Originally posted at http://mywebpages.comcast.net/gsussman/cooling_system.htm
Of all the subsystems in the E38, the cooling system seems to be
one of the ones with the highest failure rate. Somewhere in the range of 70 to
100K miles, you too will have to perform some major maintenance on it. This
usually revolves around the two main components, the water pump and radiator.
Of the two components, water pumps give you by far the most
warning. Normally it starts with the smell of coolant in the engine compartment
and degrades to a small puddle of coolant on the garage floor after sitting all
night. On others, the bearings begin to whine or shriek under acceleration or
during normal running. In either case, you will know it is time to do the pump.
The radiator is the silent killer of the two. The E38 cars, as
well as the 5 series cars are prone to a catastrophic radiator failure when
the upper hose neck breaks off. It is usually not a matter of if it will
happen, but when. When it goes, there is no warning, and no getting home. You
will sit on the side of the road, billowing steam until the flat bed arrives to
pick you and your broken machine up. There are a number of theories as to why
the upper neck breaks. Some say that the Behr radiators have a design flaw,
while others put the blame on BMW directly. The why is not what I am going to
discuss on this page, it is the "How to" when it comes to replacement.
The repairs for either or, or both of these components is within
the capacity of a capable DIY mechanic, but it takes time. Don't set out with
the mindset that "I will get the whole thing done this weekend", It's
not going to happen! Murphy's law dictates that you will break a part, or
need a bolt long after the auto parts stores have closed. For me, the end to end
procedure took 2 weeks, but 1 of those wwas spent waiting for parts. Which
brings me to my next topic.
If your car is drivable before the start of the procedure, do
not start taking stuff apart until you have ALL of your parts in. Inevitably the
parts that are missing will be the ones you need first, thus you will loose a
number of days waiting for them to come in. It will also allow you to ensure
that all of the parts are correct before you take them out of the box at 11:30pm
Saturday night only to find that you either have a broken part, or the wrong
I did not intend on this page to be a replacement for the TIS
procedures for the water pump / radiator replacement, only a source for lessons
learned, and information that is not part of the actual procedure. The TIS
is an integral part of getting this job done right. Make sure you have it.
If you don't already have one, buy the BMW TIS CD (Technical
Information Service). It is basically the entire factory service manual for all
BMW vehicles, complete with drawings, pictures, and procedures for fixing,
replacing, or servicing each and every part on your car. I would have never been
able to complete this project without it. It will also give you the proper
torque specs for all the bolts. Let me put it this way, if you are even
considering doing this job yourself, then you undoubtedly do a fair amount of maintenance
on your car. The CD will pay for itself in no time!
|You can order your copy from:
||Central Letter Shop
- Metric socket set 3/8" drive
should do. (I actually used a 1/4" drive set for over 50% of the work.
There are quite a lot of 6 to 10mm bolts to take out, and the 1/4"
drive socket set is perfect for these)
- Socket extensions (1/4" 5 to
6" long, 1/2"drive 3" long)
- 1/2" drive to 3/8" drive converter
(if you do not have 1/2" drive metirc sockets)
- 1/2" drive breaker bar (you will
need this to get off the vibration damper pulley if you decide to do the
- 1/2" drive Torque wrench,
calibrated to at least 34 N/m
- 32mm open end wrench (you can not use
a crecent wrench in place of this, it is too thick. The thinner it is the
- Fan clutch removal tool (Click
for a drawing of how to build it)
- Permatex gasket sealer (for the water
- Thread locker (medium duty, BLUE)
(Water pump bolts)
- Jackstands (These are a must have. you
will not be able to do the job without them...Ramps would also work, but I
don't own a set that the 7's front end can get over)
- Floor Jack (in a pinch, you can use
the jack in the trunk of the car)
- Various screw drivers (philips and
- 2 gallons of antifreeze
- Brake parts cleaner (helps get off the
antifreeze that is going to get everywhere)
- Electrical contact cleaner (gets the
antifreeze out of any of the plugs that get soaked)
- Vibration damper pulley bolts (TIS
specifies that these should not be reused. You can get them directly from
the dealer or from Pep Boys. Make sure you get grade 10.9 bolts)
- Water Pump + gasket
- Upper Hose
- Lower Hose
- Belts (Alternator and A/C)
- Thermostat + gasket (O-ring)
- Thermostat housing
The total parts bill was around $700 so prepare
yourself. You can get most if not all of the parts through an aftermarket
company that offers OEM BMW parts. I ordered all of mine through The Parts Bin (www.alloembmwparts.com).
