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Overheating, hissing noise from pressure cap on expansion tank , possibly faulty cap

Posted by Anonymous on

6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017

  • 25 Answers

SOURCE: I have a 2003 l200

You could have a head gasket leaking putting to much pressure in to the radiator.

Posted on Aug 28, 2008

  • 1861 Answers

SOURCE: Automatic - overheating blowing coolant

Most likely the thermostat is sticking. Get the system flushed (get that rusty liquid out of the system), replace the thermostat & put in new coolant. Should fix it.

Posted on Sep 16, 2008

emissionwiz
  • 75005 Answers

SOURCE: radiator overheating volvo 940GL 1997 model

have u replaced the thermostat? also have it checked for a leaking engine cylinder head gasket.

Posted on May 27, 2009

  • 14036 Answers

SOURCE: 1991 overheating Towncar

your pressure cap is used to maintain pressure in cooling system.over flow outlet is to let pressure off radiator when engine overheating.if clutch fan have resistance.its good long as the silicone oil isnt leaking from it.replace your thermostat.

Posted on Jun 04, 2009

dttech
  • 4803 Answers

SOURCE: expansion tank cap is leaking antifreeze from the

OK, First let's get a couple things straight.

  1. NEW is spelled with an "N"
  2. GOOD is spelled with a "G"
  3. "NEW" and "GOOD" do not mean the same thing - if they did, we would have absolutely no use for the word "WARRANTY" I have seen many people beat their heads against the wall trying to fix a problem and cant figure it out because the part that was causing the problem was "brand new".
  4. It is absolutely impossible to have it both ways. Either the cap is holding pressure very well, or it is leaking.
OK, now that I have my preaching done, I would first have to ask: Are you sure that the cap is on STRAIGHT and screwed all the way down? I have seen a few surge tanks that will actually allow a person to scew the cap on in a tilted position...flimsy plastic junk...

...ANYWAY,
Make sure that the seals in the cap are not damaged. There are two seals, the first is an O-ring that will seal the tank neck just below the overflow hose. The other is a flat seal up in the top of the cap which seals against the top of the threaded area on the surge tank. (This is the one we need to give the most attention to in your case - if the O-Ring is bad it will most likely be dumping all your coolant out the overflow hose.)

If you are satisfied that the cap seals are in good conditon, (They SHOULD look brand new! ;) ) then take a look at the surge tank.

I have seen several plastic surge tanks with "flashing" from the moulding process left on the top edge where the cap seal is supposed to seal. If there is a ridge on the upper surface that you can feel with your fingernail, it is enough to cause a leak. This can be fixed using a block and some 220 grit sandpaper. Be careful not to sand too much and/or sand it to where the top ends up angled. You may want to follow this up with some 1000 grit sandpaper to smooth it out even better.

One final note:
Make sure your surge tank is not overfilled. If it is, it will dump antifreeze untill it reaches the proper level regardless of the condition of the cap and/or surge tank.

Posted on Nov 07, 2009

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1 Answer

Why my mazda mvp 2003 over heats before one mile


Check as soon as you come to overheating position whether at that time the fan is blowing. If not check for the fan switch,if is working or not.If the fan is blowing then switch the engine off and with the fan not in operation try slowly and carefully not to burn your hands touch the radiator ventilating core surface to all sides on the radiator whether are all on the same temperature feeling. If not means that the radiator is blogged or the thermostat is blogged.If is everything in working order,let the radiator to cool down and slowly and carefully remove the radiator cap or the radiator expansion tank cap and start the engine in idle and follow the water if is rotating. If not you have to check for your water pump if is working might have worn blades. Another possibility is the radiator or expansion tank cap faulty.

Hope this helps.
Good Luck.

Aug 28, 2014 | 2003 Mazda MPV

1 Answer

I have a 90 d-150 with low fuel pressure.


If you get a noise when removing the filler cap then there is a problem in the canister purge valve . Tanks should not pressurise as you suggest but be pressure neutral. Pressure regulators are subject to dirt and other ECM settings so I would run the fault codes first to find out where the fault is likely to be.

