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Daf truck leaking water at expansion tank cap and truck overheats

Posted by Anonymous on

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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

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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...

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

Overflowing from expansion tank on a 2003 chevy malibu

Have a cylinder leakage test performed to check your head gasket. It dosn't have to overheat to have a head gasket problem. A leakage test checks if looseing combustion gases to the cooling system which would presurise the system higher than normal which causes the tank to overflow.

Sep 30, 2012 | 2003 Chevrolet Malibu

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Hi i have a 2000 ford focus it seems that the water is bubbling over and then i have to refill the water every time i go on a journey what is the problem

Does it overheat on you ??? If not,, try replacing the radiater cap..Make sure the vehicle is cold before removing the cap..If that doesnt do it,,and the vehicle not overheating,,you may have a small combustion leak..Like a head gasket..But first try the cap..

Sep 25, 2011 | 2000 Ford Focus

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If expansion tank was low on coolant, will this cause my bmw to overheat? and where is the expansion tank located on my car?

Under filled cooling systems generally do not cause a "hot" running vehicle, there is most likely a mechanical problem some where. the expansion tank on all BMW's is usually a "yellowish" colored reservoir with a black cap, the only exception is the later models that have the expansion tank attached next to the radiator (they are black with a black cap.

Apr 26, 2011 | BMW 325 Cars & Trucks

1 Answer

Vehicle began to overheat, started wanting to stall, service engine soon light came on

check coolant fluid level, after vehicle is cool allow vehicle to run adding coolant/water till the tank is full, then let it run for one minute and shutoff, allow engine to cool and **** in fluid, and more water and coolant (dextron coolant) and start the vehicle back up after it has cooled complety down. with the cap off the coolant place hand over cap, if you get immediate back pressure this isnt from thermal expansion is from a blown head gasket. also for this check to ensure water pump isnt leaking, because the pressure generated by a blown head gasket will blow out water pump seals, if there is no back pressure, but a leaking water pump, just replace the water pump.

Aug 09, 2010 | 2002 Chevrolet Tahoe

1 Answer

My coolant expansion tank is overflowing after 20 minutes running

There could be a couple of reasons for this,

1. The thermostat could be stuck closed creating more pressure than normal. Your temp guage would show a higher temperature or you have another blockage in the system.
2. The expansion tank is too full.
3. The cylinder head may be leaking. If you fill the system run the engine to normal temperature with the radiator cap off, look for quite large bubbles coming out of the filler cap. If the head is badly leaking, they can be like a volcano. The temp will rise quickly from cold and the engine will overheat in a short distance.
It does seem odd that it would only spill over after 20 mins. Suspect that the expansion is over full first if your temp is normal. Let it run until it stops and see where the level is when the engine is cold.

Feb 17, 2010 | 1996 Mercury Sable

2 Answers

Water leak from cooling system, carn't see a water leak and have tried a bottle of rad weld, but its still loosing around a litre of water to every 50 miles. Any suggestions for self repair and where to...

If there isn't water obviously appearing from somewhere it's either a head gasket failure or radiator cap. Check the oil filler cap for emulsion. Just hope that it's the radiator cap.

Oct 20, 2009 | 1996 Volvo 960

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


replace your coolant reservior cap; the rubber ring has become brittle and "steams" the coolant out as you drive

Apr 21, 2009 | 1997 BMW 318

1 Answer

Water leaking from top of expansion tank.

have you replaced the bleeder screws? and the expansion tank cap they both have O-rings that compress and will fail over time also check the hose at the top of the exp tank it also has o-rings inside it

Apr 03, 2009 | 2000 BMW 3 Series

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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