Testimonial: Coolant system overhaul

I read a bit on here, but mainly I relied on the DIY on BMW330ci.net. It took forever, mostly because I had a ton of interruptions, but it was pretty simple with basic tools. I would highly recommend following every recommendation on this DIY, including 3 feet of hose with 1.5 inch ID. It was hot as pelotas here today, and a shower/bath of coolant/antifreeze only made me confused at what was sweat and what was not great for me to ingest through my sinuses. This was in the step of removing the block drain plug. I tried to fit a funnel in there, and if I'd known the mess it cause I might have tried harder, but some lessons are learned the hard way. 70k miles until I'm reminded again, I guess.

So, guys and gals, if this is one of the more involved DIYs, you can do it. It's not that tough, and the instructions linked are comprehensive enough that you won't be left guessing.

Originally Posted by RSPDiver

a shower/bath of coolant/antifreeze ... was in the step of removing the block drain plug

When we overhaul our E39 cooling systems (M54 engine), we don't bother with the drain plug, mainly because you lose almost all the coolant when you remove the water pump & thermostat and radiator & expansion tank anyway.

Not sure if the fluid would have been lost elsewhere, but probably a half gallon came out from this plug. About a quart doused my face and shirt, so I'd love to hear from anyone else that has proven this step can be omitted! Without a very fat hose and quick moves, there's little escaping a shower.

You definitely need to drain the block.

Originally Posted by RSPDiver

I read a bit on here, but mainly I relied on the DIY on BMW330ci.net. It took forever, mostly because I had a ton of interruptions, but it was pretty simple with basic tools. I would highly recommend following every recommendation on this DIY, including 3 feet of hose with 1.5 inch ID. It was hot as pelotas here today, and a shower/bath of coolant/antifreeze only made me confused at what was sweat and what was not great for me to ingest through my sinuses. This was in the step of removing the block drain plug. I tried to fit a funnel in there, and if I'd known the mess it cause I might have tried harder, but some lessons are learned the hard way. 70k miles until I'm reminded again, I guess.

So, guys and gals, if this is one of the more involved DIYs, you can do it. It's not that tough, and the instructions linked are comprehensive enough that you won't be left guessing.

Any special tips on this other than trying to avoid the coolant bath? Or problems you ran into that gave you unexpected trouble? I'm about to tackle this myself this weekend and am a little nervous about it, though I've read and watched 100 DIYs and feel much better about it than I did before.

Originally Posted by fauchpj

You definitely need to drain the block.

Maybe your M54 engines are different than ours, but draining the block does (almost) nothing to empty the cooling system if (and that's the big if), if you're already going to remove the radiator, hoses, and water pump.

For the teeny tiny amount that's left inside, cn90 has a DIY where he simply flushes with a garden hose into the open water pump outlet.

In addition, if you pour your undiluted coolant in first, then mix with tap water (yes, tap water ... we tested NYC and San Jose tap water specifications against the BMW specifications for coolant water and they met the dozen chemical composition specs with flying colors) to the proper level (bleeding and doublechecking, of course), then the remaining fluid will be of no consequence.

Of course, if you really 'want' to remove the drain plug, there's absolutely nothing wrong with that. It's just that the drain plug in our M54 engines is in a lousy location and difficult to get to (for so little gain).

In the end, it's your choice. If it's easy for you, go ahead and remove the drain plug. All we're saying is that most of us who have written the DIYs have found that the drain plug isn't as accessible as it may seem upon first inspection. And, when all is said & done, once you remove the entire cooling system, there is precious little coolant left in the engine at that point anyway.

Still, they provide a drain plug (some say mostly for freezing environments); so, if you really want to remove it, there's nothing wrong with doing so. In fact, if you remove it AFTER you've removed all the hoses and cooling system components, I, for one, would be very curious as to how much coolant you manage to collect from that effort.

Originally Posted by ChocolateLab

Any special tips on this other than trying to avoid the coolant bath? Or problems you ran into that gave you unexpected trouble? I'm about to tackle this myself this weekend and am a little nervous about it, though I've read and watched 100 DIYs and feel much better about it than I did before.

Honestly, clear safety glasses would be really a good idea. When you're underneath trying to wrestle the lower hose off, lot's of bug guts, leaves, sand, and bull crap gets shaken out right into your face. And I know the DIYs say that brute force helps with getting that lower hose off, but be mindful that the side pieces of the radiator are plastic. Too much bending and rough effort could possibly break it off, requiring a new radiator. I used a large screwdriver to gently pry at the ends of the hose using various leverage points around the hose.

