M44 overheating

[cooljess76]

I had a hairline crack in my radiator. Couldn't see any coolant leaking out because it was so small, but every other day or so it would lose a little coolant and accumulate air. I drove it like that for almost a year, constantly bleeding and adding water. It got worse and worse to the point that I was adding a gallon of water a day! Everyone swore up and down that I had a blown HG, even though it ran fine for over 10k miles and a year later. I knew different, hooked a home made rig up to the radiator and pressurized it to about 15 psi. Heard a hissing coming from the side of the radiator where it meets the expansion tank. Replaced the radiator, no more problems.

rtbmw318- this is why it's recommended to replace the entire cooling system in one shot. Think of all the time and hassle you could have saved if you would have simply replaced the thermostat and radiator at the same time you replaced the waterpump. It's also recommended to replace the two infamous plastic coolant lines as they're known to break as well.

FWIW, I knew I had a cracked radiator, I just didn't know where the crack was. I watched it like a hawk, carried two gallons of water in my car at all times and topped off/bled the system everyday. It never overheated, not even once! Sure it was a risk, a small leak can turn into a big leak real quick, but I was ready for it. When it comes to the cooling system on these cars, DON'T HALF ASS ANYTHING! If your car has over 100k which I'm fairly certain most of them do, you're running on borrowed time! Replace the entire cooling system or face the consequences. Here's an excellent writeup to get you started:
http://www.318ti.org/forum/showthread.php?t=18066

http://www.318ti.org/forum/showthread.php?t=27940
http://www.318ti.org/forum/showthread.php?t=16068
http://www.318ti.org/forum/showthread.php?t=25956
http://www.318ti.org/forum/showthread.php?t=17020
http://www.318ti.org/forum/showthread.php?t=15411
http://www.318ti.org/forum/showthread.php?t=15181
http://www.318ti.org/forum/showthread.php?t=14068
http://www.318ti.org/forum/showthread.php?t=7937

[bazar01]

Originally Posted by Bills86e

I have not seen any loss of coolant yet. After I get the temp switch replaced so the low fan cycles, and do the re-burp proceedure, and if have
continued problems, What is the test for blown HG? Is it the Cooling System
Pressure Test attached to the radiator at cap/tank on page 170-3? (Bently)
I kill engine at RED, this is my 2nd engine.

You need to do a pressure test on the dooling system or bring it to a shop that can test exhaust gases in the cooling system.

I picked up a non-running 1996 318ti a few months back. It has 179k miles on the clock. I bought a 90k mile engine and installed it in 3 weeks. Engine came with a set of new hoses, water pump and thermostat housing and the little plastic coolant manifolds under the intake and at the back of the engine. I had those installed in the new engine. Came to find out the radiator had a big crack behind the reservoir. I had it pressure tested at a local radiator shop.
Then I tested the radiator fan and found out the high speed works but not the slow speed. Came to find out the fan resistor was open so I just shorted the resistor so the fan runs both in high speed. Still the slow speed section won't work. The fan will not cycle ON/OFF with A/C off. Had to download the ETM online and found the problem. I did a temporary fix so the slow speed section works with A/C off.
I just cannot believe the amount of tests I did on the cooling system to get it to work properly. I hate the plastic coolant system parts on this car. It needs to be replaced every 100k miles to make sure the car does not blow up due to overheating.
Other than that, the car runs like a dream and it's going to be a nice daily driver.

[pdxmotorhead]

Just as a sidebar, Redline Water Wetter will help bleed the system, and it helps prevent bubbles. I've bled the heck out of the cooling system than poured a bottle in and imediately had a bunch of air come out....

Dave

[bazar01]

Tell you the truth, i did not have any problem bleeding the system. I just filled the radiator reservoir to the brim with the bleeder open. Closed the bleeder and put the cap on, run the engine, turn on the A/C and put the thermostat to hottest, bring the engine up to temp, then shut it off.
Leave it off overnight and let it cool down. The following day, the reservoir is empty, then just filled it back up then put the cap on, run the engine with the heat full blast, bring it up to temp, then shut it down to let it cool down. Once cool, check the reservoir level and just a little low, filled it up to the mark, turn engine on with heat on full blast, temp stayed halfway on the gauge but the fan never cycled ON/OFF. The fan was a different story though.

