VK 3,3l: possible radiator leak?

[bjotob]

I keep having to top up the radiator coolant reserve all the time.
I have not noticed and leaks when the engine is cool but once it gets hot, coolant drips from the bottom of the radiator.
I have never had to top up the actual radiator, only the reserve.

Can one of those 'leak-sealer' fix the problem?

thanks

/bjorn

 

[Demons1964]

Assuming that you've checked that your hoses are tight, it sounds to me like you've got a leak that's opening up under pressure or (more likely) the leak is at the top of the radiator which is only exposed with fully circulating coolant. As you're losing coolant from the radiator via the leak, it creates a vacuum effect and sucks more coolant from the overflow reservoir - hence the need for you to keep topping up the reservoir while the radiator stays full.
I wouldn't recommend the leak sealer, you never know what that stuff is doing to your water pump and thermostat, or cooling channels in the head/block. Definitely get your radiator repaired or replaced because the leak is only going to get worse.

Mark.

 

[daggett]

Have you checked your raditator cap? These are getting old now and may need replaceing and is a good point for leaks as I have found out when the engine is hot and under pressure.

 

[bjotob]

done some more research

I have now contucted some more research

It is not the radiator cap, thats for sure. I have also checked all the hoses(atleast i think i have checked all of them) and they are not leaking.
I have also noticed that my engine gets very hot during days like these when its over 30 degrees(its close to the red on the temp. gauge). When i stop the car i can see the coolant leaking from underneath the radioator because of a hole somewhere on the radiator and helped by the high pressure due to the hot engine.

One question is, why is the engine so hot? It especially gets hot during long stops at red lights. Any guesses?

The second question is, do i have to change the entire radiator, and if so, how much would that be?

thanks

Bjorn

 

[vkberlina]

Ok,

FIrst things firdt pressure test your radiator & cap. Most _good_ radiator places can do a coolant system pressure test with under 5min work without removing the radiator from the car.
I have a tester at home, all it has is a guage and you pressureise the system and then wait to see if it looses pressure ie a leak.

If it is leaking get a recored radiator normally about $300 for a good 3 core. If you dont have aircon you could probably go for a 2 core.

cheers
Scott

 

[Demons1964]

bjotob,

Re: the really hot engine you mentioned on hot days, assuming you're not losing massive amounts of coolant the problem could be due to a few things. Do you have aircon fitted? Do you know if it's an aftermarket installation or original from the factory? If aftermarket, they may not have upgraded your radiator to a 3 core as vkberlina has mentioned. Another possibility is airlocks somewhere in the cooling system. If that is the case your radiator cap will be cool to the touch. Or, your thermostat might be knackered and failing to open fully. Or, your water pump impeller could be corroded and/or bearing might be on its way out.

vkberlina is spot on the money and I'd suggest you follow his advice with the pressure test, before going down the path of replacing multiple parts.

Mark.