huntsman

Alright so Im replacing my water pump cuz it went bad and while Im at it I will replace the thermostat and the serp belt and any hoses that are bad. Now I will drain the coolant through the lower radiator hose since either way I gotta pull it off to get the water pump out.

Anyway after I put it all together I gotta refill the coolant and purge/burp it to get the air out Im wondering how do you guys do it ?

Iv been reading and some people said to fill it through the radiator cap and then theres some coolant sending unit or something near the firewall, they said to loosen the screw up and fill the coolant up through the radiator cap and watch till it comes out that sending unit hole, this way theres no air in the system. I dont even know where that hole is at so I would have to research it and find it.

Now how my dad and uncle do it, is they told me to take the radiator cap off and fill it up, turn the car on while leaving the cap off, and it will keep burping and they said just to keep filling it up until it stops and is filled to the top.

Another way I read is to drill 2 small holes in the thermostat and I dont know how that works but basically it suppose to bleed the air out of the system by itself.

So how do you guys do it which is the best method, since I never did this I would like to know ?

Also is the overflow tank suppose to be empty of should i fill it up confused on that as well?

thanks everyone I know im in the right place asking these questions

freegdr

Burping is only for closed cooling system ,fill radiator start run untill thermostat opens then fill apply cap add coolant to full line in overflo bottle your done . recheck level in coolant over flo bottle next time is cold ...

RTorrez1

Like freegdr said you don't have to burp an open system.

huntsman

aha well thats nice

so just fill the radiator up, leave the cap off, start the car, keep filling until its full, close cap, and then u said to fill the overflow tank to the full line as well, if its an overflow tank why do we fill it ? I thought it was suppose to be empty for the most part but shiiit i dont know much, Im here to learn. So whats the reason behind filling the overflo tank ?

Unknown XJ

It allows air to get in your system.

PNWjeeper

^ if its not filled

freegdr

Expansion and contraction .......

huntsman

ahhh I see. Alright cool guys thanks for the help.

djb383

A properly functioning radiator cap is critical to the proper operation/function of an "open type" cooling system. The open cooling system rad cap has 2 valves and 3 sealing surfaces and again, all must function correctly and the entire cooling system must be leak free. The bottle and rad cap allow both coolant and any air to escape from the rad/cooling system as the motor heats up. Only coolant is allowed to return to the rad/cooling system as the motor cools.

freegdr

Exactly Expansion and Contraction

djb383

.....but 2 expand (escape) and only 1 should contract (return).

huntsman

wait wait so whats the difference between open vs closed cooling system how do I know which one I got ?

rmoore1031

Look at your radiator. Is there a radiator cap? If so, it's an open system. If no radiator cap, it's a closed system.

djb383

......and a closed system uses a pressurized (closed to the atmosphere) recovery bottle, a open system uses a non-pressurized (open to the atmosphere) recovery bottle.

robinz

Hear, hear ... I just went through this exact scenario on my 90 RENIX last month. The recovery bottle's behavior provided important clues while I was troubleshooting. Are you hearing gurgling noises coming from the bottle during operation (air in system)? If you remove the cap after a couple of hours of being off, is there still pressure in the bottle (there should be pressure)?

I followed ALL the aforementioned ways to burp the system and they all failed. It was only EcoMike on NAXJA that had the right procedure. A short synopsis of his procedure with some additional tips;

• Disconnect the heater feed hose from the water pump, at a spot between the two, to let air out, and disconnect the upper radiator hose at the T-Stat housing then fill the bottle to the top and let it drain into the radiator and the head & block.
• make sure the heater is turned on at the dash and make sure the heater hose vacuum valve does open so that the heater core fills with coolant.
• raise rear of vehicle (my added tip).
• keep the coolant bottle about 90% full.
• on the thermostat, drill two 1/8" holes in the flange 180* apart. Install with one hole at 12:00, and the other one at 6:00. This makes the cooling system self-purging of air (other source).

I also have a MAC's coolant bottle that is highly recommended.