Mechanic trying to take no fault

MCHAMMER33

MEMBER
1997 CHEVROLET S-10
128,000 MILES

I have a 97 chevy s10 2.2 4cyl, the shop I took it too replaced the timing chain, I didn't know what was wrong with it, and my truck had 20# of oil pressure which is enough to run it just fine, and they didn't check the oil pan for plastic pieces, I paid them $300 and was told it was good to go and that they test drove it and it was good, so I left thinking my truck was in perfect condition now, and everything was perfect shifting fine good oil pressure, ran like a top not a thing wrong so I thought, I drove 15 miles, and my oil pressure dropped to zero and something started rattling or "knocking" I pulled over not immediately when this happened, I mean not 5 seconds after it did this and shut it off, I sit there for a minute, started it again, never moved mind you, it was rattling so I shut it off, and checked the oil, perfect to the top of the safe zone, I called them, they sent a wrecker for free, a day or 2 later they call me n tell me the plastic pieces plugged the screen n I need a new oil pump, and that they will have to pull the motor to make sure it didn't hurt the main and rod or whatever, and they will do half the labor for free and that the book calls for 11 hours but they'll do half the labor for free, so another $400, I'm a little irritated but ok go ahead, 4-5 days or so they call me again and tell me that I need a crankshaft and bearings, and it will be $1100, before I took the truck there no knock or rattle and good oil pressure I didn't even make it home before it broke and I've been told not by them but other mechanics that anytime the timing chain has plastic gear coating it should have the pan checked to make sure there are no pieces in there to prevent what happened from happening n they never recommended that or did that, now they are arguing that it wasn't their fault speaking and that they don't know how long ive drove it like that and that the crank shaft and bearings couldn't have been that damaged in 15 miles. Help me on what I should do!

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

What the mechanic did wrong was to give you a rough estimate on the cost of repairs before he tore into the engine to know what was needed. No one expects car owners to understand the workings of the expensive pieces of machinery they trust to get them back home, but if you did, or you were a mechanic, you would understand it is very likely they didn't do anything wrong, so start with an open mind. They know another expensive repair bill is hard to swallow, and the more reputable shops will usually try to do something to help ease the burden on their good customers.

First of all, it is true that many engines use camshaft gears with plastic teeth, (nylon, actually), but the pieces you were told that broke off and plugged something didn't all break off at once. Some of the teeth broke off weeks or months ago and you were driving it like that all the while.

Second, 20 pounds of oil pressure is more than you'll find in some engines but for yours it's nothing to be proud of. In fact, that was a clue a long time ago that something was wrong and it gave you a lot of warning before the disaster occurred.

Third, going back to my first paragraph, once the knocking started the damage was done, and as someone who has had that happen three times, there's no way the crankshaft is going to survive. The "journals" are the precisely machined and highly polished surfaces the connecting rod bearings and crankshaft bearings ride on. The moving parts are isolated by the pressurized oil to prevent wear. 40 pounds of oil pressure is normal for your engine. At the mileage you listed the bearings will be worn a little making it easier for the oil to seep out. The result is lower oil pressure, and lower oil pressure results in increased wear. The engine may have indeed run fine with only 20 pounds of pressure but you were on borrowed time. With the pressure that low, each time a cylinder fired it banged the connecting rod into the crankshaft journal. That caused a moment of increased friction and metal tearing against metal. The bearings are smooth metal inserts that are very soft and that hammering action flattens them out even more. That increases the clearance and results in a further drop in oil pressure.

My best guess is the catastrophic event was going to occur even if you didn't have the recent service work done, or to put it another way, if you had the work done 1000 miles sooner, you would have driven it 1000 miles before this happened. It's highly doubtful there would have been anything the mechanic could have done to prevent this by the time he got his hands on it.

$1100.00 is not a nice repair bill but it seems awfully low for what they're telling you is needed. I had students rebuild one of my engines so labor was real cheap, but I paid almost that much just for parts and machine work.