Coolant burping

[frankandbeans]

New guy here. I have a 76 with a AMC 304 . I changed out all the cooling system minus the radiator. I flushed it and has great flow through it. After running a little bit, when I shut it down the radiator overflow burps about a quart of water/coolant out. My temp is running around 210. Should I put a reservoir tank in to catch this? I guess my other concern is the fact my radiator camp is not holding it in.

 

[Purple77CJ7]

An overflow tank is a good idea. That way when the engine cools it will keep the system full. My experience with AMC v-8's, is some times they tend to get air pockets in the back side of the block when refilled and is hard to get out. Look into a new cap if it was not changed before, about a 14 lb. cap.

 

[frankandbeans]

I replaced the cap, forget what size though. It does feel loose though. What is the best way to get the air pockets out?

 

[Old Dog]

An overflow tank is a good idea. That way when the engine cools it will keep the system full.

You need the overflow tank. Without it the system will draw air back in instead of water when it cools back down.

 

[lutry]

I had the same burping issue.
When I flushed the cooling system again, I discovered that
the heat exchanger is clogged. After removing and cleaning it
with citric acid, all the burping was gone completely. And also
no loss of cooling liquid...

 

[mtnwhlr]

You should have a overflow bottle. You have a closed or reservoir cooling system. The radiator cap includes a second sealing gasket under the shell, which rests on the upper sealing seat of the filler neck. The normal overflow hose from the filler neck runs into the reservoir tank and extends to the bottem below the normal liquid level.
When the engine is started and begins to warm up, the coolant expands. As it expands, it is forced out through the pressure valve of the cap, through the overflow tub and into the reservoir.
When the engine is turned off and begins to cool down, a partial vacuum is created in the radiator by contracting coolant. The special upper sealing gasket in the pressure cap then allows this vacuum to draw coolant back into the radiator from the reservoir through the overflow tube.
Because of this back and forth movement of the coolant, practically all the air is eliminated from the system. This guarantees that the engine block, heater and radiator are always completely full of coolant, therby increasing the efficiency of the system.
Generally on a closed systems, coolant is added as needed only to the reservoir tank, instead of through the radiator filler neck. Because of this, car manufacturers have recommended that the radiator pressure caps on these systems not be routinely removed.
I hope this helps you understand how it should work.

 

[007]

My 77 with AMC 304 has no overflow bottle. What can I use?


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[mtnwhlr]

I may have a stock one that mounts on the left wheel well I will check tomorrow.

 

[007]

I may have a stock one that mounts on the left wheel well I will check tomorrow.

Thank you!


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[Purple77CJ7]

I went to NAPA and found a universal tank that fit in the space I had. Works fine.

 

[frankandbeans]

Thanks for all the help. I added a universal expansion tank and also found out my neck on the radiator is shot. Picking up a new radiator and hopefully that will be the end of that.