Ford engines: internal parts

We had to arrange to have the engine replaced in a car we have, a 1992 Ford Taurus, with, of course, a front-drive/transaxle. Apparently a piston broke and started rattling around inside the crankcase; we could no longer drive the car.
I’d like to know:
What kind of metals or other materials are used to manufacture pistons, cylinders, connecting rods, crankshafts, etc.?
Why would the engine do this, after two years of light to moderate use (before that the car was in storage for a while)? Is it normal wear, or could there have been an abnormal situation (collision, improper repair work done by a mechanic unknown to us) that started causing the piston and its connections to weaken?

Piston broke? Me too.

IANAE but I’d say (to question 2) it’s just normal wear, really. Fords aren’t exactly Ferrari’s, but then again they aren’t Fiats either. As for what metals, I haven’t a clue.

I’m not a mechanic, but I know of a couple of situations that would eat a piston in a young engine. First, if the timing belt broke, some engines will have a collision between a stuck-open valve and a still-moving piston. Second, an oil system problem (not enough oil or a broken oil pump) can cause a piston ring failure or a fracture of a piston’s wrist pin. An oil system failure probably would cause massive damage in the rest of the engine, too.

I would say that broken pistons are quite unusual. I have personally worked on a few cars that had the old “piston, meet valve…valve, meet piston” situation when timing belts broke.

Pistons are typically made from exotic alloys of aluminum, although some high-end cars have titanium pistons.

The cylinders are typically made of whatever the block is (iron), unless steel inserts are used (such in the case of engines with aluminum blocks).

The connecting rods are almost always steel, but I have seen aluminum and titanium.

I have never seen a crankshaft that was not steel, but I’m sure someone somewhere has made one out of more exotic materials.

If you want exact materials, well…there is a long, long list of acceptable alloys for these things, and my reference books are at work.

Now, as to your other question: I suppose it is possible that the wristpin or big-end had oil or debris solidify and plug the oil holes, which denied the piston lubrication, and then it broke. I suppose it is also possible that the cylinder somehow developed rust, and a ring wedged or jammed and broke the piston there… I sincerely doubt a collision could have had anything whatsoever to do with it.

If the car was stored, Anthracite’s probably right. There was probably an opportunity for rust to develop in the rings or some other place during storage, which caused premature wear.

When professionals store cars, they make sure the cars have had relatively fresh oil changes, drain fluids that can damage, remove parts that can perish, pull the plugs and squirt in oil, etc. If this wasn’t done to your car before it was stored, odds are this caused or at least contributed to your failure.

BTW, having the engine replaced in a 92, unless you are getting a really good deal on a good used engine, may be counter-productive. A rebuilt engine for a ten year old car, plus installation, may come to a bit over what the book value of the vehicle is. Unless you have an emotional attachement to the vehicle, consider trading it or selling it.


Cyinder blocks are usually lumpen things in budget cars, but there has been a move to use aluminium blocks as this saves weight and fuel.

Aluminium blocks are mostly fitted with steel liners, however in more exotic vehicles, and on motorcycles where weight and heat transfer are critical factors due to the limits being pushed more closely, there may be no liner, instead the bores are coated in either ceramic or nitride materials. These reduce friction more than steel liners and because there is no materials discontinuity between the bore lines and the block, cooling is more efficient.

[hijack]Psst…Billy Rubin…there’s a new “What the Hell is that?”[/hijack]

You can count on yours having a cast iron block (including the cylinders), steel crank, steel connecting rods and wrist pins, aluminum pistons, and aluminum cylinder head.

I’m not sure I follow the history of the vehicle. You mention two years of use and “a while” of storage. It’s a ten year old car. Was it stored for 8 years? Are you the original owner? It would be easier to make a reasonable guess knowing the mileage on it now and when you got it, and how long it was stored.

Since you suggest unknown repair work, I assume you bought it used. That means it had X years and Y miles of use, and attendant repairs and maintenance (or lack thereof), that we know essentially nothing about.

The list of possible causes of the piston breaking is long. Neglected maintenance, overzealous driving (“hot-rodding”), foreign object in the cylinder, manufacturing flaw in the piston, etc. Unless there’s something obvious that can be determined by visual inspection (which requires engine teardown), the cause will probably never be known.

Getting technical, I suspect we don’t have an exact description of what is known of the problem. Generally broken pistons don’t rattle around in the crankcase. They can make noise in their cylinder, but if a piece fell into the crankcase it would likely be lying silently at the bottom of the oil pan. If a big enough piece of piston broke off to make noise in the crankcase, I would think there would be a much more noticeable sound in the cylinder it vacated. If there’s a sound from the crankcase, it’s usually related to the crankshaft and or connecting rods.

Minor detail, but it helps the OP…

Detroit has used iron. It’s weaker but holds oil better.

My Mom bought the car from a former neighbor–I’ll call him Paul–who had had the car in a storage lot in Lomita, about 7 or 8 miles from where we live in Gardena. (He himself was later burned out of his home: I don’t know where he went afterwards.)
I don’t know how long the car was stored there. He and she had to go to the DMV to clear the car’s title before Paul could sell it to her; he also had a mechanic make some minor repairs.
One reason my Mom decided to keep the car was that a current neighbor contacted another mechanic, who offered to replace the damaged engine in the Taurus for about $1600–some $500 less than what the local service station would charge. (A few months ago she had body work done on the car after a minor collision.)
She doesn’t drive the car much; I drive a T-Bird and I put maybe 1000 miles on it per month, about ten times the mileage she drives in the Taurus.
Thanks for the materials information. I used to drive a 1970 VW Squareback, whose 4-cylinder “pancake” engine was mostly made from a cuproaluminum alloy.

If the low-mileage use you described consisted mostly of short trips, that could be a factor in the engine’s demise. That would constitute very severe service for an engine.

The Ford 3.8 V6 seems to be notorious for poor reliability. Mechanics I’ve talked to say much more, though, about their tendency to blow head gaskets, which is followed shortly by crankshaft bearing failures attributable to poor lubrication while running with cooling-contaminated oil. That’s what happened to my '87 Taurus, anyway.

Ever notice how few of them from that time period are left on the roads?

knock is a common cause for broken pistons.

titanium pistons? never heard of that before. cast aluminum, forged aluminum, and hyperutetic (sp?) which is an aluminum that is made with a process that manages to incorporate about 15% silicon in the aluminum making is harder and stronger than standard cast aluminum pistons

The car was finished and returned to us Friday evening. The mechanic and our neighbor were with Mom when I got home that evening; the mechanic drove it back to his home in San Pedro, with me in the car. I drove back to my home; as soon as I got on I-110, the Harbor Freeway, the yellow “check engine” light went on, and stayed on for about 10 to 15 seconds; it blinked out, and a few seconds later it went on again and stayed on for another 10 to 15 seconds. It never went on again and I drove home, about 15 miles, with no further surprises. So far as I know, the rebuilt engine is running the car just fine. :slight_smile: