Running hot

Tiny
PEPPERONE
  • MEMBER
  • BMW 525
1994 BMW 525i 50000 M50 tu vanos 6 cyl 2.5 car was running fine & then I read about water pumps with plastic impeller so did't know when any service to cooling system was dones so I decieded to change almost every thing so this is what I did WATER PUMP **THERMOSTAT CHECKED BEFORE PUTTING IN**HOSES - BELTS - FAN CLUTCH- EXPANSION TANK CAP & after all this seems to run hot bled system many times & still get bubbles from bleed screw. Heater works fine upper radiator hose is hot but radiator does not get hot just a little warm. Before I put hoses back onto radiator I ran garden hose in top radiator outlet & after about 45 seconds water comming out of lower hose was clean & no debri either any help would be nice. Thank you pepperone
Sunday, November 4th, 2007 AT 1:54 PM

12 Replies

Tiny
RASMATAZ
  • MECHANIC
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Might want to Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat, Pressure test the Rad. Cap, Clogged radiator, Fan clutch, Radiator electrical fan, collaspe hoses, water pump.
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Sunday, November 4th, 2007 AT 2:41 PM
Tiny
DOCHAGERTY
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It sounds like there is still trapped air inside the cooling system, which is not unusual. Try this, fill the system with the bleeder screw open, close the bleeder and top off the system and screw the cap on tight, then drive the car and get it to operating temperature, and then just let it sit and cool off for an hour or so, then top off the system after it has cooled off. I have had the same problem you are having now, this procedure works. Also, if the radiator is original equipment(from 1994)you may wish to replace the radiator due to deposits in the aluminum of the radiator that act like insulation.
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Sunday, November 4th, 2007 AT 2:49 PM
Tiny
PEPPERONE
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I think I still have air in system. With thermostat in car radiator & bottom hose don't get hot. So I took thermostst out & filled system up & ran car. & Radiator & bottom hose got hot. Now I have 3** 88 celsius thermoststs & only the original openes at 88 the 2 new one open at about 95 celsius. Also checked oil for coolant & vice versa all good. So I put one off the new ones back & still same radiator & bottom hose don't get hot. Any help would be great thank you. Pepperone
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Wednesday, November 21st, 2007 AT 8:47 AM
Tiny
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What was wrong with the original one? It sounds as if it was working. If you install a 95c t-stat and observe the temperature gauge taking an excursion into the red area after you have properly filled the system and bled out the air, then the t-stat is very likely to be at fault. Reinstall a 88c unit and then let us know how that turns out.
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Wednesday, November 21st, 2007 AT 10:07 AM
Tiny
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Put original back in 88c. Radiator & bottom hose got warm so let it idle 1/2 hour. Needle at 1/2 way mark so took car for a ride on highway at 70mph needle still 1/2 way mark & that is with heater on. So turned heater off and needle still at 1/2 way mark when pulled in driveway opened bleeder vale & no bubbles &even top of radiator was warn bottom hose was a litte hotter. So I think it's okay now. Thanks
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Friday, November 23rd, 2007 AT 3:16 PM
Tiny
PEPPERONE
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Took car for another drive on highway for about 3/4 of an hour needle in middle heater on or off. Came back & checked bleed screw & no bubbles came out.***But top hose side of radiator to hot to touch***move my hand a long top of radiator & was just a litte warm as I moved my hand to end of radiator. Shut car off & felt radiator hot as hell next to top hose inlet but just warm any other palce on radiator. So you think I have so blockage in there. Any suggestions. Thank you. Pepperone
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Sunday, November 25th, 2007 AT 5:47 AM
Tiny
DOCHAGERTY
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When automotive cooling systems had radiators made of copper and brass they required periodic cleaning also known as "rodding out" where the radiator was removed and taken apart, cleaned of it's deposits, and then soldered back together. These days radiators are almost all made from aluminum and plastic (thank you bean counters) and either resist or preclude this activity. So to answer tour question, yes you have identified a plugged up radiator and it will require replacement. I suggest going online and search for BMW parts instead of the dealer network due to the $ issue. Use a BMW recommended coolant and distilled water to help reduce these deposits in the future.
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Sunday, November 25th, 2007 AT 9:44 AM
Tiny
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Thank you for you reply. I already orded new radiator & I have bmw antifreeze in system now that I just put in last week. So I will drain radiator & save antifreeze & put back in new radiator. Do you think this will be okay. Pepperone :mrgreen:
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Sunday, November 25th, 2007 AT 10:40 AM
Tiny
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OK to reuse anti-freeze. Remember to change every four years and use distilled water to dilute.
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Sunday, November 25th, 2007 AT 11:37 AM
Tiny
PEPPERONE
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Some body told me to check belt tensioners on car I think there all right cause when I depress belt seems to be pretty tite and when car running no wobble or slipping
. Is there any other way to check theese tensioners to see if there okay. If so can you tell me. Thank you pepperone
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Thursday, November 29th, 2007 AT 8:33 AM
Tiny
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They are self tensioning and require no adjustment
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Saturday, December 1st, 2007 AT 3:30 PM
Tiny
PEPPERONE
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Hi dr. Put new radiator in & still goes to 3/4 mark on gauge bottom hose cold & after driving car for 1/2 hour & top hose is hot but very hard to sqeese seems like water not going back to engine I belive it could be thermostat not opening. Would there be heat in car if thermostst does not open. So I sent thermostst to BEHR in germany to test it for me. Every thing is new. Don't know what else to do. How do you test a thermostat. Maybe I am not testing them the right way. I use a candy thermometer hanging in a pot & hang thermostatright next to it & see when it opens & don't open till 95 degrees celsius all the thermostats I bought total 4of them. As always thank you for your help. Pepperone
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Monday, December 24th, 2007 AT 6:23 AM

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