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Engine running...cold.

Discussion in 'E46 (1999-2006)' started by bfriesen, Oct 28, 2008.

    bfriesen guest

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    Anyone know why my temperature gauge would gravitate towards the blue outside normal running temperature even when the car has been running for a while. I noticed it this weekend while driving on the highway for about an hour. My 330ci has 52,000 miles on it so I am thinking thermostat. Anyone have helpful tips, links or advice? Thanks.
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    granthr

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    I think you are on the right trail. I would guess a thermostat that is stuck open. Does it take longer to warm up now, does it swing towards cold on long down hills that don't require any or little throttle? If so that is probably it.

    I am not sure if your car has one of the newer electrically control t-stats, but if it doesn't to really know for sure you have to remove it and test it in a pot of hot water. The bentley manual gives directions on this, at least in my Bentley for my E30 it does.

    Anyone else have advice?

    GR

    BMWguy206 guest

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    +1 on the thermostat. Common issue on the E46 models. Retail pricing is $74.00 and very easy to do. Just don't forget to bleed the cooling system!

    snikwad guest

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    I believe this is the thermostat also.
    My E46 328 was doing this, and then it started throwing a CEL that read a code that according to the bentley manual was something about, temp too low to read, or something to that effect.
    I didn't just change the t-stat, I completely overhauled the cooling system.
    Water pump, hoses, radiator, t-stat, expansion tank. I did this because of the miles and age.
    When my buddy was doing the overhaul he noted strangely, that my car was very low on coolant. He said when he removed the upper radiato hoses, nothing came out, then the t-stat, a drip, then when he removed the lower hose, there was finally some coolant drained.

    My car would run cool on the hwy, say about 1/3 of the gauge. Then once I got on the local roads, or slowed for standstill traffic, it went up to the halfway mark.
    It took seemingly forever to warm up.
    And when I was forced the accelerate briskly when the engine was running for less than say 20mins, the CEl came on, and it was always the same code, P1628 iirc, I could be mistaken.
    All symptoms pointed at a stuck t-stat. But I never got a specific code saying so.
    I'm not sure of the M52TU ems gives such a code tho.

    Hit up desertmotorworks.com for the t-stat at a good price.

    Jeron guest

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    The gauge should never move once it hits TDC. If it moves cold after getting warm or it never gets warm its 99% its your thermostat.

    Yes, you have the expensive electric/heated one.
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    mooseheadm5

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    The gauge, he means should never move. Your T-stat is bad.

    Jeron guest

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    Indeed, sorry.

    I suppose I should fix that.

    M3Driver guest

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    Make that another vote for the thermostat.....

    bfriesen guest

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    Yes, the needle on the gauge fluctuates on hills.
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    mooseheadm5

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    So car warms up, then cools off and does not warm up again. Then under higher loads, the needle on the gauge moves higher, but back down again under light loads? If this is the case, you need a T-stat. If this is the case but it never warms up, you still need a t-stat. They go bad, replace it.

    snikwad guest

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    Paul is right, change the t-stat.

    Something I've noticed recently tho.
    If I let the car idle after a cold start, I can sit for 2 mins and it barely gets to the edge of the blue portion.
    Once I begine driving it climbs faster, but it can take as much as 2-3 miles and a few stop lights before it is TDC.
    Is this normal?

    bfriesen guest

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    Is the failure of a thermostat at 52,000 miles premature? In any event, I am having my indie shop replace the part and flusch the coolat this week. Thanks to all for your comments, suggestions and advice.

    bfriesen guest

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    Changed out t-stat. All better. Gauge is rock solid down the center. Thanks again.
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    mooseheadm5

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    Failure in the 60k range is not that uncommon. Glad it is all patched up.
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    kevs330Ci

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    stuck/sticking t-stat...........

    a stuck or sticking t-stat(also referred to a map cooling fault, i think) is a very common issue on the e46 and alot of the other series of bimmers as well......i see it all the time at the shop i work at.....still though even after the repairs i would recommend keeping an eye on the coolant level reguraly(along w/ the power steering or pentosin).....these things(bimmers in general) seem to like drinking/consuming the stuff(considered "normal evpaoration").....you'll also probably get a little better gas mileage after the t-stat repair....:cool:
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    mooseheadm5

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    Usually a MAP cooling fault will show up in this case, but that can also happen if the heater in the T-stat
    (we call them an E-stat if they have the electric heater) fails, corrodes through, or has a bad connection due to leakage through the seal. Any time there is a MAP cooling code, chances are the E-stat is bad. Regular maintainence of the system should involve pulling the plug from the E-stat to check for corrosion. Coolant can wick up through that connector all the way to the computer and corrode the DME pins causing weird and very difficult to diagnose problems.

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