Darryl,<P> Never even thought of the intercooler fan. That is a good point. That would really make a dent in the operating temperature of the engine. With regards to the thermostat. If the engine cooling system comes on earlier (lower temp) it helps keep hot spots to a minimum as the temperature throughout the system is more regulated. If the thermostat was bunged then the engine temp would be affected. Sometimes t-stats will only partially function not allowing the coolant to flow properly raising the internal temperature of the engine and bringing on its associated problems.<P>Rudolfo<BR> I would go with a recore and a hard flush over "rodding" the rad. I look at it as it will be a repeat offender more often with the scaling and after rodding the rad the coolant passages will be restricted somewhat reducing its effectiveness. If you can get coolant that inhibits scaling as you may have these same problems if you are running just water.

Gord,<P>There's a lot of lore surrounding thermostats. They are very simple things whose purpose is to be closed upon startup to create an artificially small water jacket that warms up quickly to shorten the warmup cycle. Once operating temp is achieve, they open to bring the radiator into the circulation (circulation was restricted to the engine block alone).This pays dividends in reduced wear, and the emissions systems and engine computer of modern vehicles also rely upon them.<P>Putting a "colder" thermostat in an engine simply prolongs the warmup period slightly more than the factory intended. This is less an issue with diesels, as they don't have timing maps and the like in an engine computer. But I don't think it would have any impact on keeping a hard working engine cooler. Once it's fully open at high load operating temps, it's open and already providing max cooling potential for the engine. Whether it overheats or not after that point is up to the integrity and adequacy of the cooling system.<P>Regarding buildup of blockages in the radiator, I've never seen them benefit from a flush. Generally, once they're blocked with scale or other crud the 'flush' can't get in there and any thing strong enough to dissolve that stuff might also hurt the engine block itself or the many water jacket sensors. I find it best to physically remove the crud to ensure full radiator circulation.<P>DougM<p>[ 16 December 2001: Message edited by: DougM ]

One local rad shop recently told me that reverse flushing is one of the main causes of thermostat failure, though it normally does the opposite - makes the engine run too cool as the center gets displaced and allows too much flow. <BR>I agree totally with DougM - or vice versa - overheating problems are always caused by some problem in the system, and changing a perfectly good thermostat for one of a different temp will not fix the problem, nor will wetting agents.<BR>Gord, - most Japanese vehicles are modified for the country of sale - except of course, private imports.<BR>Darryl<p>[ 16 December 2001: Message edited by: DarrylH ]

I was away from my office for a long time. I found many comments in my topics and I will answer your some questions. <P>My truck was made in Japan and imported to Peru.<P>I am not he original owner of the truck but I bought it three months ago and am fixing it little by little. <P>Before, I usually pour destilated water or from the river. But now I am educated and the next time when it is necessary, I will fill the radiator with refrigerant/coolant only and no water.<P>About the opening temperature of thermostat is 80 Centigrated. I haven't changed it and it is original from manufacturer.<P>About the DarrylH's comment on the intercooler fan, I haven't tought it but I will check it in the next time when I bring the car to the shop.<P>I also agree that by using potent dust flushing in the radiador may harm the water tubes in the engine block and the car shop has not done in such way but by cleaning with rads.<P>The engine warmup from bottom to the horizontal level (normal) of my truck takes 4 minutes with the engine iddling at 2,000 rpm. Is that the engine warmup long or short time?<P>Some off road fans from here told me that it is common to see some trucks diesel get overheated engine when perform a long climbing sand dunes. They advised me to try to manage to get lower RPM as possible in order to avoid the use of turbo which is the main cause of engine overheating. The turbo is only good for power to run faster in a short trail but very bad for working hard on a climbing (the par on diesel engines drops in steady line after the 2,000 rpm line) and the maximum par for the truck is around 2,000 rpm. By climbing on sand at 2,000 rpm., I am sure it won't overheat the engine for a very long slopes.<P>Rodolfo

Rudolfo,<P> With regards to coolant, the coolant has to be mixed with water to achieve the maximum benefit of its properties. Coolant is designed to stabilise the cooling system. It prevents problems of scaling caused by running plain water in mixed metal cooling systems (iron engine block, aluminum heads, and brass in the radiator). It also provides a safety margin on those cold nights when water would freeze and expand in the block pushing out frost plugs and possibly cracking the block. Up here in Canada we mix it 50% water and 50% antifreeze which prevents the water in the system from freezing to about -40 centigrade. I also spent a lot of time in the middle east where we also used antifreeze in a 60% water/ 40% antifreeze. It helped keep the engine from overheating as the ethylene glycol helps the water in the cooling process. Are you using any antifreeze in your cooling system? If not I would suggest strongly that you do. Hope this helps<P>Gord

