Heater inlet pipe and water pipe
 

I have a 99 Z3 2.5 liter 6cyl with 95000 miles, I have no history on the car, I am planning to replace the heater inlet pipe and water pipe (plastic parts) has anyone replaced them on the 6 cylinder. My bentley manual does not seem to cover the subject. From what I have read, the intake manifold must be removed, are there any special precautions that should be taken when replacing the plastic water lines? I had read somewhere the water lines on earlier cars were metal. if so could a earlier metal pipe be used as a replacement? How complicated is the job of removing the manifold and replacing the lines?


Thanks for any information.

Your 1999 Z3 2.5 M52 has a plastic water pipe under the manifold, the Heater Inlet Pipe, 11531705210. This is apparently the only plastic pipe on that engine, according to the view in RealOEM which also has a photo that can be enlarged:
http://realoem.com/bmw/showparts.do?...43&hg=11&fg=35

Going back in RealOEM to the first 2.5L 6-cyl M52 engine in 01/1998, the same pipe is shown as plastic.

Going back in RealOEM to the first 1.9L 4-cyl M44 engine in 07/1995, a similar pipe is shown as plastic except instead of being under Cooling System, it is under Engine Housing.

I have not heard that this pipe was ever metal as an OEM part. Such a pipe in metal, with all its mounts and fittings, would be very expensive to manufacture.

To get an idea of what replacing your heater inlet pipe might be like, here is a video about rebuilding the cooling system on a 4-cyl M44. That pipe shows up in Msg # 5.

Heater inlet pipe and water pipe
 

Thanks for the link and information.

It's a DIY thread, not a video, and here's the missing link:
http://www.318ti.org/forum/showthread.php?t=18066

At 95,000 miles, the whole cooling system should be replaced, not just those two plastic pipes. In accessing them, you have to remove so much. I have studied out replacing the cooling system on my Z3 1.9L, using RealOEM.com. You might do the same for your 2.5L, whose parts will be completely different. Put the last 7 of your VIN into RealOEM, save the link, and it will be easy to go back and navigate for your car. Here's my 1.9L. RealOEM gives typical prices and is not a store; BMW dealers are much higher, and stores like BMW South Atlanta and Bavarian Autosports will be less.

COOLING SYSTEM REBUILD Z3 1.9L
Brass bleeder screw Bav. Autosp. RBS 1
Coolant - dealer 82141467704 1

Radiator
Fan shroud fasteners 17111712963 2
Radiator 17111728907 1
Gasket ring for temp. switch 32411093596 1
Radiator cap 17111742231 1
Expansion tank 17111712835 1
Gasket ring under exp. Tank 17211712965 1

Water Pump & Thermostat
Water pump 11510393338 1
O-ring for water pump 11511714519 1
Thermostat w/housing 11531743017 1
Axial gasket for thermostat 11531743179 1

Hoses
Upper radiator hose - right 11531743535 1
Upper radiator hose - left 11531743295 1
Lower radiator hose 11531247261 1
Hose on top of plastic heater pipe 11531247398 1
Hose on end of plastic heater pipe 64218400295 1
Double hose on plastic @ rear head 11151247903 1

Plastic Connectors
Plastic connector pipe on block 11531714738 1
O-ring for block connector 11531709157 1
Plastic Y connector on head 11531743679 1
O-ring for Y connector 11511739691 1

Manifold
Lower intake manifold gasket 11611734684 1
Upper to lower intake man. gask. 11611247478 2
Block coolant drain crush ring 0 then 7119963200 1

EDIT: I don't know if a 6-cylinder even has the plastic connector on the rear of the head.
EDIT: RealOEM typical prices total to $800. A BMW dealer could be many times that, while online vendors will be less than that.