Hello everyone,

i have a problem with the water temperature on my 1993 rx7 fd. The problem started after converting the FMIC to V MOUNT.
{Before the v mount conversion the car had a lower thermostat than stock, and during the conversion it has been replaced for a stock one. Also, before the conversion the water pump was not functioning properly and it was also replaced by a new one.}

The car was running fine before the v mount conversion, but when the mechanic finished the conversion he informed me that he did a lot of effort to take the air out off the radiator water system circuit, but air appeared to still be inside. He then gave me the car back and told me to try to take the air out of the system.
I drove the car and noticed that the radiator fluid level buzzer was starting sometimes when i was on low rpms, and then i was rising on medium rpms steadily and the buzzer sound was stopping. Some other times mainly on low rpms the buzzer sound was starting and also the needle of the water temperature was going swiftly towards the H indicator and after a few seconds, it was dropping instantly to the normal temperature. This is the point where i decided to park the car for a few months. After 2 months i decided to start the car's engine and leave it on idle to see what happens. I opened the water cap and noticed that the water level was low and it needed around half a litter to fill up. I filled the water and started the engine and let it work on idle for 10 minutes, then i started revving it up to 3-4k rpms and everything was working normally, so after that i drove the car for around 20miles / 30km and everything went fine, water temperatures fine, no buzzer sound. The next day i opened the water cap and it needed again around 300-500ml of water so i filled it up, then drove for around 20miles and everything again was fine. The third day i filled the water again around 200ml and drove it for 10km, everything was fine untill i stopped to the gas station and then had to do a warm start to the car. The buzzer sound started almost immediately after starting the engine and was being activated when i was moving on low rpms, as soon as i was going to medium rpms the buzzer sound stopped. The fourth day i filled a bit of water and i went driving but after 2 miles the buzzer sound was activated and also the water temperature needle went two times to the highest point and then dropped instantly to the normal temperature. I noticed that when the water temperature needle raised, water was being poured on the street from the plastic water tank overflow. (like air was pushing the water out of the overflow.)
I noticed that with the cold starts i was having the opportunity to open the water cap and refill the lost water, whereas when i stopped for gasoline refuel and then did a warm start, the problems began, ( radiator water spilling to the ground through the overflow, water level buzzer sound and water temperature needle rising to the full)

Sorry for the long thread, i believe it may help on the identification of the problem.
If anyone can help i would highly appreciate it. I also appreciate anyone reading this thread.

Thank you in advance!
George

 

paragraphs are helpful.

bleed your cooling system properly.

 

Which Vmount setup did you install? Post some pics.

Sounds to me like there is a leak (or multiple leaks) in the cooling system. Which makes me wonder what Vmount kit you used and what parts were used on the cooling system and the competency of the installer.

 

First off, welcome to the club!

A fabricated V-mount setup may not be in an ideal configuration for water to bubble to the top. With a kit like the GReddy V-mount I wouldn't expect problems getting air out.

That said, look into getting a Lisle funnel. Lots of threads on it, really helps to get all the air out of the system. Plain and simple, you WILL have cooling issues if there is air in the system. If there's a high point in the system that is trapping air that could be a problem.

Dale

 

My experience – I think I finally have it beat on my conventional system.

1. Pressure test the system and make sure that it holds pressure. Test cold first, then hot just to make sure. My aftermarket air-water separator had a corrosion channel in the radiator cap seat.

2. Make sure that fluid in the overflow tank is getting sucked back into the system as it cools. I used a bit of clear PVC tube plumbed in series with the overflow hose. The radiator cap housing on mine was holding the return flap on the radiator cap closed. Air was being slowly sucked in from somewhere during cooling. (Pressure test at that stage was OK)

3. Are you running an air-water separator? You need one. Is it mounted as high as practical

4. Is there a restrictor with built into the air-water separator tank or the hose back to the radiator to slow the return flow? I used a 2.5mm (3/32”) orifice.

5. The funnel mentioned in post 4 helps bleed a lot of air out of the system but it doesn’t get it all. You will still need numerous top ups over the following days. Burping the radiator hoses and venting the lines to the idle control helps

6. I recently used a vacuum filling system and the fill was a lot more complete as in there was a lot less subsequent topping up required. Just make sure that your aftermarket hoses can withstand or recover after a full vacuum application.
7. An air pocket will form between the filler cap and the take-off hose to the air-water separator. The air-water separator can’t remove this so its appearance should not be a concern. Just keep topping up until it no longer forms

 

The radiator is pwr.

 

air separator looks like it's below the thermostat housing.
you should probably raise it.