rx7boss

iTrader: (2)

Hello all i have a 93 rx7 that has been sitting for 2 years I checked the coolant before starting it.I noticed it was low so i filled it.Problem is that I run the car let it sit check it the next day and it is low again.Where is it going?How often do heater cores leak?How many lbs of pressure could I pressurize the coolant system to find the leak?

sandy_RE

does it blow any smoke?

if there is no leak you can find than the coolant is probably low
top it up and bleed the air bubbles out of the system and see if it fixes the problem.

the safe lbs of pressure should be on the radiator cap.

rx7boss

iTrader: (2)

It doesn't blow smoke right away,but after about 5 min of idling white smoke does come out for about a min.Do i need to get the thermostat to open to pressurize the system or can I do it while its cold?

TomU

iTrader: (11)

If you don't see any under the car, it's probably being burned by the engine caused from a blown coolant seal. Search that to find ways to confirm.

rx7boss

iTrader: (2)

tnx for the help

rx7boss

iTrader: (2)

so I found out that the coolant seal is good.thank the lord!but im suspecting the heater core.Do these leak a lot?

sandy_RE

whats the car doing now is the coolant still going low??

check to see if the passenger side footwell is wet, if it is then the heater core is leaking
or it might be dry if its a small leak.
and heres a vid of how to remove it if your keen, the car in vid is RHD but I dont think itll be that much different.

rx7boss

iTrader: (2)

Yeah its still going low.I'm trying to find a diagram of the way the coolant flows in the car engine and radiator.My plan now is to vice grip the lower hose in front of the heater core just to see if the pressure drop stops.What do you think?

sandy_RE

the coolant flows into the top of the radiator then out the bottom hose.

is it dropping off a little bit or heaps?

is it dropping pressure when doing the test?
im not sure that clamping the hose would do anything as the coolant probably would not flow through the whole system.

if the coolant is only dropping a little bit keep topping it up and running the car to temperature
then let it cool down and if its still low, top it up again and do the same thing, you might have a bit of air in the system.

if that doesn't work then go over everything easy to get to again and make sure nothings leaking. otherwise if everything looks alright and you reckon the water seals are good then it probably is the heater core.

TomU

iTrader: (11)

Rent a coolant system pressure tester from an auto parts store. Pressure test as-is (let it sit a while, even over night). Check any loss. Bypass the heater core (or plug the inlets to the engine), then pressure test it again. If there's no difference, it's not your heater core.

sandy_RE

yea good idea to bypass the heater core and see if that changes anything then youll know for sure if you have to replace it.

lOOkatme

iTrader: (19)

My car was recently leaking coolant out the radiator cap. I smelled fluid and I couldn't figure out why I was losing fluid. I started looking around and the coolant was coming out the bottom of the radiator cap and going over the housing only when it was hot and pressurized. was enough to lose coolant but not enough to ever hit the ground.

rx7boss

iTrader: (2)

I also have been suspecting the radiator cap,but I need to get the adapter to test that.I didn't have enough time to bypass the heater core today I will keep you guys posted on what I come up with tomorrow

TomU

iTrader: (11)

Test the cap first, that's easy. Or, just get a new one (but I've heard that new does not necessarily mean it's good)

rx7boss

iTrader: (2)

Like most things now adays! (new doesn't necessarily mean good)lol

Sgtblue

iTrader: (16)

Going back to your initial post...exactly how low was the level the next day?

rx7boss

iTrader: (2)

an oz.Wierd thing I found while pressurizing system i heard a bubbling sound in the hose from thermostat to ast.So i took off and tried to find a hole so i blew through the hose and it was blocked to the point where very little air would go through. i had to take a screw driver to clear it of sludge.I think that may have been keeping an air pocket that may have been throwing me off.I ran out of time so we will see if that fixed my issue.

sandy_RE

does the car overheat at all??

change the hose, bleed the system again, top it up and see if it stops.

once its fixed id be flushing the system out and using fresh coolant, theres probably more of that sludge in the rest of the cooling system.

Sgtblue

iTrader: (16)

Only one ounce? I doubt you're losing coolant.
You will never be able to keep the coolant level at the filler neck full. You can fill it up right to the cap and it will always fall the next time the cap is removed. The overflow bottle (not included in that diagram above) is at a lower level and the vacuum that draws coolant back out of it as the engine cools isn't strong enough to draw it back all the way up to the level of the cap on the filler neck. You can keep filling it up, and that ounce or so of coolant will simply stay in the overflow.
It might need flushing, but if you're not overheating I'd stop worrying.