Keep me from killing my car with fire: coolant leak from cold side hose

Backstory for those who don't lurk in the OT thread:

Two weekends ago I replaced my old plastic radiator which was starting to leak with a fleabay all aluminum replacement and an OEM hose kit from bimmerworld. I used all new hoses.

Problem #1: The temp sensor or fan switch or whatever it is that mounts in the side of the radiator was oozing fluid after driving. I finally got that to stop last weekend (after driving the car 4 hours) by putting a new aluminum gasket on it.

Problem #2: The car was still leaking fluid from the same area. No matter what I do to try and make it, the car would not leak at home in its own garage. It sadistically waits until I'm at the office so it can be extra inconvenient and embarrassing.

Last night I rolled underneath it when I got home and noticed fluid seeping from around the cold side hose fitting on the radiator (the big fat one under the expansion tank). Everything else is dry, the temp sensor, expansion tank, bleed screw, return hose and expansion tank hose. I waited for the car to cool down, loosened the clamp and made sure the hose was all the way on, then slid the clamp up closer to the edge of the hose (but not on it) and tightened it to be "pretty tight."

I drove it around the block pretty hard, until it had been at temperature for about 10 minutes. Then I stuck it back in the garage and waited. I checked it and inspected it with a mirror a few times, everything was bone dry. Same story this morning.

I take it to work this morning thinking all is well. I just went out to check it over my lunch break, and it had left me what must've been its 6th fcuking puddle of coolant.

Without my mirror or a jack I can't tell beyond a shadow of a doubt exactly where its coming from, however, the puddle was in the exact same spot, immediately under the expansion tank (i have no undertray). So unless the expansion tank which was dry last night spring a leak this morning, that cold-side connection is still a problem.

Remember, new aluminum rad, new hose, new clamp. In an act of desperation I tightened it until I couldn't turn the screwdriver anymore. If that fixed it (doubtful at this point) then I suppose this post is pointless.

However, if it didn't fix it, I probably won't know until tomorrow, because this psychopath's MO is to behave perfectly at home when I have a full arsenal of tools to diagnose and fix it, and then be a massive pain in my ass when I'm at work with no tools and have tons of sh!t to do.

Assuming brute force tightening didn't fix it, what can I do to make my car hold fluid? I still have the old hoses which I think were ok, and I have the old rad but I think it is the one that was leaking. I

know it seems small and silly, but this is almost pushing me over the brink of getting rid of the car. I wanted to keep this car for the rest of my life and have it be my perpetual project. But I also thought that I'd have a salaried position by now instead of being strung along on a contract, and that I'd be able to pick up a modest daily driver, so I'd have the ability to just park the bimmer when it does stuff like this and get to it when I get to it.

However, the cards didn't fall that way, I'm on a contract making the same amount I made when I started, I have no solid plans or financial capabilities to add a daily driver to my stable anytime soon, and I just don't have the time or the mental capacity to deal with little crap like this every day, making my car nearly unusable and insanely messy.

Dude, I wish I knew the answer

It sounds stupid coming out of my mouth but....

Is there fluid in the thermostat housing when the car is cold? Could I slip that hose off on the top end, slide an extra clamp or two over it, and clamp this problem connection along the whole damn fitting?

I don't know what else to do. I can't replace anything... its all already brand new. I think maybe in a last ditch effort I'll drop it off at my shop tomorrow. Its the ultimate defeat but option #2 is selling it or catching on fire and calling my insurance company

It's totally ridiculous that the car is leaking from the hose... But it's no reason to sell the car. There could be soooo much worse problems. Just look at the **** that's happened to my car


Does it have those notches in the hose nipple, or is it just smooth?

Try adding another clamp and/or a wider clamp, and see if that does it.

edit: Looks like you thought of a second clamp at the same time as me. Just unscrew the clamp completely so that it opens and you can wrap it around the hose. You don't need to remove the hose at all.

Originally Posted by SlimKlim

It sounds stupid coming out of my mouth but....

