Better cooling for the Jimny?

Tomhorntoad wrote: Jimny runs hot when driven for long distances at speed. I've had a water pump and coolant change and cleaned out the rad. But is there a upgrade or something I can do?

How did you clean out the rad?

When the tubes silt up and block , backflushing with the hosepipe won't clear them. The usual trick is to lose the coolant*, and fill up with dilute hydrochloric acid (muriatic acid/brick acid) then run it for a while. This will convert the silt into soluble chloride salts, and clean out any tube that water can flow through. It will gradually eat into the blockages and clear them given enough time.

It usually causes the tiny pinholes that were blocked by silt to spring a leak though, and I wouldn't let it go through the heater core.





*I think the acid reacts with some antifreeze

I'm a little intrigued by the 'locking of the fan'.....how do I do this?

You don't need to, unless the viscous unit fails. If you must, people contrive something with cable ties.

with a cold engine switched off, try and turn the blades. They should rotate with some resistance.

If they spin freely, or there is play in the fanblades, then the viscous unit is shot, and you need another.

You should not need a fan when driving at 50mph as there should be more than enough airflow through the radiator, the fan is for when you are not moving at speed.

The most likely reason for overheating is the radiator is partially blocked (either externally with mud, or internally with silt), if the thernostat isn't stuck, and there are blades on the waterpump.

I suppose the oxygen sensor could be faulty, and the car is running too lean, but they normally fail and cause rich running.

I had the same problem radiator looked fine and was flowing when I cleaned it whoever it wasn't until I took it out I found that the radiator had a hole in it at some point and had been sealed by previous owner. Bought a new radiator off eBay about £40 and it fixed the issue. For £40 its worth it!

I'm thinking I don't get much air flow with my arb bumper .... Also doesn't help

Tomhorntoad wrote: I'm thinking I don't get much air flow with my arb bumper .... Also doesn't help

The Aussies make the ARB bumper and don't have any issues with cooling in their heat so it won't be the bumper's fault.

I think test the fan as suggested above. If that's ok buy a new rad for what they cost and change the coolant a few times over with a strong mix to break down and clear out any silt from the engine its self.

Kirkynut