Mar 14, 2014 | Dodge D150 Cars & Trucks

2 Answers

Cant find the valve to let air pressure from my radiator for my water to flow right


FILL COOLANT SYSTEM UP BY POURING COOLANT IN THE EXPANSION TANK UNTIL COOLANT LEVEL STOP DROPPING IN THE EXPANSION.WHEN YOU POUR COOLANT IN EXPANSION TANK AIR BLEED OFF THROUGH THE SMALL COOLANT LINES GOING TO EXPANSION TANK.WITH PRESSURE CAP OFF RADIATOR COOLANT LEVEL IN EXPANSION IS AT FULL COLD MARK.WHAT YOU TO DO CRANK ENGINE UP LET IDLE WARM UP UNTIL COOLANT DROPS IN EXPANSION TANK KEEP ADDING COOLANT UNTIL STOP DROPPING STAY AT FULL COLD MARK.WHEN COOLANT LEVEL START RISING IN EXPANSION TANK.PUT PRESSURE CAP BACK ON RADIATOR.WHILE ENGINE IDLING WATCH TEMPERATURE GAUGE.IF START CLIMBING TURN OFF ENGINE LET IT SIT FOR LITTLE WHILE TAKE A LARGE RAG OPEN RADIATOR PRESSURE CAP A LITTLE AT A TIME TO KEEP FROM GETTING SCALDING TO RELEASE AIR IN COOLANT SYSTEM.WHEN PRESSURE IS RELEASED OPEN PRESSURE CAP ADD MORE COOLANT IN THE EXPANSION TANK.CRANK ENGINE AGAIN LET IDLE WHEN TEMPERATURE GAUGE START CLIMBING. TURN OFF ENGINE WAIT FOR WHILE BEFORE OPEN RADIATOR PRESSURE CAP.WHEN YOUR THERMOSTAT OPENS WHEN TOP RADIATOR HOSE IS HOT AND ENGINE COOLANT TEMPERATURE GAUGE STOP CLIMBING AND COOLANT LEVEL STOP DROPPING IN THE EXPANSION TANK.ALL AIR IS EXPELLED FROM COOLANT SYSTEM TO KEEP ENGINE FROM OVERHEATING.

Jun 10, 2011 | 2001 Cadillac DeVille

1 Answer

Over heats until I turn the heating on full but the heating not working properly


Sounds like an airlock in the radiator,which will require the system to be bled out. The old school way was to undo the rad cap to relieve pressure,put the heater on full,slacken the bottom rad hose so that it leaks and then stick a hose into the expansion tank. Turn the hose on slowly until a steady stream with no bubbles comes out of the bottom hose. Now nip the bottom hose up,and turn off the tap. The only problem with this method is that it will flush out a lot of your antifreeze so it may be best to get a garage to do it for you. You could also have a faulty expansion tank cap. These need to be air tight to raise the pressure and allow heat to be generated a bit like a kettle. Could just be a few pounds. I'd try the expansion tank cap loose first with nothing else, leave the car like this,running for an hour,with the heater on max. You may get lucky. There is a slim possibility your rad fan could be gone too, listen out for it kicking in.

Jan 02, 2011 | 2003 Volkswagen Passat

3 Answers

Can a worn out coolant cap cause overheating


There is no radiator cap on the Northstar engine.
The only cap is on the surge tank (or expansion tank) and is pressurized.

So the answer is Yes, a faulty surge tank cap will result in the loss of coolant and therefore lead to overheating.

The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.
If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.
The hose goes in to the engine to a crossover and comes out the other side close to the thermostat housing,the blockage may be there.

Jul 05, 2010 | 1998 Cadillac DeVille

1 Answer

I have a BMW 318i 1999 model. am having a problem with water licking. at first the water tank had a crack and i replaced with a new one. after i traveled for some 100 Km the Pipe from the water tank and...


