rebuilt 1998 cooling system over the weekend (m) - The 7 Series (E38) Message Board

Hi,

On Friday I drove into the garage with the overflow tank leaking. Luckily I read this board so I had all the parts ready to go for a complete rebuild (radiator, tank, hoses, water pump, thermostat, belts). The two big pains are getting the radiator out and in, and removing the waterpump gasket residue. Other than that, it's a piece of cake.

I can say that the "replace radiator" description at e38.org, along with the TIS were fairly complete. Here are quick list of steps with notes in case you are thinking of doing this on a 1998 (made 11/97). I omit all the obvious steps like remove hoses, connectors, etc.

1. drain coolant
2. remove air cleaner top & flow sensor, then remove air cleaner bottom.
3. remove expansion tank (I just cut the top hose)
4. remove fan cowl
5. remove radiator

It is unclear how the radiator clips work from the literature. With a flat screwdriver they pop open and unfold towards the rear of the car. The top rotates back almost 90 deg. before release. The TIS never shows them open.

Also it is unclear how to remove the radiator. It turns out it doesn't just "lift straight up" in the 1998. The driver's side rubber mount is captured between its rest stop and some hard tubing. The radiator must be removed by carefully bending the "S" shaped AC tube on the passenger side to move it away from the radiator, lifting the radiator slightly and moving the pass. side of the radiator to the rear of the car. Then work the driver's side mount out by moving towards the pass side about 1 inch. Then it can be removed from the top. Replacement is a pain also and includes getting the side and bottom clips aligned before dropping into place.

6. remove fan and clutch (special tools)
7. remove fan belt

It is not ness. to remove the tensioner, just remove the top two bolts and lean to the driver's side to make room for wp removal.

8. remove ac belt
9. remove water pump pulley
10. remove vibe damper (careful, it drops right off after the last bolt)

It is not necessary to replace the vibe damper bolts as was stated in the e38 inst. Just reuse them and add a drop of locktite blue. The TIS says "replace bolts" in the install section, but I am pretty certain this means "reinstall bolts," not buy new ones.

11. remove water pump bolts and gently pry the wp off and pull it straight back.

Unlike the TIS says, you can remove it and replace it with the thermostat attached. Here I should note that the 1998 wp has a fabricated metal impeller (sheet metal blades brazed to sheet metal plate). The new dealer ones have a plastic impeller. I got an aftermarket one from alloemparts with a cast metal impeller. Finally, keep a big tray under the front of the engine to catch coolant.

One reinstall tip is to affix the top tube to the overflow tank end FIRST, then do the radiator nipple side by lifting the cowl a few inches after the radiator is properly seated.

My radiator nipple failed at 85K (a couple of months ago), and the expansion tank at 90K (this weekend). The radiator upper neck appears to be still good.

So now I've got a bunch of used cooling system parts for sale :)

Will

98 740i d e a d s t o c k