1998 BMW Coolant Change Recommendations

Thank you for the great information everyone! It really helped my decisions here. The Real OEM site was super helpful as well. I ended up passing on the FCP kit. I was on the fence, then the kit became unavailable due to the lower radiator hose being backordered with no ETA, so between that and the feedback here it kind of sealed the deal. I ordered this hose from the local BMW dealer instead to the tune of ~ $68!

This is what I went with from FCP: a new water pump (metal impeller Hepu), thermostat, upper radiator hose, BMW expansion tank, new cap, expansion tank hose, fan clutch and blade, coolant level sensor and the BMW coolant. I noticed I already have an aluminum thermostat housing installed, so I just ordered a new gasket. All of these were either BMW parts or listed as "OE." I decided to buy all new nuts and bolts for the water pump, thermostat housing, and fan clutch since they were all quite cheap.

I decided to hold off on replacing the hoses that went to the throttle body and heater core because it looked like the job required removing the intake manifold and they still seemed in fair condition. Hopefully I won't regret this! 🤞 I also passed on the clamps because the current ones appear to be original but still in good shape.

To echo Craig in Canada's comment about these engines running at different temps - there seems to be two common thermostats for E36s. The Mahle one in the FCP kit is actually listed as not for any 328 after MY1996. It looks like for some reason BMW went from an 88 degree to 92 degree thermostat mid model. I doubt it makes much of a difference, but I went with a 92 degree BorgWarner thermostat to follow what was spec'd.

Independent from the cooling parts - it's also due for front and rear brakes, so I went with Zimmermann rotors and Textar (listed as the OE supplier for BMW) pads. I picked up the Motive European Power Bleeder kit to aid in getting some fresh brake fluid in the system. I'm hoping this (with the appropriate adapter?) will work with my Accord as well.
Sounds like a sound plan. The Motive should work great for both vehicles - I use mine on the BMW & Subaru.

I was going to ask if the vanos seals have been replaced but being a '98 it might be a single vanos and not apply (I have a '99 528 which I believe was the first MY they put the M52TU in the 5's).
Sounds like a sound plan. The Motive should work great for both vehicles - I use mine on the BMW & Subaru.

I was going to ask if the vanos seals have been replaced but being a '98 it might be a single vanos and not apply (I have a '99 528 which I believe was the first MY they put the M52TU in the 5's).
M52TU switchover was during 1998 depending on the model. For the E39 the switchover was 9/98. And there was a wealth of overlap from 3/98 to 9/98 where parts were switching over (like belt tensioners) and you were never quite sure what was on the car without going out and looking at it. My 4/98 was a mix - I think the AC belt system was post-update while the serpentine belt system was pre-update. Stuff like that - couldn't just use RealOEM, you had to verify. Fun!

I had an M52 and the single VANOS seal replacement was still well worth it IMO. I used one of the early Beisan kits while he was developing them. The double VANOS of the TU is probably even more worthwhile.

The driving indicator that I observed which told me the seals were due was that the car seemed extra good accelerating at part throttle when the oil was partially warmed up and coolant almost fully warmed up. Things were warm enough to move freely and run on operating temperature maps but the oil was still a little "extra thick" compared to when fully up to temp and it resulted in more pressure in the VANOS system, actuating it "properly". After doing the seals the engine always had this little but of extra performance at all temperatures.
The overhaul was pretty problem free especially considering this was my first time doing it. Two of the water pump nuts started immediately rounding off, but with a bit of heat and switching to a six-point socket I was able to get them off. I am glad I went with ordering replacement nuts / bolts! However, after ~ 40 miles I don't see any leaks other than the plastic radiator drain bolt has a very slow drip leak now. Pretty funny that a little ~$3 part is the last to be causing a problem. I have a replacement on order along with another gallon of BMW concentrate. I may try to save this jug for the future if I can be quick enough replacing the drain plug / catch anything that drains in a clean container to refill. Anyone just capture and refill when the coolant being drained is essentially brand new?

I believe it may have just been the seal that failed on the old water pump. It appeared pretty flattened at this point, but the bearing still felt to be in good shape. The metal impeller of the old pump (top in the picture) looks to be better quality than the new Hepu replacement. Looking through my service records it appears the thermostat / WP were last replaced in 2006 at 65k miles.

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Thanks for the suggestions on the Vanos rebuild! This is a single Vanos M52. The car still feels pretty lively, but I'll see if I can notice similar symptoms that I'm due for a rebuild. I'm glad to hear the Motive will work well for both vehicles! Brakes and fluid are next on the list.
You're probably already done the job, but the radiator drain does have a nipple that you can slip a hose onto to direct and capture the coolant. In any case, it doesn't flow that quickly, so either way, not much would be lost.

I've had experiences where attempted preventative replacement of the bleed screw and drain plug has resulted in the new ones seeping, so I end up reinstalling the old ones.

The drain plug has a tandem o-ring arrangement, and the bleed screw has a single o-ring. They're relatively simple, but for whatever reason, the stupid little parts can end up leaking, even if they're not junky aftermarket parts, or overtightened.
I've put off replacing the drain plug as I have noticed a little drop of coolant appearing on the bottom of the driver side of the radiator. I fear what I thought was the leaking drain plug could be some seeping from where the plastic end seals with the aluminum portion of the radiator. The drop strangely only seems to appear after the car cools down and it's so minor it's hard to track down exactly where it is coming from. I'm going to continue to drive it a bit to know for sure, but I think a radiator might be in my future as well.