I just discovered last night that the coolant expansion tank in my wife's truck has a crack where it's leaking severely when hot and pressurized - it nearly emptied the tank in a 45 minute drive.
Someone at one of the stores I called mentioned that some people have used high temperature epoxy to fix holes and cracks in these. I of course didn't think to ask what kind or if they had it in stock, since I had in mind replacing the whole thing, so now I'm waiting for a call-back about it. In the meantime I thought I'd ask here if anyone knows what to use, or if I should just replace it. I can get a new tank locally or online, but not for a day or two - I was hoping to find something right away, like today or maybe last night, so patching it is appealing. Or it could be a temporary fix until I get a new one.
I pulled it out and can see there's a ding type crescent crack about 1 cm across where it may have been hit with a tool or maybe a pebble kicked up from the road. There's plenty of room for a big glob of epoxy on the outside. Unfortunately, the inside is not accessible, so I can't put anything there, and all the patch force will have to be taken up by adhesion on the outer surface. The plastic material is that usual black glass-filled alloy. The only marking that may indicate the type is ">PA6.6-GF30<" molded in with part number and date info. The tank is otherwise in good shape, so it seems it should have plenty of life left. The truck is a 2007 BMW X5 4.8i.
An alternative is to drill out a small hole in the crescent, then put a screw with rubber washers etc if I can at least work a piece of hardware into the inside. Or, a hole would allow me to get some of the goop on the inside, but it's not enough to do much cleaning of the surface around it.
Does anyone know of this kind of repair or suitable adhesives? It will have to work in the under-hood environment with oil etc, and at coolant temperature, and be able to bond properly with the plastic.
Ed
