The Mitsubishi Pajero Owners Club®

[assassin]

Many people disregard the cooling system until a problem occurs, but simple servicing can save a multitude of other problems, and considerable expense, and its not difficult for the average home mechanic, and now is the time to do such work; before winter sets in.

Over time cooling systems deteriorate, this is for a variety of reasons, mainly natural deterioration and the subsequent build up of contaminants from this deterioration, much of this can be avoided with this simple guide to cooling systems.
Before starting always ensure that the heaters are set to the hot position so the heater matrixes will drain and refill, this will prevent airlocks from forming when it is refilled with coolant.

To begin with we need to drain the water from the cooling system entirely, simply undo the radiator drain plug, then remove the vehicles bottom radiator hose, the swift movement of water will remove much of the dislodged contamination, and it will come out with the water. Replace the bottom hose and the drain plug, fill the system with plain tap water, fill slowly with a watering can or similar, after every couple of litres massage the bottom radiator hose to level the water out and dispalce any trapped air which may give problems, always fill very slowly. Run the engine to working temperature and check all the heaters are all working when the engine is hot, check the temperature gauge to ensure it is not overheating and creating any more problems.

With the engine fully up to temperature, drain the plain water off, if it is murky it is removing contaminated water from problem areas such as heaters matrixes, if it is really brown and discoloured, repeat this stage until the water drained off is nearly clear.

Refill the system again, only this time put a good quality cooling system cleaner into the radiator, use in accordance with the manufacturers instructions, then drain the system when it has done its work. Remove every cooling water pipe you can find and insert a hosepipe and fully flush through, do not forget the front and rear heater matrixes, and back flush the radiator itself, this will leave you with a fully flushed and clean cooling system.

If appropriate, or thoroughly recommended, replace the engines thermostat and radiator cap at this point as it is good insurance, also check all the cooling system pipes, replace any which are showing signs of wearing or damage.

Work out the systems cooling capacity and pour in the required amount of anti-freeze first, i prefer a 50/50 mix, this works well in most engines, and pouring the anti-freeze in first ensures any remaining trapped water in the system receives the correct mixture. Remember to massage the bottom hose after every couple of litres, and fill very slowly, when the system is around 3/4 full lift the front of the vehicle as high as possible to prevent any air pockets from forming, then massage the bottom hose again, this will release any trapped air. Top up with pure water, and i recommend adding a radiator sealant at this stage, i prefer "Bars", because decent products act as lubricants for moving components such as water pump bearings, and they find any small leaks from the previously removed hoses, basically it is another cheap insurance. Do not forget to add a water/anti-freeze mixture to the expansion bottle.

Once full run the engine until hot, this will circulate and mix the water. anti/freeze/radiator sealant mixture while watching the temperature gauge carefully, once fully hot, check the heaters are giving good heat output, a cold one will indicate an air lock in that radiator matrix. If everything is satisfactory give the vehicle a run for at least 10 miles, use slow speed roads, and higher speed roads such as dual carriageways, rev the engine hard to displace any small pockets of remaining air back to the radiator.

Leave the vehicle to fully cool, once fully cooled remove the radiator cap and check the water level, top up if necessary.


Some strange facts about cooling systems: Anti-freeze is a misnomer, its main duties are as a corrosion inhibitor between the dissimilar metals and components used in modern engines, preventing freezing is a secondary function, but a very important secondary function.
Running with no, or too weak a mixture of anti-freeze can cause erosion of other engine components, these are mainly the cylinder head gasket, this eats away at the gasket around the waterways between the engine block and cylinder head, this weakens it over time and leads to premature failure. It can also cause problems for other gaskets, sealing rings, and rubber based components such as pipes.

Modern anti-freeze requires changing every two years as it loses its corrosion inhibiting capabilities after this time, but the latest anti-freeze lasts for around 5 years, so replace the older stuff with the newer and significantly better 5 year life product as it contains inorganic corrosion inhibitors.

Always keep a topping up bottle for your cooling system, mix water and anti freeze at a 50/50 mix and only use this to top up with, many people simply use water, this weakens the anti-freeze mixture and reduces its life and effectiveness, topping up from your pre mixed bottle prevents this.

If you have a water filter at home, filter an appropriate amount of water to fill your cooling system with, this removes many of the problem metals and chemicals such as chlorine and flouride which cause many of the cooling system problems. If you do not have a water filter, boil the kettle and collect this boiled water, allow it to fully cool and use this, this does remove a quantity of water contaminants, but is not as good as a water filter.