Hi. Normally if the pipes or hoses are too old, it's normal to get burst especially if your car is lack of Service Maintenance. Another thing is if the engine is overheating and the expansion tank cap is faulty (stuck Close), the weakest parts of cooling system will burst.
When you replaced the damage parts I suggest you to replace Thermostat Valves as will. Also I would suggest after the repair to do Cooling System Pressure Test encloding Expansion Tank Cap pressure test, Bleed cooling system properly, Monitor Coolingling Fan and Engine Temperature Operation.
I hope this tip will help you to solve your problem and if it's still existing I hope you don't mind to inform me and I'll try my best to help you as much as I can.
Thanks and good luck

Mar 06, 2010 | 1999 BMW 318 ti

1 Answer

Low water cooling light comes on, everything seems ok at idle.


Sounds like an air lock in the cooling system, allowing steam to build up pressure and crack the expansion tank, this also suggests the cap on the expansion tank is faulty and not releasing the pressure early enough.

Aug 14, 2009 | 1999 BMW 318 ti

1 Answer

Putting water in a mini


From the top of the radiator (which is on the right hand side of the engine) beside the pressure cap there is a small hose pipe which leads to a plastic tank on the bulkhead.

This is called the expansion tank

On the side of the expansion tank is a level mark which shows how much water goes in there

If that is totally empty go back to the pressure cap on the radiator and unscrew it anti -clockwise (Only when the engine is cold and is not running).

Fill that up with cold water (Do you need anti-freeze in the water in your part of the world?)

Once that has been topped up replace the pressure cap making sure it is turned until it locks firmly then go back and fill up the expansion tank

Turn the engine on and let it run a while, water may escape from the expansion tank if you have over filled it.

If there are lots of bubbles and noises from the cooling system have it checked in case you have a leaky head gasket


Jun 12, 2009 | 2004 Mini Cooper

2 Answers

1991 overheating Towncar


If car heats up quickly and overheats , the problem is the thermostat. The thermostat stays closed and traps coolant in the engine untill it reaches about 185 degrees , than the thermostat opens and allows coolant to flow to the radiator where it is cooled by airflow. ( airflow while driving is usually sufficient ) while idling , or in slow trafic , the fan keeps air moving through the rad. The heater core is strictly for heat in the winter inside the car. The thermostat is the most likely cause of the problem , and even if it was good before , the overheat / boil situation likely cooked it anyways. I am assuming the water pump is still getting turned by a belt. No water circulation by pump would cause same symptom as bad thermostat. Overflow and expansion bottles are designed several different ways on different cars , but the theory is that as the engine heats up and the coolant expands , it goes to the tank. Later , as engine cools down after being shut off , coolant contracts. Radiator is replenished by coolant returning from expansion bottle.

Jun 04, 2009 | 1991 Lincoln Town Car

1 Answer

Water leak from top of expansion tank.2000 BMW 316i se


The water (coolant) in the expansion tank will rise and fall with the engine temperature. What the expansion tank does is collect and return coolant to and from the engine. When the engine warms up the coolant gets hot, builds up pressure and opens up the radiator cap. The coolant then goes into the expansion tank. Now when the engine cools down the pressure drops in the cooling system and the pressure drop (vacuum) pulls the coolant back into the engine via the radiator cap. The radiator cap allows the cooling system to build up pressure and by doing so increases the boiling point of the coolant, but when that pressure exceeds the caps rating the cap opens and the coolant goes to the expansion valve. The cap has another part to it that when the engine cools down and a partial vacuum is created in the cooling system a "valve" in the radiator cap opens and allows the coolant to be drawn back into the engine. I would look at your radiator cap to see if any gunk or build up is on it, and check the rubber gaskets for cracks. It's easiest just to replace the cap because they are inexpensive and easy to replace (2-10 dollars). The expansion tank should have two hoses on it. The one on the bottom comes from the radiator and the one on the top (possibly part of filler cap) runs down and is open to the ground. That way if it is overfilled or becomes overfilled it will slowly leak onto the ground. When and if you change your radiator cap, make sure the engine is cooled down, remove cap and start engine and turn heater to full blast, full heat. Leave the cap off and let it run until engine warmed up. This should burp out any air pockets that may have happened when coolant was changed. Also top off the coolant in the radiator while it is running. Hope this helps and good luck

Apr 03, 2009 | 1992 BMW 3 Series

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