Leaking coolant reservoir

GN 87 has a leak somewhere in the coolant reservoir. Noticed when I made a look under the hood. Car sitted several months in the winter sleep.

I took the reservoir off and tried to check where is the problem. No leak when filled it with water in our bathroom. How to test it better, some pressure in to the tank somehow or how?

Best regards,

buick8791

AFAIK, an '87 didn't use a pressure cap on the remote reservoir. The original stepped cap is supposed to be vented. If it leaks after running it may be more due to temperature than pressure.

Thanks,

but there was quite little coolant, when I left the car into the wintersleep.

In addition, when I took the battery off after couple of days, there was not any
signs of greater leak, didnt see. The leak seems to be in the bottom area somehow and comes down towards the front reservoir fastening bolt continuing the route down into the battery bottom platform. The cap area is dry...

Why I dont find the problem. I should understand the situation if I have added fluid and `my hand was not in condition.... but I don`t remember.

Hi,

I found the leaking point! Not so accurately, but it is in the bottom side very near to the front fastening ear.

Thanks Blue Bowtie,

br buick8791

If you can get the plastic really clean, it can be welded. Polyethylene is one of the plastics that takes that pretty well. There aren't many good adhesive/sealants, however. I've done that with coolant overflows and windshield washer reservoirs more than once.

Hi,

and thanks for the answer again!

Where I can find polyethylene stuff for welding? Some people says, that oil canister stuff is good for welding. An other advice is to glue or "weld" it Permatex plastic welder. I don´t know how to use that stuff at the moment, but
the instructions are in the internet of course.

There is some hair crack in the area I told before. Now the more accurate inspection with magnifying class to locate the leak point.

Thanks again Blue Bowtie!

I use an actual plastic welder, with a hot air nozzle and LDPE filler material. It's a lot like brazing or soldering but the filler doesn't fully liquify and flow like molten metal. The result is a pronounced "bead" of material over the surface.

The tank is likely polyethylene, are are most coolant reservoirs, washer reservoirs, fuel tanks, and even milk bottles. It must be completely clean to get a solid bond.

Hi again,

the hair crack starts from very near to the front fastening "cup" if you look from bottom side of the reservoir and and continues towards to the hose fitting about five centimeters.

I feel that the crack will become from some tension when bolted on and the plastic will be weakened over time.

Now I have to find the welding system or use the glue. Hope the welding system has good instructions.

Yes I will clean the area throughly before fix.


Tanks again Blue Bowtie!

BR buick 8791

Hi again,

I repaired the GN coolant reservoir hair crack with Loctite two component stuff. Don`t leak at the moment. But, the engine hood stuff will touch the coolant reservoir cap maybe causing later the new crack. the reservoir is a little bit higher in it`s position now when installed some soft material under the fastening ears. Or the situation has always been same, from the factory.

So because the reservoir cap is quite high, could I replace it with some lower cap arranging it with breathing holes or so? the original is not the pressure cap as you know.

Thanks in forward!