Heater problems

Hi all,
Looking for advice, I’ve got 2002 Jimny the heater is hardly blowing any hot air the top hose seems to warming up but not the bottom one also when I removed the rad cap the water looked brownish.

I'd have said that sounds like the thermostat has stuck open allowing fluid to circulate without allowing it to fully heat up.

If your coolant looks like rusty water theres also a chance the heater matrix is clogging up which won't help.

I changed ALL fluids on my car when I first got it, including the coolant which just looked like minging blackish water

Change the thermostat. The brown water could come from a rusty thermostat aswell. Someone could have had pure water on it

Rusty water in your cooling system means oxygen is in there.
Could just be lack of maintenance, where oxygen gets in over time.
Could be a leak.

I would have a look around the engine, radiator and below the centre of the dash for signs of rusty water indicating a leak.

I would top up the radiator, turn off the heater fan but set the temp to hot. Then I'd leave it running until the temp gauge showed half way. Thats when your thermostat should start opening. When it gets there the heater fan should blow hot air when you turn it on.

If you want to check the thermostat, wait until the engine is cold, remove the thermostat. Boil the kettle, drop the thermostat into a mug of boiling water and you should see it open. Best not to use your own mug but I work in a garage so there are plenty of mugs there!

Delux wrote: I work in a garage so there are plenty of mugs there!

heheh - its exactly like that where I work, too

You can flush it with tap water which is free.

A lot of people don't bother using distilled water, but if corrosion is becoming an issue my advice would be to fill it with coolant and distilled water; its not so expensive.

Surely tapwater is distilled in a tank or reservoir before you turn the tap on, making it distilled water anyway? LOL!

I've never heard of distilled water being used in cooling systems before and I done my apprenticeship with the Romans! If there is corrosion in the cooling system it is 100% caused by Oxygen getting into the cooling system via a leak or allowing the coolant level or anti freeze content to fall.

If you allow the coolant level to drop, air (which has oxygen in it) will fill the space the coolant took up. Leading to corrosion. If the coolant level has dropped it means a leak.

Anti freeze has corrosion inhibitors in it so low anti freeze content means corrosion. A drop in anti freeze content is caused by neglect or someone having to top up the coolant with water. Indicating a leak.

That said, your car is 16 years old so I would expect there to be a bit of corrosion in the cooling system.

If one heater pipe is hot and the other cold, the water is either not circulating well (which is probably caused by a dodgy thermostat) or a drop in the water level (leak).

You could fire the parts shotgun at it and just fit a new thermostat but if you remove it and check it first you will know it is faulty. A thermostat is pretty cheap but fitting parts you dont need is expensive. What will you do if you fit a new thermostat and it isnt any different?

If you check for leaks, check the thermostat works and try bleeding the cooling system (the bit where you leave it running with the heater fan and radiator cap off) it will increase your chance of fixing it first time.

The worst job on any car is redoing the job you have just finished!

I know its not that critical particularly in a modern car where there must be only a few litres of coolant anyway.
I'm in an extremely hard water area and avoid using tap water in anything other than my tea.
We use gallons of distilled water in aircraft cooling systems as distillation removes minerals and organic material so is more pure.
There is a lot of discussion about this in many vintage car forums as many early cars dont have water pumps and rely on the sole efficiency of thermo-syphon. Moreover on an 80 or 90 year old system there is an obviously greater need to reduce any chances of corrosion than ever on an already internally corroded (through age) engine . Its on this that I base my reasoning

This is all very true, Max.
In modern engines the only time people usually talk about distilled water is for the battery. You would need around 6 litres of distilled water and anti freeze to fill a Jimnys cooling system from empty. The Jimny has a lot less ferrous metal in its cooling system than your typical vintage car, so like the Mrs. at the pub, tap water is fine, LOL!

I think the point I was trying to make is, rather than read too much into how to stop the water looking rusty the OP should concentrate on establishing whether there is a fault or not.

If you top up the cooling system, turn the heater fan off, set the temp to hot and run the car at idle with the raiator cap off you can ensure the cooling system is bled properly and monitor whether the thermostat is working or not, establish whether the water is circulating thru the heater matrix or not and determine whether you have an obvious leak or not. It costs nothing, its easy, it does not involve breaking out the toolbox, it does not involve spending any cash and you can even have a cup of tea whilst doing it.

To me, it seems madness anyone would not do this as a 1st step with any problem concerning the cooling system. You have to test the system to see what works and what doesnt!

I am sure you would agree, regardless of whether you are working on a plane, vintage car or Jimny you should start with the easiest and most obvious?

Absolutely! Always do the easiest solutions first [smiley thumbs up needed here].

I didn't replace the coolant on my Jimny myself when I first got it almost 12 months ago - I just threw it at my local Suzuki dealership along with a full service and a myriad of other jobs - simply for speed of getting it back quickly otherwise I would have done it all myself, so I'm not that familar with the Jimny. the coolant weas black!
I think however that on mine (M13A) the thermostat is an utter pig to get at; during the summer I had a small coolant leak from an area around the top right side of the engine. I'm told it was the pipe between the block and thermostat housing that had began to leak; it had corroded. Again, I had to throw it at a local workshop as I didn't have the tools (or time) to do it myself, so my knowledge of the cooling arrangment for the Jimny is sparse but it does seem a bizarre place to put a thermostat.
My modern (1979) Midget is an utter nightmare to bleed; it seems to have air pockets in all sorts of places in the system and takes ages to properly sort out.
The old Midget (1932) is still in a million pieces so I have no first-hand experience of that yet. The radiator is made of lead and brass and weighs a ton without any water in it!