Help with Radiator / Water Pump

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Mike W.
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Location: Sonoma County

Re: Help with Radiator / Water Pump

Post by Mike W. » Sun Jun 03, 2018 3:01 pm

Get something like this, then start shooting different parts of the cooling system. https://www.amazon.com/Thermometer-Non- ... hermometer If you see 180 coming out of the radiator you'll know the switch isn't the problem.

While not following normal bleeding method isn't the best way to do it, the heater working has always been my test to see if it's bled or not. Since it is working I suspect it is bled. I've also seen small holes drilled in thermostats to help with bleeding, 1/8" or so and some with a small hole with a loose plug in it that I suspect mostly seals under water pressure. Overheating on the highway is a common sign of a plugged radiator, but not always. The aux fan on 530i's helps, but not a whole lot, it's pretty small compared to the ones on 528i's and single speed. Get a thermometer and shoot some temps, but my money is on the radiator. The cooling systems were marginal when new and 40 years later it's probably got deposits on the inside of the tubes even if it flows ok. I think the early radiators were 30 or 32 tubes, E28 radiators have an aluminum core and 38 tubes. I had an aftermarket one in an E23 long ago that had 50 tubes. Same height, just slightly wider. That car never ran hot with that radiator in it.
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

cory58
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Location: Charlotte, NC

Re: Help with Radiator / Water Pump

Post by cory58 » Mon Jun 04, 2018 3:25 pm

Thanks for all the responses! Here is an update.

1. As I expected, 3 of the 4 socket/allen head screws holding the pulley on the water pump stripped once I put some real force on them. Thankfully a great BMW mechanic in Memphis (John Cox) showed me how to break loose stripped screws/bolts with a chisel and hammer. Worked like a charm! One problem solved.

2. I was able to get at the bottom alternator bolt from underneath the car and release the tension on the belt.

3. Since the radiator got a clean bill of health, here are the parts I'm replacing: fan clutch, water pump, thermostat, thermostat cover, any stripped, partially stripped and rusty bolts/nuts. This may seem like overkill, but I want to take the car O'fest in July and don't have time to replace things one-at-a-time and then take everything apart again when the problem persists.

The main parts order won't arrive for over a week, so there won't be any new news for a while.

Mike W. - You may not remember our initial discussion on mye28.net about this problem. I have an IR temp gun, but just took a temp of the left side of the radiator (217 degrees) when the fan would not come on with the new switch. I did not think to get a reading from the output hose - duh! I will do that when everything is back together.

Thanks again for all the responses and helpful ideas.

Cory
1977 530i
1988 320i Touring (euro)
1992 325i Cabrio
2015 328i (wife's car)
2001 325i (R.I.P., still missed)

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528i-1981
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Re: Help with Radiator / Water Pump

Post by 528i-1981 » Mon Jun 04, 2018 5:10 pm

If you're dishing trade secrets, I'd love to hear about the hammer and chisel trick. Sounds like we've got some time to kill on this thread ...
(oo=00=oo) Eric
1981 528i Manual

cory58
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Location: Charlotte, NC

Re: Help with Radiator / Water Pump

Post by cory58 » Tue Jun 05, 2018 9:04 am

528i-1981 wrote:
Mon Jun 04, 2018 5:10 pm
If you're dishing trade secrets, I'd love to hear about the hammer and chisel trick. Sounds like we've got some time to kill on this thread ...
Not really a secret, just something I wouldn't have thought of on my own. Works best on screws/bolts with thick heads, like the fillister-type head on the allen screws that I stripped. Just place the head of the chisel on the side of the screw head and whack it so that the force wants to loosen the screw (counter-clockwise). I start with the chisel almost 90 degrees to the head. The first few whacks make a slot in the screw head that will hold the chisel as you progressively angle it more and apply additional whacks. The lower the angle, the more of the force tries to turn the screw. Took me about 20-30 light-to-moderate whacks to loosen each of the screws, which was not bad. I've seen rusty larger hex bolts that look like they put up quite a fight before giving up and turning.

Cory
Last edited by cory58 on Mon Jun 11, 2018 1:28 pm, edited 1 time in total.
1977 530i
1988 320i Touring (euro)
1992 325i Cabrio
2015 328i (wife's car)
2001 325i (R.I.P., still missed)

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Robert Bondi
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Location: Austin, TX

Re: Help with Radiator / Water Pump

Post by Robert Bondi » Fri Jun 08, 2018 5:36 pm

I spent years working on making my 77 530i run cooler. I've conquered most of those demons and
have done just about everything listed in the FAQ. I currently run an all-aluminum custom version
of the E28 radiator.

http://www.firstfives.org/faq/cool/cool.html

The aux fan switch is available in at least 3 T specs: 99C, 91C, and 82C. Earlier cars only use
one switch. I run the 82C switch. Midway on the dash temp gauge is about 80C from my calibration work.
Robert
77 530i
77 Euro 528

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