[Google]

[DawnH]

well written up, cheers

[tangray1]

Really good post, but could i ask when it comes to refilling are there any problems accosiated when it comes to LWB models that have rear heater thet must have a heater/aircon matrix at the rear, and i could see this to be a real problem with air locks ? are there bleed nipples along the line ? mine`s a 3.2 DiD lwb.
                                              Cheers now...

[assassin]

Mines also a 3.2 LWB with the rear heaters/climate control, and there are some issues which can be dealt with with a little attention, i too noted the potential for air locks in this heater. I have a slight downhill slope, i face down to drain the system and use this to flush the entire system to ensure as much drainage as possible from the flushing is removed as a considerable amount of water can be trapped.

Whenever i fill any vehicle i raise the front, i do have the advantage of a high lift hydraulic jack, and fill it very slowly, only a couple of litres at a time, massaging the bottom radiator hose disperses the air and levels the water out, so pre-mix the coolant and add slowly. One other tip is to remove one of the highest hoses which feeds the system, this also prevents air locks as the air can be displaced through this hose and allow the water to fill the heaters properly, as soon as water appears, quickly install the hose. This applies to most modern vehicles. Do not run the engine to distribute the coolant, it often only agitates the water and admits more air on occasions, increasing the risk of air locks.

I have not found any bleed nipples, but have not looked as doing it this way does not require them.

[zesty]

Fairly new to this whole game and picking up tips along the way. Recently solved a water leak with Radweld and refilled the system with Halfords recommended antifreeze and water straight out of the tap. The question is this, having read this thread and others I now know that I should have used distiller water, however should I let it go for the winter and do a full flush in the spring or bite the bullet now and waste all the antifreeze etc and start again. Thoughts please

[gegs750k4]

should have fixed the leak and not used a sealant in it... just my thoughts though

[Bago]

Excellent write up Assassin, which antifreeze type should i use in my 1994 SWB 2.8?

[assassin]

On everything up to Mk III models you use the traditional non OAT anti freeze which lasts for 2 years which is normally referred to as the 2 year blue anti freeze as the cooling system contains "yellow metals" and these react with the long life OAT type anti freezes.

For MK III's and MK IIII's you only use long life as the cooling systems only use aluminium components and no yellow metals.

Sorry folks, should have made this clear.

[4x4traveller]

Assassin this is great exactly what I needed and i'm sure will benefit many others.  I think this should be made a sticky as all the information is right here in one easy to follow guide great work.

       

[Simon_W]

I agree, it's an excellent write-up. The recent additions to the thread drew my attention to it.

I am interested in the advice to use Bars Leaks as a matter of routine.  I thought that leak sealants tended to clog the waterways in the cooling system, and therefore weren't recommended. Also if there is a small leak in the system, isn't it better to be aware of it, and be able to fix it, rather than have the symptom masked by a sealant?

[kenthepipe]

I always remember many years ago ( when they were affordable   ) I owned a 4.2 E-type Jag, I bought a genuine workshop manual for it, and in the section on draining / refilling the coolant system it was in black and white that Jaguar recommended the use of Barr,s leak additive. Note this was a genuine Jaguar w/shop manual, not Haynes.

[Simon_W]

[The procrastinator]

[Rob546454]

Good write up, but I would advise agains stop leaks really seen what they can gum up. Also lets not forget the viscuous fan; You can have a top notch cooling system but if the fan has lost fluid and isn't locking up it will still overheat.

[assassin]

I recommend Bars Stop Leak for one reason only, it isn't a leak curing product as it is a multi function product which doesn't clog cooling systems.

Lumps you see in it when you put it into the cooling system break down and become a lubricant and lubricate any moving components such as water pump bearings and coat things such as waterways or impellor blades with a fine film which prevents further corrosion on a clean cooling system and by doing so it prevents corrosion occurring and is a second line of defence to the anti freeze.

By prolonging the life of your anti freeze by coating everything and preventing corrosion build up, and acting as a lubricant it seriously prolongs the life of your cooling system and when you are working the engine heavily off road, or towing that heavy load it gives insurance and peace of mind to such users; if you develop any small leaks for a silly reason it will seal them to stop you losing water and it does this very quickly so you don't lose any quantity of water and overheat which with its other benefits will allow you to complete a journey and not blow your head gasket.