Had this problem lately after doing the timing belt tension adjustment.
Mejo barat din ako sa coolant e. I use tap water as coolant only.
Before di masyado nagffroth. konting bubbles lang.
But yesterday was different.
the radiator filler neck is full of white froth (like coffee froth but its white).
what can cause this frothing phenomena?
started the engine cold with cap removed, no water gushing out.
no oil contamination in radiator.
no water contamination in crankcase.
no water contamination in A/T.
got no thermostat.
engine is 4d56T. water pump is vee belt driven (not timing belt driven).
head gasket is about 1 year old (i used the meiji brand, and i think an inferior gasket)
prior to this, months ago stream of bubbles (very very small sized) always show up. after topping it up with water, water level would go down after the air pockets come out. and so on
i have to admit also na hindi ko pa na retighten ang cylinder head bolts ko after the head gasket was replaced last year.
and i suspect that the bolts are coming loose and the engine is not yet drinking the cooling water.
my problem is that the head bolts are allen hex type bolts at wala ako mahanap na bolt wrench na allen that can be fitted to a 1/2 drive socket wrench.
what i did before was to cut an allen key and weld it to a socket. i made two pieces.
both fabricated wrenches failed during the removal and assembly. and you can't buy 1 pc of allen keys but a set.
seems more complicated pala kesa sa naiisip ko. i'm not sure pero baka factor iyan sa frothing sa radiator mo. aside from that wala na akong mai-susuggest since ikaw ang mas nakakaalam ng sasakyan mo.