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Timing belt

Discussion in 'E30 (1984-1993)' started by cj morgan, Apr 4, 2008.

    cj morgan guest

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    hey everyone. i've been looking through the service records on my 1990 325i and found that my oxygen sensor and timing belt havent been changed since 110,000. I now have 172,000 miles on the vehicle. I've heard that the timing belt should be changed every 32,000 but i just havent gotten around to changing it. Is a ruining my engine driving my car without the timing belt being changed or will i be alright? thanks
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    eicarguy

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    you're living on the edge of disaster...

    Do the belt job!

    It isn't that hard. Replace the water pump, change coolant, check cap and rotor, clean engine front and have some peace of mind. When the belt breaks the repair cost will exceed the value of the car.

    I changed every 60,000 or when I changed cars - which was more common.

    ei
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    Brian A

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    I think everyone would agree the belt needs to be changed immediately.

    It is critical that E30 timing belts be changed every 50,000 miles or 4 years. If the timing belt fails, the results are catastrophic. The engine essentially self-destructs. Kaboom! The reason is that the timing belt times the valves so that they are out of the way of the pistons when they move into the same space that was previously occupied by the open valve. Without the timing belt, the pistons and valves "interfere" with each other.

    Honda, interestingly keeps upping their timing belt change specification. For a Honda Pilot, it is now every 105,000 miles which is also an interference engine. However, I am not sure many people would even agree that its okay to push it to 60,000 miles on an E30. The specification has remained at 50,000 miles or 4 years. It is doesn't seem worth the risk to push your luck even one extra mile.

    cj morgan guest

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    would replacing the timing belt also increase performance?
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    Brian A

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    Unfortunately not. It only synchronizes the timing of the pistons and the valves.

    cj morgan guest

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    well how can do i know the belt needs to be replaced?..i may be missing some service records. is there anyway of telling how much longer the belt has by just opening up the hood? thanks
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    eicarguy

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    Yeah, they're reinforced with fibreglass and don't stretch so as to alter timing.

    ei
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    MGarrison

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    I'm not entirely sure, but I think ei's point is: unlike a standard accessory v-belt which stretches, and it's deterioration can be seen or noticed, the reinforced timing belt doesn't show an indication of it's imminent demise.

    And, as mentioned, it's catastrophic to the engine when it fails. If the belt breaks, you'll trash your valves and your head, and it's unlikely the pistons wouldn't have to be pulled or replaced as well (along w/ rings, etc.)

    Since you don't know w/ absolute certainty the date or mileage of the last belt change, you should just do it, don't wait.

    cj morgan guest

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    Okay so i've looked at a new water pump and timing belt and found them to be around $100 all together at bavauto.com. My question is, why do shops charge so much to have it installed. Is there any other part i need to change the timing belt? I know it's a pain to get too but i had a $700 esitmate from a dealer just for labor. I have all the necessaey tools in my garage and some knowledgeable people willing to help. Is it too much of a risk to perform the replacement on my own?
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    eicarguy

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    Do it yourself. There are descriptions of this job on the web. Pelican has a nice one:

    http://www.pelicanparts.com/bmw/tec...ming-Belt/101-Projects-20-E30-Timing-Belt.htm

    Get the tensioner too, heck if you have the coin get the whole kit.

    Use the proper pulley holding tool to get the let hand thread fan off - unless the last guy put channel-lock teeth marks all over your water pump pulley.

    Make sure your 8mm socket is good for the cap bolts, they let go but with too much effort. Anti-seize them. The rotor takes an allen and is just as tough sometimes.
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    MGarrison

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    If you don't have the Bentley manual, it's highly advisable to add that to your order. Labor rates are what they are, it's a time-consuming job. You're paying for their experience in doing the job before and their knowledge and ability to do it properly and quickly, plus having the tools and parts needed for the job.

    Timing belt, tensioner, water pump - that's the minimum parts for the job. You should do the tensioner since you're doing the belt - if you have a problem w/ the old tensioner before the next change interval comes up, they do not recommend re-using a belt that has been used, and you'd have to get another new one.

    Bavarian Autosport sells the tool for holding the fan pulley, plus a thin 32mm spanner wrench you'll need for removing the fan/fan clutch assembly (if you're lucky, your friends have those tools already).

    Make sure you keep the fan clutch in a vertical position (as installed on the vehicle) while it's off the engine; the fan clutch fluid can leak out if you lay it flat and then you'd have to replace it.

    Since you have to pull the radiator and your accessory belts, you'll need coolant, and it's a good time to replace any belts or coolant hoses if they're due.

    You can do the job yourself, certainly - however, don't rush it, you want to be careful not to make mistakes. I'd say allow for two full days to get it done, that's probably enough time if you have everything in hand needed for the job (these types of projects almost always seem to take much longer than you think they will, or should).

    Dissassembly (generally) is relatively easy, putting things back together takes more time. Check the procedure outline to see if you need a torque wrench for any final tightenings. Carefully note orientations and positions of things as you take them apart. Since you've never done it before, take pictures as you go along so you'll know how it should look if you happen to forget something between disassembly & re-assembly.

    I tend to thread bolts back into the holes they came from so as not to lose them, or lose track of where they go.

    A large tray of some type is useful for catching coolant - the bigger the better; I have one that's not quite square, but about 3 ft. on each side w/ 8" walls.

    The radiator top mounting bolts run through a rubber isolation grommet, that should have two metal washers, same size as the grommet, on each side. Be careful as you remove the top mounting bolts (they're more like a large sheet-metal screw thread than a fine-pitch machine-bolt thread) that you don't drop/lose the washer between the radiator and the front nose of the car as you pull out the bolt. The mounting bolt is the only thing that holds the washer in place.

    cj morgan guest

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    I have a Haynes manual. Will that work?
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    az3579

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    The Haynes manual is nowhere near as good as the Bentley manual. Bentley goes through certain things in much more detail and is specific to your car, while the Haynes manual isn't specific to your car but may includes another series. The Haynes manual I have has 3 and 5 series models, and I'm sure there are some things that vary between the two models, so it's not as detailed as it can be.


    Also keep in mind that the Bentley manual is over twice as thick as the Haynes manual, and there's good reason for that. It has information that the Haynes manual doesn't cover, so it's not just detail that you're missing out on.
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    MGarrison

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    Ditto on AZ's - if you plan on keeping the car for the forseeable future and would like to mediate maintenance costs by doing what you can yourself, then you'll use your Bentley manual over and over and over (mine is actually somewhat falling apart - if you want to preserve it a bit, keep your hands clean when your using it, don't drop it, and don't toss it around or let it oh, say, slide and bang around in the trunk :) ) If you want to be compulsive (shhh don't tell the copyright police) make copies of the pages you need for whatever you're doing and get those dirty.

    By the way, nitrile gloves from Harbor Freight are a great way to help keep your hands clean on car projects (buy at least two boxes at a time for when you run out of the first box).

    The Bentley manual isn't always 100% perfect, but it's the best you can get for a reasonable price - and it is very, very good.

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