I've been having overheating issues with my 2002 Vitara 2.0 4 cylinder for a couple of years now. The needle is usually vertical or slightly below (let's say 11:30 on a clock). Now it goes above. And sometimes it goes all the way to the red. BTW, it only ran in red for a few seconds... I was lucky enough it happened only a few blocks from home.

So in two years, I've changed the thermostat 3 times and the waterpump 2 or 3 times. I've never found an actual problem.

It was okay for about 9 months now. It got fairly hot a couple of weeks ago.

This week, I forgot my keys in the truck (running) Doh! But once I figured out that problem it's been running hot ever since. Twice it went into the red as stated above. Just a couple of blocks away from home.

I'm fed up of changing parts for nothing  ... And I'm not a big enough Suzuki fan to start putting electric fan and such... I'm just going to get rid of it and buy a Grand Cherokee if all else fails...

Any ideas? So please help in the name of Suzuki! 

Thanks!

Make sure your rad is clean inside and out.  If you have AC then you also have to make sure there is no dirt\debris in between the condenser and the rad.  Make sure you have a rad shroud also. You also might have to check your gauge as it could be defective and your engine is cooling fine.

The radiator is clean (has not seen any off-road ever), the shroud is in perfect condition and the cooling fluid level too.

I'm starting to wonder about the gauge... Where is the sensor in the engine?

On the back of the head, intake side, between the head & the firewall.

Just a thought.... how many miles do you have on your truck?  If the radiator wasn't serviced regularly or at all (flushed and replaced coolant) it is conceivable your radiator isn't cooling your truck like it should because the coolant is degraded OR it has a partial blockage.  On my '91 sidekick I chased an over-heating problem at about 150K miles, replaced thermostat, pulled the radiator and had it boiled, flushed and pressure checked, still over heated.  Replaced radiator - done deal.  Yours appears to be sporadic... but you could check it any way by letting your engine warm up to operating temp, then open the hood, manually increase the throttle a couple thousand RPMs and watch your top radiator hose.  If you do have serious blockage inside your radiator the hose will attempt to collapse a little from the water pump suction (and not enough fluid flow).  OBTW... you can't be sure your radiator doesn't have a serious restriction by viewing into the radiator cap.  It may look clean and green down but there can still be some blockage.

I'm not sure if this will help. My 16V had a clutch fan that went bad few months ago (not sure if yours has one) it was doing the same sporadic overheating. With the engine running look at the fan movement and throttle up. If the fan does not seem to increase speed (usually they move slower at higher rpm) it could be the source of issues.

Zack

A bad fan clutch is a possibility in cases of intermittent overheating, the trick is in noticing that there is a pattern to the overheating, which, from a "behind the wheel" stand point, would be overheating at idle, or during low speed/low gear operation - for example in heavy traffic or towing, but not at free way speeds.

The easiest way to check the fan clutch is this ...

 - with the engine cold, before you first start it, open the hood and with the engine off, try to turn the fan, it should turn, but with a fair amount of resistance
  - start the engine and let it idle for a a few minutes, five minutes or so, and then switch off and try to turn the fan again, it should turn, but this time with less resistance.

If the fan spins freely with the engine off - or - if you cannot turn the fan with the engine off - the clutch is shot.

Well, I got a new car for daily driving so I will have plenty of time to work on the truck. I'm not giving up.

Thank you for all the suggestions.

I've also noticed that the heating isn't working. Maybe the heater core is blocked.

Once that is fixed, I have to work on the rusted rockers and make new bumpers. I'm going to try to build a snow bruiser. Wish me luck!

Well, I got a new car for daily driving so I will have plenty of time to work on the truck. I'm not giving up.

Thank you for all the suggestions.

I've also noticed that the heating isn't working. Maybe the heater core is blocked.

Once that is fixed, I have to work on the rusted rockers and make new bumpers. I'm going to try to build a snow bruiser. Wish me luck!

That may be a key factor in your overheating problem - try bypassing the heater core with a loop of hose and see what effect it has.

On most engines the thermostat is in the water outlet from the cylinder head to the radiator, where it is in direct contact with the hot water, and opens based on the temperature of that water - however, on these engines, it's on the return line from the radiator to the engine block, where the water is cooler and I believe it depends on a flow of hot water through the heater core to open properly.

...On most engines the thermostat is in the water outlet from the cylinder head to the radiator, where it is in direct contact with the hot water, and opens based on the temperature of that water - however, on these engines, it's on the return line from the radiator to the engine block, where the water is cooler and I believe it depends on a flow of hot water through the heater core to open properly.

There is also a bypass line from the engine to the thermostat, which bypasses the radiator - I assume that's open when the main flow through the radiator is closed by the thermostat.

Here's what I have on the cooling flow.

If the thermostat is closed, there is no return flow from the radiator so whatever circulation occurs must pass through either the heater core or the throttle body - the heater core uses roughly 1/2" diameter lines, with the throttle body lines being  significantly smaller.

More important, it is this "bypass" that channels the warm water directly to the "business end" of the thermostat, the wax pellet that causes it to open & close, and that is why I believe that without a flow of water through the heater core, the thermostat will not open.

I'm not so sure; the diagram I have shows the bypass going straight from the engine to the thermostat, not requiring feed through the heater core or the throttle body.  Of course, if it is blocked as well......