engine and drivetrain Overheating Problem - Stop And Go Traffic

[Stuart]

My son's 74 has a temp issue.  In stop and go traffic on the freeway it gets hot.  If he gets off on to city streets it comes back to normal.  What's the trouble shooting checklist here?

 

belt

water pump

thermostat

coolant level

 

Where should we look first? 

 

Stuart

[zinz]

How hot is hot? Temp gauge in the red, or just higher than the 3 O'clock position? Big Jack Fahuna told everyone at MidAm that a 2002 can run at between the 3 O'clock and the Red position and still be okay...  Personally, I wouldn't like mine to be anywhere close to red for very long.  I think he really meant that it can safely operate under the red.

 

Here's a great pic of the gauge and the actual numbers (that can only be read with gauge removed) These numbers are in Celsius. Middle of the gauge is 190-200 F (per Mr. Lylte)  http://www.bmw2002faq.com/topic/115927-temp-gauge-actual-temperatures/

 

 

Remember, in dire straits, always run the heater to help bring engine temps down.

 

I would start by flushing the coolant system and put in fresh coolant, making sure you properly drain the block and then burp the system on re-fill. For a quick-fix, you can add Water Wetter which will help, or you can run a 30-70 coolant mix (more water will make the system run cooler) Here's a decent thread about this.. http://www.bmw2002faq.com/topic/76049-bleeding-coolant-system-sound-reasonable/

 

These "fixes" will get you by, but it may be that you need to rebuild your radiator....especially, if you are seeing temps return to normal once out of stop-and-go traffic.  I've seen a similar situation in my car in 100 degree days.

 

 

 

 

 

[percy]

My son's 74 has a temp issue.  In stop and go traffic on the freeway it gets hot.  If he gets off on to city streets it comes back to normal.  What's the trouble shooting checklist here?

 

belt

water pump

thermostat

coolant level

 

Where should we look first? 

 

Stuart

 

 

 

 

 

I can't tell if you are describing a problem or not.  Some temperature swings are normal.  You mention "hot" but that does not tell me whether the temp needle is in the center of the gauge, near the red bar, or above the red bar.  There is a slight margin of safety, but if you read your manual, virtually anywhere between the two colored bars is acceptable.  Naturally the center of the gauge is the best target.  

 

Assuming the temp gauge goes very close or over the red, you pretty much answered your own question.

 

There have been many posts concerning cooling issues and I would suggest thumbing through a few.  Since the '02 engine is liquid cooled, it is not much different than any other water-cooled engines, and that goes for troubleshooting.  Got a repair manual?

 

First, I would look at the obvious things you mentioned, including insuring sufficient coolant in the system.  Always a good idea to check the oil too, because without sufficient supply things can also run hot (or worse).  Next, consider the possibility that the gauge is sending mixed messages.  A thermometer can be helpful to avoid fixing that which wasn't "broke."

 

If all of the above presents itself as A-Ok, then the temperature swings indicate a marginal cooling system.  This could be due to several things:  Loose fan belt, blocked or plugged radiator,bad radiator cap, tired thermostat.  It may not be obvious, but I have seen a waterpump that looked perfectly new from the outside only to discover that the impeller was so corroded as to be practically nonexistent.

 

I don't advocate this for any street car, but I had an '02 with an oversized radiator.  The mechanical fan had been removed in favor of an electric version and the radiator was so effective that the electric fan rarely, if ever, engaged (even with a thermostat set for 180F).  The car ran that way, often in traffic, for 15+years.    I mention this because you could watch the temp gauge swing between the blue area to the center of the gauge depending upon the airflow encountered in traffic or at speed.

 

I am guessing much of your problem can be addressed by simple maintenance, and that may include flushing the system.  Your son should remember that when things get uncomfortably hot, to stave off overheating, he could engage the emergency radiator found next to his right knee, (the heater).

 

Best of luck.

[Hans]

I'd be checking fan belt tension and age first. Glazed and/or loose belt won't help. Then try spraying water through rad fins from the back. Engine cold/off. Check for large bugs on the front. Then try system flush. When was rad last flushed? Take it out and take to a rad shop.

[Chamonix72]

I chased cooling issues for a long time. I replaced the thermostat, water pump and the hoses. The cooling problems went away when I put in a new radiator. My car temp runs hotter when it's in traffic, but I stuck in an electric fan and that keeps things under control.

Edited August 2, 2014 by Chamonix72

[OriginalOwner]

3 years ago:

--  a local radiator shop did a full-on cooling system flush to get "everything" out of the block.

--  installed a new 3-row core radiator.

--  new thermostat "just because."

--  now using about a 10%antifreeze--90%water mixture.

 

Still ran hotter than I thought it should.

 

1 month later, I just happened to remove the radiator cap and look in:  there was some slimy gunk laying on top of the tubes.  I pulled the radiator, turned it upside down, inserted a garden hose into the outlet, and washed out a "large amount" of gooey mushy stuff, sorta like superthick oatmeal that stuck together.  I'm guessing the goo was hanging up/hung up in the outlet fixture on the head, and finally got washed loose and moved into the radiator.

     Immediately thereafter, the temp needle never went above the 3 o'clock position, even on a 100+ degree day.

 

These days, the temp needle does not go above the 3 o'clock position, so I'm firmly convinced there was a "stuff" blockage in the block/head that finally (after who knows how many years) washed out.

      Note that the full-on block flush didn't wash it loose & out of the system.  Or else the flush simply loosened it up enough that it took another month of driving to break loose and get flushed into the radiator.

 

Cheers,

 

Carl

[Hans]

I've seen rad flush products that you put in and then drive for a few days. Seems reasonable. The rad is fairly easy to get out and haul into a rad shop for testing. This doesn't sound like thermostat problem.

Edited August 1, 2014 by Hans

[jessiejake02]

I used to have overheating issues at highway speed.  I went to a radiator place and had my radiator re-cored. no more issues.

[TobyB]

 

The cooling problems went away when I put in a new radiator.

i'm thinkin' this...

 

t

[Stuart]

I've got a line on a new EO radiator for my son's 74 tii but its for a car with AC.  Any issues as his car does not have AC?

[jgerock]

I've got a line on a new EO radiator for my son's 74 tii but its for a car with AC.  Any issues as his car does not have AC?

Only difference that I know is that the bottom tube is canted upward at about 45 degrees on the A/C type radiators to help clear the A/C compressor.