aaz building pressure in the coolant......STILL!

[giulianot]

Update: So I bought  a new rad and replaced the rad and that seems to have solved the problem. I think that the old rad was restricting  of coolant flow and the coolant was by passing through the heater core only. I'm just really glad the problem is fixed and it was not a cracked block :oops:

[passatdiesel]

I have similar symptoms, what can a person do to verify if the radiator is plugged or restricted? Only starts to overheat when the engine is worked hard, if it's a brief acceleration, the heat slowly builds and disipates just as slowly. Gauge will slowly climb to 3/4 of the way on the temp gauge slowly, but then if not pulled over, will increase fast past that point, spewing out coolant out the expansion tank. Replaced the cap, hoses, thermostat, expansion tank. Verified that the thermostat works the way it's supposed to. I have the coolant drained, no discoloration or debri when draining. Also used a rad flush once on it. Is there any harm in just filling the rad with the rad flush mix and letting it sit overnight? I would just plug the bottom discharge off the rad. Wouldn't let the rad flush sit in the engine, only the rad. Just and idea.

[jtanguay]

I have similar symptoms, what can a person do to verify if the radiator is plugged or restricted? Only starts to overheat when the engine is worked hard, if it's a brief acceleration, the heat slowly builds and disipates just as slowly. Gauge will slowly climb to 3/4 of the way on the temp gauge slowly, but then if not pulled over, will increase fast past that point, spewing out coolant out the expansion tank. Replaced the cap, hoses, thermostat, expansion tank. Verified that the thermostat works the way it's supposed to. I have the coolant drained, no discoloration or debri when draining. Also used a rad flush once on it. Is there any harm in just filling the rad with the rad flush mix and letting it sit overnight? I would just plug the bottom discharge off the rad. Wouldn't let the rad flush sit in the engine, only the rad. Just and idea.

i doubt there would be harm by letting the rad sit with rad flush in it, but its not the way the flush was designed to work.  it uses the heat from the engine to help dissolve the buildup.  try using vinegar to clean really bad deposits.  it'll work somewhat good, but then try with hot vinegar, and it works REALLY well!  :wink: also the movement of the hot liquid will help break apart any deposits.  i've had it done on my car, and i let it idle a good half hour or so with the rad flush.  i used prestone's super heavy duty flush, and it worked GREAT.  i've never had so much heat out of the car  :lol: but i'm not sure if that flush will work if there is a complete rad blockage...  if its that far gone, a new rad might be a good idea

i'd be more inclined to buy a cheap rad as well...

[passatdiesel]

after pulling the rad out, I soaked it in some rad flush, but apon inspecting, i was able to force water from one side of the rad, where the fan switch is located to the inlet/outlet of the rad, so with that flow, i feel the rad isn't plugged up too much. From what i could see on the inside of the rad, it looked like a healthy aluminum color, little to no oxidation. Running my finger along the bottom of the rad, i couldn't feel any deposits. I've got the rad installed again, having the  switch out, i was able to fill the rad and get most of the air out, now it's just a matter of squeezing hoses, to work what little air is left.

[jtanguay]

after pulling the rad out, I soaked it in some rad flush, but apon inspecting, i was able to force water from one side of the rad, where the fan switch is located to the inlet/outlet of the rad, so with that flow, i feel the rad isn't plugged up too much. From what i could see on the inside of the rad, it looked like a healthy aluminum color, little to no oxidation. Running my finger along the bottom of the rad, i couldn't feel any deposits. I've got the rad installed again, having the  switch out, i was able to fill the rad and get most of the air out, now it's just a matter of squeezing hoses, to work what little air is left.

run the car with the rad cap off and give it a few good revs.  let the car get up to operating temp so the t-stat opens, and you should be good to go.

[Golf/Jetta]

I use a regular razor blade and stand it on edge to almost a 90 deg angle and drag it around the surface to be cleaned.

i use a 90 die grinder with the softess (used) surface conditioning disc. much faster.. just don't go crazzy

[Rabbit TD]

Also on the thermostats, I've had problems 2 times with anything but a German one.  Don't get these from Autozone or Advance