Cooling System Mod/Upgrade?

[Z3MROADY]

I've seen a couple threads that warn of a cooling system issue with the Z3 and to search the manifesto for the mod. Is this the mod they are talking about?

http://forums.bimmerforums.com/forum...m-overhaul-kit.

There are quite a few DIYs in the cooling system group ranging from hose replacement to radiator upgrades so any help would be appreciated. When I do a search for this mod I only get one thread in the Z3 section for some reason - "S52 Cooling issues" and it doesnt really talk about a mod or upgrade.

I thought it might be a good winter project Thanks!

[Luftwaffe1O1]

I've seen a couple threads that warn of a cooling system issue with the Z3 and to search the manifesto for the mod. Is this the mod they are talking about?

http://forums.bimmerforums.com/forum...m-overhaul-kit.

There are quite a few DIYs in the cooling system group ranging from hose replacement to radiator upgrades so any help would be appreciated. When I do a search for this mod I only get one thread in the Z3 section for some reason - "S52 Cooling issues" and it doesnt really talk about a mod or upgrade.

I thought it might be a good winter project Thanks!

You wont get too much consensus on upgrades. My stock cooking system (warerpump/radiator/hoses etc) made it to 150k with no problem. I just replaced it all with new oem stuff.

Many many others were not so lucky. But stewart waterpump is supposed to be a good upgrade, and I suppose going to the s54 radiator is a decent upgrade as well

[Z3MROADY]

You wont get too much consensus on upgrades. My stock cooking system (warerpump/radiator/hoses etc) made it to 150k with no problem. I just replaced it all with new oem stuff. Many many others were not so lucky. But stewart waterpump is supposed to be a good upgrade, and I suppose going to the s54 radiator is a decent upgrade as well

I guess I'm looking for details on what happened to all those that were "not so lucky" in order to find a common issue among them. I dont really want to stray from stock unless there is a known issue with a particular item. Ive come across some threads complaining of the plastic fan and a fan delete mod. Id like to keep everything under the hood as original looking as possible but if there is a design or quality issue that needs to be addressed I'll upgrade to prevent damage.

[rickwinger]

When I had the cooling system work done in October I went with the Graf metal impeller water pump and a metal thermostat housing. And I read a bunch of stuff before arriving at that decision.

I'm laying in bed reading this on my ipad (about had it for this day) but tomorrow I'll find and post all of my collected cooling system threads for you.

[Tommm]

back about ten years ago R&T did a used car classic on the Z3. the weakness of the factory cooling system was pointed out by every expert. YMMV.

Metal rusts. rusty metal is a warning. plastic cracks from heat cycles. plastic doesn't give a visible warning.

the early waterpumps used a plastic impeller that disintegrated. the plastic impeller was replaced with a metal one. the bearings were not upgraded to handle the extra weight.

bmws are notorious for overheating. the s54 radiator fits in the same spot as the original but has additional cooling capacity.


putting in a better aftermarket cooling system increases the car's value, decreases the chance of a catastrophic failure, and doesn't look any different than a stock system when the top is down and the wind is in your hair. That's why I bought a roadster - the wind in my thinning hair. Is that why you bought yours, or did you buy yours to look at the engine compartment?

[rickwinger]

Okay. Here is my personal compilation of cooling system threads from three different forums. (If the powers that be kick me to the curb for reading in multiple places, it was nice knowing you all...)

bimmerforums

http://forums.bimmerforums.com/forum...S52-fan-delete

http://forums.bimmerforums.com/forum...oling-Overhaul

http://forums.bimmerforums.com/forum...m-overhaul-kit

http://forums.bimmerforums.com/forum...is-morning-and


Edited by moderator: Rick, we have a policy that forbid linking to competitive sites. Please see the Rules of the Road on the forum header. As such, I removed a number of your links. I know you meant well and you provided a very comprehensive post but I must moderate to those rules. So those links had to go. I hope you understand. Thanks, Terry

Now, regarding the Z3 cooling system, what I found in my reading is that the enthusiast' consensus is to replace/rebuild the cooling system around the 60,000 mile (96,560km) mark.

About the time I congealed that thought I looked and my new to me Z3 was at 89k miles. And, lacking an invoice or mechanics' work order to confirm it was changed earlier, I had to decide whether to take a chance or do the job for peace of mind. Since my wife also uses the vehicle and I consider her safety paramount, I decided to do the job for peace of mind.

So then my question became "Go with OEM or with aftermarket upgraded parts?"

Before I speak to that question, I want to digress to a conceptually related tangent that touches the core of your "OEM or upgrade" question.

I also ride motorcycles, and for a number of years I read and posted quite a bit at several different motorcycling forums, and for a time I served as a moderator at the GWRRA forums. The whining about all things mechanical was legendary -- keeping in mind it came from a very small percentage of Gold Wing owners. (For example, almost 300,000 Z3's were produced. I would venture the percentage of owners who post on all related internet venues is a very small representation, and that can skew the perception of the magnitude of any problem).

