Radiator Sag, Who Knew??

[TheMtechnique]

I had an odd find this past weekend while doing my timing belt/general maintenance & cleaning of my engine bay. I was under the car undoing the fan shroud and noticed the shroud being stretched in the center where I have it secured to the radiator via zip tie. I had a few moments of confusion before I noticed the radiator looking quite bent, or bowed at the bottom. After I pulled the fan shroud and fan I yanked the radiator and found quite a failure. I have never seen nor heard of this happening, but upon searching for possible cause I learned that on the e36 and e46 chassis this type of thing actually does occur, though theres no real reason anyone has come up with outside of, "they just get old and do that". I could accept this but this radiator is only about 5 years old at the most, and probably has less than 30k on it. I cannot remember or find the brand I ended up purchasing, but I know it wasn't a cheap one. So, anyone else experienced this? kind of nuts...


IMG_2285 by Simon Feldstein, on Flickr

IMG_2286 by Simon Feldstein, on Flickr

[e30austin]

woah. i've been doing this a little while and i've never seen anything quite like that. look on the top or the bottom for a date stamp or manufacturer tag. really curious who made that one.

[TheMtechnique]

Ill look for the manufacturer today and report back. I cant see any logical reason for this, I mean its a vert and all but chassis flex could not do this. I doubt that front crossmember even flexes. And, the damn thing is still square, besides the bottom! Perplexing. I'll let you know what brand when I find it. Its definitely not a factory BMW radiator, but I always try to afford factory BMW or closest in quality I can find..

[roguetoaster]

Has to have been an issue with the brazing process, or environmental exposure once installed. Definitely odd, maybe see if you can easily pull the fins out higher up in the core and see if the issue is throughout the whole unit.

[TheMtechnique]

I'll check that out since this thing is beyond junk. Only two numbers on the radiator, >PA66 GF30 , which apparently refers to the plastic compound used on the end fittings of the radiator. "Polyamide (nylon 6,6), 30% Glass fiber. Its very strong and is easily bonded and welded"

The other number came back with nothing specific.

There is a red sticker on there with a phone number, looks generic sticker but ill call it for warranty purposes. This thing might be Nissins brand.

Pics for reference

IMG_2422 by Simon Feldstein, on Flickr


IMG_2423 by Simon Feldstein, on Flickr

[TheMtechnique]

woah. i've been doing this a little while and i've never seen anything quite like that. look on the top or the bottom for a date stamp or manufacturer tag. really curious who made that one.

I really hope DP 1975 doesn't mean Date Production 1975 X-D !! Im going to buy a new rad anyway, but I'm super curious about this failure.

[e30austin]

29th week of '05 was when it was manufactured. still crazy, i've genuinely never seen a radiator do that, without failing completely. kind of crazy.

1-800 Radiator loves to push their cheap, Chinese made radiators (sold under "CSF" or the like), but oddly enough, if you call the dealer and order an E30/E36 radiator, the Chinese unit is what shows up. disheartening. either way, i'd throw that piece of crap straight in the trash and buy the Behr/Mahle unit, with the understanding that you'll have to replace it within 10 years or less.

[Stanley Rockafella]

That's an original rad.

I had the same thing happen on mine. Funny thing for years after I first bought the car in 2003, it always ran hotter than it should have.
As a result, I replaced the fan clutch and countless thermostats etc. My mechanic even insisted the rad "looked fine".

Fast forward about 13 years, and while I had my HG replaced the mechanic (different one) mentioned my rad was "sagging".
He insisted it needed replacing which I permitted the additional cost.
Sure enough, after the replacement the car never hit the "12:00" mark again, or any point after that.
Even in the hottest summer temps, she's always right around "11:30".

[Vincenze]

It's a sign of a clogged radiator and/or poor water flow.

When water flow is restricted at one end, a pipe can easily bend from the increased water pressure.

[Vincenze]

BMW even makes modern camshafts using a similar phenomenon.

It inserts a pipe into a die and pushes oil inside of the pipe. The pipe expands and takes the shape of the die.

[zaq123]

looks like c cooling passages got deformed/expended. Not sure about your geo location or car's history ...maybe it is a freeze damage?

[TheMtechnique]

That's an original rad.

I had the same thing happen on mine. Funny thing for years after I first bought the car in 2003, it always ran hotter than it should have.
As a result, I replaced the fan clutch and countless thermostats etc. My mechanic even insisted the rad "looked fine".

Fast forward about 13 years, and while I had my HG replaced the mechanic (different one) mentioned my rad was "sagging".
He insisted it needed replacing which I permitted the additional cost.
Sure enough, after the replacement the car never hit the "12:00" mark again, or any point after that.
Even in the hottest summer temps, she's always right around "11:30".

Not original rad.. But OE spec.. I had a HG blow, fortunately upon startup in my garage. I was suspect of this happening as I had been experiencing coolant loss for about a year. I had a leakdown test performed (and passed), and kept an eye on my fluids for contamination.. after the blow HG a few months later I had the cylinder head rebuilt and put a new HG in my garage, along with all other items you would replace if you were pulling the head, including a radiator since the old one was factory... Fast forward 4 years or so and I did notice the car started to climb above center on the temp gauge after a long freeway drive, in offramp or city traffic. But never really overheated or got close to the 3/4 tick on the temp gauge.. Maybe this failure has been a long time in the making as that was at least 2-3 year ago. Im just happy it didn't grenade

[TheMtechnique]

29th week of '05 was when it was manufactured. still crazy, i've genuinely never seen a radiator do that, without failing completely. kind of crazy.

1-800 Radiator loves to push their cheap, Chinese made radiators (sold under "CSF" or the like), but oddly enough, if you call the dealer and order an E30/E36 radiator, the Chinese unit is what shows up. disheartening. either way, i'd throw that piece of crap straight in the trash and buy the Behr/Mahle unit, with the understanding that you'll have to replace it within 10 years or less.

Yea its a bummer how hard it is to source certain good parts these days, its a huge bummer that the dealer would sell that X-( I hadn't even noticed the 1-800-radiator sticker on there until yesterday. Im obviously putting a new unit in there and will purchase one from Behr/Mahle, and pray its stamped with "Made in some country that gives a fuck". I think a decade of service is just fine, in fact Ill probably be excited to do the job again well before the 10 year mark.

[TheMtechnique]

It's a sign of a clogged radiator and/or poor water flow.

When water flow is restricted at one end, a pipe can easily bend from the increased water pressure.

Thats good to know, and the only actual reasoning I have read so far. It does make sense, maybe Ill cut it open systematically and look for a blockage, just for science

[TheMtechnique]

BMW even makes modern camshafts using a similar phenomenon.

It inserts a pipe into a die and pushes oil inside of the pipe. The pipe expands and takes the shape of the die.

Thats interesting.. Thats probably a ton of PSI of fluid pressure! Now i wouldn't call a radiator stout, but I'd expect a blockage to clear before the deformation seen here..