You only need to drain it from the petcock when draining the system. You do not need to drain it now. Volvo red blocks can get air pockets (especially in the heater core) but are not difficult to bleed. Open the heater valve. Fill the reservoir to a normal level. Give the lower hose a few squeezes and if bubbles come up to the reservoir lowering the level bring it back to normal. Run the motor while keeping an eye on the temp gauge and feeling when the thermostat opens (grasp the upper hose to tell). Most times you'll see the temp gauge rise just before the thermostat opens--then it will drop as the coolant in the radiator moves into the block. While it's warming up check to see if the heat comes up (set to defrost for an easy reach). Give the lower hose a few more squeezes. If it hasn't come up by the time the thermostat opens hold the idle high (2,000 rpm or so). A minute or two of that will push an air blockage out of the heater. Top up the reservoir when done. -- Dave

'' I also have some Prestone antifreeze flush with water mixed in there now. Is it possible the cleaner did some damage to a head gasket? ''


I suggest you get totally rid of that antifreeze flush. I believe these contain aggressive chemicals that will clean surfaces almost to bare metal. Any left may corrode your radiator and worst of all your heater core.

The way I proceed is as follows: I flush old antifreeze every 3 years and never use any chemicals. I open heater control valve, I disconnect the bottom rad hose, open the block drain valve,remove the thermostat. I disconnect one of the heater hose and flush with very low water pressure from the garden hose. Heater core must not be exposed to pressure more than 5 psi. I also flush engine through the thermostat hole and then flush radiator. It is a good idea every 6 years to remove the rad, lay it flat and spray a strong jet of water to expel sand, small rocks and dirt out, and at the same time check its condition.

I reconnect everything except I leave the thermostat hole open and watch the new coolant level in the engine hole. When liquid level is close I then install the thermostat with blue silicone on the gasket. I found this makes a good seal. Also, I put never seize on the 2 nuts.

I calculate how much coolant and water I add. I use distilled water or dehumidifier water. I let engine warm up with heater valve open. For a couple of days I carry a quart of coolant mixture in the trunk to top up if necessary.

This works for me.

Hi there, thanks for the mutual comment.

I thought about the possibility of a hot engine coolant change for a moment.

I have never thought about doing a coolant change under enough to enough heat that there was pressure! I seriously doubt you could have done that so the engine must have been somewhat cool?

Even with it nicely warm, by the time the old coolant left and you were able to refill it, the head would have lost heat.
Besides when you refilled it ,the new coolant comes up from the bottom of the cooling jackets and lastly into the head.
Aluminum gives up heat rather quickly compared to the iron. The iron would have warmed up the coolant as it filled.

As far as using a cleaner flush for a coolant system, my heart does not, warm up, to using any kind of thing like that.

If the system was maintained correctly there will never be a need for it ever!
Distilled water keeps rocks out and the newer GO5 OAK five year formulas are the way to go, since you got to go with them!

I stay away from pre-mixed as well!
They don't tell you squat about what kind of water source they use!
It's not their car and definitely no warranty of being better than the straight stuff.

Just easier for the "not knowing groups." Just as expensive as the straight stuff, that use to be only $7-8! The "Jack the Price Up" game was used against all customers, no matter the brands!
The Shipping and Handling costs, to put both on the shelf, are the same.

Hello, you still will need two gallons and what to do with the extra bottle you paid for? Crazy stuff, for the lazy & rich credit card bone heads!

I was told, by a radiator shop professional, that the cleaner flushes that Prestone makes is the best thing made for increasing their business.
You cannot or should not ever clean a block with a radiator attached. They make more powerful pumps and solutions that get totally removed not just sort of neutralized for that purpose!
Engine rebuilders use a dip tank IF it gets that far anymore!

Whatever was in the block, that might never ever get moved by normal pump circulation, goes right directly out into the radiator.
The radiator has small passages that act just like a trapping filter. They have seen loose deposits freshly laying right on top of tubes or on the bottom sides in our case.
The flow in the radiator was already to slow or spread out to go anywhere else to far from the pump!

If it plugs the tubes, then it's remove the radiator time!
Repair by Rodding or replace it all together.
Replacing is twice the cost but if the fins are flaking off, replace it!
Aluminum and "O" ring plastic capped ones are usually are not repaired!

If the engine is overheating to begin with its the thermostat, radiator or a pump!

After talking to him I realized that those "parts shelf cleaners" are like the modern invention used by plumbers, called the center piece of "sliced bread!" About as cheap to make too!

If they have a copper line dripping water that they want to solder up joints on, they pack it lightly it with bread and solder away!

When done they turn on the spicketts and the water turbulence flushes the wet bread out!

That is unless, you have washer hoses with screens and ice makers down the line. :-)

Always a caveat somewhere, like a radiator!

Just read your other post while I could still Edit!

Check the wiring to the front sensor. That wire can get flaky up to the gray firewall connector.

Squeezing the top hose should help burp air and show a level movement in the coolant reservoir.
Open the heater valve the next time you drive.

Air should and will rise to the highest point in the system after stopped.
The top hose is about as high as you can get.

Ongoing edit :-). Volvo from Heck covered it too! My aren't we active today!


Phil