Is it possible to get an air lock in my engine cooling system in my 394?


With my 394, I dumped the coolant from the radiator, put a cleaner in, drove it for a few hundred kilometres. dumped the water from radiator, undid the valves at the bottom of the block. The water was chocolate coloured. Removed thermostat housing and put the hose in for about 20-30 minutes until water ran clear from the bottom valves.


Thermostat and housing back on.


Filled radiator. Thermostat was closed so ran car for a very long time, even went for a drive. Came back, radiator still full, took thermostat housing off, thermostat was open, so thermostat works .


There seemed to be a hell of a lot of water came out of that block when I first dumped it, but now only enough goes in to fill the radiator.


Is this motor prone to getting an air lock on coolant re fill?
Is there a pressure relief valve at the top of block?
Should I leave one of the bottom valves slightly open until re fill complete?
Any suggestions?

I checked the manual and Technical Information Bulletins I have but nothing is listed nor mentioned.


Thanks
John.

 

Maybe. I always fill from the thermostat housing if I have drained the block, then install the thermostat, housing and hose and then fill the radiator.

 

Also when you start it up leave the cap loose, so the air can come out.

 

This was my next try before releasing a valve to fill, thanks for the confirmation, I'll be giving that a go.

 

Thanks 442Harv, I had the radiator cap off to see what was happening to the water, being a large engine took some time to get hot and after water not going down took car for a run (with cap on tight).

 

Normally an air pocket will show up as a rapid increase in temp. for the gauge. I've found with stubborn air pockets that if you stuff a water hose into the radiator with moderate flow it will force it out. Then I would double check my anti freeze .

 

Temperature sensor won't show how hot the engine really is if there is no water on it.

Best to check if your getting heat inside the car using the defroster, that will tell you if you have at least enough coolant as to not over heat the engine. You can then either loosen the thermostat housing or wait and squeeze the top rad hose once the thermostat is open. Could be some debris has loosened and plugged your thermostat or even part of the water jacket somewhere. It's always good to know how much coolant you added vs the system's capacity to be certain.

 

Just tried to fill from thermostat housing, took about 2 litres of water at most.

 

I never fill from the thermo housing as it is below what the normal level should be in the radiator.

 

If coolant system is drained completely, with a cross flow 2 row rad I put 4 litres in the rad or till you see it at the top of trans cooler.... no higher.... then fire the car up, leave it on high idle until you see the antifreeze flowing through the tubes, at that time I put the front defrost on high feel the heat coming out, thermostat opened, no heat thermostat not opening ( replace) kick it down off high idle, let the antifreeze level out idling, fill rad to the top let idle for 5 min allow to purge itself for final fill. put a pan under the car to catch the overflow. Once it has purged top up on medium idle put cap on good to go. !! top off overflow bottle Hope this helps.
( x2 I wouldn't start filling at the thermostat passage)

 

Instead of using regular tap water for the rad, I use distilled water or water from my de-humidifier, and mix 50/50 with anti-freeze.

 

When I first got the car, the heater was leaking onto the passenger floor (dripping). So I by-passed the heater by running the hose from heater tap to water pump, totally missing the heater.


Would this make a difference?

 

Nope.

 

Didn't think so, done this before with no dramas.
Thanks.

 

The reason top fill from the thermostat is to get it into the engine before the radiator is filled. After filling from the thermostat, you seal the housing and connect the hose and continue filling at the radiator. With the thermostat housing installed before you fill it, there is a chance that air is trapped in the engine block, not allowing coolant to fill the block. Running an engine with air trapped in the engine block can heat it up very quickly, before it burps and fills the block.

 

as a rule, whenever i replace a thermostat(part of a cooling system clean & flush) i drill a 1/8" hole in the outer diameter, inboard of the sealing ridge, of the thermostat, if it doesn't have one already. this allows air to bleed while i fill the system. as stated above, "burp" the cooling system with the radiator cap off and the engine running until no more bubbles appear at the filler hole of the radiator.


bill

 

Yes,
Completed 76olds' trick along with brown7373 all to no avail.


Hi Bill, brown7373, she obviously hasn't "burped" as level not gone down yet.


Anything else to try?


Would there be a plug at the top of the motor to let excess air out? I cannot see one.

 

Did you try sticking a water hose into the neck of the radiator with it warmed up and force the bubble out? Works every time.

 

last thing you want to do is to add cold water to a hot engine.

