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Old 07-31-2011, 01:46 AM   #1
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Engine vibration at 3k, and other first time buyer questions

I looked at an 01 Boxster today with 156k miles, asking price $9000. I'm not sure what to think. It's the first Porsche I've ever driven. It seems decent, body and interior are in good shape, handles well, drives well. But I need your expert advice. I know nothing about boxsters beyond what I read today on these forums and on the websites in the sticky thread for first time buyers. However, I do know cars, so don't be shy with technical answers. I've done everything from ECM tuning to engine and tranny rebuilds, turbo mods, etc.

So the worst thing about this car is an engine vibration at 3k (2.5k to 3.5k at most, goes away outside that band) that makes the whole car shudder/buzz. Everywhere else the engine seems smooth enough. This happens when revving at a standstill, or driving in gear.

Could it be due to bad motor mount(s)? At least one is definitely shot - it has the characteristic clunk when shifting briskly.

The gas gauge reads empty when there's gas in the tank. Is this almost always fixed with recalibration? Why does it get miscalibrated?

What are the chances of RMS or IMS or other terminal engine failure if the car's survived for 150k+? I'm not poor, but I definitely do not want to deal with engine failure. This will be my girlfriend's daily driver.

Should I just walk away, or run, while I'm ahead? Or will this car likely run to 200k+ without major issues? Some cars run past 200 without batting an eye. Is the Boxster one of them, or can I expect a linear or exponential number of problems with age? What fatal signs can I look for, other than oil leaks, oil in coolant...? What compression numbers should I be looking for?

Thanks, and sorry for the newb questions. There's only so much information I can absorb in a few hours I know there's a million questions in this post, but please try to answer as many as you can. Thanks again.

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Old 07-31-2011, 03:09 AM   #2
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The 3k vibration is a classic sign of a bad motor mount, another is a lot of movement in the shifter when accelerating after changing gear. If you change out the motor mount, replace the water pump at the same time if it has any significant miles on it. The water pump has a plastic impeller that will break up when it fails and send bits of plastic through out the head and block that can block the coolant passages and lead to overheating and cracked heads, etc.

If you do both the mount and the pump atthe same time, they are both very easy. To replace the mount, you have to lower the engine a few inches, which then gives you much easier access to the waterpump and to do the waterpump ypu have to remove several coolant hoses around the motor mount which makes replacing the mount much easier. IIRC, Pump is around $250, Mount around $150, very expensive Porsche coolant around $100.00.

Now to the IMSB (RMS is not terminal, just messy and can mess up the clutch) of which books worth of posts have been written online. Its a known defect but no one except Porsche knows the real failure rate. If it goes, generally the motor is completely detroyed and unrebuildable.

There are many cars that have gone 100k-220k+ mileswith no IMsB problems, other fail at very low miles, < 20-50k. Anecdotal evidence is that cars driven consistently at low RPMs, < 3000k, tend to have higher failure rates, while those driven on the track or "driven like they stole it" have lower failure rates.

Problem is that its hard to diagnose an IMSB that is going bad and catch it before failure. There is a classic rattle it makes before failure but the rattle can last for days or weeks, or just seconds before failure. Some never get the rattle. One way of diagnising a bad IMSB is to check the cam timing variation on the computer (Porsche or Durametric). If theere is a significant difference in timing between the cams, righ and left side, good indicator of a bad IMSB. Finally, metal and plastic (from the IMS bearing seal) in the oil filter is another warning of a bad IMSB. If you can, pull the sump plate and see whats collected in there.

There is an aftermarket replacement bearing that costs about $750 for the bearing and special tools needed and once the tranny is out, the replacement is a couple of hours. I don't have any signs of a failing IMSB and I'm going to replace mine when the clutch goes, but after the initial panic from all the IMSB horror stories on the interwebs, I've calmed down.

Pelican Parts, in the Tech section has good write ups on engine failure modes and IMSBs.

$9k sounds pretty good, I recently got my 2000 2.7 w 114k miles for $7500. Its definitely a buyers market out there. I would try to beat up the seller a little more.
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Old 07-31-2011, 07:47 AM   #3
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I had the 3000 rpm vibe, and replacing the motor mount seems to have gotten rid of most of it. I agree with the importance of replacing the water pump at the same time.

I used the stock unit in both cases.
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Old 07-31-2011, 10:16 PM   #4
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Thanks, guys! Another question that I forgot to ask: is a fan-like noise normal when slowing down or sitting at idle? I'm guessing the radiator fans come on in these situations, but just checking.

And what's the deal with the gas gauge always showing empty?

Thanks.
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Old 07-31-2011, 10:29 PM   #5
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Yes the rad fans can come on, but you should make sure the rads aren't blocked. A relatively simple DIY is to pull of the front bumper and give both the engine rads and a/c exchangers a real good cleaning.

