Coolant loss, suggestions please. Here's what I know/did...

[EricV]

Hi there. First off, hello again. It's been about two years since I frequented this board, and as always I appreciate everyone's time and expertise! Here's what I can tell you...

It's a '93 525i manual, well taken care of with 104K on it. I have had it since 70K. I am losing coolant, and can't for the life of me figure it out. It drops about 1-2 inches down the overflow resevoir about every two months. About two years ago I had the radiator/water pump replaced (w/ metal impellar and also a metal housing for the thermostat), and if I inspect all that I can actually see w/ my own eyes all looks well. No dripping or crusted up seepage at the hose connections at any of the obvious points, nor at the auxilliary pump near the firewall (which, by the way, has always made buzzing/groaning noises at start up.) Likewise, I do not smell any coolant inside or have any tell-tale fogging of the windshield indicative of heater core leakage (another common problem for e34's.) It is driving me nuts.

Any suggestions as to what I may check????

Here's my fear....It is cold here in VA and it blows a fair amount of white smoke in the cold. As it is white, it's hard to discern if this is normal vapor or coolant burning. Perhaps my head gasket is toast or maybe I have a crack somewhere in the head or block. The thing is, I have no whitish residue on my oil cap or the dipstick. But couldn't the crack be someplace introducing the coolant to combustion w/out contaminating the oil? Now this has been a problem for a few years, and it doesn't appear to be getting worse, and if it is only marginally. That's some comfort. The car seems to run normally and pretty strong.

I am sure there's a plethora of hoses/ares I can't get to. I have had a couple of garages take a perfunctory look at it, and each has said "damned if I know."

ANY advice or suggestion on how to proceed and what I may check next are greatly appreciated!

Many thanks for your time and patience-

Eric

[DaCan23]

and you've never found any coolant on the ground? or seen any steam coming from the front while running?

I suppose a crack in the block could lead it straight to the exhaust, which would fry your cats, and then your car would run like crap. But if it runs fine and your not overheating. Then it has to be a hose.

If you have a crack in the top of one of your hoses then it may only leak out when its pressurized. Get a telescoping mirror and check all around when its running when the cars warmed up. Especially in the rear of the engine.

[CheapCheap1]

Ummm, I also have a the same leaky coolant issue on my '95 540i/A (68+K miles).

In my case, it's leaking from the "top RH (driver side)" of radiator (where the metal-Aluminium clampped on the plastic end-block) has some "tiny" leak -- it has some white stains. So I taped a piece of tissue to the seal area & found it soaked w/in the 30 mins of driving.

Pls check the same area...well, your '93 525 may be different than my '95 540.

However, I still haven't decided on how to seal it.
I would be very appreciated, if someone who has BTDT could give some advice...on how to seal a small leak on the radiator.

[EricV]

very strange indeed. I will take yet another thorough look as it's beena while, but I have tried the telescoping mirror to get to all the spots I could.

I have read about how the expansion tank running up the side of the radiator has an o-ring seal that expands/conttracts and therefore looses vcoolant, but again I am seeing no residue. That's why I am at a loss, I cannot seem to find any reasonable explanation other than the fact that I may be (gasp) burning the coolant through combustion through some kind of crack/leak.

I hope to keep reading responses and thanks for your input!

Eric

[mattyb]

the concensus on any radiator leak for ur car is to replace the radiator. what u are suffering is the same as I not too long ago and countless others before us. There begins the dream to seal it up because it seems so small or repairable. It is not! u might stop it for a while but what u r seeing is the general level of disentergration of all the plastic involved in the radiator set up. sorry mate but u gonna have to start shopping for another. theres heaps on the search function. the "small leak" is deceptive. it probably has about 3 months left maybe. Cambridge did a good photo story for the 540i. have a look for it.

[mattyb]

in saying that im not a complete defeatist. The core was immaculate and ive kept it so that my mate can build a stainless expnasion tank and right the very rare tragic wrong that bm did with this idea of plastic.

[EricV]

so I am guessing that's not it- or at least it does not appear to be. I am leaning towards one of two things in my scenario:

1.) Internal leak resulting in the combustion of coolant

2.) Very small leak that "blows off" at speed or burns off in some spot I cannot see. If such is the case I am content to wait until there is an obvious failure of the cooling system. This is OK, as the car just does short local jaunts.

Thanks!

[DaCan23]

Just to be sure, when its cold you only file the tank up to the fill line right? Cause it you filled too much, then you'd lose the inch or two down to the fill line via the expansion overflow... just checking...

[EricV]

it's the little oft-overlooked things!

Thanks-

Eric