1991, 740 Sedan

B230F non-turbo

130,000

The other day when I was looking over my Mom's 740, I noticed that there was no coolant in the plastic overflow bottle (passengers side). I found that the plastic neck where the upper radiator hose attaches to the radiator had broken, and was inside the hose, causing the leak. It looked as if the plastic had rotted. I was able to remove the broken off piece and then reattach the hose to the neck, and it seems to be holding firmly enough, but I figure it would be best to extend the length of the neck if possible. Volvo does not sell the neck part separately, it is part of the entire radiator.

Volvo tells me I must replace the entire radiator ($300 + for a new one). There is nothing wrong with the radiator except for the plastic neck. Radiator shops do not repair plastic parts.

My thoughts were to weld or glue a thin piece of plastic to the neck. I want the plastic to become as fused as possible into one piece. Here are the questions:

1. Weld or glue?

2. What kind of plastic is the neck made of?

3. I assume I need to get the same "type" of plastic to bond to the neck - right? Or can I mix different types to create a bond? For example: ABS to Polypropylene? What about the heat of the coolant - will a different type material hold up to 200 + degree heat of the coolant?

4. Unless I find a thin enough piece of plastic to put over the neck it will increase the diameter too much for the hose to go over it - but I think I can get it on. Putting a piece on the inside diameter would decrease coolant flow, and the hose size too - seems worse. I think using the outside diameter is best - your thoughts?

5. What is your opinion on using that Purple Colored, Plumbers Bonding Adhesive for those white plastic pipes they merge together? Does it bond well enough and does it withstand high heat?

Thank you.

Sincerely,

Robert