Turbo diesels of many different persuasions-Nissan, Toyota, Mitsubishi, Holden(Isuzu)- are very common here in Oz and I can't say that I've seen a lot of them overheat while working hard. <BR>They are generally very stable in the engine temperature department. Most of my experience has been in tropical areas so it is quite hot and humid which does nothing for cooling assistance. One thing I have noticed is when the ambient air temperature drops they go better and better, something to do with cold dense air.<BR>Just thought I'd add my 2 bobs worth.<P>Take care out there,<BR>CraigB [img]images/icons/smile.gif" border="0[/img]

Gord, good to hear from your advises. I am still little confused with products for the radiator of engine. When I read the Yellow product: Prestone : This says it has a perfect mixing of Refrigerant/Coolant and it withstand a range of temperature from as low as -18 Cent and as high as 128 Cent. The zone where I travel has a range of temperature from around -5 C in night on high mountains close to Lima (very few ocasions) and as high as 35 C (most of time) when I travel on sand deserts along the Peruvian coast hunting for a solitarie and nice beach. Should I mix the Prestone with water (60% of water and 40% of Prestone)or none water and only all Prestone?<P>Graig, good to hear from your references. When I traveled on the Amazon Jungle (temperature is around 34 Centigrated and the weather is very humidy) and the truck didn't have any problems with the engine temperature since the road is generaly flat in spite of the fact of speed and the A/C is on. But by traveling the sand desert, the engine makes a lot more effort specially for a long climbing, specially for a loose sand.<P>Rodolfo

50% H2O / 50% coolent-antifreeze is normal.<BR>This mix lowers the freeze point to somewhere around -20C and raises the Boil point to about 110C<P>100% H2O is the best at transfer of heat yet will freeze at 0C and boil at 100C @ 1-Atm (normal sea level pressure)<P>100% coolent-antifreeze will change the freeze and boil points, yet will not transfer heat (Our goal) as well.<P>Also make sure that your pressure cap is working properly, I replace about every 5 years to be safe. 14 lbs-sq in (2-Atm?) will raise the boil point above 120C. This is the pressure cooker principal. You can raise the temprature past boiling IF you increase Pressure. Thus a defective cap will cause early boil over. <P>BOYLE'S LAW (usually for gases): PV/T =C; Pressure * Volume divided by Temp. is constant. Volume is constant in a cooling system... so If the temprature goes up(even past the boiling point), so will the Pressure. If we exceed the pressure of the cap, the pressure goes down but the temprature is the same and the volume goes up (and fluid spills into the expansion/overflow chamber) when the temprature cools, the pressure drops and sucks coolent back into the rad. When the boilover happens, the volume expands quickly. <P>Ever notice that a hot engine will almost always boil over if you remove the cap.

Rudolfo,<P> Check and make sure the Prestone is not premixed. Yes that is antifreeze. If it is premixed (it should say on the front of the jug) and your existing coolant is water you will dilute it further. If you can get an antifreeze tester you can measure the amount of coolant in your system. It looks like a teardrop shaped plastic syphon with a hose on one end and a bulb on the other. A 50% water/ 50% prestone mix will be ok if that is the easiest for you. I would go with the 60%water/40% antifreeze mix as it doesn't get too cold down there. Also make sure you have a clean rad outside when you are travelling in the desert. A rad full of silt will not work as well as a clean rad. We used air pressure to blow off the dust. Make sure if you do this it is done by holding the air nossle to the side as it can force silt into your rad.

Hello Mustangjs, Yes that the Boyle's law applies very well to the radiator problem. The cap of radiator is from original manufacturer and it closes the radiator very well. When the gauge of the temperature is on normal level (horizontal), I can open it without any problem but if the gauge indicates hot, I will never open it until the enginee cools down. Thank you for your comments.<P>Gord, Perfect explanation. The prestone marketed in Peru is written in spanish and it is already mixed with water desionized, refrigerant and coolant and it is ready to pour into the radiator without any other mixing. It has no teardrop shape but a rectangle shape. Many thanks<P>Rodolfo<P> [img]images/icons/wink.gif" border="0[/img]