On the water wetter, you are only supposed to used that on pure distilled water with no glycol. I don't want to run on pure distilled water and water wetter so i opted for the glycol coolant.

[cooljess76]

Originally Posted by bazar01

Tell you the truth, i did not have any problem bleeding the system. I just filled the radiator reservoir to the brim with the bleeder open. Closed the bleeder and put the cap on, run the engine, turn on the A/C and put the thermostat to hottest, bring the engine up to temp, then shut it off.
Leave it off overnight and let it cool down. The following day, the reservoir is empty, then just filled it back up then put the cap on, run the engine with the heat full blast, bring it up to temp, then shut it down to let it cool down. Once cool, check the reservoir level and just a little low, filled it up to the mark, turn engine on with heat on full blast, temp stayed halfway on the gauge but the fan never cycled ON/OFF. The fan was a different story though.

On the water wetter, you are only supposed to used that on pure distilled water with no glycol. I don't want to run on pure distilled water and water wetter so i opted for the glycol coolant.

That's not the proper method of bleeding the system. While it might have worked for you(perhaps you think it worked), the proper way is to park the vehicle on a hill or incline. With a cold engine, start the vehicle, turn heater on full blast, remove bleed screw, slowly fill the expansion tank while massaging the hoses to release trapped air until a steady stream of coolant flows out of the bleed hole. Allow engine to reach operating temp and then cool off, repeat process several times.

While you may think you've released all of the air because you didn't see any bubbles or whatever, there's probably still air trapped in your radiator. Air bubbles travel up and often get trapped in the radiator. You need to run the heater to get the coolant to circulate through the entire system. Say there's air in the heater core, if you don't open the heater valve, the air will remain trapped. Also note that if the bleed port isn't elevated to the highest point of the system(ie parked on an incline) and the car is sitting level or on a decline, air will travel up to the highest point and remain there.

[bazar01]

Originally Posted by cooljess76

That's not the proper method of bleeding the system. While it might have worked for you(perhaps you think it worked), the proper way is to park the vehicle on a hill or incline. With a cold engine, start the vehicle, turn heater on full blast, remove bleed screw, slowly fill the expansion tank while massaging the hoses to release trapped air until a steady stream of coolant flows out of the bleed hole. Allow engine to reach operating temp and then cool off, repeat process several times.

While you may think you've released all of the air because you didn't see any bubbles or whatever, there's probably still air trapped in your radiator. Air bubbles travel up and often get trapped in the radiator. You need to run the heater to get the coolant to circulate through the entire system. Say there's air in the heater core, if you don't open the heater valve, the air will remain trapped. Also note that if the bleed port isn't elevated to the highest point of the system(ie parked on an incline) and the car is sitting level or on a decline, air will travel up to the highest point and remain there.

I cannot disagree on that!
Just to let you know, whenever I bleed most of my cars except the 911 of course, the front wheels are always on a ramp. Cheers!

[pdxmotorhead]

I posted this tip elsewhere, but just in case,

Water Wetter helps purge air, it lowers the surface tension of the bubbles and they pop which allows the air to pump through the system and evacuate.

Its dramatic on my jeep, bleed it all and then pour in the stuff and almost immediately I get a bunch of air out of the system.

Dave

[xxxJohnBoyxxx]

Originally Posted by cooljess76

I had a hairline crack in my radiator. Couldn't see any coolant leaking out because it was so small, but every other day or so it would lose a little coolant and accumulate air. I drove it like that for almost a year, constantly bleeding and adding water. It got worse and worse to the point that I was adding a gallon of water a day! Everyone swore up and down that I had a blown HG, even though it ran fine for over 10k miles and a year later. I knew different, hooked a home made rig up to the radiator and pressurized it to about 15 psi. Heard a hissing coming from the side of the radiator where it meets the expansion tank. Replaced the radiator, no more problems.

rtbmw318- this is why it's recommended to replace the entire cooling system in one shot. Think of all the time and hassle you could have saved if you would have simply replaced the thermostat and radiator at the same time you replaced the waterpump. It's also recommended to replace the two infamous plastic coolant lines as they're known to break as well.

