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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #51  
Old 06-01-2010, 11:36 AM
justin182 justin182 is offline
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Hi Chief,

I'm a little late to the party, but thanks for the great info! I'll definitely be looking into this for my '03 540. I've only got about 53,000 miles so I'm probably due for an overhaul in the not-to-distant future. The idea of reducing the pressure in the cooling system seems very intelligent to me.

If I understand the physics, the operating temperature of the NPG coolant is not substantially different from the oem coolant, it just has a much higher boiling point. Since the liquid never gets hot enough to boil, the pressure stays relatively constant, close to zero.

I have read that many cooling system failures, at least in our V8s, are from radiator necks and expansion tanks cracking/breaking. It seems to be the consensus that this is likely due to repeated heat cycling of the plastic and less to the pressure in the system. If the NPG coolant operating temperature is not substantially less than the oem coolant, then I'm not sure this would reduce those failures.

That being said, I'm still all-in on reducing the pressure in the system. This seems a very logical way to reduce stress on all the system components.

Anyone else have thoughts?
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  #52  
Old 06-01-2010, 12:34 PM
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chiefwej chiefwej is offline
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Quote:
Originally Posted by justin182 View Post
Hi Chief,

I'm a little late to the party, but thanks for the great info! I'll definitely be looking into this for my '03 540. I've only got about 53,000 miles so I'm probably due for an overhaul in the not-to-distant future. The idea of reducing the pressure in the cooling system seems very intelligent to me.

If I understand the physics, the operating temperature of the NPG coolant is not substantially different from the oem coolant, it just has a much higher boiling point. Since the liquid never gets hot enough to boil, the pressure stays relatively constant, close to zero.

I have read that many cooling system failures, at least in our V8s, are from radiator necks and expansion tanks cracking/breaking. It seems to be the consensus that this is likely due to repeated heat cycling of the plastic and less to the pressure in the system. If the NPG coolant operating temperature is not substantially less than the oem coolant, then I'm not sure this would reduce those failures.

That being said, I'm still all-in on reducing the pressure in the system. This seems a very logical way to reduce stress on all the system components.

Anyone else have thoughts?
While I would agree that heat cycles weaken the plastic components, it is the pressure that causes it to finally crack. We will see. Since I am planning to keep my 540 for a long time, i will see how long before any cooling system issues crop up.
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  #53  
Old 06-01-2010, 12:44 PM
CrushersBMW CrushersBMW is offline
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I definitely am interested in this - and I'll keep watching to see if there are any problems.

I'm not convinced that the pressure in the system is causing the failures or the repeated heat-cycling. I'm also wondering if there is a flaw in the cooling system design as my '87 Mercury V-8 and '96 Ford V-8 had a zero pressure expansion tank and the pressure regulator in the radiator cap - and they both went over 150,000 miles - on the stock expansion tank and radiator (but it was metal ) I'll have to look over schematics on the E-39 and figure out how the systems are different....

I also continue to wonder what the auto design engineers were thinking when they came up with plastic high-temp components....... Weight savings and production savings maybe, but certainly not reliability.....

I figure I have to do one re-build of the cooling system as the current one is past 60K - and I'm keeping an eye on it........ But, if i Evans saves me doing another one, I'm all for the Evans NPG+

Keep us posted!
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  #54  
Old 06-01-2010, 03:31 PM
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chiefwej chiefwej is offline
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I'll bet your '87 Merc didnt have a 2 bar (>29 psi) pressure cap. Thirty pounds per square inch is fine for tires, but when cooling systems are under that kind of pressure, we see the results. Most cars run maximum pressures in the 14 - 18 psi range. I'll see what the below 5 psi range does.
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  #55  
Old 06-01-2010, 04:04 PM
haolibird haolibird is online now
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Chief,

I have had Evans in my car over 6 months now, and all is well.

It's gratifiying to see your post, as it justifies, somewhat, what I already knew.

Now, if you can steer this into an oil post, were MY oil is agreed upon as being the best, it will make my YEAR.

Thanks,

Tom
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  #56  
Old 06-01-2010, 04:48 PM
CrushersBMW CrushersBMW is offline
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Originally Posted by chiefwej View Post
I'll bet your '87 Merc didnt have a 2 bar (>29 psi) pressure cap. Thirty pounds per square inch is fine for tires, but when cooling systems are under that kind of pressure, we see the results. Most cars run maximum pressures in the 14 - 18 psi range. I'll see what the below 5 psi range does.
I'm reasonably sure it didn't run such high pressures. But, the design was such that if the pressure exceeded 15psi or so, it allowed the fluid in the radiator to vent to a zero psi expansion tank. When the system cooled, it would siphon the vented fluid back in to the radiator. The radiator was at pressure, but the expansion tank wasn't.

