Auto Repair Advice

Question:

Kevin

My Subaru builds up presure and blows the top pipe even with the radiator cap is of and it sounds like the water is boiling in the block i pulled the thermastat out tested it its ok then put it back in then i changed the radiator because i thought it mite be blocked but it still does it im pretty sure it ant the head gasket or cracked head that is the problem there is no water in the oil or oil in the water but i think as a resalt of it getting so hot. i think or hope it mite be the water pump what do u think

Answer:

With the engine warm, when you rev the engine, does the water level in the radiator go down? This would be an indication that the water pump is working if the level drops when you rev the engine. (don’t take the cap off when the coolant is hot to avoid getting burned, take it off before you start the car). This won’t tell you if the water pump is leaking though, and won’t tell you if it’s working at higher RPM’s. Sometimes the vanes on the pump will separate from the shaft and will keep the pump from pumping coolant at higher RPM’s.

It could be the head gasket or a cracked head even if there is no oil in the water or water in the oil. The head gasket can leak between the combustion chamber and the coolant passage and create excessive pressure in the cooling system. Also if the head is cracked in the combustion chamber area, as the intake charge is compressed, it will leak into the coolant passages and pressurize the cooling system. The only way to tell is to pressurize each combustion chamber one at a time and look for bubbles in the radiator. This should tell you which cylinder the leak is at. Most compression testers can be hooked to an air compressor to perform this test.

Good Luck,

Kevin

It just occured to me when shopping for new tires for my wife’s Envoy that there is more to think about when buying a new car than the upfront cost of the vehicle.

Like buying a copier or printer, it’s the consumables that end up saving or costing you money in the long run. Some manufacturers will actually almost give away printers to sell you overpriced ink cartridges for years to come.

On a vehicle your consumables are brakes, tires and filters. Let’s look at the tires today and the choices you can make at the dealership when picking out a new car.

Tires: Probably the most expensive of the three consumables, tires will end up costing you $300 - $800 for a set of four depending on the size and type. High performance tires with a higher speed rating will cost more and so will larger diameter rim sizes. The popular trend is to have a lot of wheel showing and little tire sidewall. In the case of my wife’s Envoy GM put 17″ chrome wheels with 65 series tires on it. The cheapest tire available for my wife’s car was over $125 at my local tire store. A good set of Michelin’s were over $180 per tire. It’s a SUV, not a sports car, and a good 15″ tire would be fine. Checking tire prices at tirerack.com shows a $20 - $40 price difference between a 15″ and 17″ tire. So the next time you are at the dealer looking for a new car, consider the fact that those huge shiny wheels will cost a pretty penny when having to replace the tires mounted to them.

Kevin Schappell