So ... after a 4+ week ordeal that started out as a mis-diagnosed master cylinder failure (mis-diagnosed as the clutch assembly), another noise was found. Nissan found the crank shaft thrust bearing broken off and sitting in the oil pan. The car is a 2001 and has 50k miles on it.

I'm writing this due to amazement and wonder. I'm amazed that we're getting a new engine for free and I'm wondering how this could have happened. We've had the car for ~8 months and never really noticed this "noise" that the dealer noticed. Doesn't mean it wasn't there, only that we didn't notice it. However, they completely botched the clutch install the first time in addition to the mis-diagnosis. The car didn't even need a new clutch.

Is it possible that when doing a clutch install you can inadvertantly break off this bearing or is it more likely that it has been like this since we bought it?

Additionally, I'd like for someone to tell me how this bearing works and where approximately it is located. I'm trying to educate myself so I can determine if they even could be at fault for this. It's all covered under warranty and not really a big deal money-wise, but I'm worried about resale. I'm sure the car will run like a beast once we get it back, but I'm just concerned is all.

Any and all information would be very much appreciated. Thanks.

 

I'm not certain what a crankshaft thrust bearing but I think it's a bearing that's between the Crankshaft and the flywheel to your tranny, there is a bearing in between. But I can't visualized where and what it would look like. But that's what I think that is.

 

I searched my AlldataDIY subscription for my 2000 max, and nothing came up for "thrust bearing" that had the word "crankshaft" associated with it. If they mean the Crankshaft Main Bearing, then yeah that would be bad, but I doubt a clutch install could do that... and you'd be having MUCH bigger problems than a "noise" you never noticed.

But a "Crankshaft thrust bearing"... that sounds a little suspicious. Just to be sure, I'm searching google.
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ok, well this site at least confirms there is such thing as a "crankshaft thrust bearing": http://www.aera.org/Tech/tb1465r.htm
strange that alldata didn't have any info on it...

 

The crankshaft thrust bearings prevent end play in the crank. That means that it can't move back and forth in the journals.

 

The thrust bearing is normally installed on one of the main crankshaft journals. They are slighty different in design from a standard main bearing because it has extra surface areas that cover the 2 sides of the main journal it is installed on. That minimizes the end play (back and forth motion) of the crank. It is normally measured with a dial indicator and must fall within the parameters to prevent the crank from knocking and causing excessive stress and wear on the moving parts.

 

Well, for those that googled, you may have seen this. For those who didn't click here. It clearly lists the following under "Diagnosing the Problem":

Transmission related problems:

As you can see, quite a few of these questions would be answered "yes" in this case because the clutch was not only replaced, but replaced improperly the first time. Not only did they screw up the install, but they gave the car BACK to me telling me it was like new. So - the car was driven ~20 or so miles with an improper clutch installation. Not to mention that the bonehead mechanics were probably using the "if it don't fit, shove it" technique of clutch replacement.

 

Do you agree with the above post? That it interacts enough with the tranny that if you did clutch work you could possibly do damage to this bearing?

 

I agree with you on that one Big_Ham. Good info, i'm learning here. hehehehe

 

I believe that it is possible if there is enough pressure pushing against one side of the thrust bearing from an improper trans/clutch install.

 

On the other hand, if the thrust bearing were bad it could make the clutch look bad when it wasn't.

 

That's a possibility also.

 

Clutch was never bad. Master cylinder was bad. When they first replaced the clutch and gave the car back to us the car had the same exact symptoms it did when we brought it in. This tells me that the clutch had nothing to do with it. The second time around they claimed to order a clutch "spring" - which I assume would be one of the springs in the pressure plate - and a master cylinder. Before the thrust bearing was even diagnosed, but after the master cylinder install, the car was driven by the Service Manager Director (the only guy I'll deal with anymore) and it was determined the clutch was in perfect operation.

Basically this speaks to the fact that I believe the following:
1. Clutch never needed to be replaced. This was a master cylinder problem all along.
2. That noise was never there before we brought the car in, and in the improper installation of the (unnecessary) clutch, they also managed to break the thrust bearing sending it into the oil pan.