Only bending one valve?

[ihartmacz]

I'm going to look at a car tomorrow that may possibly have ONE bent valve. It's a 2000 Chrysler Concorde with the 3.2L engine. 130,000 miles.

The guy claims that while driving, the timing belt broke. His mechanic claims that the car has one bent valve. Remember, this engine had 4-valves per cylinder. If the timing belt broke, I don't think that just 1 valve would bend (the valves are actuated by a Y-shaped rocker arm off of one lobe on the cam, so both sides open an equal amount). This engine has reliefs in the piston for the timing belt to slip 2 teeth. I think that since this car is also an automatic, that the engine would pretty much stop turning the second the belt breaks. If valves were bent, there would be a skip in at least one cylinder or no compression on many.

The guys says the engine runs well but will occasionally have a "miss" at idle due to the bent valve (according to the mechanic); this is also accompanied by a CEL.

What do you all think? I think the CEL will point to the cause of "miss." I also think that because of the broken timing belt, the mechanic was trying to get this guy to pay for a $1,300 valve job.

[FDSpirit]

You can do a compression test to further investigate as well. Running a scanner would return maybe a random misfire? Not sure on that. Not too familiar with a lot of CELs at the moment. I'd think that if the timing belt snapped, I'd think more than one valve would be bent though for your reasoning and some others.

[ihartmacz]

If that engine went as far as so bend valves, it would be completely FUBAR'd. He was on the highway when it happened, he says. By that reasoning, if the converter was in lock-up mode, it would possibly break the transmission, too.

I'll see if I can rent a scanner and hook it up when I get there to see the code. I can't do a compression test because I don't have the car. If I buy it, that will be the first thing I do.

Who rents a scanner ODB II scanner?

[FDSpirit]

No idea. I'd call Advance or the Zone to see if they'd let you borrow one for the day. The only problem though is they ask for ID when you need it. Well around here they do at least.

[ihartmacz]

lol I can show my ID.

[FDSpirit]

Lol. Not show them. Let them hold it for like collateral or something. That's what they told me, but never actually took mine, so who knows.

[watkins]

Autozone charges full price for loaner tools. You get it all back when you return the tool. This way anyone who keeps/forgets to return a loaner isnt costing the company money.

[eggwich delfiero]

Scanner tool would be a good way to go, if you have one or can borrow one. But it may not necessarily tell you what the cause is, just the symptoms. But that's the way to go. I guess nothing may fully describe the problem until you crack things open, which would be post-purchase.

Compression test would be good, but like you said, it won't happen before buying the car.

An easy thing you could do, if you have a laser temperature gun, is shoot it at the base of each individual header tube running out ye olde exhaust manifold. If one of the cylinders is missing, and thus compression is down for that cylinder, temperature will be lower for the corresponding pipe. Plus, laser temperature guns are just fun to have in general, lol.

[FDSpirit]

^ . I've never used the scanner at AZ, but the one at AAP was very generic. Even the guy told me that it could say one thing, but it could actually be something different that was causing the car to throw a specific code. Either way, AZ's loaner program is a good idea. Just don't forget to bring the stuff back .

[ihartmacz]

Having the code is better than nothing at all. I decided not to even look at the car. Not worth it.

[theholycow]

That car is a major gamble. I hope the price is rock-bottom, barely more than scrap value.

Buy a cheap code scanner. You should have one if you have any interest in DIY diagnostics. It's the first thing you should do when you have a Check Engine Light, whether or not there are symptoms. A cheap code scanner will give you all the codes that will trigger the Check Engine Light (or Service Engine Soon light), the standardized OBDII codes.

Unfortunately the basic one at HF is currently not very cheap...$60:
http://www.harborfreight.com/can-obdii- ... 98568.html
For that price you can get the UltraGauge which appears to kick ass:
http://www.ultra-gauge.com
It's competition for the ScanGauge II at a fraction of the price with some major advantages (though a few disadvantages).

Anyway, if "it could say one thing, but it could actually be something different" then you're using it wrong. The scanner's job is to give you code numbers, not a diagnosis. The text readouts exist merely to save you the effort of googling it. The most important part is the code number. Get on Google with that code number and the model of the car, look for forums about that car and find the code there, you'll find what commonly causes that code in that car.

Regarding misfire codes:
P0300 is the random/multiple misfire code
P0301 is misfire on cylinder 1
P0302 is misfire on cylinder 2
etc.

If there is a bent valve then the scanner won't help much. It can only tell you what the computer can sense (or at least infer from sensor data).

Advance Auto loaner tools work the same way as Auto Zone, at least at the two locations where I've borrowed tools. I don't know if either one offers code scanners as part of the loaner program though.

[ihartmacz]

I told the guy that I wasn't coming down today because of the bent valve situation. Here's how it went.

Him: "You don't want to come down and look at the car? You know the 3.2L is a Mitsubishi motor, right?" PROBLEM, GRAHAM? U JELLY?


Me: This is where I shut him the f**k down.


"First of all, if you break the timing belt or it slips more than two teeth; it will bend at least 2 valves in multiple cylinders. The rocker arm is Y-shaped and two valves open at the same time -- there is no way to just bend one. Secondly; the 2.7L, 3.2L, and 3.5L are NOT Mitsubishi engines. They were designed and built by Chrysler. THE ONLY MITSUBISHI ENGINES USED BY CHRYSLER WERE THE 2.6L i4 in the K-car, 2.4L i4 SOHC, 2.0L DOHC, and the 3.0L V6 (2V and 4V)."

Y U NO THINK CHRYSLER MAKES ENGINES?!?!?!!

[FDSpirit]

. I'm surprised his response wasn't:

[ihartmacz]

If he would have challenge accepted to me, I would have done the "are you f**k serious face"