Faulty water pump sometimes hard to diagnose

Q. I have a Audi with a strange overheating problem that no one can seem to find. For the most part the car will run great with no problems at all and then randomly the temp will go way up and the car will overheat. Do you have any suggestions?

A. We had this exact situation on a ’98 Audi that was in the shop a few weeks back. It turned out to be a bad water pump. It took us a while to catch it because initially everything was working properly. What was happening though was the pump was intermittently locking up and not turning; once we caught it in the act it was clear what was going on. In this case the water pump would randomly stop turning, which in turn would stop the water from circulating.

Water pumps on the Audi, Volkswagen and some BMWs can cause mysterious overheat problems. I have seen before where the impeller on the pump begins to slip on the shaft and cause the car to randomly overheat. I have also seen it come off the shaft all together and in a couple of cases it has corroded away. The only way you can be sure is to take the pump off the car and actually check the impeller. Assuming everything else is working properly, have the water pump removed to see the condition of the impeller.

Trailer maintenance

Don’t forget to check the trailer over before heading out on vacation. Whether it be a boat trailer or a camper, I highly recommend you have it serviced before you take it on the road.

There are four things you should pay attention to:

Tires

Trailer tires tend to deteriorate over time more from lack of use than tread wear. Inspect them carefully for dry rot and make sure you have a good spare with you. You’ll also want to be sure you have a way to jack the trailer and have the right size wrench with you.

Wheel bearings

It’s easy to forget about these but it is critical they be checked, especially on a boat trailer. The backing in and out of the water is hard on the wheel bearings on a boat trailer and they definitely should be checked every year. Nothing worse than a bearing failure at speed … you could potentially damage the axle.

Lighting

Always make sure all the lighting works properly and I recommend you check it well ahead of time and not the morning you’re getting ready to leave. Lighting repairs can be time consuming and could delay the start of your trip.

Brakes

If your trailer is equipped with brakes you should have the system inspected completely, both at the trailer and the controller in the truck if they’re electric brakes. If your trailer is heavy enough to have brakes you will want them working properly, especially during a hard stop.

Taking care of these items will ensure peace of mind and worry-free travel on your vacation.

Ÿ Douglas Automotive is at 312 S. Hager Ave., Barrington, (847) 381-0454, and 123 Virginia Road, Crystal Lake, (815) 356-0440. For information, visit douglasautomotive.com. Send questions to underthehood@dailyherald.com.