1998 BMW Coolant Change Recommendations

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To give some context...

I realized this year that I cannot recall exactly when the coolant was changed last on my '98 BMW 328is. This spring it would occasionally start to overheat and I figured out the issue was down to the system being a bit low on coolant. At the time I added approx. 30-40oz (didn't seem like much) of some filtered tap water, bled the system, and it has been running great since.

I would like to get the old coolant / bit of tap water out of there before it is stored in an un-heated garage during the upcoming Michigan winter. The coolant visually appears fine and is a greenish-amber color. The car has always been serviced by the dealer, myself, or an indie shop that specializes in BMWs so even if it isn't the OE blue coolant I am assuming it was something that met similar specs.

Other than being a bit low earlier I haven't experienced any coolant-related issues.

My plan is to....

just drain the radiator, refill, and bleed the system. I figured this might be the safest bet to not "shock" the system and a full flush might not be necessary since I'm not trying to "fix" anything. Next spring I would do a greater overhaul replacing the expansion tank and coolant hoses and then refill with more fresh coolant.

Am I wrong in this approach? What coolant would be best, especially since it will have to mix with whatever doesn't drain out of the block / heater core? I am leaning towards the BMW blue stuff, but it looks like Zerex G-05 is recommended on some forums for BMWs. I would be open to the Zerex and any other aftermarket options if there's a compelling reason to use it instead (like it might play nicer with mixing).
 
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I have a 98 328i also. I just run Prestone and distilled water. Recommend by my BMW mechanic. Been running it since a top end rebuild around 50k miles ago. Coolant has been the least of my problems. Usually things in the cooling system break before the coolant is in there too long.
 
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I also recommend sticking with the OEM BMW coolant or any of the applicable products sold at the local auto parts stores marketed specifically for that application. As mentioned, it's sold as European "blue" coolant, VW G-11, BMW OEM, or Glysantin G-48. My local BMW dealer charges $22 for a gallon of concentrate and what you get at most auto parts stores are pre-mixed at 50/50 so it's actually a bit cheaper to just get it at the dealership. I think full price is $26 a gallon at the BMW dealership so even at that price it's cheaper than Autozone. Add a gallon of distilled water from the grocery store for $.89 and you have two gallons of "ready to use" coolant.

BMW suggests a replacement interval of every four years.
 
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To me, anything that's worth doing, I try to do properly. I'm not talking but an elaborate OCD multi-step flush, but I'd at least drain the block as well.

The cooling system holds ~11 quarts. Draining just the radiator is going to leave a large proportion of the old, unknown coolant in the system, and reduce the effectiveness of new coolant added to it. Radiators, expansion tanks, water pumps, and thermostats may be easy to reach and replace. 23-year old heater cores are not, so I try to treat them as nicely as possible.

The block drain is at the rear, adjacent to the O2 sensor, which partially obscures it, but is otherwise not that hard to reach, as long as the front end is lifted. But it does have a crush washer, and a raincoat is advised. Set the heater controls of full hot to open those valves.

NAPA carries G48 full concentrate. It's on special this month. Some stores also choose to carry the OE branded jugs of BMW and MB coolant. G-05 is a very similar HOAT coolant, and more widely available, so some use it as an alternative.

It's easy, and tempting to choose the easier path. I've been there. But it's a slippery slope, and one that German cars don't tolerate well, and the consequences may manifest themselves in an unpleasant and expensive fashion later on.
 
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I also recommend sticking with the OEM BMW coolant or any of the applicable products sold at the local auto parts stores marketed specifically for that application. As mentioned, it's sold as European "blue" coolant, VW G-11, BMW OEM, or Glysantin G-48. My local BMW dealer charges $22 for a gallon of concentrate and what you get at most auto parts stores are pre-mixed at 50/50 so it's actually a bit cheaper to just get it at the dealership. I think full price is $26 a gallon at the BMW dealership so even at that price it's cheaper than Autozone. Add a gallon of distilled water from the grocery store for $.89 and you have two gallons of "ready to use" coolant.

BMW suggests a replacement interval of every four years.
+1

I use the BMW coolant in my E90 and other BMWs I service. It's actually cheaper to buy the concentrated BMW coolant and then some distilled water than whatever they are selling at Autozone that might be compatible. I think the last time I bought BMW coolant I got it from Amazon, or from a dealer selling it on ebay. It was cheaper than buying the coolant for my Wrangler.
 

cutlassvillager

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Thanks everyone! I'll plan to go with the BMW stuff and will take a look at the access to the block drain and probably end up draining that too. Any idea on the size of the crush washer?
 

cutlassvillager

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Thanks for the real OEM post! I used that crush washer part number at the dealer when picking up the coolant. The process of draining the block was very messy, but easier than I had anticipated so I appreciate the suggestions to just do it right. I think (but am not certain) a VERY small leaf might have fallen in the coolant while refilling (thanks to the fall weather), but it was so very small I'm hoping that's negligible. The old coolant was a dark-ish amber, so I feel better getting that unknown combo out of there!
 