Anyway, I’m no longer active in GWRRA (got out of big bikes), but I do still own a Suzuki DR650 – which is considered by some to be the quintessential mid-sized adventure touring dual sport bike. So I still read and post occasionally at a forum called Adventure Rider.

Model specifics aside, there are two types of inmates at that asylum -- those who accept that two-wheeled mechanical conveyances are designed to be ridden, need periodic general and sometimes specific maintenance, occasionally fail or break down, and always cost money. This group accepts that R&D and factory engineers produce a bike within specific parameters to be ridden a certain way on specific terrain.

By comparison, there are those inmates (God lov’em) who think their bike is a family heirloom and stash on the mantle showpiece, that maintenance money is a rip off, mechanical failures should never happen, and that manufacturer engineers at any level are complete idiots.

The first group I simply call riders. They enjoy their bikes and accept that it costs time and money to own one. I have read dozens, if not hundreds, of ride reports where riders rode their bikes all over the world without a major problem. Regarding the Suzuki DR650, in July 2010 a partner and I rode the Continental Divide Trail on matching, mostly stock DR’s without a single mechanical mishap.

That second group of inmates, however, is a crowd I call Kool-Aid drinkers. The Kool-Aid drinkers would have one believe that a ride across town to bike night is a sure prescription for catastrophic mechanical failure. And amid the thumper owners they would have one believe the DR650 was released by Suzuki with a wretched engine, suspension, fueling system, and overall design. They would likewise cry foul if a Gore-Tex lined riding suit failed to keep a rider completely dry upon being thrown into a swimming pool. In short, nothing is perfect enough for them, and the levels to which their shared whining, fault-finding, and group neurosis will rise is unlimited.

Now, having said all that, when reading the cooling system threads I had to ask myself “is this sound mechanical advice or the BMW forums version of Kool-Aid and superstition?”

And back to my previous question, after deciding to do the chore my question became "Go with OEM or with aftermarket upgraded parts?" (I.e., is the "upgrade only or you will die on the roadside at rush hour" vein of thought the besotted result of internet forum Kool-Aid?)

There are some things I can and will do myself, but I also work 55-60 hours a week during certain seasons of the year. This is one of those seasons so I was faced with having the work done by shop.

And at that point I opted to trust the techs’ experienced judgment. He went with an upgraded water-pump (Graf), and a metal thermostat housing. The other parts were OEM or equivalent. And when he took the old water pump out he found it was a replacement and not the original…

At the bottom line it boils down to a judgment call. I erred in the direction of caution.

Finally, the fan failure issue seems to be most common among owners who red line their cars. So at that point driving style becomes a wild card. Which could invoke the opportunity for yet another tangent…

There's no charge for all this -- and good luck with whatever you decide!

Rick (I have the verbosity out of my system, thank you) in AL

[Z3MROADY]

bmws are notorious for overheating. the s54 radiator fits in the same spot as the original but has additional cooling capacity.

Great info everyone, Thanks!! Dumb Q: I saw a post about the "fan delete" (thanks rickwinger). So if they are prone to overheating why the fan delete mod? I can see changing out the fan if old ones tend to be brittle and crack but a delete? Curious.

[jaaa]

There are many issues here on the overheating. The basic one is the plastic parts that crack, leak water, and good bye engine. They include the radiator, expansion tank, and thermostat housing. The other issue is a bad water pump. It can, when it goes, take out the fan by unbalancing it and then you have fan blades piercing the hood/radiator(ever price a hood?). The fan delete is more a hood protector project than a cooling issue.

[rf900rkw]

First off, the cars are not prone to overheating. There is more than enough cooling capacity to deal with most any street situation. They get on just fine without the engine fan. Some say the cooling system is prone to early failure. I don't agree with this, but we'll save that for a bit. This is different from overheating, a failure causing an overheat rather than an overheat causing a failure. If the cooling system was to fail, hose burst and dump the coolant, waterpump up and dies, etc., and the coolant is no longer flowing into and out of the radiator, having a fan blowing on said radiator will do no good.
One of the alleged failure points of the cooling system is the fan itself exploding, sending blade fragments through hoses and radiators and the hood. Many theories are put forth onto why this happens, and in truth there are probably many different root causes. But the outcome is always the same. You can either constantly replace the fan, clutch, engine mounts. Or you can pull the fan and chuck it. I can tell you from experience they make very poor frisbees. I have an E36, E46, two Z3s and a E39 in the driveway, all fanless.

On the experts and the high cooling system failure rates. Of course the experts know this is true; they read it right here in these forums. I see a parallel with BMW cooling systems and Lucas electricals of the 1960s. The Lucas stuff was shit, right? Everyone knows that. And everyone knows that with absolutely no first hand experience, but it must be true because everyone else says it is. I can tell you from decades in the business that there is little basis to this. Indeed, a large number of the failures seen were self-inflicted by well-meaning owners trying to protect themselves from this mythical prince-o-dark.