Perhaps I'm wrong, but it seems like the expansion tanks come apart because they are pressurized - which is a different design. Or, maybe the expansion tank explosion happens because the cap is blocked and allows the tank to retain pressure for which it wasn't designed - in which case it's the cap's fault, not the tank.

The radiator cracking is most likely a result of the thermal cycling and the pressure - which is higher than "standard" cars. Additionally, that higher pressure allows the fluid to remain liquid longer. I'm not sure what the boiling point of water is at 2 atmg, but it's considerably higher than 212F. That pressure is required to get the higher boiling point for higher operational temps - which only makes the thermal situation worse.

Like I said, keep us informed. I don't see a downside to the addition of NPG+. And if the addition keeps me from replacing a cooling system after the next replacement, I'm all for it.
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  #57  
Old 06-01-2010, 05:18 PM
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Very interesting thread and informative posts, Chief. For those of us who have had cooling system issues (this means you) it is especially interesting to hear this solution.

But, the cooling system is much more than just the radiator and expansion tank. Yes, the cheapo hoses/expansion tank/connectors fail, most likely due to pressure. But many of us get leaks in the water pump (or the pump just goes bad), the thermostat and/or housing, and related hoses. I don't think reducing system pressure will prolong the life of these components, so really you're maybe saving a few hundred bucks for the rad and exp tank. It would be interesting to hear what an experienced BMW indy thinks about NPG.

Personally, I would be really nervous with a cooling system that is allergic to water. Operating the car in a desert under the assumption that if the system starts to overheat you can repair it with duct tape seems risky to me. I suppose as long as you have spare NPG in the trunk you're ok, but one thing about water (and antifreeze) is that it's readily available. And god forbid some idiot tech puts water in there. Are there big warning stickers on the radiator neck?

Just MHO of course.
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  #58  
Old 06-01-2010, 07:02 PM
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Per there website info:


Unexpected loss of coolant: In the event of a highway emergency resulting in a coolant loss, NEVER ADD WATER EXCEPT AS A LAST RESORT. Evans NPG+ and Evans NPGR waterless coolants are compatible with Evans HDTC and may be used to replace modest percentages of HDTC. If water is the only fluid available, use it to get home with and as soon as possible (preferably within 2 weeks) re-install Evans HDTC. Water left in the system will cause cylinder liner cavitation and other problems.
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  #59  
Old 06-01-2010, 09:49 PM
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Water left in the system will cause cylinder liner cavitation and other problems.
Do I read that correctly? Water will cause the cylinder sleeves to collapse?

Speaking of physics ... it would be interesting for someone to explain the sequence of events that cause that!
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  #60  
Old 06-02-2010, 08:00 AM
justin182 justin182 is offline
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Do I read that correctly? Water will cause the cylinder sleeves to collapse?
No. Cavitation refers to the formation of empty space within a substance, bubbles in this case. If water is in the system with NPG, the combination of normal operating temperature and lower than oem pressure will cause the water to boil. The resulting bubbles pop with surprisingly high force and damage the wet side (coolant side) walls of the cylinder liners.
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  #61  
Old 06-02-2010, 09:40 AM
wyowolf wyowolf is online now
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I meant to say that if you use this stuff and breakdown its ok to add water or coolant to get home by. some of the previous posters were worried about a breakdown...

am seriously considering this stuff... one less thing to worry about breaking...
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  #62  
Old 06-02-2010, 11:56 AM
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Originally Posted by justin182 View Post
No. Cavitation refers to the formation of empty space within a substance, bubbles in this case. If water is in the system with NPG, the combination of normal operating temperature and lower than oem pressure will cause the water to boil. The resulting bubbles pop with surprisingly high force and damage the wet side (coolant side) walls of the cylinder liners.
Wow, I'm impressed, cavitation explained clearly in two short sentences.
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  #63  
Old 06-02-2010, 12:22 PM
justin182 justin182 is offline
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Wow, I'm impressed, cavitation explained clearly in two short sentences.
I do what I can to please the people!
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  #64  
Old 06-08-2010, 07:21 PM
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Well, I did a 1,000 mile road trip with the local BMWCCA chapter. We went up to Canyon de Chelly in northern AZ. Full AC on at desert high temps, and climbing through the mountains. No problems, in fact several times after running hard, just to see, I popped open the radiator cap. Never more than that same little psst, about like opening a beer can. There couldn't have ever been more than 2 or 3 psi in the system.

So far, the Evans NPG+ works exactly as advertised. I am very pleased. I will continue the long term observations.
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  #65  
Old 06-08-2010, 07:34 PM
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Sweet, good to hear it Chief.
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  #66  
Old 06-09-2010, 09:19 AM
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good move and thanks for posting ur results--i think im going to do the changeover--my 540i just turned 140,000 rhis week and im scared of my cooling system failing--where can u buy the evans coolant?
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  #67  
Old 06-09-2010, 12:25 PM
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Great thread Chief. FYI how bout just keeping an extra gallon jug or so in the trunk in case of a breakdown in BFE? It would suck to have to add some water to limp home then completely drain the system then spend more $$ to put all Evans NPG back in. Anywho great stuff and very informative. Chief how many miles do you have on the beast and how many overhauls have you done?