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Re: messy block drain...

On my 1998 528i (M52 engine) I recall that the block drain dumped coolant all over the suspension and subframe and it could run everywhere. I had a system where I had a short piece of clear tubing 1" or 1.5" diameter. I would route it around the suspension, into a bucket and near the block drain. From above I had the tubing held in my pinky and turned out the drain bolt the last couple of threads with my thumb and forefinger. As soon as it let go I shoved the tubing against the block. The bolt and all the coolant went down the tube into the bucket with nearly no mess. For whatever reason I was just thinking of this yesterday...
 
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Yeah, draining the block is a mess, but it's just one of those things you learn to deal with. Haven't felt enough desire to concoct a more elegant solution, other than loosening the plug and holding it against the opening to allow it to stream out in a somewhat controlled manner (but still stream down your arm), rather than having it gush out and douse everything, including you (hence the "raincost" mention above).

At least spalshed coolant is a lot more benign than oil, which leaves a real mess.
 

cutlassvillager

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Unfortunately, the success was short lived. I've put a few hundred miles on the car since the coolant change and I have just now acquired a small coolant leak. I haven't taken everything apart yet to take a closer look, but I believe it is coming from the water pump. That's not too bad since I was planning to do a significant overhaul of the cooling system anyway (just wasn't planning it quite this soon).

I am leaning towards this kit from FCP Euro.

Does anyone have experience with this kit? My initial plan was to just replace the expansion tank (I see some cracks in it), upper / lower radiator hoses, thermostat and water pump. I'm wondering how necessary all the other items like the temp sensor, thermostat housing, heater hose, etc.

I am also considering this clutch fan delete option otherwise I'd just replace the fan clutch to be on the safe side.
 
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A couple of random notes.... I had an E39 '98 528i (M52) for many years and DIYed everything on it. I expect more similarities than differences for our vehicles.

1/ The thermostat housing is prone to leaking because of the three bolt design. Back in the day there were aluminum aftermarket designs but they often came with unintended consequences or had crappy seals and leaked for different reasons. The OE plastic part was only $13 and pretty easy to change with the main fan out of the way. I just went with the OE part. I think I changed it twice between 1998 and 2012.

2/ BMWs of the era are known for cooling system issues due to the plastic. HOWEVER. There were several different engines in the era and they ran at very different temperatures. M52 93C, M52TU 98C, M62 108C. There was a lot of similarity in the plastic system design but a huge difference in temperature and pressure (most notably). M52 cooling systems did not explode like M62s, and M52s are a little more tolerant to overheating than M54s, but don't bank on that. I did replace my expansion tank as a precaution, but I believe I had my original factory radiator when it was hit in 2012.

3/ DIY instructions for a pump change like to show all kinds of "short cuts" to not remove parts. When I did a pump & stat change I pulled the whole radiator (like TIS says to do) and it was a little more hassle but a joy to work on. Lots of room to work, no scraped knuckles, no cramped quarters, and I could clean and inspect everything.

4/ There was debate about pump design. I ensured to get an all metal water pump with no plastic parts in the impeller and was quite happy. It was changed preemptively, neither original or replacement ever failed or leaked.

5/ It might be unpopular but I LOVED the dual electric aux pusher fan combined with clutch main fan. Aux fan as backup and for cold AC, and you can't beat the volume of air moved by the clutch fan when it is required. The catch is that the proper clutch part was ended for the M52. I did have to replace the clutch because it got noisy like a bad steering pump. They revised all the different part numbers into a single part# for all of the engines. Unfortunately the "cool running" M52 never made enough heat to ever engage the main fan again after that (the air coming through the radiator heats a bimetal strip on the front of the clutch itself causing it to engage - it is not operated by "coolant temp" per se but that is an influencer). For those who might be thinking the new clutch was just defective, I thought that too so I spun it on my dad's E39 540i (M62TU) and it operated as normal on that engine.

Perhaps there have been developments here I haven't been following, but I missed the proper fan clutch operation after I had to replace it. (e.g. if you came to a stop in warm weather with the AC off (no electric fan) when you pulled away the main fan would be engaged for ~5 seconds). If I still had it and it was working I would not modify it out of the equation. Not sure if the E36 had an electric fan at all. The E39 had both.
 