5998, i would do the bleed hole thing i mentioned, there can't be any air in the motor after you do that. after that, burp the car by running it at an idle until no more bubbles appear at the filler neck of the radiator. grab the heater hoses to feel any air pockets in them. you shouldn't feel any percolation in the hoses.

bill

 

you may want to check the water pump , or the tubes in the rad have too much hard water build up around the tubes which wont allow the coolant to flow properly. You may want to take the rad out and do a flow test. Stand the rad up rite fill it with water blocking the upper hose neck off with your hand and see how quickly the water comes out. Poor flow = recore . Try what Eric mentioned as well the hose trick first. Also as bill mentioned drill a 1/8 hole in the stat .

 

Chocolate colored coolant sounds weird, what type of rad flush did you use? Sounds scary !! Head gasket ? Since you ran the car with the heater bypassed the car would run hotter since one heater hose runs thru the passenger side head/intake the other hose either runs to your water pump or the heater hose connection on the rad if your car has air. I would do some checking.

 

No air on this car, hose runs to water pump. I'd say the water was just old. I used Barrs radiator cleaner, a granular powder type.

 

No air so it should be a 2 row correct ? Tubes look ok ? Not too much white hard water build up ? The only thing I would assume at this point would be the lower part of the rad is plugged up with sludge and possibly the powder. Or the prior owner put to much stop leak in and its blocked something up. In that case I would pull the rad and do a flow test . I don't like the powder type rad cleaner myself . I like Wynns rad flush myself .

 

I think its a 2 row. Tubes look good. That's always a problem I worry about with older motors with the stop leak. Good idea with the liquid cleaner for next time though.


The radiator/motor took just over 12 litres this arvo. Around 13 U.S qts.


The heater I have bypassed has to be a litre or so, the book doesn't tell me, perhaps someone has a guestimate on this?


I will check the bottom engine valves tomorrow and see if any water comes out.

 

The radiator/motor took just over 12 litres this arvo. Around 13 U.S qts.


The heater I have bypassed has to be a litre or so, the book doesn't tell me, perhaps someone has a guestimate on this?

12 litres is a lot of coolant for a 2 row, you must have a 3 or 4 row, Usually 8 litres max in a 2 row. I hope you found the problem !!

 

The radiator is fairly wide, its like the one I have for my Chev. 3 or 4 core as you say.


She has taken about 13 litres so far and that seems the capacity minus heater core. I released both bottom valves on engine and water came out. So she appears full. I will be driving this weekend and see if it releases any further air locks if any.

 

What do you mean when you say you released both bottom valves on the engine and water came out ? I never heard of that before. Do you mean you have 2 drain ***** at the bottom of the rad?




I hope the air lock has worked its way out, good luck let us know how it goes .

 

[QUOTE=76olds;648972]What do you mean when you say you released both bottom valves on the engine and water came out ? I never heard of that before. Do you mean you have 2 drain ***** at the bottom of the rad?



No, 1 **** at bottom of radiator.


2 ***** on bottom of engine block. The 394 has 1 each side just above sump towards front of the engine.

 

hi 5998,

I had the same thing with mine, the stuff in the radiator looked like a chocolate smoothie !
I also ran a cleaner through it and then flushed it.
I did this by removing the bottom rad hose and the heater hose that come out of the head on the passenger side (open the heater tap)That way I could flush the heater core by putting the hose in the heater hose, then the block by putting the hose in the heater tap.
I replaced the bottom rad hose put my finger in the heater hose and filled it from the radiator letting it run out of the heater tap before replacing the heater hose onto the tap.
The biggest problem with these cars is the lack of a temp gauge, so its really hard to tell what they are doing.
I fitted a TM4 Engine watchdog to mine ( hidden in the glovebox ). This gives you a digital read out on the engines temp and a settable alarm.
This saved the car when It caught fire as the alarm went off instantly , the fire is hotter than the 100 degrees and set the alarm off meaning I got to it very quickly.
Cheers Scott

 

Pic of the Engine Watchdog

 

Thanks Scott,
Radiator water was fine, engine water dumped from block was choccy colour. I have bypassed my heater core so no need for me to worry there.


Thinking maybe the heater tap may be blocked or not working, I have the hose from the water pump running to it.

 

There is a new old stock heater tap on ebay at the moment, brass one.
Do the non AC cars run a vac operated heater tap?

 

Yes, there is a tube going from the back of the bell to the firewall, to the controls.