[Mikeb]

Hi, I’m new to this forum and I haven’t had many issues with the Suzuki (Grand Vitara, 2.4 petrol, 2016, 90,000km). Last week I travel about 80km and noticed a little overheating and topped up the radiator 3/4 litres. Every thing was fine driving around Adelaide, and then I suddenly noticed the heat gauge go up rapidly and I lost about 3 litres of coolent. I then travelled 60-70km from Adelaide to Victor Harbor - if you are familiar with the road you would know that it’s quite hilly- and the gauge didn’t move. Then the motor started overheating. Did the normal things like pull over and let it cool down topped it up with quite a few litres and this condition continued every few kilometres. The radiator developed a leak 1 year old! I assumed the thermostat failed and replaced that, and put in a new radiator along with a new radiator cap. I thought I had bleed all the air out of the coolant lines but it continued to overheat after only 1 or 2 km. After a few hours of bleeding bubbles out of the system, ie, burping the bottom hose, placing funnel in the radiator cap hole and running the engine the front of the car jacked up it ran fine for about 3 hours which included suburban driving up and down hills and a 30km country road trip and the the temperature suddenly went up and down very quickly the 8km further on it started overheating with stop and start driving until I got home. When the engine cooled down I could see their was no loss of coolant. I put a funnel into the radiator and topped it up a bit with coolant and could see a few bubbles come up. I also checked the coolant with a combustion leak detector but it came up negative. Went for a 15 minute drive and the gauge didn’t move from normal. Totally flabbergasted as to what might be the issue. Runs beautifully. I also doubled checked the new thermostat for correct orientation and that the bleeder was at the top. Hope someone has and idea or two that I can follow up on. Thanks for taking to time to read the post and your consideration. Cheers. Mike

[Mikeb]

Hi, and thanks for accepting my post. Since posting the issue I am now wondering if I actually have an electrical sender/receiver fault. What I have noticed is that temperature changes quite quickly on the dial and when I pull over to avoid overheating damage that it cools down astonishingly quickly which has only just dawned on me! I just went for a drive and the temperature did eventually go to hot, very hot and the drop down quite quickly which I don’t think it would do if it was genuinely hot. While monitoring the engine I just kept driving this time and it kept moving about. When I arrived hot with a hot engine , like the dail at its highest there was no indication of overheating from the engine bay, overflow take or any of those alarming creaking and cracking noised tha normally accompany a hot engine. Thanks for taking the time to read my post. Love to hear your views. Mike

[Gwagensteve]

Sounds like a head gasket to me.

A sender fault won't make the engine consume/push out large volumes of coolant which was the start of the problem.

Since then you've continued to have issues intermittently with air in the coolant and temperature fluctuations.

When senders aren't in contact with liquid the temperature displayed on the gauge drops. i.e if there is an air pocket around the sender the reading will fall so I would give no weight to a gauge that shows hot and then rapid drops.

They're also rarely faulty a way that makes them wildly, randomly vary. They'll tend to work or not work. A random fault like that would more likely be on the 5V side of the instrument cluster which would make all the gauges go crazy.

I would have the coolant system pressure tested and a compression test carried out.

[HarryHoudini]

Welcome..

Yes,if its not the thermostat its most likely the head gasket or a cracked head itself.

[Mikeb]

Thanks for the feedback. I’m not loosing fluid and the combustion leak test indicates that it isn’t but I still can’t ignore the possibility. Cheers Mike

[Mikeb]

I think your explanation (Gwagensteve) is sound and it explains the symptoms very well. I’ll have get a compression test etc organised. Thanks. Mike

[Gwagensteve]

The cooling system is effectively sealed, in that if the recovery tank is working properly, the system should stay brim full, drawing coolant out of the recovery tank as it cools. you discuss topping up the coolant and also bubbles in the system. That means air is getting into the system and therefore coolant is getting expelled or consumed.

Assuming the cap is working properly and the hoses etc have no leaks.

[Mikeb]

The open cooling system and top was during the process of removing any trapped air from the system. After placing the radiator cap there is no loss of coolent even when it does get very hot. After considering your comment on the temperature sensor unit and making additional observations during the overheating I agree that is not the problem in fact it’s working as it’s supposed too. I have booked the vehicle in for pressure testing and compression testing. It will be interesting to hear what there results are. I still can’t get over the fact that it can go into overheating quite quickly and in the same day run perfectly under the same “apparent “ conditions. Thanks again and I’ll post the outcome of the testing for learning purposes. I think I will be taking the head off some how. Cheers. Mike

[Gwagensteve]

Get yourself an IR thermometer and learn what good and bad looks like at the thermostat housing. Probably the cheapest way to diagnose what is going on.

[shep]

Check the block, the 2.4 is good for cracking and then leaking. My 2.4 GV did it.
There is a good post on here somewhere about it.

Mine was easy to spot the crack as dried coolant built up on the block

[Mikeb]

1). I have bought a ir gun and will focus on the thermostat housing. Good idea potentially useable information. Thanks.
2) I’ll check the block as I can’t rule anything out but I’m not losing coolent. Cheers

Thanks all
Mike

[Andygoodbloke]

Head Gasket sounds the likely suspect, but also check the oil level as if this is over full it maybe where the water is going look at the oil filler cap and see if it is covered in a mixture of oil and water which looks like Mayonnaise- water can't simply disappear without a trace. I have worked for garages in the UK and they have a test strip they dip into the radiator water to test for signs of exhaust gas, not sure if this is available in Aust and NZ but would answer the question of it being the head gasket.

Other things to check is the steam coming out of the exhaust if the leak is going into the cylinder? - this is likely to foul a spark plug and give you lumpy idle of 3 cylinders.

Heater hoses maybe worth inspecting as these are used during the winter and can leak under the bonnet and also under the dash or passenger floor - is it wetter than it should be - is the car always steaming up?

You maybe able to go to a local garage and get them to pressure test the cooling system which will highlight any leaks. Water pumps can also cause leaks and water loss.

Hope that helps
cheers Andy

[Gwagensteve]

It sounds like the combustion check has been done in the coolant.

[Mikeb]

Yes you are correct and your assessment earlier was spot on. I’ll about to take the head off! 10+ 1 and I’ll have a better idea. I’ll let you know. Very exciting stuff. Cheers. Mike