Coolant Temp. sensor

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Some Guy with a BMW
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Coolant Temp. sensor

Post by Some Guy with a BMW » Mon Dec 18, 2017 1:03 am

Hi,
Maybe this is a silly question - but to replace the coolant temp sensor, would I have to drain the coolant? I ask as it's mounted high up on the system, so I'm not sure if it's going to gush out or just leak a bit, nor I don't want to put an air bubble in the system either.

Another quick question - are the feltrings on the speedo cable a real must have? I seem to have lost one whilst replacing the speedo.

Thanks,
Chris
1961 Volvo PV544
1974 Boler
1981 BMW 528i
1991 Volvo 240 5-speed
1998 Tahoe (truck/tow/vacation-mobile)
2014 Tiguan (wife's car)

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Lock
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Post by Lock » Mon Dec 18, 2017 1:13 am

For the coolant sensor, a little coolant would probably leak out - anything lower than the reserve tank is going to flow out so I'd swap them quickly, a bit but nothing major. Once it's reinstalled you have the air bleed screw next to it anyway so start the car up and bleed any air out.

Not sure about the speedo cable though as my car doesn't have one anymore, someone else might know?
1979 528i 5-speed conversion G260/6
1979 Honda CX500

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Mike W.
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Post by Mike W. » Mon Dec 18, 2017 12:14 pm

Do it cold/cold and or remove the radiator cap before so there is no pressure in there. Leakage should be very minimal.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

T.Hanson
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Post by T.Hanson » Mon Dec 18, 2017 2:56 pm

Unless there is an expert reason out there for ordering new sensors from BMW, pay attention to their pricing. As long as they fit the OEM specs we would not believe the very large cost savings in checking Rock Auto, Pelican, Autohauz, any of the aftermarket parts dealers.

It's nuts. As it is with relays and other items.

Some Guy with a BMW
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Post by Some Guy with a BMW » Tue Dec 19, 2017 2:14 am

Thanks very much for the replies.

Any thoughts on the feltrings being much needed?
1961 Volvo PV544
1974 Boler
1981 BMW 528i
1991 Volvo 240 5-speed
1998 Tahoe (truck/tow/vacation-mobile)
2014 Tiguan (wife's car)

T.Hanson
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Joined: Wed Jul 26, 2006 7:39 am

Post by T.Hanson » Tue Dec 19, 2017 9:36 am

Let's guess if the engineers thought they were a good thing for some reason. Then if we decide no big deal, the possible consequences short term, or long. Finally (?), the time / money factors involved in ordering, replacing.

I see on realoem.com it is two bucks for one.

Some Guy with a BMW
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Re: Coolant Temp. sensor

Post by Some Guy with a BMW » Wed Apr 11, 2018 10:15 pm

I'm having a spot of trouble ID'ing a couple of the coolant temp sensors (81 528i USA manual)

In the pics below, do I have part (# 13621357414 water temp sender) ID'd correctly as #3 in my pic, and if so what part is #4 - OR, is Part #4 in my pics #13621357414 water temp sender and if so then what part number is #3 in my pics?

I can see it on RealOEM, but it does not list the part in the description.

Any help would be much appreciated.

Thanks
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1961 Volvo PV544
1974 Boler
1981 BMW 528i
1991 Volvo 240 5-speed
1998 Tahoe (truck/tow/vacation-mobile)
2014 Tiguan (wife's car)

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Mike W.
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Re: Coolant Temp. sensor

Post by Mike W. » Thu Apr 12, 2018 12:30 pm

Since I sometimes get on guys for horrible pictures, Nice Shots, nice and clear!

The large brown one is the thermo time switch, it controls the cold start valve.
The white one is the FI temp sensor.
The single terminal one is for the temp gauge in the inst cluster. It has nothing to do with the FI.
The green vacuum switch doesn't allow vacuum advance before it reaches a certain temp. But really has virtually no effect on driving in the real world.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

Some Guy with a BMW
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Joined: Wed May 31, 2017 12:57 am
Location: British Columbia

Re: Coolant Temp. sensor

Post by Some Guy with a BMW » Thu Apr 12, 2018 11:15 pm

Thanks for the comment - for the record I was slightly off - #4 in the pics is part number 13621357414 (temp sensor) and #3 in the pics is part number 13621 362599 (thermo-time switch) just in case anyone is looking down the road.

One follow up question; I plan to replace the brown gauge wire as it seems to be non-op, but of the other three sensors, which might be most likely to contribute to rough cold idle (car is very rough idle when cold - smooths out pretty good when warm, give it gas cold or warm and its very smooth - so just cold idle)?

