Before you get after me I was not the one who installed it, I bought the car like this. I have a 1988 N/A (GXL I think) it has a replacement S4 engine but I do not know from what year.

The person who I bought the car from did not have much of a history on the car but believed that if it was after market it was better. So the car has a super thick aluminum radiator that could cool a big block V8 and a electric fan that does not even pretend to fit well. There is a 3/16" tube coming off of the thermostat neck that feeds into what I believe is the stock overflow tank after that there is a tube that goes from the overflow tank to the radiator.

Now the problem is not with overheating I do not believe there is a blown coolant seal issue as the exhaust does not produce any smoke after the first five minutes of fuel rich rotary warm up fumes. However, there is a substantial amount of air in the system which requires my having to add coolant every time I drive the car. I have tried bleeding the system multiple times to get rid of the air even so far as jacking the front of the car up, filling the system up until the disconnected top heater hose line started leaking out hooking that back up and running it using a modified soda bottle funnel until the thermostat opened up and kept poring water until it would not take anymore. I then let it run with a brand new thermostat cap with a pressure relief lever letting air bubble out into the overflow tank.

When I shut the car off though there was little to no coolant in the top hose and I was back to square one.

I am thinking about finding all the used components radiator, fan clutch etc. and installing a stock system but that seems like it is going to cost a fair amount. Is there any way to correct this system and get it running properly or should I reach into my savings and pull out what I need to go back to stock? Anyone any good with designing cooling systems or know where I could find some information on the subject? Is there something else I may be missing here? I will see about getting some pictures of the setup a little bit later if I can.

 

Can you see fluid under both radiator caps after your car cools down?

 

are you there are no leaks anywhere? all the hoses are in good shape?

 

If this is actually how it's set up, it's wrong.
The feed from the rad to the overflow tank goes to the inlet side, which extends to the bottom of the tank so the tube is always immersed in coolant.
The outlet from the overflow tank is an air vent and needs to be exposed to atmosphere.

 

See that is what I was thinking I am not sure how best to block off the 3/16" outlet coming off of the radiator cap neck for one. Any ideas? Also I am still unsure if this will fix the issue or if there is some other component of the cooling system I might be messing up or missing entirely.

I will double check the radiator cap but there is no fluid opening the top filler neck cap most of the time unless I have operated the car for less than 30 minutes before checking, in which case there is enough from the last refill to see it.

I have never found any leaks and am always checking constantly. The hoses were a thought I had as well they all seem to be in good shape. Not to say they could not be better but I would think replacement is safely half a year or a year away.

I was having issues these issues before but I believe that they may have gotten worse when I had to remove the heater hose line when I removed the intake manifold and had the fuel injectors cleaned to fix my leaky injector issue. I think I managed to get more air in the system when I did that though I had hoped my attempt to get the air had taken care of that.

 

As promised here is a picture of what the coolant system setup is like now with the top radiator cap removed for filling.



I managed to find a way to cap off the 3/16" inlet on the radiator and tried again leaving the vent hose on the overflow tank to vent.

However, after running this system until the thermostat opened I had the exact same problem but worse as the coolant streamed out of the vent hose once the car was warmed up and when I shut everything down the top radiator hose was completely dry again. I still cannot seem to manage to purge the air from the system, only coolant.

 

that radiator cap on top of the radiator is ok, just disconnect the line on top of the radiator, and cap off the nipple. let the line dangle ( or just trim it ) but still leave it connected to the overflow tank. this will revert you back to the stock setup.

 

do you know your fan type btw? if its a pull or push type? you may have the fan hooked up backwards

 

" exact same problem but worse as the coolant streamed out of the vent hose once the car was warmed up......"

could be the water seal getting blowby causing the coolant to dump out.....

could also be a worn out radiator cap......

also never had 2 radiator caps on a cooling system; not usre if that would be an issue....

may want to get the S5 neck (plastic) that doesn't have a cap to the thermostat housing....

not sure how that would run. maybe others have experience running 2 caps........

try pressure testing the cooling system......

good luck

 

i already stated how to fix the problem.

 

He stated this " I managed to find a way to cap off the 3/16" inlet on the radiator and tried again leaving the vent hose on the overflow tank to vent."

In the same post further down he then posted that the coolant is streaming out the vent hose after reaching running temperature.........

sounds like he still has issues so I made some suggestions........^^^^^^

 

It is a push style, not sure off of what car. Though I am am not sure. What difference would it make?