Is there fluid in the thermostat housing when the car is cold? Could I slip that hose off on the top end, slide an extra clamp or two over it, and clamp this problem connection along the whole damn fitting?

I don't know what else to do. I can't replace anything... its all already brand new. I think maybe in a last ditch effort I'll drop it off at my shop tomorrow. Its the ultimate defeat but option #2 is selling it or catching on fire and calling my insurance company

Im at this point with my oil leak, I can't determine where its coming from 100% so shop is calling her name, I hate to do that so much

Originally Posted by cj.surr

It's totally ridiculous that the car is leaking from the hose... But it's no reason to sell the car. There could be soooo much worse problems. Just look at the **** that's happened to my car


Does it have those notches in the hose nipple, or is it just smooth?

Try adding another clamp and/or a wider clamp, and see if that does it.

I suppose.

The hose nipple has a bulge on the end of it for the hose to fit around but its smooth otherwise. If I pull that hose off at the thermostat when its cold am I going to cover my garage in coolant?

^Yes, there will be at least a good amount of coolant still in the hose... But like I said, you don't need to worry about that at all since you can get the clamp on without remove the hose.

Or just try moving the clamp to directly behind that bulge. Should allow a tighter seal.

Ok, I'll try opening up a clamp all the way and adding one or two on there, as many as will fit behind the bulge in the fitting. Hell if there was a parts store close to work I'd take a mental health break and go do it right now. I have a pile of clamps sitting in my random drawer of magical things at home, hopefully there is at least one in the right size in there. I'm going to go home after work and put those clamps on there then go up to Reston and check out that M3 for jesse's buddy.

Sorry to hear about your oil leak jesse. I have a small seep but its not really stressing me out right now, I'd be furious if it was making me top it up everyday though.

My level is not changing really, but it is hitting the ground when parked and making a half dollar size spot, not puddle...i just hate leaks of any sort. Im thinking its going to be the oil pan gasket. :/
Hopefully the additional clamps will fix your issue joey..fingers crossed.

Originally Posted by B1MM3R

My level is not changing really, but it is hitting the ground when parked and making a half dollar size spot, not puddle...i just hate leaks of any sort. Im thinking its going to be the oil pan gasket. :/
Hopefully the additional clamps will fix your issue joey..fingers crossed.

Ah, yeah mine has been leaving little quarter sized drops all over the place. I actually think it migtve been the drain plug, but I 1.) didn't tighten the oil reservoir down enough so I made a huge effin mess, so I've had auxiliary runoff from that the past week or so and 2.) Im parking over all the old oil droplets so I can't tell if it has stopped since the oil change.

Yeah, I'll keep you guys posted. I have to stay a late for a few minutes at work, so I'll blast home, add the clamps, get lauren and go to reston to meet that dude. I'm gonna show up in a filthy E36 that may or may not be leaking coolant at a considerable rate, he's going to think I'm such an idiot.

Tell him its just water from the ac

I've said it before, I'll say it again.


PRESSURE TESTER! You'd find the leak in about 1 minute, easily.


Did you replace the expansion tank? That could easily have a crack in it that only leaks when a certain amount of pressure fills it.

Its not the expansion tank, I could see it seeping out of this connection the other day. I didn't replace it in this project but its only a year and a half or so old, I had to replace it the old one because it was cracked.

I feel like if this was a crack or something, it would be easy to find when the car was hot because judging by the amount of fluid it leaves on the ground, it would be literally spraying out of the car when it was under pressure at running temp. Its got to be some weird issue with a deformed fitting or something on the radiator. I just don't understand why it will hold pressure fine when its hot, and sometimes cool down bone dry.

Last night I left it in the garage to cool down while I went to check out another M3 for Jesse's friend. When I got back it was bone dry underneath. Typical. I slid the hose back on the fitting as far as possible without pouring too much coolant on the ground, then gooped a bunch of RTV on the fitting. Its damn near impossible to get perfect 360* coverage when a steady stream of coolant is running down your arm and you're trying to reach a fitting from below when you can't see it, but hopefully I got enough on there. Then I slide the hose back up, tightened the one clamp, and added another further up the fitting.

