Vtx531

The two screws near the leak seemed a bit loose. I tightened up the screws a bit and the leak seems to have stopped and holding pressure.

Now to sort out the air in the system...

At 16 psi and sprayed with soapy water to show the leak...

Thank you for your advice I really appreciate it. So you think there are two issues...

1. Air in the system... say I use the vacuum fill method, do I need to completely drain the system first? I would imagine the answer is yes.

2. Bleeder valve... I could actually see air bubbles coming out the bleeder valve between the top half and the bottom half where there screws are. What would be the fix for this?

Regarding the vacuum filler: I rented a pressure tester from autozone today. It has quick connect fitting that attaches to the expansion tank. I wonder if I could come up with a fitting from the hardware store that would attach. The U-view looks to be basically a ball valve with some fittings and a length of plastic hose?

May try that later...

In the meantime, last night I drove around. Car didn’t overheat but did have steam escaping the cap. The part number ends in -00 so I will order a new cap. I don’t think there should be steam escaping if the car is not overheated. I couldn’t pressure test the cap because none of the adapters fit the cap.

Right now I am experimenting with the pressure tester. I pumped the cooling system up to 15 psi and as the pressure increase, the coolant level in the tank decreased. Is that normal?

It started loosing pressure slowly but it looks like the pressure is escaping the bleeder valve. The metal pull tab isn’t doing anything because the pressure is causing the valve to pop up automatically. Is that normal?

Seems to have leveled off at about 12 psi and not loosing pressure any further. When I let the pressure out, the coolant level comes back up and the bleed valve closes. Upon adding pressure again, the coolant goes down. Looks like the bleed valve starts to open at about 4 psi.

Tried refilling again with the burp valve up (with distilled water for now). Still overheating after about 2 miles. The needle sorts of climbs slowly then gets jumpy and goes to the right.

Looks like the tank could use more coolant. If I try to remove the cap, steam comes out and then the coolant level rises back up on its own and will overflow if I don’t replace the cap. So unable to put more coolant in.

Now that the car has cooled down, I went out to Discover the tank was low and I could remove the cap and it stayed low. So I topped it off again.

Do I need to just keep repeating this procedure of warming the car ip and letting it cool and refilling?

The videos and writeups I have read about filling the coolant don’t really mention this problem. They make it seem like you can fill it up and drive normally (without overheating) and just keep topping it off over a few days.

I guess that could explain why that hose going “out” of the thermostat doesnt feel hot.

So cooled return fluid goes into the thermostat? Is that the opposite of most vehicles?

Thanks I already opened the vent valve and drove around and refilled with coolant multiple times but that didnt seem to help.

Is that large hose coming out of the thermostat supposed to feel full of coolant and hot when the car is warmed up? Could there be a blockage?

I dont really understand and couldnt find a diagram of the plumbing for the cooling system so I don’t know what hoses are what.

i am thinking I need to take off all the plastic underbody panels and check fo blockages but hard to imagine that both radiators would be blocked, there should still be some flow I would think.

It has already had the waterpump, thermostat, and coolant temp sensor replaced by local shop (prior to me buying it).

It seems like the large hose coming out of the thermostat is not getting hot and not filling with coolant (when the car is warmed up). I put my hand on the hose and it is hot near the thermostat but not further down the hose. Almost feels like it is full of air, I can squeeze it and there is pressure inside but doesn’t feel the same as the other large coolant hose.

I tested the thermostat in boiling pot of water and verified it is opening.

I can hear the fans running. Fan fuses are good.

What should I check for next?