The service was great, and the prices were even better. The radiator for example
is about $600 from the dealer, the same part (original BMW, not
aftermarket) through these guys was $297.
Hints, Tips and Things to Watch Out For
While not directly applicable to the procedure, these tips, techniques and
things to watch out for will potentially save you a number of days and dollars,
while you wait for parts the were needlessly broken due to an accident.
- From the start, remove the air box top cover, air filter, air intake hose,
and the mass air flow sensor. This will give you more room to work.
- You may find it easier to work if you remove the front bumper. It comes
off with 4 small bolts in the wheel wells and 2 T-50 Torx bolts on the
underside of the bumper, outboard the license plate frame. While there is no
technical reason for the bumper removal, it keeps the paint from getting
scratched while you are working, and gives you more room to work. The bumper
can be taken off or put on in 5 minutes, so there is no reason not to do it.
- The entire engine block coolant drain does not have to be performed (TIS
states you should). You are only really concerned with the radiator, and
there is no need to drain the whole block. This will save you about 3
gallons of antifreeze.
- THE FAN CLUTCH IS LEFT HAND THREADED! If you are not thinking, it
is easy to over-tighten it instead of loosening it.
FAN AND POWER STEERING PUMP PULLEYS ARE PLASTIC AND EXTREMELY BRITTLE!
If you even bump
them with a wrench, there is a very good possibility that they
will chip out, and require replacement ($20 dealer only part). I
chipped mine, and the dealer ended up ordering the part 3 times because each
one they got from the warehouse was chipped (4 days lost). It would be a
smart idea to tape some bubble wrap around them as soon as you have access.
get the vibration damper bolts out, use the breaker bar. Use sharp quick
pulls on the handle to break the bolts free. A long slow pull will actually
cause the engine to turn. An impact wrench would be better for this
application, but there is no room to get in there. I tried to use a
1/2" drive socket handle, but couldn't get enough torque to get the
bolts free. The breaker bar made it easy.
removing the water pump, make sure that the 2 pipes running from the back of
the engine to the water pump are not pulled from their mounts in the back of
the engine. I have heard they are a real pain in the butt to get back on if
lower radiator rests, which support the tabs on the left and right side of
the radiator, come off without unbolting them. There is a plastic latch that
when pushed either toward the outside or inside of the car (don't remember
which way) will release the rest and allow it to slide off.
BMW TIS specifies that the radiator comes out from the top of the car. I was
unable to do that without removing the A/C condenser lines and bleeding out
the refrigerant, so I removed it from the bottom. This
required some coaxing, pushing and cussing, but is possible.
you have the fan clutch removed, keep it vertical. Do not let
it lay on it's face or backside. I have heard that laying it flat can cause
it to leak and become no good. You also want to check it out and make sure
that it has not already leaked. (This may be an additional replacement part)
- Check out your fan blade. Make sure it is not chipped or cracked in any
way. If it is either, or if you suspect it in any way, REPLACE IT! The cost
of a new fan is nothing compared to the cost of replacing the hood, if it
comes apart while the engine is running.
- After things are back together, and you have refilled and bled your
cooling system, be aware that over the next 2 days or so, your car will
consume an additional 1/2 to 3/4 gallons of coolant. Be diligent, and keep a
watch on the level. As a precaution, keep a gallon of antifreeze in the
trunk until the system reaches the steady state level, this normally occurs
within 2 days, or 4 heat up and cooldown cycles.
Just a quick insight of what you are in for:
|Click on the thumbnails for a larger images