BMW 525i -- May 12th, 2005

Time to start digging our way down to the head gasket. I've pulled the radiator out, and the ignition leads have been disconnected from the plugs and coil and are resting gently -- after a lifetime of hard work -- on top of the intake plenum.

The accessory belts have been removed, and the coolant hoses, distributor, timing belt covers, and timing belt have been removed. Note the corrosion and calcium deposits on the thermostat housing. This is the sort of damage you can expect from running a coolant mixture consisting mostly of tap water and insufficient corrosion-inhibiting antifreeze. Very bad. Very, very bad. While pure water does conduct heat better than a water/antifreeze mixture, and therefore arguably cools slightly more efficiently, your engine is built to use a mix of water and 'freeze. Therefore, if you're running pure tapwater in your engine then you are a fool. Stop it!

The exhaust manifold has been removed. Some of the studs unscrewed from the head, one of the studs was already broken off, and one snapped. So only two broken studs are left in the head. Since the head is aluminum and the studs are steel -- two metals which just love to amalgamate into a corrosion-fused unholy union at every opportunity -- I'd say that's not bad.

Note the shiny section of the camshaft pulley where the belt has been riding. Close to the edge, isn't it? This occurs when the belt becomes worn and stretched (or the tensioner fails) and is no longer maintained under proper tension. It was almost riding off the pulley and was only held back by the timing cover -- into which it had sawed a deep and angry groove. The front edge of the belt was thoroughly chewed. I estimate the belt had less than an hour of running life remaining. Then it would have snapped like a dry twig. This is an interference engine -- loss of the belt would have caused the pistons to "interfere", or hammer mercilessly, into the open valves. The head, and possibly one or more pistons, would probably have been destroyed.

The hole in the block below the camshaft pulley is where the water pump goes. The water pump has been replaced at least once. When it was last installed, it was put on with gallons of gasket goop and no gasket. The goop was smeared everywhere inside and outside the pump, and the impeller was 50% clogged with gasket goo. That means less than 50% efficiency in coolant circulation. Somewhere out there, there is a mechanic committing horrific atrocities like this on poor, unsuspecting, innocent cars. If you find a mechanic who does this, you should take him out into the parking lot and feed him gasket goop until he sees the error of his ways.

Here's a heap of removed bits on the garage floor:

And more removed bits on the window sill:

And even more bits:

Here, you can see I've wrapped plastic bags around the transmission oil lines to keep dirt, spiders, etc., from getting in.

More next time!