Larz

I've spotted a coolant leak at the overflow tank on the passengers side. It looks like it's up top. I barely see it. Does the overflow tank have to be replaced as a unit, or can that elbow up at the top come seperate? Should I take it out from the top or go from underneath?

DamonB

Overflow tanks rarely go bad and leak. If your caps are worn the overflow can stay too full and coolant will leak out the top of it. The overflow is not sealed because it's not under pressure.

If the overflow is full and leaking the problem is that it's too full (AST cap or line to overflow is bad), not that it's gone bad.

Larz

You mean the line coming off the nipple on top? Where does that lead to? How much crap do I have to remove to route another one?

Retserof

iTrader: (1)

The hose itself (from the AST nipple to the overflow tank) is probably ok. Instead of tearing things apart to check the hose, more likely the problem is that there is a slight air leak where the hose attaches to the AST nipple. This has no clamp on it from the factory and is only a wedge fit, so install a clamp there. It could also be that your AST pressure cap is faulty. Replace it. Then remove the excess coolant from the overflow tank and make sure that the coolant level at the filler neck on the engine is correct.

BlueTII

The overflow tank has a hole in the top to allow excess coolant to spill out. The real problem is either your ast cap has lost its integrity or there is something faulty in the coolant system allowing air in (cracked hose, pinhole in the radiator, etc). If you are adding coolant on a regular basis and it is spilling out the overflow when you turn the car off then these are the things to check first. If you replace the cap and can not find any flaws in the hoses then you will have to consider that a coolant seal has failed in the engine. One of the sure signs of seal failure is coolant expelling from the overflow tank.
Now if you have been trying to add coolant to the overflow tank, that is the incorrect place to be topping off the system. That should be done at the thermostat housing.

Larz

I put a hose clamp at both ends of the line. I replaced the cap on my Pettit AST. Now I've got dribble coming from the coolant warning sensor. I'm going to try some blue rtv on the threads and see if that stops the dribble. The motorad cap on the AST was already getting rusty. At least they're cheap. Thanks for the help guys. And for anyone having the same trouble as me, pop your headlights up to get the last mounting bolt to remove the passenger headlight (just hope you have small forearms like me). Move the light out of the way and you can get to the nipple with ease.

Retserof

iTrader: (1)

Larz, you may not need that blue rtv.

Sometimes the low coolant sensor vibrates loose and simply needs to be snugged up (when the engine is cold), but be careful not to overtighten or it may crack. Or, since it is made of cheezy plastic, it may be weeping because it already cracked and has to be replaced. Either way, you won't need rtv.

Larz

Sweet. Thanks for the advice.