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Discussion Starter · #1 ·
So we have been having an issue with the cooling system on our '96 that we have yet to solve. When we got it (after sitting for 7 years), the system was in pretty poor shape. Fluid in it was basically clear and not full so after reading some of the sticky's we set out to do the cooling system right.

Replaced the water pump, thermostat and used bmw coolant after a full flush. Nothing "weird" came out during the flush. Radiator was "newer" as it was in a front end accident. Cooling fan works but it wouldn't come on reliably.......

We burped the system often until one day the coolant flange on the head blew out that required us to do some real fancy work to get a new one in there after the blot snapped in the head. Replaced all the heater core hoses back that way as well.

She was running good until our latest problem......she overheated again after about a solid 2.5 hours of driving. This time we saw steam coming out of a crack in the radiator which we believe is new damage. We are now putting in new upper/lower hoses and a new radiator and cap. We also took off the water pump and thermostat and everything looks fine......even cut open the old radiator to look for blockages - nothing.

At this point, most thing will be new and we have heat in the cabin. I'm concerned about this "pressure" that has been building in the cooling system....short of a new radiator cap, does this mean anything to you guys? Car runs like a raped ape with no other issues other than the overheating episodes. We are installing a new temp sensor with the radiator as well.


I'm at a loss of what else we could do.......could there be something internal we are missing? no oil in the coolant at all.

Thanks
 

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D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
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Pressure test the system. My guess is it's still losing coolant somewhere, which allows steam pockets to form in the head and elsewhere. I'm sure during that 2.5 hour run before the most recent work was done, it was leaking somewhere then, too, and finally overheated when the coolant got low enough.
 

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Discussion Starter · #3 ·
Thanks - Whats the best way to test the pressure in the system, do I need something special?

As for other leaks, i assume since we see no oil in the coolant and a clean oil change a week ago these would have to be all external leaks?
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 100K miles NOKIAN WR G3 20K miles
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Properly mixed engine coolant above 265°F is at some pressure above 15 psi atmospheric pressure.
 

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It could be an internal leak ... a blown head gasket could cause pressure to build up in the radiator ( if there is a sweet smell for vaporized water coming out from the radiator, this could be a sign) and also if your exhaust is damaged it could cause gases to return into the radiator and cause pressure build up (not a main cause but worth to check)

BMW E36 318i, 1996
 

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Discussion Starter · #6 ·
It could be an internal leak ... a blown head gasket could cause pressure to build up in the radiator ( if there is a sweet smell for vaporized water coming out from the radiator, this could be a sign) and also if your exhaust is damaged it could cause gases to return into the radiator and cause pressure build up (not a main cause but worth to check)

BMW E36 318i, 1996
With no oil in the coolant or vice versa, could it still be a blown head gasket?
 

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Also check the oil on the engine oil cap, if there is a white color mixed with the oil ( sluggish feeling) the water could be mixing in and thats where you are loosing additional water and causing the pressure to build up on the head of the pistons and reliefs it into the radiator ( starting signs that the head gasket could be deteriorating)

BMW E36 318i, 1996
 

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With no oil in the coolant or vice versa, could it still be a blown head gasket?
Yep, sometimes its a start, i had this issue once and ended up replacing the head gasket, and it would be great also if you check your air mass because sometimes they tend to take more air than required.

BMW E36 318i, 1996
 

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Discussion Starter · #9 ·
We have a spare radiator cap so we are going to rig it up to test the pressure in the system. Both caps we have are the 200 caps so pressure is pretty high on the cap.

Doing a compression test on the cylinders this morning as well......is this a sure fire way to tell if there is a head gasket problem? we don't have mixing in the oil or coolant and she doesn't continually steam/fog out of the exhaust but given the issues we've had, i'm trying to test for the blown HG.
 

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Discussion Starter · #10 ·
All 4 cylinders came in at the 155/160 psi range.......a good thing to see but the mystery remains.
 

