Coolant system issues - advice please

[bobbyp]

I've been fighting a nagging issue with "low coolant" warnings over the past year. I narrowed down the problem to the area around the radiator neck. I've searched pretty extensively regarding the radiator neck failures on E36. So, I took off the upper radiator hose from the neck and did some inspection. Neck looks perfect. No cracks - looks almost brand new (don't know when the radiator was replaced last). Over the past week I've tried different things to eliminate the leak - which drips down from the neck near the hose connection. I've tightened the clamp, repositioned the hose and clamp slightly trying hard not to overtighten. But, it still leaks after it sits for a while (after running). Probably leaks under pressure, too, but I can't tell.

I did notice that the upper hose was much larger at the ends than in the middle and shows a little abrasion damage but it is not cracked. Just isn't 'stiff'. Since the radiator neck looks to be in very good condition I was going to just replace the upper hose to see if the leak stops - sounds like a cheap first step.

So, given the symptoms above and the condition of the parts as I described (neck and hose) do you think that the hose is the problem? I guess I'll find out soon enough but I was looking for comments from anyone who had leaks of this nature in their car.

[art@rmeuropean]

The crack might be so small that you don't see it.

[Theodore]

The sensors spaz out. Might try replacing it. Have you actually checked the coolant level? The hoses are supposed to be larger at the ends...

[TLK]

You don't mention about if you are actually losing coolant.

The sensors can be a problem, and some folks (me included) have cars that permanently complain even though there is no problem depite having replaced practically everything. The ultimate solution in that case (on a '93 325i) was to unplug and jumper the sensor to shut up the check control.

[bobbyp]

Yea, I'm losing coolant. It is in a puddle under the car when I park and the expansion tank goes empty after a week or so. Also, I see coolant down the side of the radiator. It may be a hose or a tiny crack in the neck that I can't see. I looked at the neck closely from all angles but I'm sure I could easily miss it if it is small. I'll find out next week when I replace the hose. Thanks for the replies.

[Theodore]

Replace the radiator ASAP. They are time bombs and it will need to be replaced anyway.

[bobbyp]

Probably will end up doing that, T. I don't want to replace a perfectly good radiator if it's just the hose, though. I also don't know when/if it was replaced by previous owner (which does concern me) but it appears to be in good condition. If I stop the leak with a new hose do you still recommend a replacement?

[Theodore]

Absolutely. I replaced my whole cooling system a few months ago. If you are bored and wanna search there are tons of threads with radiators dying on people. They can seem fine, and then just crack and drop all your coolant at any time... I've heard that ~60,000 miles is what they're good for. You can get the factory replacements for a not so bad price, or spend a ton and get a fluidyne like me :((great looking peice though)

[art@rmeuropean]

You can look on the passenger side of the radiator, there should be a sticker on the side with the date on it.

[IronButt II]

Absolutely. I replaced my whole cooling system a few months ago. If you are bored and wanna search there are tons of threads with radiators dying on people. They can seem fine, and then just crack and drop all your coolant at any time... I've heard that ~60,000 miles is what they're good for. You can get the factory replacements for a not so bad price, or spend a ton and get a fluidyne like me :((great looking peice though)

+1

When that radiator decides it's time to go... It'll be time for you to stop, whether you want to or not. For about $300... you can replace the rad, hoses, expansion tank, and sensor. Cheap insurance when you consider the alternative. If you've ever watched your baby being loaded onto a wrecker... you'll know what I'm talking about. :(

[CRYPTiC]

I had this problem for a while. My radiator was seeping coolant out of the upper neck ... then the hose finally cracked. I replaced the hose, but coolant was still seeping and you could see a trail of dried coolant slowly form on the side of the radiator. Pelican Parts sent me a 10% discount code, so I finally decided to just get a new radiator. Haven't had a problem in the few months since.

FWIW, at the time that I did the radiator, I also replaced all of the coolant hoses in the engine bay. The hoses connecting to the heater valve were slowly seeping, too. :(

[bobbyp]

You can look on the passenger side of the radiator, there should be a sticker on the side with the date on it.

Date on the sticker is '98. 75K miles. Looks like I'm buying a new radiator and some other coolant parts. Now I have a winter project - since I put her in storage November - April.

