people towing just aren’t aware of it, until maybe the head cracks.
What can be done to reduce the temperatures’? Some say a bigger exhaust which would be a $1000 gamble as now one seems to be able to say if the temperatures will drop that much. Intercooling? Same thing, a fair bit of expense/mucking about, results unknown. I’d be interested to know how others have found towing with these motors and if they found any way around the high temperatures.

personally i havent found a 4 cylinder yet that can tow as good as the striaght six's from either nissan or toyota stables

imho chev 8 is the way to go for any tow wagon

What brand EGT gauge?

The mitsi Pajeros with the 2.8 Diesels are the same, plenty of grunt but make a ton of heat and cook heads

UBZ and I tow our Suzuki's around alot, he has a 1KZTE powered surf and I have a 300TDI L.R.

What we do when we are towing with a our 4cyl turbo diesels is not thrash them.

At the bottom of the hill we usually engage 3rd, keep the rev's up at around 2000/2500rpm, pull the throttle back to about 2/3rds to the point where the maximum boost just starts to drop off and just take your time. The idea being you are pumping the maximum air into the combustion chamber with only just enough fuel to maintain it, but at the same time the engine is burning at its coolest as it is not over fueling. That usually allows you to sit at between 60 and 70km/h.

Provided you don't overheat it, you let it cool down properly after a long hard run, and you keep your airfilter clean and the cooling system is good then there's no reason to get overly worried.

They crack heads as a matter of course over time. It will crack one eventually.

The optimum temperature for diesel combustion is 88 degrees, just as a useless bit of information for ya

EGT gauge is an Auberins digital. I guess taking it easy up hill is one thing but being the slowest vehicle on the road is taking some getting used to. BTW it has already cracked a head with the previous owner (receipts for $4000 worth of repair) hence going over the whole cooling system. Must admit to being pretty disappointed with this thing as I didn’t think 1.5 ton was such a big load - starting to think about that 80 series…

Hi

Have a read here

http://www.toyotasurf.asn.au/forum/view ... 113#229251

Is this a surf issue??

Henry

DieselBoy wrote:UBZ and I tow our Suzuki's around alot, he has a 1KZTE powered surf and I have a 300TDI L.R.

What we do when we are towing with a our 4cyl turbo diesels is not thrash them.

At the bottom of the hill we usually engage 3rd, keep the rev's up at around 2000/2500rpm, pull the throttle back to about 2/3rds to the point where the maximum boost just starts to drop off and just take your time. The idea being you are pumping the maximum air into the combustion chamber with only just enough fuel to maintain it, but at the same time the engine is burning at its coolest as it is not over fueling. That usually allows you to sit at between 60 and 70km/h.

Provided you don't overheat it, you let it cool down properly after a long hard run, and you keep your airfilter clean and the cooling system is good then there's no reason to get overly worried.

They crack heads as a matter of course over time. It will crack one eventually.

The optimum temperature for diesel combustion is 88 degrees, just as a useless bit of information for ya

I have to agree with this, i have towed numerous vehicles with a heavy trailer over the rimutakas with no worries
only mods were the exhaust and dump pipe and the bonnet spaced up drift style chur.. oh and i ran the heater on full up the bigger hills,
but yeah just back off full boost and like db said keep the revs over 2000

Toyota guages lie sometimes
They will crack heads (later if cared for)
drop a gear if crawling up a hill (over 2000rpm is good)
3inch exhaust on mine helps
maybe fit an intercooler (so much difference in power)

Throw a 71 degree thermostat in it .

Dump pipe , the best cooling you can get

What is the tow rating of your surf, as a new hilux is only 2300kg. And your caravan is on the upper limits of that considering the aerodynamic of it.

The 2 best things are a aluminum radiator from aussie always on trade- me and a bottle of oil in the viscous fan.Mine ran the coolest with no grill and front bumper so lack of air flow is a problem.

kow1 wrote:I’ve recently started towing a 1.5 ton caravan with a 1KZTE manual, non-intercooled Surf........ Driving into Cheviot with a head wind, 90kMH, water temperature 100°C or on the final hills leading into Blenheim, have to crawl up in 2nd gear to keep the temperature below 100°C. Something wrong with the cooling system right? Without the caravan the temperature never gets above 84°C. Following advice I’ve now had fitted a pre turbo EGT gauge and here’s the thing, it basically takes nothing to get the EGT over 700°C with the caravan on. ........

couple of quick things here.
100c water temp is not overly hot.
700egt is getting up there but probably still short of the max for the engine.

you have manual which rules out most of the typical surf overheating problems.

getting rid of egr and butterfly setup will help. check the inlet manifold is not clogged up with soot from the egr.

the two main things to keep it cool is big exhaust and intercool.

QUADRACER wrote:Dump pipe , the best cooling you can get

2nd that, 2.5inch the whole way back, made a huge difference. When i tackle the kilmog and dunedin motorway, 700 would overheat and 600 it was fine.

on mine I've removed the egr,throttle body & installed an inter cooler which gave about ~150deg c drop before turbo @ 100kph and then a 3" dump pipe from turbo which dropped it about ~100 c so it now runs at about 300-350 @ 100kph on flat road.

