Heat from powdercoating won’t harm rims

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This article was published 19/02/2010 (5724 days ago), so information in it may no longer be current.

QUESTION: I have a question. Will powder coating my aluminum ATV rims weaken them with the heat used in the process? Thanks in advance for the advice.

ANSWER: The heat from powdercoating won’t harm the rims. During the powdercoating process, the “paint”, which is really a plastic powder often with a polyester base is sprayed on the clean parts using a special spray gun. Your wheels will have a static charge formed on them by the equipment so the powder is attracted and clings to the metal parts. Then the metal is heated just enough to melt the powder, which is in the 90 to 120 degree C range, far below the annealing or melting point of aluminum alloys. It is the metal that needs to reach this temperature, not just the powder. The melted powder forms a bond on and around the metal to create a tough attractive finish.

If the metal parts were to be heated too hot, the powder is damaged, so any problem would be obvious. Professional powder coaters are very careful about maintaining the correct oven temperatures. If it is too cold, the powder doesn’t flow well and the finish doesn’t look good. The parts can be sprayed and baked again but this takes additional time. Oven temperatures that are too hot also create poor finishes and waste money to heat the oven.

If you are doing the coating yourself with one of the small home powdercoating kits, the part must be absolutely clean. Different types of powder require slightly different baking temperatures, so some experimentation may be required.

Many aluminum automotive wheels are finished already with a powdercoating process at the factory. Treat the finished wheel like it has paint on it for the best appearance and if you balance your wheels, be careful to use coated wheel weights or stick on weights, as this reduces the chance of corrosion at the wheel weight positions.

QUESTION: I have a 1993 Ford Fiesta. My son was plowing through some snow and the electric cooling fan for the engine became jammed. He continued to drive it until it overheated and steam came out of the engine compartment, at which point he parked it. Several hours later we went back to the car and put some coolant into the radiator, started it up and drove it home.

It seems to be operating fine and we were able to free the electric fan, but there is a little steam coming from the engine block about half way down and a few drops of coolant can be seen on the ground after it has sat for a while. The coolant level also drops slowly when we have been driving the car around town. I can’t tell where the steam or coolant is coming from exactly, but wonder if there is something that I can use to seal the leak? We thought of using silicone on the outside of the engine but someone told us that won’t work. Any ideas?

ANSWER: I suspect that the leak is coming from the cylinder head gasket area and a careful visual inspection should be able to see stains or leaks from that area. If you can’t see it, dye can be added to the cooling system and a black light used to highlight the leak. When the engine overheated, the cylinder head most likely warped. Now it can’t clamp the head gasket properly and a coolant leak has developed.

An external leak is a problem, but an even bigger problem occurs if the coolant is leaking internally into the cylinders and draining down into the engine oil pan. A little antifreeze mixed with the engine oil can damage engine bearings in only a few kilometres of driving. You can check the oil level to see if it is rising, or carefully loosen the oil pan drain plug to see if coolant comes out. The coolant will sink to the bottom of the oil pan, so it will drain out before the oil.

If the leak is from the head gasket, the cylinder head will need to be removed and resurfaced to make it flat again. A new head gasket and head bolts will be needed to reinstall the cylinder head again.

Jim Kerr is an experienced mechanic, instructor and member of the Automobile Journalists’ Association of Canada.

kerr.jim@sasktel.net