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Unfortunately, the success was short lived. I've put a few hundred miles on the car since the coolant change and I have just now acquired a small coolant leak. I haven't taken everything apart yet to take a closer look, but I believe it is coming from the water pump. That's not too bad since I was planning to do a significant overhaul of the cooling system anyway (just wasn't planning it quite this soon).

I am leaning towards this kit from FCP Euro.

Does anyone have experience with this kit? My initial plan was to just replace the expansion tank (I see some cracks in it), upper / lower radiator hoses, thermostat and water pump. I'm wondering how necessary all the other items like the temp sensor, thermostat housing, heater hose, etc.

I am also considering this clutch fan delete option otherwise I'd just replace the fan clutch to be on the safe side.

Forget the FCPEuro kit as some parts are made by Rein. Rein doesn't have the best reputation for quality. My suggestion is to find the part #s in www.realoem.com. Enter the last 7 characters of your car's VIN. Hit enter and bookmaker the page. Part #s are in engine and radiator sections Then go to FCPEuro to buy cooling system parts that are labeled "OE." "OE" means the part is identical to the part that has the BMW logo. Plan of replacing everything at one time as this is far better and easier than piecemealing it. There are techs on both sides of the clutch fan delete question. I don't know how hard it would be to convert your car to an electric fan but it can be done. However, electric fans seem to be made in China, and their quality is suspect. Me? I'd stick with the fan clutch as long as the part is labeled as "OE."

The installation of aftermarket cooling system parts is strictly verboten.
 
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The Rein line belongs to CRP. While i wouldn't choose their suspension parts over something like Lemforder, the simpler stuff like cooling parts is fine, and I wouldn't lump them into the same class as URO or Meyle.

You'd probably end up with CRP hoses anyway, and the radiator cap I got was made by the original OEM (Reutter). Take a close look at the picture of the "Behr" cap in the kit, and you'll notice that it, too, has the true OEM's name ground off, so while they may produce the radiators, they don't produce the cap. The South African-made Behr replacement radiator I have didn't impress me in terms of quality anyway, so even a trusted name is no guarantee.

Wahler (owned by BW) is the OEM for the thermostats of those engines. You can compare the design and construction of the two and see which is preferable to you, but I wouldn't have any issues with trying the Behr. I've had my issues with Walher units as well (the strut on my last one fractured, leaving it stuck partially open), so it my actually be a better unit.

The clamps appear to be Norma/Gemi, which are good quality.

Things like the thermostat housing and water pump will vary in quality and experience.

Unfortunately, it's a choice between an aftermarket part that may be of a seemingly more preferred material, but suffer in terms of design and quality.

The straight six engine water pumps gained notoriety for impeller failures (losing grip on the shaft), so BMW went to metal impellers, but then later switched back to composite. There's noting inherently wrong with composite, and the material won't matter if the execution sucks.

Look at the of the pumps on the market and the crude design and construction of the metal impellers on some of them aren't something I'd trust.

Those, along with the "fan delete" (vroom!) are loaded questions that you can look further into yourself, and come to a decision.

However, it should be noted that extracting the old pump can be a problematic experience. But good fortune can come as a result of a well-maintained engine that has had regular coolant changes, so the pump isn't corroded in place, as well as working slowly and methodically to remove the old pump. Be judicious in torquing the bolts in small, and even increments on each side Blindly cranking on the bolts, without regard to applying pressure to both sides evenly, may result in it end up being cocked in the bore, and the breaking the ears off the old pump. That then calls for more extreme measures and hassle.

Personally, I prefer being able to chose all of the components individually, so pre-assembled kits don't have any appeal to me.
 
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I used an OEM composite water pump, Behr tank (not recommended, get OEM from dealer), aluminum thermostat housing, aluminum WP pulley, and BMW OE fan clutch. I also got the late E30 coolant tank cap. Lower psi, not sure it matters but I feel better. My mechanical fan/clutch works fine, you can hear it when hot or after parked. Not sure how recent the update was to the part. It’s maybe 8 years old?
 
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I replaced the entire cooling system in my M52TU when it was about 10 years old due to it being a common failure point. I was able to get BMW components at a reasonable discount. The radiator was Behr and the pump had a metal impeller (not plastic). I also replaced the fan blade & thermostatic clutch after hearing a horror story about a failed clutch that kept the blade engaged at high rpm and the blade disintegrating violently with blades puncturing the hood.

Only advice I'll add is regarding the expansion tank - when filling or checking the level, remember the top of the bobber rod should be no higher that the lip of the tank (not sticking all the way extended up).
 

cutlassvillager

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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.
 
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