1998 VW Beetle 2.0l, 5-speed manual w/ 138xxx on the clock.

I know this isn't a site for VW's, but I figured coolant systems are pretty standardized and you guys have been so helpful on issues I've had with my Mini, that I though I'd throw this one out there.

On my way home today, the lower radiator hose popped off the radiator on the interstate and dumped out all of the coolant. I realized this was due to my brother and I not properly fastening the clamp back on after replacing the thermostat. Popped the clamp back on the best I could and replaced the coolant, only to have it pop back off 1/2 mile down the road and flooding out the coolant again. Ended up walking 4 miles to the nearest store and bought another jug of coolant and screw clamps to fasten the hose. Fastened the hose, put in the coolant, and began driving off again.

Three miles later, the overheating light comes on, and upon inspecting the engine, the reservoir had bubbling coolant and overflowed once with expansion cap secured. Replenished the coolant and left the cap off only for it to bubble up again and it sounds like coolant is bubbling inside the upper radiator hose and inside the block. I must have added three jugs of coolant to it today.

I'm stumped on this one. I've flushed radiators before and have never seen bubbling coolant before, but I have been up since 3 AM, so I wouldn't put it passed me to have a brain fart... lol

I did a little research on it... The hose was still in good condition and no leaks to be seen at any place in the coolant system. The thermostat was replaced a 1,000 miles ago, so it's a miracle that this didn't happen sooner. I don't believe it's the head gasket either because the car is performing better than ever. No rough idle or lost of power. The coolant is flowing, so I don't believe it's the water pump... Maybe air is trapped in the lines and just needs flushed out? IDK.

Any and all replies will be highly appreciated...

 

The first thing that came to mind was... when you mention your brother failed to tighten the clap, is is possible he installed the thermostat in upside down?

If the the answer to that question is NO, then I would most likely think that you have a lot of air trapped in the system... I'm sure the VW has a coolant system bleeding procedure. sort of like this...


Best of luck...

Motor on!

 

It also sounds a lot like a bad head gasket. The hose might be popping off from combustion gases getting pumped into the cooling system (the source of the excess bubbles).

You can do a cheap test to see if you have combustion gases in your coolant to check. Some local stores sell the kit or Amazon does as well. Might be able to borrow a cooling system pressure tester as well if your local auto parts stores do tool loans.

 

Thanks for the replies. I'm really dreading the possibility of a blown head gasket... But we replaced the thermostat today. Thought it might have been stuck closed... We haven't gotten coolant for it yet, so we won't know if this fixes it or not until probably tomorrow. Will follow up tho.

 

I would just put distilled water into it until you know you solved your leak. No sense wasting money and generating a little pollution each time it dumps it out on the road...

Hope it is something simple.

 

Whelp, it ended up being the thermostat. The engine overheating must have cooked the little guy and made it stuck closed. Explains the bubbling tank.

Thanks for the replies and thank God it wasn't the head gasket!

Although riiiight after we fixed the VW, my Mini sprung a coolant leak... The plastic around the bolts that go into the radiator (ones underneath the plastic retainer clips) cracked and the pressure shot the bolt right out it. Leaked the coolant all over the ground. It's just one thing to the next when it comes to my luck with cars...