help overheating

[tom4bren]

Bubbles in your radiator is not a good thing. What was going on at the time is important though.

Was it just a couple of small bubbles or were they big bubbles that just kept coming?

Was the engine hot at the time?

Was the radiator full?

I recommend you start over with the basics. Start with the most basic first.

Check to make sure the radiator hoses are OK (you can even do that before replacing the thermostat). With the engine at operating temperature, make sure neither of the hoses have collapsed. It doesn't sound like that is what your problem is but check anyway.

Take the VX to a radiator shop & get the radiator flushed & pressure tested. They'll should be able to spot any potential problems if there are any.

Most often the thermostat is the problem. Even though it was just replaced, do it again & get an OEM replacement from Isuzu (they are almost always better than the aftermarket ones from the box stores).

[etlsport]

I think that what he is talking about is when taking the pressure cap of the radiator bubbles come up in the overflow tank. That is probably a good thing. Means that the radiator is holding pressure.

[tom4bren]

I didn't get that. It sounded like the bubbles were in the rad.

Flushing the radiator probably won't help but considering the age of the VX, it's not a bad idea.

I'm trying to think of anything, other than a blown head gasket that would cause those bubbles. Since his oil is clean, I'm kinda leaning away from the head gasket.

If the lower hose is collapsing when the engine gets hot, that could be restricting the flow to the point that it overheats (boils) and the bubbles are actually trapped air in the system that are just working their way out. Of course, if the thermostat is staying closed then the lower hose could still be collapsing even if there is nothing wrong with it.

http://www.dummies.com/how-to/conten...Id-131604.html

Hey, it's a starting point.

[zadam123]

I took of the radiator cap While it still was hot The overflow tank started overflowing And some bubbles c.ame from the radiator 4 a second or 2. It doesn't look like any hoses collapsed. If it is the head gasket has anyone had it done and how much?

Is there any definite test to see if it's the head gasket,watter pump, thermostat, or even radiator. My mechanics guessing games are costing me a fortune

[tom4bren]

To test the head gasket, you can pick up a compression tester at your local auto parts store & check the compression on each cylender. That would be the first indicator but only if it's a major leak. You're better off taking it to a garage to get them to do it and to perform a bleed down test at the same time (not sure if the guage you pick up at auto parts will be adequate for that).

I'm still leaning towards the thermostat. It's not unheard of to get a bad one out of the box. If you do go that route, make sure they bleed the system like Ascinder mentioned. Does anyone know the procedure for that on our VX? Even though it's not easy on our beloved VXs, it is something you can do at home. That should save you a few $$$.

There is no test for the thermostat without removing it. Same for water pump. Radiator can be flushed & pressure tested.

I feel for you zadam. I replaced the thermostat twice on the Eclipse, the water pump & timing belt, 2 temp sensors ... all were fine. It appears that it's just a relay that's causing my problem. That's not your problem though since your fan is coming on (mine's not).

[Ascinder]

Almost sounds like the mechanic failed to completely bleed out any remaining air when he did the thermostat. Your system may be trying to purge it. Do what Tom said and take it to a radiator shop(not the mechanic) and tell them the story.