What are some car-repair jobs you always wished you could do but have never done?

If it's a 20-year-old Toyota the original exhaust was stainless, but it was a ferritic stainless that will eventually corrode with enough heating cycles.

"Stainless Steel" is actually a whole lot of totally different things in three different and hardly-even-related families.

--scott

My 2000 Acura TL has an all stainless exhaust system. I'll never buy another car or truck without a stainless exhaust system. That is one headache no one needs.

It's higher voltage to get a spark happening more easily in lean mixture land but it's the *high energy* that allows the longer duration spark. It's one of the reasons manufacturers went to individual coils - only need to supply spark to one cylinder so gets a very long dwell time with plenty of coil saturation.

Up to 20k. All the old oscilloscopes had a range, from memory, up to 25-30k.

A lot of cars these day have EMS that learn and that means they can compensate for poor quality fuel and take advantage of better quality fuel by modifying the ignition map to suit.

Not can, does happen. For the knock sensor to operate, there needs to be a knock first. FWIW, you don't generally get a really big knock first off. It's progressive and starts with a small knock which generates more heat which generates a bigger knock and so on.

The carburetor sprays atomized fuel into the cylinders but when the intake manifold, cylinder head, cylinders and pistons are cold, it's very difficult for vapourisation to take place so liquid fuel enters the cylinders.

It is difficult to rebuild the oil film above the oil control ring. It takes a little time. In that time the cylinder walls and rings don't have the protection of the oil film and most wear will take place. That is why cylinder bores will always wear tapered with most of the taper occurring above the oil control ring. A vehicle in continuous use and always warmed up, such as a taxi or a long haul truck, has much less cylinder wear.

Been there, done that, with E Series Leyland Engines. Have to say though that if the valves and seats are decent, adjustments are not regular events. There's a lot of margin built in. If you don't mind regular clearance checking and adjustments, you can run closer than factory specs and gain the effect of a hotter cam.

A set of pre-measured, marked and sorted shims is a handy thing to have around.

Look up the process for providing UV protection for tyres. The concept is essentially the same.

Pads, under extremes of heat, give off gases. It is the presence of those gases *between* the pads and the disc that prevents the friction from happening. The gases make the pads operate more like a hovercraft. The slots provide a means by which the gases can quickly escape. In a road going car, slotted rotors are probably overkill. Not so on high performance vehicles.

Especially useful where you are working on one of those bastard bits of machinery where you have a mixture of metric and SAE bolts and nuts.

Removing mass reduces heat holding ability. The material removed does not provide a gain in surface exposure. The real gain is providing a path for the gasses coming off the pad surfaces to escape from between the pad and rotor. Reduces the hovercraft effect.

I trade my cars in when I'm sick of them.

am

ter

I'm surprised to hear you say load is a major factor in engine life. AIUI v ery few engine failures are due to big end bearings or rings these days, an d those are the 2 parts mainly affected by load. A lot of parts wear accord ing to how many revs they do, thus going a given distance at lower rpm wear s them less. But I'm certainly open to re-education.

NT

I'm sure I tried everything that seemed in any way possible. I don't even like thinking about it any more :-(

Any scoring on a rotor will fail it. As you say, there might be less than 50% of the pad surface in contact with the rotor surface. No way will that bed in properly. You will get localised overheating both on the pad and on the rotor.

Are metrinch wrenches still available? Did anyone ever buy them?

They are still out there and new versions seem to pop up now and then. They can be handy in the rust belt if you're out on the road.

Chains are hardly ideal. Chains wear. The wear changes the pitch between the links and the links no longer quite fit on the sprockets. It turns into a self reinforcing cycle. More wear = worse fit, worse fit = accelerated wear. Eventually the poorly fitting chain will jump one or more teeth on the crank gear or start breaking the teeth on the cam gear.

The other effect of chain wear is retarded cam timing. The more worn links between the crank and cam, the more the camshaft timing gets retarded. I changed timing sets on conventional OHV engines and that usually advanced the ignition timing from 5 to 10 degrees, suggesting that chain wear had retarded the timing by that amount.

It wasn't only the changes in point gap that was changing the ignition timing on these old cars.

It's no surprise that fiberglass/rubber timing belts ended up being used on most OHC engines.

Could be modern chains are better engineered than the old ones. I can't say.

But I still prefer belts. Even on a tight package like a Dodge Neon with the 4 speed auto, the replacement isn't too bad, once you know the routine.

I love front wheel drive, especially in the snow.

Alot of the old motors used to have hot spots, such as exhaust ports and the manifold heat riser on V type engines, which would coke up the oil quickly. This coked up oil would plug up oil passages and an old motor could be partially starved for oil even if it was full of clean, clear oil.

The heat riser could be designed out of EFI engines.

Give the leaded gas ban credit for longer lasting exhaust systems, too. Leaded gas contained some nasty stuff to eat away lead and lead oxide deposits and that nasty stuff would also chew away at exhaust systems, spark plugs and engine components.