Other than that, it's very straight forward and just takes time. Start in as cool of weather as you can, and don't work on it if the engine is still even a little warm, just in case you do take an inpromptu bath.

Originally Posted by fauchpj

You definitely need to drain the block.

+1

SO much coolant poured out of the block when I did it. And btw, don't you think they'd put that plug in a place where it will drain without going EVERYWHERE?

Originally Posted by mhs328Ci

+1

SO much coolant poured out of the block when I did it. And btw, don't you think they'd put that plug in a place where it will drain without going EVERYWHERE?

You would think so. A lot of DIY's recommend using a plastic hose to drain it, but I don't see how you can manage to get the bolt out and fit a hose up there at the same time.

It takes a good bit of extensions and flexible sockets to get to it though.

Originally Posted by RSPDiver

Not sure if the fluid would have been lost elsewhere, but probably a half gallon came out from this plug. About a quart doused my face and shirt, so I'd love to hear from anyone else that has proven this step can be omitted! Without a very fat hose and quick moves, there's little escaping a shower.

Did you remove the plug before or after removing the water pump? What bluebee seems to be saying is that if you remove all the other crap, the amount left in the block is going to be a fairly small amount. Not really worth going through the trouble of draining at that point. This is in-line with my experience

Originally Posted by TerraPhantm

Did you remove the plug before or after removing the water pump? What bluebee seems to be saying is that if you remove all the other crap, the amount left in the block is going to be a fairly small amount. Not really worth going through the trouble of draining at that point. This is in-line with my experience

I removed the plug after draining the radiator (both plugs).

I've done it twice and there was a good bit (1/2 gallon) that came out.

It is not that much trouble to get to the drain, you just need the 'right' tools. (Flexible socket extension helps a lot)

Originally Posted by RSPDiver

the DIYs say that brute force helps with getting that lower hose off, but be mindful that the side pieces of the radiator are plastic. Too much bending and rough effort could possibly break it off, requiring a new radiator. I used a large screwdriver to gently pry at the ends of the hose using various leverage points around the hose.

We, on the E39 side of the house, like you, came up with a DIY in the bestlinks for removing the radiator hoses using only axial forces (Fa):
- How to to non-destructively remove the heater hoses (1)



In fact, if you look in the bestlinks, you'll see how to non-destructively remove most of the (admittedly brittle) cooling system components that broke upon removal (ask me how I know):

- How not to remove the nipple from the E39 radiator (broken radiator nipple)
- How not to put your E39 fan clutch back on (crooked fan clutch nut)
- How not to bleed your E39 cooling system (1) (broken bleeder screw)
- How not to replace your E39 thermostat (thermostat loom misplaced)
- How not to remove your E39 expansion tank (broken expansion tank nipple & cn90 repair)

Here, for reference, are some of the DIYs for non-destructive repair:

- Tricks to replace the M54 fan clutch nut (1)
- Innovative solution to the M54 lower-hose thermoswitch o-ring (1)
- How to non-destructively remove the brittle plastic radiator nipple (1)
- How to non-destructively remove the brittle expansion tank nipple (1) (2)
- How to properly remove the original OEM BMW Oetiker clamp (1)
- How to not misplace the thermostat wiring loom (1)
- How to properly replace a broken bleeder screw (1)
etc.

Originally Posted by fauchpj

A lot of DIY's recommend using a plastic hose to drain it, but I don't see how you can manage to get the bolt out and fit a hose up there at the same time.

You can use your thumb and forefinger to slowly unscrew the plug while holding the hose end with your other three fingers. As soon as the plug is free, let it drop into the hose, and immediately press the hose end to the drain to capture the coolant. After the deluge has ended, you can retrieve the plug from your collection bucket.

This

Sent from my ADR6300 using Bimmer App

Originally Posted by bluebee

(yes, tap water ... we tested NYC and San Jose tap water specifications against the BMW specifications for coolant water and they met the dozen chemical composition specs with flying colors)

Would you mind sharing a link to this comparison? There's a lot of hard water to be found out there in public and private water supplies.

Originally Posted by bluebee

Still, they provide a drain plug (some say mostly for freezing environments)

You may be thinking of freeze plugs, which are intended to pop out and relieve pressure on the block if the system freezes solid.