Thanks,
C
1961 Volvo PV544
1974 Boler
1981 BMW 528i
1991 Volvo 240 5-speed
1998 Tahoe (truck/tow/vacation-mobile)
2014 Tiguan (wife's car)

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Mike W.
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Re: Coolant Temp. sensor

Post by Mike W. » Fri Apr 13, 2018 11:30 am

The white one is the only one that could have any effect on idle.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

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528i-1981
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Re: Coolant Temp. sensor

Post by 528i-1981 » Mon Apr 16, 2018 6:52 pm

Only peripherally related - the bleed screw on my 81 528i is ... or was ... the slotted one, optimistically designed for a flat blade screwdriver. It's really stuck. I've tried dribbling different types of thread oil on it for weeks at a time, and it won't budge. The slot is mangled now. I confess to my shame that I've even locked a pair of vice grips onto it and tried to get it to move, but no luck. My temperature sensor for the gauge only ranges over the first 1/4 of the face (unless it's really hot when it will peg the needle) and I'd like to replace it, but I'd like to have the bleed screw replaced with the hex head version before replacing the sensor.

Any suggestions? Do I have to drill out the plug? Has anyone replaced the bleed screw with a larger diameter screw from another source?
(oo=00=oo) Eric
1981 528i 5-speed

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Mike W.
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Re: Coolant Temp. sensor

Post by Mike W. » Tue Apr 17, 2018 11:57 am

528i-1981 wrote:
Mon Apr 16, 2018 6:52 pm
Only peripherally related - the bleed screw on my 81 528i is ... or was ... the slotted one, optimistically designed for a flat blade screwdriver. It's really stuck. I've tried dribbling different types of thread oil on it for weeks at a time, and it won't budge. The slot is mangled now. I confess to my shame that I've even locked a pair of vice grips onto it and tried to get it to move, but no luck. My temperature sensor for the gauge only ranges over the first 1/4 of the face (unless it's really hot when it will peg the needle) and I'd like to replace it, but I'd like to have the bleed screw replaced with the hex head version before replacing the sensor.

Any suggestions? Do I have to drill out the plug? Has anyone replaced the bleed screw with a larger diameter screw from another source?
With the shape of the bleeder screw I don't think replacing it with something different would be a good idea. Heat, persistance and perhaps a good penetrating fluid along with the vice grips are all you can do short of replacing the cover, which has gotten relatively expensive new.

Image
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

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maybeillbuyit
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Re: Coolant Temp. sensor

Post by maybeillbuyit » Tue Apr 17, 2018 1:14 pm

528i-1981 wrote:
Mon Apr 16, 2018 6:52 pm
Only peripherally related - the bleed screw on my 81 528i is ... or was ... the slotted one, optimistically designed for a flat blade screwdriver. It's really stuck. I've tried dribbling different types of thread oil on it for weeks at a time, and it won't budge. The slot is mangled now. I confess to my shame that I've even locked a pair of vice grips onto it and tried to get it to move, but no luck. My temperature sensor for the gauge only ranges over the first 1/4 of the face (unless it's really hot when it will peg the needle) and I'd like to replace it, but I'd like to have the bleed screw replaced with the hex head version before replacing the sensor.

Any suggestions? Do I have to drill out the plug? Has anyone replaced the bleed screw with a larger diameter screw from another source?
I just thought I would add to this. I've been in this spot before and spent all kinds of time messing around with one of those early bleed screws. I never did get it out but wasted lots of time. Then I snapped the bolt off the on the cover, Only to find out later that the neck of the thermostat cover was so corroded it needed to to be replaced. The replacement is ridiculously expensive but includes the new bleed screw. Recently I had the exact same thing happen to my new e12. Stuck screw and corroded cover. Just replaced with the new part. Basically make sure the cover and the housing are worth the trouble before you spend a bunch of time fiddling with them. Remove those hoses and see what kind of condition they are in. my .02 cents
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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528i-1981
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Re: Coolant Temp. sensor

Post by 528i-1981 » Tue Apr 17, 2018 7:36 pm

Thanks guys.

As it turned out, I needed $4 worth of knurled nuts for the taillight covers in the trunk. They have them at bavauto.com, but I needed to spend $99 for the free shipping. It turns out that adding the thermostat cover and the temperature sensor brought me right to that free shipping. I can now tell my wife how thrifty I'm being.

Do you think a dab of antiseize on the bleed screw will do any good?
(oo=00=oo) Eric
1981 528i 5-speed

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maybeillbuyit
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Re: Coolant Temp. sensor

Post by maybeillbuyit » Tue Apr 17, 2018 10:58 pm

Anti seize probably wouldn't hurt but like the pic above the new bleed screw has a hex head so its probably not going to be a problem unless you leave it for 40 years. :lol:
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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