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Cooling System Issues In Tropical Climates


emmetHK
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Hi all,

I'm a relatively new owner of my 73' 2002.  I've had it for the past 6 months or so.  I live in Hong Kong and I am trying to get this car set up as my daily driver.  This car hasnt been driven much in the last 10 years and for the past few months, I find myself breaking down quite regularly and having to get towed to my mechanic's garage (3 times so far).  Everytime i feel like i am making progress, I use the car a few weeks only to have something else go wrong.  One of the issues I am most challenged by is the cooling system.  The climate in HK is usually over 32 degrees C (>90 F) for about 9 months of the year, with high humidity. There isnt any issues as long as I am moving, but Hong Kong being Hong Kong, there is a fair bit of traffic in the city and when you get these termperatures + humidity + traffic = tow truck (for my car anyways).  I even had a 12" DC fan installed infront of my radiator to push air through (part of my AC system), but this hasnt seem to have had much improvement when sitting in traffic.

 

So my question to all of you more experienced 2002 owners is, What can i do to improve the stock cooling system to allow me to sit in traffic without having to stress whether or not my car is going to over heat?  I've seen discussions about tropical cooling fans - but does this really make a significant enough difference? I also have seen 'tropical' radiator upgrades - any one have any feedback on these?

 

I've already changed all hoses,belts, water pump, 71 F termostat  and fan blade (standard 360mm) and now looking at replacing standard radiator with a larger 'tropical' one + tropical fan blade (400mm). 

 

I am particularly interested to hear from those owners who are living in similar hot climates regions(Southern United States, PR...etc)  I would love to hear what you have done to overcome these issues.

 

Thanks,

Emmet

 

 

 

 

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Biggies are air in system, leaks in system, and timing too advanced, lived in Sacramento California, 100 f days in summer and when system was right had no troubles. Very sensitive to air bubbles in head, refill coolant very slowly, think vacum line syphon, get a pressure test done and retard that timing a bit, stock should handle 90 degrees no prob.

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Hi thanks for the hints.  Im sorry, but im not overly well versed in understanding what is required here...

 

Air in system - how is this tested? how is this removed?  and how is this prevented?

Leaks in system - i assume this is simply done visually?

Timing too advanced - sorry what does this mean?

 

On a seperate note, I've just had the existing radiator removed and as you can see from the photos, the fan blade was brushing up against it making that circular pattern. Will changing the engine mounts put this right? 

 

 

 

radiator.bmp

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First I would use a thin screwdriver to straighten all bent fins on both sides of the radiator.  It takes patience but is not mentally difficult.

 

Here in Honolulu at 85 degrees F a radiator with half the fins gone will provide adequate cooling on a non-AC car if other elements are correct:  timing, dwell, coolant full.

 

It is common for BMWs or the 1970s and later to need care when refilling the radiator.  Park on a hill with the front of the car highest, heater on and slowly add coolant.  The intent is to get any and all pockets and bubbles of air out of the cooling system.  Run the car a few minutes to warm everything up, then park on the hill again and check coolant level.  It's called bleeding the cooling system and I expect there are many threads detailing desparate attempts to get cooling restored.

 

If you run AC in hot weather, you're on your own, but others have reported success.  I never liked the additional complexity and failure tendencies of air conditioning.  I roll down the windows and/or open the sunroof.  Or speed up if at all possible.

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Unfortunately this radiator is leaking so i need to replace it anyways.  I've found a 'tropical' radiator, im still trying to determine what the difference is, im guessing it is bigger?  Just wondering if any of you out there have installed something like this and have much success controlling the overheating issue.  Again, my biggest concern is when i am stuck in traffic on a hot day with or without A/C on.  I was told that it was better to keep the AC on since it would activate the DC motor and force some air through.  I guess this offsets the higher idling RPMS?

 

What is timing? Dwell?

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It gets pretty hot in South Australia (though not humid) a core have found that a standard cooling system in good condition can cope fine (Irun an 82 degree thermostat for example).

I recommend that you drill a small hole in the bottom plate of the thermostat to help with the trapped air issue. This is very common when refilling the system and you may need to run it at idle until the stat opens, stop and top up. Leave to cool and then run again /top up. Squeezing the hoses helps too and if you have a water choke it can help to leave the very top hose disconnected while you slowly fill to let air out.

See if you can get a 'high efficiency' three row radiator core(three rows of tubes from top to bottom) installed to your top and bottom radiator tanks (the sections with the inlet /outlet pipes. HK is definitely the kind of place you can get this done so shop around. The radiator shop will also flush the rest of your system. With this and the other changes you have made you should be good.

