Once off overheating

[losh1971]

Ute VR V6 overheated for the first time ever since my ownership. It boiled really badly, enough to force some coolant out the overflow. Trying to track down the issue. RACT found the fan relay hard to remove and suggested this may be the issue. Is this a common problem? I will definitely go to Holdens next Wednesday and grab a new relay. I just want to make sure this doesn't happen when I'm an hour out of mob reception. So need some info so i can cover all my bases.

 

[lowandslow]

If it over heated while you were moving the fan relay wouldn't matter.
Sticky thermostat perhaps?

 

[losh1971]

I pulled out of Bunnnings and drove about 3km. Got to the traffic lights traveling at 50kmph, stopped with engine running twice and noticed the temp guage on full. Pulled over and it was boiling. RACT removed the relay but it needed prising with a screwdriver to get it out. Swapped it with heater fan relay and drove 30km with no more issues. Not sure if aircon had anything to do with it as i pretty much always have it running. After the breakdown aircon remained off.

 

[losh1971]

If it over heated while you were moving the fan relay wouldn't matter.
Sticky thermostat perhaps?

can the thermostat suddenly stick shut after a 1.5hr drive and then reopen 15 mins after shut down and stay open?

 

[Wozza]

Have you been checking the level in the radiator from time to time...Ive seen the rad level drop with no or little expansion bottle level change...normally rad cap or a blocked/broken line to the expansion bottle....

 

[losh1971]

Have you been checking the level in the radiator from time to time...Ive seen the rad level drop with no or little expansion bottle level change...normally rad cap or a blocked/broken line to the expansion bottle....

haven't open the rad for over a month. Expansion tank has been working up until the last time i checked which was about a week ago. If it was blocked the boiling unblocked it as it filled the tank to overflow and sucked back down again 15mins after i stopped once the temp gauge went to full and got the car running again. Before it boiled i drove a good 4hrs today during the course of the day. After swapping the relay it has been fine, although the trip back after overheating was only 30mins, with one stop at the supermarket half way.

 

[Wozza]

Pays to keep an eye on rad level.....its happened to me were the bottle was fine and the rad was 1/2 empty....nfi what the real cause was ....since Ive been checking the rad hasnt happened again on either commodore.....So maybe rad cap gets stuck or gummed up and sticks, like I said no real Idea...just a gut feeling

 

[losh1971]

Yeah I will have to keep an eye on it. I checked just now and it was full. I will grab a new relay from the stealer regardless and replace it to rule it out. When I started the engine after it boiled the fans didn't cut in until the RACT man removed the cover, which ended up with him bumping the relay. Before he arrived i started the engine and the fan didn't kick in and the temp was 3/4, so I shut it down. I told the RACT man about the fans and thats when he removed the cover. He reckoned fan relays are a common issue, but he may or may not be qualified to give a proper diagnosis.

 

[losh1971]

Dunno if this makes a difference, but i drive on corrogated roads for around 30mins per trip twice a week. Other thing is the front fan mounts have been repaired and new plastic mounts fitted to the fan as it had a knock to the front at some time its life.

 

[Wozza]

As you run with the aircon on most of the time means that the fan is running every time you drive....this could cause the relay to over heat or he fan to wear out....The missus VX killed one of the fans as she runs aircon all the time (she has the climate control on all the time) and finding a good working 2nd hand one was pretty hard as both the fan motors in the VX are different...new I couldn't find one locally....