[Carbonized]

Where exactly is this sticker located? The only sticker on the passenger side (or altogether rather) on my radiator is one that just says:

1 728 909
1 723 464
Made in Germany
BEHR 21.766.10.003
and a bar code

I'm trying to determine if I've got the original radiator or if this is a replacement unit as I just bought my M3 this summer w/ 85k on the odo.

There was also a small square blank green sticker that was peeling off down further on the passenger side.

Thanks for any info
//B

[bobbyp]

Where exactly is this sticker located? The only sticker on the passenger side (or altogether rather) on my radiator is one that just says:

1 728 909
1 723 464
Made in Germany
BEHR 21.766.10.003
and a bar code


Same place. Passenger side. Mine says "BMW Datum: 1998" and a bunch of numbers like yours. No BEHR. No bar code.

[Carbonized]

Hmm, perhaps mine was replaced w/ an OEM equivalent then...?

[Theodore]

Hmm, perhaps mine was replaced w/ an OEM equivalent then...?

You'll find out one way on the other! :D

[Carbonized]

^ Not funny :stickoutt

[Theodore]

^ Not funny :stickoutt

but true! :biglaughb

[malter]

if coolant is up to level and you are getting "low coolant" message usually it is the coolant sensor right underneath the expansion tank. it screws into the tank. you can either clean the one you have, sometimes it clears the message. it's a cheap part $10 or so.

[RotaryBzzz]

Something else you might consider is the thermostat. Doing my entire cooling system 2 years ago, I replace the waterpump w/ OE BMW and the thermostat with OEM aftermarket (Behr i think). I had seepage issues as well at the top radiator neck the entire time.

Anyway, fast forward to this year, I flush the cooling system and decide to replace my thermostat b/k it seemed to be getting a little bit stuck open meaning the car was taking a bit more time to warm up. As this kills gas mileage, I decided to replace upon the next coolant flush.

Flushing the coolant and installing a new OE BMW thermostat, I'm noticing I don't get that damned seepage anymore. I don't know if it was a function of that aftermarket thermostat, but like many on the forums believe....on critical parts like waterpumps & thermostats, it's probably best to stick with OE BMW.

I could be wrong as I'm no cooling system expert, but I believe the thermostat wasn't opening/closing correctly & overpressurizing the system at the top causing coolant to push out.

.02

[bobbyp]

OK. I purchased a Behr from oem auto and am installing it this weekend.

I have installed the radiator (well, set in in the bay with the fan and hoses connected) however, it seems to fit lower in the engine bay than the original and the original radiator clips to not hold it firm in place. Not even close. The radiator just rocks forward and back. The radiator also does not have a connector for the 'sensor' on the side. All there is there is a plug.

What am I doing wrong? Do I need different clips to attach it to the bay? And, do I need to reuse the sensor plug from my old radiator??

[bobbyp]

Problem solved. I did a search here and found 1 post identifying why my radiator sat low. There are 2 rubber boots underneath each side of the radiator that I didn't know I needed. I took them off the old radiator and it rode higher in the bay. The clamps held. I also reused the sensor plug from the old radiator.

After the bleed procedure, I'm all set. No noticible leaks so far. Thanks to all who helped me through this!

[art@rmeuropean]

Where exactly is this sticker located? The only sticker on the passenger side (or altogether rather) on my radiator is one that just says:

1 728 909
1 723 464
Made in Germany
BEHR 21.766.10.003
and a bar code

I'm trying to determine if I've got the original radiator or if this is a replacement unit as I just bought my M3 this summer w/ 85k on the odo.

There was also a small square blank green sticker that was peeling off down further on the passenger side.

Thanks for any info
//B
On the side of the tank there should be a round circle stamped into the plastic with a date inside. It should have two of those circles, one with the year and one with the month.

[ultimachi]

Change it out ASAP. Unless you want to be stuck on the side of the road with a blown headgasket and a warped head. I think 130 dollars is worth it.....do you?

I got the PWR 40mm all aluminum radiator, Stewart high performance water pump, fan delete, 16 inch spal curved puller fan, new hoses, thermostat. All it took for me was one "low coolant message".

[ZimDoc]

Pressure test the cooling system and look for a leak.

If there is a leak, find it and place the part that has failed.