The reference to timing refers to ignition timing. Having your timing too far advanced can cause an otherwise good engine to run hot. Set this with a timing light.

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Whether your car runs hot at speed or while idling at a stop is an important detail when trying to diagnose problems....

 

You can also drill a small hole in the thermostat valve to prevent it from blocking air bubbles when you are filling the coolant. Massaging and squeezing the lower radiator hose can also help force out bubbles. There is quite a bit of information on the forums regarding the filling and bleeding of the coolant system. 

 

I would also flush the engine block coolant passages. If you have lots of sludge coating the coolant passages inside the engine cannot efficiently transfer heat to the coolant fluid as well as said sludge restricting flow.

 

Check the accuracy of the coolant temperature sensor with an ir thermometer.. Perhaps the car is not running hot- you just need a sensor. 

 

Use correct BMW coolant. Its blue.... You might consider a different ratio of coolant to distilled water- it does not sound like it freezes there. 

 

You said you are getting a new "tropical" radiator- I assume this means or is equivalent to "high density". You can see how many coolant passages your radiator has by looking inside with the cap off and the coolant level is low enough. Your old original radiator probably had only 2 rows of passages. I would hope your "tropical" radiator has 3. 3 cores give the radiator greater ability to exchange engine heat into the air as well as increasing the water/coolant capacity....

 

You could have a head gasket leak.. Exhaust gases are entering the cooling system and vice versa.. This will cause hot running. 

 

As was mentioned before- Engine timing should be checked. If the timing is too advanced your engine is going to run hot as well as possibly cause internal engine damage. 

 

Your engine could also be too lean causing it to run hot...

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My car runs fine at speed. It runs at about 30-40% of the temp gauge (or 4 o'clock position). The temperature will begin to creep up slowly in stop and go traffic. Nt immediately, but noticeable within 5 mins and quite high within 20 mins. Always a bit stressful and as a result I have opted to simply avoid certain areas. From what i am hearing, it seems like an overhaul of the cooling system should resolve this...as much as I hate sitting in traffic, I would like to have confidence that I can sit there and not worry about over heating.

Will using the AC cause the engine to run hotter?

I'm sorry but how is timing checked? Is this standard for all cars or is there a specific timing for 2002's?

Head gasket leak - how is this checked?

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Do you have the fan blade installed correctly, which is to say:  so it pulls outside air through the radiator (airflow from the front of the car into the engine compartment ..... you don't want it pushing hot engine air through the radiator.

 

http://www.bmw2002faq.com/topic/138840-cooling-fan-and-alternator/

 

 

I prefer to use an 85% water/15% antifreeze mixture.  My engine runs hotter as the coolant mix gets toward 50/50, so I use a lower percentage of antifreeze for heat management.

 

Cheers,

 

Carl

Edited by OriginalOwner
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The orientation of fan blades does not change when turned over, simple physics here, check it out, it will cause the fan to fould the radiator, worth looking into. You mentioned checking your engine mounts for fixing fan hitting radiator, more likely loose fan bolts, wrong water pump, ie 320 I or wrong fan blade ditto 320 i. Dont know history on car but has the front end ever taken a hit? Lots to cover on your qwestions, some pics could take us a long way in understanding your problems, start down loading.

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If the car is getting warm at stops while idling that sounds pretty normal... If your fan does not have a shroud around it- get one! I think that is part of the "tropical" option for 2002s...

 

Also make sure your idle rpm is set correctly. If your idle is too low then the fan won't turn fast enough at stops and the water pump will not be moving as much coolant through the system....

 

Do research here and elsewhere and give yourself an education. The information is all here! 

 

One final thing to consider would be to switch to an electric fan. Ireland Engineering has a very straight forward electric fan kit. Advantages are improved cooling at stops (depending on fan size of course and your cooling system is otherwise working correctly)... Others claim less noise, better mpg, and more power....

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It sounds as though you are not neccesarily a do-it-yourself person, so I'd ask your mechanic to check the ignition timing (dwell) for you. A professional will look at the specs for your model and make adjustments if necessary. Actually, if you're due for a major tune up this may be the time. Valve adjustment, new filters, thermostat(possibly), plugs, points... Just maybe this will eliminate most of your problem. And of course a new radiator (with shroud) will be good.

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If your fan does not have a shroud around it- get one! I think that is part of the "tropical" option for 2002s...

 

Ironically, at least for the U.S. market, the only shroud available fits the 360mm fan. The 400mm "tropical" fan will not work with the factory shroud. Thus, you're left deciding between a larger fan or a shroud. I have no idea whether BMW made a shroud, available in non-U.S. markets, that accommodates the 400mm fan.

Steve

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