Overheating and blue smoke

[Antshiel]

Just got home to find blue smoke bellowing from the arse end of my 92 2.4lte surf and the temp needle racing towards the red. Took thermostat housing appart only to find there's no thermostat present. I have refilled with coolant/water and started again, when the temp starts to get up all the coolant starts bubbling through into the expansion tank and overheats again. It seems the coolant isn't getting through the engine at all. Could it be a blockage? Somebody pleees help

[TonyN]

Sounds to me like someone has had overheating issues in the past, and pulled the stat in an attemp to fix it.

Could be the head has cracked properly now or the radseal has worn out and your seeing the effects.

Pull the hose off the heater valve on the bulkhead and push a hose in it, if you get water coming out of the rad, put the cap on and see if water comes out of the other end of the heater valve, this will flush the cooling system and prove water is flowing.

Check the water pump belts are OK and the heaters blow hot.

[Antshiel]

Sounds to me like someone has had overheating issues in the past, and pulled the stat in an attemp to fix it.

Could be the head has cracked properly now or the radseal has worn out and your seeing the effects.

Pull the hose off the heater valve on the bulkhead and push a hose in it, if you get water coming out of the rad, put the cap on and see if water comes out of the other end of the heater valve, this will flush the cooling system and prove water is flowing.

Check the water pump belts are OK and the heaters blow hot.

Cheers tony, i might go and have a go at it now. I was supposed to be going on my maiden mud voyage tomorrow at Cowm quarry, Iguess professor sod's been waving his wand, thanks

[Antshiel]

Tony, there's 2 valves, any particular one?

[TonyN]

Tony, there's 2 valves, any particular one?

Should just be one, on the bulkhead left of the fuel filter bracket. The hose comes across the back of the motor, does a 180deg bend and goes into the valve.

[Antshiel]

Found it cheers m8 im going to try it right now, so i might be bothering you again in about 20 mins lol.

[Antshiel]

Right ive done this and all works like you said. Is this good or bad?

[TonyN]

Bad, you want to be finding something wrong with the cooling system, then there is a chance the head is OK!

I'd put a new cap on (the seal could leak or the spring be soft and its not holding pressure) and a stat in and see how it goes.

Make sure there is no airlocks and try again.

[Antshiel]

The rad cap seems fine, the pressure seems to blow through the expansion tank and not the cap. Wouldn't putting a stat in pressurise the cooling system even more?

[MattF]

The rad cap seems fine, the pressure seems to blow through the expansion tank and not the cap. Wouldn't putting a stat in pressurise the cooling system even more?

The cap shouldn't let anything into the expansion tank until a specific
pressure is reached. Putting a 'stat in should actually lead to the system
running cooler if everything else is okay, as it regulates the coolant flow
around the engine. It's the rad cap that pressurises the system.

[Antshiel]

Hi Matt, so what you are saying is that it could be just the cap that is causing all this grief?

[TonyN]

Like Matt says the stat regulates coolant flow, less when its cold more when its hot, the trouble with no stat is on some engines the pump is to good, without the stat to control water flow, it gets pumped in and out of the rad to quick, and doesn't get time to cool down.

The cap has lots of jobs, a seal on a spring, that opens at a set pressure to let water into the expansion tank (when coolant really hot) and the main seal that stops the coolant leaking out the top of the hole. Also a return valve that lets water syphon back from the expansion tank as the coolant cools and contracts.

[Antshiel]

Bad, you want to be finding something wrong with the cooling system, then there is a chance the head is OK!

I'd put a new cap on (the seal could leak or the spring be soft and its not holding pressure) and a stat in and see how it goes.

Make sure there is no airlocks and try again.

Tony im sorry to keep picking your brains but should i be able to push the spring on the cap or not. It seems quite easy to do?

[TonyN]

Tony im sorry to keep picking your brains but should i be able to push the spring on the cap or not. It seems quite easy to do?

see post above!



THe spring is the pressure stamped on the top of the cap, 0.9bar noramlly.

The spring could be weak, but without comparing it to a new one you probably won't be able to tell.

[Antshiel]

Right then thanks guys i'll get a new one and give it a whirl, Wheres the best quality caps come from Dealer or Milers?