Before I fitted an Intercooler on stock boost my intake charge got up to 138c no wonder these things crack heads now with an intercooler she is down to ambient temperatures

138c is not all that hot. my nissan would be well an excess of that. intake temps is not the sole cause of the overheating.

When you think colder is better e.g. more dense more oxygen for engine performance 138degrees C going into your engine is not that flash

cooler is always better. turbo diesels really do need intercoolers.
but its not a fix for overheating. they overheat because of inlet restriction and cooling system faults.

intercooling and big exhaust gives you more headroom so egt's don't get to high and crack the head. but it will not stop it overheating if you radiator is blocked or fan not working.

tweake wrote:cooler is always better. turbo diesels really do need intercoolers.
but its not a fix for overheating. they overheat because of inlet restriction and cooling system faults.

intercooling and big exhaust gives you more headroom so egt's don't get to high and crack the head. but it will not stop it overheating if you radiator is blocked or fan not working.

I second that.

Yes we know that is just common sense, from what he as told us he as put brand new radiator and viscous clutch in

egr is a prik, causes so much carbon build up in the inlet manifold, engine starves itself of air and gets hot then cracks the head, remove and blank it off. a snorkel is a good cheep way to get a bit more air which helps with hills/motorways..

Afraid the more air from a snorkel thing is a bit of a myth mate, its documented you need to be doing well in excess of what most 4WD's can do for it to be of any effect. If anything, rear facing snorkels can help but not front ones.

NJV6 wrote:Afraid the more air from a snorkel thing is a bit of a myth mate, its documented you need to be doing well in excess of what most 4WD's can do for it to be of any effect. If anything, rear facing snorkels can help but not front ones.

There are two things needed for a diesel to work efficientally is air in and exhaust gas out.

NJV6 wrote:Afraid the more air from a snorkel thing is a bit of a myth mate, its documented you need to be doing well in excess of what most 4WD's can do for it to be of any effect. If anything, rear facing snorkels can help but not front ones.

Yeah, I remember one article from a while back, someone had crunched the numbers and the figure was around 130km/h to create 2psi from a 4" snorkel.

A snorkel is actually a huge restriction to your intake. Its added resistance due to its length, its twists and turns, and the turbo has a big 1.5m+ standing column of air to get moving which increases turbo lag.

Not all radiators are created equal some are just rubbish.

another thing worth noting is to not take out thermostat as it speeds up the water flow to much and actually reduces the cooling effects of the radiator

is it auto? Does it still have the trans cooler in the bottom tank of the radiator? They create a lot of heat (even more when towing) and limit water flow. I would also look at more boost. You might find that when your putting ya foot down rather than getting any more power its just chucking in more fuel causing it to run rich and get hot. A bit more air flow will help this eg. boost

exhaust will help, right from the turbo is best

it shouldn't be running rich unless theres an intake blockage ie from the egr soot. the other thing is they running a throttle controlled butterfly in them. so less throttle means it chokes off more air. bloody emission systems.

increasing boost can be good. but you run into the problem of the air temps start getting seriously hot and the overall effect is your pushing in less air rather than more.

i forgot one other thing. sometimes the timing belt stretches and throws the timing out a bit. that can cause higher temps.

Thanks for your replies.
To go over some of the points raised in the forum:
EGR soot in the intake: The 2 intake pipes where cleaned out 3 years ago when the head was replaced. It will be interesting to see how much is in there now. I have disabled the EGR and the intake auxiliary butterfly is been configured to always be fully open, except during shutdown.
New timing belt 9000kM ago.
Exhaust: I will initially replace the muffler with a straight through unit. I’m also thinking about replacing the dump pipe. The standard exhaust is 2.4” internal diameter so I’m not sure how much would be gained by changing to 2.5” so would need to go to 3”. I will probably do the exhaust changes in stages to see how it effects the temperature.
The radiator is new and is 40% thicker than stock. I refilled the fan viscous clutch and it seems to flow a lot of air, but it is difficult to tell how much slip there actually is.
Lower temperature thermostat: A curly one. As has been said above, 88°C is the optimum combustion temperature. Running the motor cooler than this may reduce the engine efficiency and possibly cause more sludge in the oil.
My Surf has the standard 82°C unit fitted. It is interesting to note that the Surf V6 motor also has an 82°C thermostat in the bottom hose, where is the 2.7 4 cylinder has an 88°C thermostat located in the usual position on the head. I think possibly Toyota has just said that the radiator will drop the temperature about 6°C and so stuck in a lower temperature thermostat to compensate. This assumes that the temperature drop across the radiator is a constant, which I doubt. I would be a lot happier if the thermostat was in the conventional place, regulating the actual water temperature leaving the engine.
If the standard 82°C thermostat is fully open by 95°C, the question is what gain, if any, would be made dropping this temperature if (as some say above) 95°C isn’t too hot. Possibly the answer is a thermostat that opens at the usual temperature but is fully open a little sooner.
I need to get a thermocouple into the bottom hose to see what the radiator temperature drop actually is and the temperature of the water going into the engine.

At the end of the day I still think the crux of the problem is the EGT’s generated that are threatening to take out my head, valves and pistons. I am pinning my hopes on the exhaust mods but I will also try the hill climb method described above.