BMW Forum -

BMW Forum - (
-   3-Series (E36) (
-   -   Radiator hot on one side cold on other side (

mikeinmaine 01-10-2013 10:15 AM

Radiator hot on one side cold on other side
Hi ALL, Still trying to get heat in 93 318is. So found that on in side of radiator the side of rad gets hot but on the other side when you feel the rad up and down the side its cold. Now i took the rad off and in the sink water will go thru from one hose to the other SO my question i guess is Can the rad be not letting coolant to circulate but when i have it laying down on sink let water thru? I realize this might be a stupid question but at the end of any clue why no heat:headsmash:headsmash

Lord Vader 01-10-2013 08:40 PM

The radiator takes hot coolant from the engine, and circulates it through tiny pipes inside. Cold air rushing into the engine cools the coolant down, where it then flows back into the engine to cool the engine down. Make sense? As long as the car isnt overheating this is normal.

mikeinmaine 01-10-2013 11:34 PM

Thanks Vador, yeah i figured it would be cooler but the hose and whole side of rad is cold,used to chevys or subareas until my daughter bought this 318is, and those other radiators are not that efficient. Was really,really hoping that was a problem as new therm,new heater core,new water pump and my heater(water) valve is working but tried unplugging it also as its supposed to be open then(i guess?). I just dont know what to do as its my daughters car and its winter in maine,lol. Tried bleeding it a ton of times and ways and don't know WHY:headsmash no heat:conf:conf:conf

mikeinmaine 01-10-2013 11:45 PM

Heat selector spin knob on heat too and knobs on as hot as it can go. Plus checked vents for maybe door not working right but i get plenty of air flow its just not hot,pushing it to call it luke warm. The 2 heater hoses going in to HC do get warm to hot but the return is cold and it just isnt getting hot enough to heat the air when the fans running,at all.

mikeinmaine 01-11-2013 05:17 PM

Could one of my heater hoses or where they're under intake manifold maybe be plugged so my engine is getting cooled but its not circulating enough hot coolant to heater core? And if so any ideas on how i could make sure theyre not plugged,besides tearing it all apart and visually checking them?

Lord Vader 01-11-2013 10:12 PM

When you bleed the system do you raise the front of the car a few inches? Most people recommend this as it helps get air bubbles out that might not have been able to. When bleeding it do you let the vehcile warm up to operating temp first? This is done to allow the thermostat to open and allow more coolant flow.

If their was a leak, you would smell it, and possibly see fluid leaking through the dash.

mikeinmaine 01-11-2013 10:28 PM

I have tried with it up on jack stands,maybe 10 inches up,maybe too much raising the car? I didnt try with it up just a few inches though. I dont think i have a leak but maybe its not circulating into heater core enough,thats why was wondering if maybe heater hose or something is plugged to heater core,if the car doesnt overheat does that mean no blockage anywhere? I have warmed it,but should i warm it then shut off and fill overflow while bleeder is open,is that what you mean LordVador? i even drilled a tiny hole in top of thermostat to help bleed it,think thats messing with me? Have also drained block and no foreign materials came out either. My daughter has my car so really need to figure it out,lol. Thanks so much LORDVADOR as you're the only one willing to help me figure this out and i REALLY APPRECIATE IT:rule:rule

Lord Vader 01-12-2013 09:10 PM

Woah, you drilled a hole in the top of the thermostat? Your gonna need to replace that now.

One thing i can think of, is the plastic lip for the hose on the radiator becomes brittle over time and can crack. Inspect this. Broken peices of plastic *could* be the reason the heater hose is potentially clogged. If its broken it will require replacement of the radiator.

Here is also a good DIY on the heater valve: Pelican Technical Article: BMW Heater Valve Cleaning/Flushing

mikeinmaine 01-12-2013 10:10 PM

I have another thermostat,but I have done that on other vehicles to help air bleed out even if therm is closed. Actually a Porsche mechanic gave me that tip. I will try the unmodified therm though and see if that's it ,maybe BMWs don't like it,it's only like 3/32but maybe. As it was explained to me only a tiny bit of coolant goes thru,not enough to matter,and its drilled at very top. I will also have to inspect all coolant related parts for anything that might have broken off and lodged in system.. Thank you😄. Will keep you informed of developments😄

Chevyguy 01-22-2013 07:58 PM

Mike, I own a 318ti and I was having the same problem. Started after adding radiator stop leak to the cooling system to block a small pin hole in the rad.
I've used it many times before on my domestic cars and never had any troubles.
Usually only use a half bottle. The same pellets are added in the cooling system from factory for most new domestic cars (not sure about the imports).
If someone else had added this at any time in the past it could still be plugging up some of the smaller coolant passages. I disconnected both hoses to the heater core at the firewall and used a compressor to blow air through the lower inlet (sure it wouldn't matter which one you used) using an air blow with a shop rag wrapped around the end to help seal the opening of the inlet. Go easy with the air pressure and see if it's coming out of the top outlet. A lot of the sealant pellets get caught up in the heater core and most of it can be cleared out this way. If you find a lot or if it blocks up again you might want to flush the system with a chemical flush such as Prestone ,then drain and refill again.

side note:The chemical flush works best with straight water. Save the coolant you drain out if you just replaced it. You can refill the system with it as any pellet material will sit at the bottom of the container.

It'd be worth checking to make sure you have unrestricted flow through the new heater core just to rule it out.

mikeinmaine 01-22-2013 08:08 PM

Thank you Chevyguy, i will check that out tomorrow or the next day and post my results here for you to see:). I actually think there was some gunk in the coolant system as when i first did the water pump it seemed like there was some slimy properties to the coolant,didnt see chunks but that very well could be the problem. Will flush it again too but with prestone like you suggested and blow out heater core too. Praying your onto something:). I also have been a chevy guy my whole life and this is my daughters 2nd bmw but my first one working on.:)

OICU812 01-24-2013 01:26 PM

Hi Mike, I have 1995 318ti I just replaced the thermostat. The one that was in it had a small indent at the top to let a little antifreeze by, I replaced it with a German one that had no visable bleed hole or indent but had a arrow to point up. The German stat was bad, it may have opened once but failed from the beginning. Upper right hand hose as your standing in front of the car was hot, bottom left hand hose was cold, you could hear water boiling from upper hose, gauge went a tick past 12 noon. Third thermostat had a small bleed hole with a small rattle rivit in it. I wouldn't pull the stat you drilled, that was my next step.

mikeinmaine 01-24-2013 01:34 PM

Yeah oicu812 i didnt change it anyways because as my Porshe tech said if anything it would help the air bleed out whether open or closed and that tiny pinhole doesnt let enough coolant by to make the motor not run at temp:). Thanks for helping me out,i really appreciate any input from any one nice enough to take time to give it:). Havent had a chance to flush again since been wicked busy,but will update thread as i know anything,or lack of,lol. Cheers:)

Turbohugh 01-27-2013 11:07 PM

You may have a bad water pump I had the same problem (well the hose issue as well as others, turned out to be my water pump. See my post in a new thread).

mikeinmaine 01-28-2013 01:01 PM

Turbohugh, Just put in a new one. Thanks:)

All times are GMT -5. The time now is 08:12 AM.

Powered by vBulletin® Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

For the best viewing experience please update your browser to Google Chrome