And to the poor sap that is getting shanked on the Zionsville can you highlight why they have denied your request for a new or rebuilt rad? I found this on their site just now. If I paid $600+ for a rad I would damn sure follow their guidelines closely. Goodluck!

"Lifetime Warranty!
Zionsville Autosport guarantees our radiators for life to the original purchaser. Purchaser must provide proof of BMW coolant use at first installation and once every two years thereafter. "
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  #68  
Old 06-09-2010, 08:51 PM
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chiefwej chiefwej is offline
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Great thread Chief. FYI how bout just keeping an extra gallon jug or so in the trunk in case of a breakdown in BFE? It would suck to have to add some water to limp home then completely drain the system then spend more $$ to put all Evans NPG back in. Anywho great stuff and very informative. Chief how many miles do you have on the beast and how many overhauls have you done?

And to the poor sap that is getting shanked on the Zionsville can you highlight why they have denied your request for a new or rebuilt rad? I found this on their site just now. If I paid $600+ for a rad I would damn sure follow their guidelines closely. Goodluck!

"Lifetime Warranty!
Zionsville Autosport guarantees our radiators for life to the original purchaser. Purchaser must provide proof of BMW coolant use at first installation and once every two years thereafter. "
If you read my first post, you would note that I ordered a case (4 gal) of NPG+. Since the cooling system only holds 12 liters (2 3/4 gal), I have an extra gallon+ for my trunk.

I have only done one cooling system overhaul (at 50k miles), and am trying to avoid ever doing a second. The car was just short of 62k when I put the NPG+ in.
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  #69  
Old 06-09-2010, 09:06 PM
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Originally Posted by chiefwej View Post
If you read my first post, you would note that I ordered a case (4 gal) of NPG+. Since the cooling system only holds 12 liters (2 3/4 gal), I have an extra gallon+ for my trunk.

I have only done one cooling system overhaul (at 50k miles), and am trying to avoid ever doing a second. The car was just short of 62k when I put the NPG+ in.
I did read your post and I didn't realize you kept the leftovers in your trunk. However I was referring to others who mentioned it could be an issue in a pinch. Easy enough fix obviously. And damn cooling overhaul at 50k. I assume that was preventative. Anywho, great thread all the same and will be interesting to see if anything else develops.
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  #70  
Old 06-09-2010, 11:08 PM
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Nope, not preventive. My radiator cracked at 50k, so I did the radiator, expansion tank, fan clutch, thermostat, idler pulleys, etc. In fact, I did the radiator twice. The first one they sent me was bad. I just don't want to do it again, hence the NPG+.
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  #71  
Old 06-10-2010, 06:51 AM
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Wow that has to be some sort of record for a rad failure at just 50k. Unbelievable! My little 525i made it to 120 before I did a complete overhaul as a precaution. Can't blame anyone for wanting to avoid doing that more than once. Did you go all stock with replacement parts?
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  #72  
Old 06-10-2010, 07:04 AM
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My cooling system was leaking around 55k at t-stat. No explosion TG but I'm sure it wouldn't have been long.
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  #73  
Old 06-10-2010, 07:12 AM
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Quote:
Originally Posted by chiefwej View Post
Well, I decided that if I run a zero pressure cooling system, I may not have to do that next cooling system overhaul. No pressure, no exploding radiator.

So I ordered a case of Evans NPG+ waterless coolant. Not cheap at about $120, but if it saves an overhaul............... The case was 4 gallons. It took 12 liters (or about 2 3/4 gallons) to fill the system. That leaves over a gallon for top-ups, since you can't add water or any other kind of coolant with Evans.

I fully drained the system, radiator, lower hose, block drains, and ran the heater pump to get it out of there. I must have got it all because Bentley says it holds 12 liters and that is exactly what I got in it. So everything must have been out and there can't be any air trapped in there. After the NPG+ fill I changed the 2 bar cap for a 1.4 bar one.

With a boiling point of 375 degrees there should never be any pressure in the system now.
Tempting but put a glass of it the freezer, too thick in morning? Hard on pump?
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  #74  
Old 06-10-2010, 01:07 PM
Dworkin Dworkin is offline
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Very interesting thread! Please be careful taking the radiator cap off when hot. Tho it doesn't appear to be pressurized, I'd hate for you to get a bad burn.
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  #75  
Old 06-10-2010, 02:32 PM
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Sorry, see below.
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Last edited by chiefwej; 06-10-2010 at 02:40 PM.
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