I put it in the driveway and let it idle until it was up to temp and then left it overnight. It was still dry this morning, and I brought the level in the tank back to the cold line. Now its sitting out in the work garage, the little sociopath's favorite place to torture me. I'll go out and check it a few times this morning, if it continues to leak I'm calling my shop, I just don't have enough time in the day to keep dicking around with something that shouldnt even be an issue. If this extra sealant and clamp method doesn't work, I'm completely out of ideas.


Oh, and fwiw, the fitting didnt feel deformed or bent in any way when I slipped the hose off of it, but the hose did come off easier than it should. Maybe its just too small for the hose?

That's a possibility Joey....might have to go to advance and get a smaller hose...but hopefully no more leaky with the rtv

I really dont want to get a generic hose for that side, I don't think it would make the corner from the radiator to the thermostat without collapsing. We'll see though. I just ran out and checked on it. The A/C runoff from the neighboring car had run all the way under mine and out the front of it.


"GODFCKGSUMBITCHWHYDOYOUHAVETO...... ...oh"

No drips coming from her as of now, I'll go back out over lunch and check. ~10 o'clock has been her favorite time to leave me a puddle. Hopefully this is a good sign. Its like you were saying on the phone last night Jesse, how can something so simple be so damn complicated to fix.

I know man, stuff like this gets so agrivating...speaking of, the gauge wire thats used on the shift knob...its crap and broke, so uh yea...now Im going to take the knob apart and run proper size wires for pos and neg and then all should be good

Makes no sense, its like one of your co workers is dumping a water bottle under your every day to mess with you

Originally Posted by Mr Gusta

Makes no sense, its like one of your co workers is dumping a water bottle under your every day to mess with you

I know right.

I just went and checked it, its still dry and pretty much all the way cold, so I don't think its going to leak today.

The level in the tank has gone way down, but that's not a big surprise. I let a lot of coolant out of that hose last night when I tried to seal it up. I let it run last night and topped it up before I left for work, but I've never had a BMW bleed all the way down from just idling once, it always needs another tank's worth after a good drive.

I'm not calling victory yet though. If it manages to make it 24 hours without needing the level adjusted or leaking anything then maybe we're in the clear.

Originally Posted by Mr Gusta

Makes no sense, its like one of your co workers is dumping a water bottle under your every day to mess with you

.I think that's gotta be it.

Sent from my LG Revolution 4G using BimmerApp

easiest way to bleed an e36 is have the car off and fill it while your squeezing the upper hose, when you get water from the bleeder, put the screw in and put your hand on the opening where the cap goes, keep your hand on it to seal it and squeeze the hose a few times and add water after until it is topped off and put the cap on.


shouldnt have to check it ever again if you did it right

Originally Posted by Mr Gusta

easiest way to bleed an e36 is have the car off and fill it while your squeezing the upper hose, when you get water from the bleeder, put the screw in and put your hand on the opening where the cap goes, keep your hand on it to seal it and squeeze the hose a few times and add water after until it is topped off and put the cap on.


shouldnt have to check it ever again if you did it right

Huh, I'll have to keep that in mind next time I have to do this. Which will hopefully be a long, long time from now. (Assuming I dont walk outside to a puddle in 10 minutes.)

I do the hose squeeze thing, but I've never done the hand over the opening part. My methods are roughly:

1.) Fill while squeezing hose until water comes out of bleeder, close bleeder and reservoir.

2.) Turn car on and run to temp, let it cool down. Top off fluid in reservoir.

3.) Drive the godfearing crap out of it for 15 minutes. Let it cool down. Top it off again and done.

Your way definitely sounds more efficient.

Don't forget to turn your heater on max heat, fan set to Ludicrous Speed.