radiator hose swap...
 

Perhaps you guys could help:

For the '87 535is

I need to swap out a leaky coolant hose. I’m currently at work, so I can’t go outside to check the specific hose but I’m pretty sure it’s the hose that attaches to the thermostat housing just in front of the fan and snakes its way to the bottom the radiator. Is it necessary to drain the coolant from both the radiator and the engine block in order to swap out the hose or can I just drain the radiator, and provided that the coolant looks good, perform the swap, top off the fluid, and bleed the system?

Whether it can be done, or not, I think it's a good opportunity to do a complete flush and refill with new coolant. As long as you're already working on the system.

Though, assuming that the 535i is like any other car I've worked on (and maybe it's not?), you can probably replace the hose without draining the radiator or what's in the engine block. If you attach the new hose (one end at a time), quickly, right after removing the original, you should be able to avoid losing some/most of your coolant. Be prepared to catch the stuff that does flow out with a drain pan, though. I'll bet that if you keep the radiator cap on, it won't flow out as fast either.

Top it off, bleed it, and you should be good to go.

But again, I'd take this opportunity to do a full flush and refill.

Thanks ff; I'll consider the flush, but I want to say in looking at the records from the PO that he flushed the system within the last year. If the fluid looks bad I'll open up the system for sure, and flush her out a couple of times.

Went ahead and drained the whole system. The PO had but some green shit in there. I replaced the hose, and refilled with BMW coolant.

If you can't document when they were last done, consider doing the radiator, thermostat/housing, and water pump as good preventative maintenance.

Alex

I think the Altima was on its original coolant. It certainly has its original brake and clutch fluid. 11 years and 186,500 miles. :eeps:

I went back and forth in my head before changing them. We'll see what can of worms I opened by tampering with a delicate microcosm.

You know it. The second car I ever owned was a first Gen Escort GT (LOL...). At about 100K miles, I decided that I should change the PCV valve. You know, to improve engine performance. Once the new valve was in, I couldn't keep the car running. It would stall at every stoplight (ZHP, anyone?). I put the old PCV back in, and it ran great again.

Some maintenance items are better left alone after a certain point. :)

Well fortunately the car runs great. But it needs a fuel filter, cap, rotor, wires, could probably use new front control arms and swaybar bushings and endlinks.

But so long as it passes inspection... I'll probably leave it alone.

That's the fun stuff, though. The part swaps are simple, inexpensive, and make a real, positive difference in how the car runs.