The gas gauge shows empty because (a) it's broken, or (b) you've got your foot in it all the time.
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Old 08-01-2011, 07:11 AM   #6
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The IMS is still a potential problem, but that's not enough to stay away. It's the gas gauge and the vibration and the fact that any car with 156K miles is bound to need a bunch of repair and replacement, whether it's a Porsche or not. Of course a good PPI would be useful, but then you are investing probably $400 up front before you even own the car, and at your price level, even that is significant. If you have a lot of time and money to fool with very expensive repairs, then go for it ... otherwise you could get a Boxster with half the mileage for only a few thousand more. You could easily run up $2-3K in repair bills on this old car, and the lower-mileage Boxster will always have higher resale and less need for constant repairs.
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Old 08-01-2011, 10:36 AM   #7
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+1 on what John said.

I would walk away from this car because it sounds like the car I bought and still have. High mileage, in need of lots of repairs, and most of all, it's not an S!

Save more money and buy an 03S or younger with half the miles on it and good records of maintenance and repair. The glass rear window and larger motor and brakes will never be a regret when you finally get them.
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Old 08-01-2011, 11:36 PM   #8
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Let me rephrase. The fan noise... is it supposed to come on very regularly right as you're slowing down below 15mph or stopping? Ie is speed a factor in turning the fans on? On previous cars I've driven, the fan is controlled only by a thermostat, not by speed.

I read in the faq that the gas gauge can show empty when the tank is not, and it needs to be recalibrated. Is that a common problem? How far can it go out of calibration? Ie how many gallons before it registers? The "dealer" said he put 10 bucks in and it still showed empty.

On my Vette one of the tank sensors can occasionally stick and throw a code and turn the gauge to 0. A trouble code reset and/or a bunch of fuel system cleaner can fix it. Is this a known issue on Boxsters?

Thanks.
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Old 08-02-2011, 07:53 AM   #9
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steel, the passenger side engine fan runs based on a thermostat in the motor compartment (I think). It will even run after you shut off the motor for a minute or two if it's really hot.

My fuel gauge never read 4/4 so I had my mechanic zip tie off the hoses inside the fuel tank that were getting in the way of the float. This didn't fix the problem so I paid him to swap out the sending unit and recalibrate the fuel system with a PST tool. It has to be done with the tank nearly empty and dribbling in fuel while someone watches the electronic display on the PST tool.

Now I get almost 4/4 when I top it off. Might be my fault or issue now... I swapped out my black gauge faces for silver ones a while back and I may not have put the needle on in the exact same place it came off.

However, I'd rather have it show a little low than artificially high and me run out of fuel or burn out my fuel pump for running with too little fuel in the tank to keep it cool.

Hope this helps.
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Old 08-02-2011, 08:07 AM   #10
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The fan noise you hear is most likely either the radiator fans or the engine compartment fan or both. These will cycle on and off somewhat randomly, especialy the engine compartment fan. They are definitely not directly speed dependent but they might appear to act that way under certain conditions. I know that if my engine compartment fan turns on, it tends to do so when I stop (but not always).

I wouldn't worry about the IMS much. If its gone 156K miles, it is likely to make it to 200K.

The fuel gauge could be out of calibration or something is broken. Assume something (like the sender in the gas tank) is broken and you won't be disappointed.

Please, please, please spend the $300 and get a Pre-Purchase Inspection! This will tell you the condition of the vehicle and what needs to be fixed and how much it will cost. I can assure you that a Porsche with 156K miles is certain to need some fixes. I know its a pain in the rear but it will be the best $300 that you ever spend.

I'd definitely work the seller on the price. About 8 months ago, I bought my 1999 with 82K miles for $10K - and Boxsters haven't gone up in price since then. Its a buyers market and this car will at least need the fuel gauge and the motor mount and likely a few other things fixed/replaced.

In terms of price, $9k is near the top of KBB retail. A more realistic price in this market is $7500. I'd offer $7K and use the PPI to justify the lower price and negotiate from there.
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Last edited by thstone; 08-02-2011 at 08:10 AM.
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Old 08-02-2011, 11:15 AM   #11
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hey, steel_3d, regarding the fuel gauge not working: while it could just be straight up broken, if the tank runs close to empty and you do not fill it up either completely or I believe at least 3/4 full (someone else to confirm?) the gauge will not operate properly and would actually require that the dealer recalibrate it for you. I believe there is something in the owners manual about that, because I'm pretty sure that's where I read it. It sounds like it's just broken, really, but when you told me that the guy says he put 10 bucks in (meaning 2-3 gallons out of 16), the fuel gauge hasn't received enough fuel from the empty level to show a proper reading.

Whether you pick up this particular Boxster or another, I'd recommend never letting the tank drop below 1/4 (indicated) to ensure that you don't run the risk of running dry should the gauge be out of calibration. I know my gauge exhibits the same problem as RandallNeighbour, but what usually happens to me is that the gauge will read a little over 3/4 after filling the tank, after driving for a short distance the float moves the rest of the way to read full, and then within maybe 50 miles of driving it's making its way back down to 3/4 and starts reading normally from there. So for me, from 3/4 to 1/4 it's accurate enough.
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Old 08-05-2011, 06:45 PM   #12
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Thanks for the help, guys! While I'm gonna skip this car, cause my girlfriend's not ready, we may consider another Boxster when we start looking seriously. At least now I know a little more about P-cars than I knew before, which was nothing

Thanks

Steve

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