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Compression test should show if there's a combustion chamber to cooling circuit leak. You can also buy a test kit a most auto parts stores that will check for combustion by products in the coolant if you want a double check.
If the cooling system pressure check passes (system holds pressure), then you may have not gotten the system fully bled. I've seen a couple times where there was still some air in the system, there was warm air (not hot) for heat, and the coolant temp gauge was holding at the 12 o'clock position, and then after running for a bit it spiked into an overheat when the air found its way to the water pump and coolant flow stopped.
 

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Discussion Starter · #12 ·
Compression test should show if there's a combustion chamber to cooling circuit leak. You can also buy a test kit a most auto parts stores that will check for combustion by products in the coolant if you want a double check.
If the cooling system pressure check passes (system holds pressure), then you may have not gotten the system fully bled. I've seen a couple times where there was still some air in the system, there was warm air (not hot) for heat, and the coolant temp gauge was holding at the 12 o'clock position, and then after running for a bit it spiked into an overheat when the air found its way to the water pump and coolant flow stopped.
That does sound familiar (it being fine then the gauge moves up). We will have replaced mostly everything with this next round so we will run it a bit and bleed it often.

My dad is doing the system pressure test once we get the new parts on it
 

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Discussion Starter · #13 ·
So we don’t smell coolant out the back pipe but there is and always has been water that drips out the back. Would I get one without the other?
 

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Screamin demon
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I think we need to clarify a few things going on here.
If you repeatedly having overheats then its a for sure thing that your head is warped if its ever gotten to the red mark. There is no maybe about it. Most hg jobs are more of cracked or warped heads then actual gasket failures. Not to mention your engine sat for 7 years.
2. If not, did you bleed the cooling system properly that includes the heater core and of the like? Every time?
3. A faulty hg or cracked head can be symptomatic in MANY ways. Mixing coolant and oil is only 1. Loss of compression can happen but isn't a sure fire diagnosis nor is it realistically specific by itself to anything. Loss of coolant inexplicably is just about the only always symptomic experience.
 

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Discussion Starter · #15 ·
We are throwing in the towel on it. It has good compression and no coolant in the oil but it continually overheats and we have to shut her down. I believe its going out the exhaust as we just went through another flush and almost 4G of fluid and nothing is dripping or leaking so its going somewhere.

Stinks because it ran good and is otherwise in good shape.

Wondering if we should part it or just sell it as is.....anyone have thoughts on which is better to do? I'm into the car for about $1,500 not to mention all the free labor from my dad!
 

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Screamin demon
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Well. Realistically, if you find a good head. At a junkyard or second hand for cheap, a top end rebuilt kit is like $120. So realistically your problem COULD be fixed for around $200 and about 10 hours labor for a newb. IF you find a good junkyard head.

A lot of people on here will say that's horrible idea,.. But if the engine was good that the head came off, then there's no reason to think there's anything wrong with it. Chances are if there's no cracks= never overheated=good head.
 

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Discussion Starter · #17 ·
$800, going for parts......... what a fail! I might look to find another that runs but needs some love
 

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D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
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Rule of thumb when picking parts at the salvage yard: WRECKED cars are preferred for engine and drivetrain parts. It shows it was mobile when taken off the road. A salvage yard car with a straight body is suspicious of having had an engine or transmission failure.
 

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Screamin demon
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Eh, I somewhat agree horns. Id bet that the geographical location is a large factor in salvage parts ethics. Lol. Most e36 or the like BMW I get at my workplace are there from either engine failures and its obvious when tested and marked, but mostly from failed emission testing and the repair cost is just over the cars value. For instance today a 2001 528is came in with 130k and a broken headlight.... And clogged cats. That's it. Beautiful black car. Not 1 driveable issue. Even had mint style 5s with a spare even, and a m steering wheel. Business Bought the car at auction at $325, the car was originally a trade in and auctioned off. A good salvage yard would have the proper information concerning a vehicle, if not for customer, bit also to minimise returns and hassle.
 
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