FWIW, I knew I had a cracked radiator, I just didn't know where the crack was. I watched it like a hawk, carried two gallons of water in my car at all times and topped off/bled the system everyday. It never overheated, not even once! Sure it was a risk, a small leak can turn into a big leak real quick, but I was ready for it. When it comes to the cooling system on these cars, DON'T HALF ASS ANYTHING! If your car has over 100k which I'm fairly certain most of them do, you're running on borrowed time! Replace the entire cooling system or face the consequences. Here's an excellent writeup to get you started:
http://www.318ti.org/forum/showthread.php?t=18066

http://www.318ti.org/forum/showthread.php?t=27940
http://www.318ti.org/forum/showthread.php?t=16068
http://www.318ti.org/forum/showthread.php?t=25956
http://www.318ti.org/forum/showthread.php?t=17020
http://www.318ti.org/forum/showthread.php?t=15411
http://www.318ti.org/forum/showthread.php?t=15181
http://www.318ti.org/forum/showthread.php?t=14068
http://www.318ti.org/forum/showthread.php?t=7937

Jess I would agree but first post say he put a new radiator in. I read everything very closely before posting the dreaded head gasket. Everything has been replaced with new and he says no water leaks.

So questions is were is the water going and how are bubbles getting in there?

My internet guess is blown head gasket or cracked head, hope I'm wrong but if OP is saying he replaced everything on first post were is the water going and were are the bubbles coming from? Only one place I can think of is head gasket or crack in head...Sorry but that's the facts man

[cooljess76]

I forgot all about the first post, lol. You're right Johnboy, well let's keep our fingers crossed it's something else

[dave45056]

Bill, What made you start this cooling system rebuild?
And you mentioned this is your 2nd engine. Has this engine ever been cooling correctly?
I am also curious how much coolant you have had to add.

This may not be great to hear in Florida, but the first symptom of low coolant is no heat at idle. Anyone on here that has had a coolant leak knows that sign. So you can drive it to get it through a heat cycle using that as a guide to stop and let things cool down.

I can't stress enough to do the burping proceedure on an incline as stated earlier and make sure the heater control knob is set on the hottest setting and fan on high. Plan on 2-3 repeats.

If you are still losing coolant and don't see any spot of coolant under your car, then I would try a leakdown test, or a test for exhaust fumes in your coolant.

Keep us posted

[Bills86e]

Thanks for the info. This is/was a good known 2d engine. Put new (this)
engine in and prob was there, so never drove it, I know better. It has been quite a long haul finding the problem. fan was bad, ECT sensor was bad, 3rd fan switch now.
Now I am in the burp process of start til warm, shut off, let cool, then bleed, repete.
What is still not answered, is WHEN does low speed come on?
I may have burned contacts in ECM?
One thing I have replaced but not wrote is that I bought a plug with
8" of the three wires for fan switch. The old one was heat destroyed
when 1st fan Low Speed went south.
Can you tell me when the low speed fan initiates? (it now works).

[cooljess76]

Honestly, I can't remember ever seeing my fan come on aside from high speed when I operated the A/C. IIRC, CirrusSR22 said the same thing. If everything is functioning properly, there's really no need for the low speed cycle to come on. Maybe sitting at idle for an extended period in extreme heat conditions???

[Bills86e]

I know that if there is air at radiator top the switch will not work in air.
that when its burped right, it will operate guage at 12 o'clock,
and thermostat opens closes.
The manual is not explaining the low speed ON/OFF.

I am terribly afraid to drive this car because OH can happen quickly
and expensivly. The last engine was diagnosed overheated because
of low speed fan failure. The fan switch plug fell apart from the failure.
Now with new engine I replaced all parts I can think of to keep this from
happening again. Just seeing the needle move from 12 toward red zone
while burping just.......well, any way, I need more help if you can.

[cooljess76]

If it's overheating while you're filling/burping it, it could only mean one thing. Coolant isn't circulating through the engine. This may be caused by one of 3 things: air in the system, a broken/stuck thermostat or a bad water pump. This might sound stupid, but check to see that your belt is routed correctly. Maybe the water pump is spinning backwards and not circulating water the way it's designed to. I dunno man, I'm just as stumped as you are.

[cooljess76]

At this point, I'm willing to bet that the belt might be routed wrong. Keeping my fingers crossed as this would be an easy fix and a big load off your shoulders