Help, cooling system not circulating

[JHarris1385]

I just followed this process and still have a lot of air pockets in my coolant. I noticed once I shut off the engine and popped the radiator cap off there was bubbling in the overflow box. I may have gotten a half gallon of juice in her.

Did you try replacing the radiator cap along with all of the other items you mentioned, (or did the new radiator include one?). If the cooling system isn't kept properly pressurized, all of the hot coolant from the system will simply rise quickly to the top of the radiator because it's boiling. A properly functioning radiator cap that keeps the system pressurized will keep all of the coolant in a liquid state though.

It's also important to ensure that no air pockets formed during the coolant filling process.

• Fill the coolant slowly with the engine off
• When the radiator is full, then fill the reservoir to the "Max" mark
• Install and tighten radiator cap
• Idle engine for 2 to 3 minutes
• Stop engine, reopen radiator cap (Carefully!! Hot!!, and refill coolant level if low
• Tighten radiator cap and warm up engine at about 2000 rpm
• Set heater to highest temperature position to allow coolant to circulate into the heater water system
• Make sure thermostat is operating (radiator hoses should get hot)
• Idle engine for 5 minutes, then shut off
• Allow engine to cool, remove radiator cap, and refill coolant level if necessary

I don't know if I've ever seen a fitting on or near the thermostat housings on a VX that allow a person to burp the cooling system when adding coolant (the engine on my car has one), but if a cooling system is filled too quickly and air pockets form in the cooling passages, overheating can occur. That possibility and a faulty radiator cap are my first two guesses anyway.

[tom4bren]

J,

It's not uncommon for the radiator reservoir to boil when an engine overheats. That's probably what you're seeing (not trapped air in your cooling system). Even if there is another problem with your cooling system, you need to replace your thermostat. If your engine overheated to the point of boiling your antifreeze, your thermostat is almost certainly cooked.

My recommendation is to get your radiator professionally flushed, replace the thermostat (or better yet, removed from OEM location and put in one of those inline thermostats that deermagnet posted about). Try running the engine again & if it still overheats, then it may be time to replace your waterpump.

[JHarris1385]

Was the above the best procedure to filling my radiator? I flushed and ran some gasket leak repair in it.

[tom4bren]

Was the above the best procedure to filling my radiator? I flushed and ran some gasket leak repair in it.

That would be the procedure for a 'problem' car. Normally a cooling system is self purging so you wouldn't have to go through all of that. You'd just add coolant as needed. If for some reason your particular engine is overheating, then Yah, the above procedure should be followed to eliminate the variable of trapped air in the system.

Keep in mind as well that the 'gasket leak repair' that you added could clog some of the tubes inside your radiator if you already had a corrosion build up. That's why I said that you should probably have your radiator flushed (to eliminate that variable). A garden hose flushing will probably not help in this situation.

[Y33TREKker]

Was the above the best procedure to filling my radiator? I flushed and ran some gasket leak repair in it.

It's based on the filling procedure taken from the Isuzu manual, and not necessarily just for vehicles with possible overheating problems. The main idea behind it is that overfilling any cooling system too quickly can cause air pockets, which can cause overheating if they're not eliminated.

[tom4bren]

It's based on the filling procedure taken from the Isuzu manual, and not necessarily just for vehicles with possible overheating problems. The main idea behind it is that overfilling any cooling system too quickly can cause air pockets, which can cause overheating if they're not eliminated.

We'll have to agree to disagree. On most cars, as long as there is coolant in the reservoir, normal driving will allow any air in the system to go into the reservoir and be replaced with coolant the next time it cools down. If that ain't happenin, then there is a design flaw or there is something FUBAR in the system. AFAIK other than the PITA thermostat replacement, we don't have any design flaws in our cooling system that would cause trapped air pockets.

I'm not disagreeing that it's what's recommended by Isuzu ... or even that it's not a valid process. It's just way over the top for regular maintenance.

[Y33TREKker]

We'll have to agree to disagree. On most cars, as long as there is coolant in the reservoir, normal driving will allow any air in the system to go into the reservoir and be replaced with coolant the next time it cools down. If that ain't happenin, then there is a design flaw or there is something FUBAR in the system. AFAIK other than the PITA thermostat replacement, we don't have any design flaws in our cooling system that would cause trapped air pockets.

I'm not disagreeing that it's what's recommended by Isuzu ... or even that it's not a valid process. It's just way over the top for regular maintenance.

Agree to disagree then, since the process listed was simply meant to minimize the chance of any air pockets forming during the coolant refilling process, not the steps required to check the coolant every time a person wants to check the coolant.

[tom4bren]

Agreed - we're both too bone headed to give in

[Y33TREKker]

Agreed - we're both too bone headed to give in

How can you say that when we've not even been talking about the same thing?

[JHarris1385]

I am riding with a jug to work tomorrow to see where I am at after a 10 mile drive.

1/2 gallon or so in the radiator and filled to the max line in the res. tub.


I flushed with a prestone product and then put some head gasket repair in (did not work) and then rinsed her out with the hose and refilled with the amount above.

Looks like I need a professional flush, and a thermostat replacement.

Might as well do water pump, timing...etc while I am in there. Should be an adventure!

[EVO]

Not very likely but I have had the misfortune of installing two bad thermostats!! Drove me nuts!!