I see the same thing with BMW cooling systems. To start with, saying BMW cooling system is a misnomer. The M44, M/S52, M54/52tu and S54 each have a very different system, each with it's own unique strengths and weaknesses, bleeding procedures, and such. But one thing that applies to all and is almost universally misunderstood, is the system pressure. People look at the expansion tank cap, be it 1.4 or 2.0 bar, and assume that *IS* the system pressure. Nope. That cap is not a regulating device, it is just an emergency safety release valve. Think of your air compressor out in the garage. It runs at what, 125psi. Somewhere on that tank there will be a safety valve that trips at, say, 175psi. That doesn't mean the system runs at 175psi. Changing that safety valve to a lower value will not "protect" the compressor. And if you change it to below the regulated 125psi, you'll have a mess.
Same thing for the expansion tank cap. It is merely a last line of defence safety valve. Changing it down to a lower value does nothing, until you go too low. So what sets the pressure in the BMW system.... this took me a bit to get comfortable with... is the design of the system itself. The air volume in the expansion tank is the buffer that sets the pressure. The less air volume, the higher the system pressure.

Thus, it is my firm belief, the most damaging thing you can do to a BMW system is too overfill the cooling system. And since the world knows the systems are "crap", people want to make sure it's full.... give it some extra just to be sure. And the pressures go way up. And the system fails prematurely. And the forumlore is proven...

The best preventative cooling maintenance, on a weekly basis, is to make sure the coolant level is on the minimum line.

[Blacklane]

Wow, what great and insightful posts. I would also like to add that there are several YouTube videos on BMW cooling system failures that show some of the failures such as a broken water pump impeller, split coolant reservoir, etc. so you understand how they fail.
I do think it's important to replace all of the plastic cooling system parts as preventative maintenance rather than waiting for a catastrophic failure. After that, it's sort of a personal choice where and when to use upgraded or stick with original parts. I usually consider both, then decide which is the best value for my use, factoring in the labor cost as well.

[BMWBergy]

I apologize if this is a repeat, but I didn't read through everything above... all too verbose.

Fan delete is a preference issue. Some opt to REPLACE the mechanical belt-driven fan with an electric unit like SPAL.

I don't disagree with Randy that your stock system is just fine in terms of capability and capacity. I will say that, like all systems, it needs maintenance - and at your mileage and age, it's time. My recommendations are simple:
Stewart water pump
BMW thermostat
BMW thermostat housing
BMW radiator hoses
Behr (OEM) S54 radiator (Pelican Parts sells for under $200)

If you want to be 100% safe (or paranoid), replace your coolant reservoir as well.

To go full-bore, visit zionsvilleautosport.com

[Z3MROADY]

Thanks all. That answers my questions. I'll read through all the comments and links closely and plan my maintenance. Appreciate it.

[rickwinger]

FWIW, for a while the more I read the more I worried, Of late the more I read the better I feel.

Life is filled with paradoxes...

[Z3MROADY]

[QUOTE="Is that why you bought yours, or did you buy yours to look at the engine compartment? [/QUOTE]

Both.
and so far so good!

[Luftwaffe1O1]

I think there is definitely some truth to yh3 cooling system woes, I have never experienced them. My e36 m3 made it to about 74k miles without any issues (except it lost a fight with a mountainside).

I had an e30 whose cooling system made it quite a ways. Amd my m52tu made it to 150kish or so.

It has become sort of the thing to say that you must replace tour cooling system every 60k miles, this seems a bit ridiculous to me. I would say there are many factors not just mileage to take into account.

Type of driving, age of vehicle, and mileage should all be looked at. The only vehicle I saw personally have their water pump go boom, was my gfs e90 325i. It failed at about 80k miles.

I think if the car is more than 10 years old and you are unsure if it needs a refresh it is a good idea. On top of that, after 60k miles just keep an eye on the hoses etc. If they are brittle and ready to go, you will see it, or help it along by touching it. I just notice a trend of a lot of people throwing parts at unnecessary intervals at their cars. But thing is, a lot of the aftermarket parts are good in theory, but there is not enough data on how long they last outside of anecdotal evidence.

I can guarantee there are a lot more oem setups out there, and as a result a lot more failures to be reported.

So take evrything you hear with an open mind and draw some conclusions yourself. I went with oem parts merely because my cooling system made it for a long time, and was of the mindset if it worked that well for me, why go with something else. Others were obviously not as lucky.

[Z3MROADY]

The favored upgrade waterpump appears to be the Emp Stewart with all metal impeller but it is very pricey. Who has enough miles on the other metal impeller models by Graf, Bosch, and Meyle to be able to say they are dependable and a good value? Any others? They are less than half the price of the Stewart. I'm not opposed to spending $200 or so on the Stewart but if there are great reviews for a less costly one I'll consider it.