I take it that this would mean a rebuild or some type of weld trick I keep hearing about.

The two cap thing is a bit strange to me too. I have a source on all the parts to get it back to stock using 86 parts for $40 so I may do that. At least I can troubleshoot a stock system.

First thought was the radiator cap the cap that was on the car when I bought it has a number in the center that says 1.4, as far as I know this is in reference to kilograms per square centimeter equaling approximatively 19 pounds per square inch. I went to the parts store and asked to see the cap they had in their system for the car which had 0.9 stamped on the center. I chose to disbelieve the man at the counter who said the numbers did not mean anything since the manual states it should have a 13 pound per a square inch spring on the cap which relates to 0.9KpC and got the cap that had a red pressure relief pull tab. So am I assuming that using a brand new stock pressure radiator cap should work.

 

sounds like a faulty coolant cap.

http://mazdatrix.com/b8.htm

FC's have 2 types of coolant caps, a pressure cap and flat cap. Flat cap goes on the radiator and pressure cap goes on the waterpump neck.

 

and if you want to be absolutely sure its not a blown coolant seal. search for champagne test.

 

Well after finding new threads to read and going over other ones I have determined I am not going to get any answer until I get the system pressure tested.

I removed the cap from the radiator and replaced it with the one 1.4 cap that has a spring that is too stiff. I thought it helped for a little bit, but the car went back to it old tricks after a little bit. I have a brand new pressure cap on the water pump neck.

The low tech coolant seal check method of looking to see if there are bubbles on a cold start was clean i.e. no bubbles until it was hot. Though I know the only way to be 100% certain is to get the coolant tested for Hydrocarbons but I am not sure that I can keep enough coolant in the car for long enough to be tested. I had read that someone had a leak on the exhaust side so they did not get bubbles until it was warmed up. I am hoping that is not the case since like I said there is no evidence coming from the exhaust.

I found a couple hoses on the intake that I had stupidly thought were vacuum lines but realized that they were in fact coolant lines so I got those in better order after jacking the car back up and filling the system until coolant was running out of those lines and hooking them back up. After the car warmed up though there was air in the tops of those lines and coolant was once again flowing out of the vent tube coming off of the overflow tank until half the coolant had come out of the vent tube and most of the cooling system was just pressurized air.

I just went down and picked up an Autozone pressure tester hopefully it will work well enough I can figure out what is wrong. I will post again soon and let you know how it went.

 

So I replaced the hose that blew up like a balloon when I pressure tested it clamped down on all the hose clamps. Back Flushed the system. Filled it up again when I had finished and despite everything seeming to be fine after it had been warmed up to normal operating temperature then five minutes later when I was sure it was working correctly it started venting coolant from the vent tube constantly until I turned the car off, once again I have a dry cooling system. I am really starting to think that even though there are no symptoms I must have blown coolant seal.

 

Maybe I'm an idiot but I'm pretty sure that the upper radiator cap should not have a nipple coming off it. Wouldn't that force coolant from the radiator and the upper cap into the overflow bottle at the same time?

My S4 has a stock rad with a taurus e-fan. The hose comes off the radiator cap, into the overflow bottle, and the other side hangs down to vent to atmosphere. I think you need to eliminate the upper cap with the vent.

That just seems like the obvious answer to me, I'm just assuming I'm wrong because no one else has mentioned it.

 

every answer you seek is already in this thread. are all washington people like you?

 

I already tried blocking off the nipple coming from the actual radiator leaving the tube for venting coming off of the overflow tank to open atmosphere. SirCygnus' first post here already mentioned this and I followed that instruction.

What resulted is now every time the car warms up after five minutes it starts a constant flow of coolant from the vent tube until the whole cooling system is dry. I thought maybe the valve going into the coolant tank was hooked up backwards for a minute so I actually switched it around right when it started pushing coolant out. When it stopped pushing coolant out I thought I had it fixed but it turns out that it just stopped it for a little while and started back up again when I drove it.

I sincerely hope that comment is not directed at me though I am certain it is. I am not really looking for answers anymore since it seems clear that this has to be a blown coolant seal otherwise it would not be forcing coolant instead of air out of the vent tube. Except for my last post where I stated this I do not see where that answer is in this thread. Why the Champaign test is clear no bubbles and why the pressure test of all coolant caps and the system came back fine I do not understand. Anyway I am just going to sell the car this is proving to be more work than I am willing to deal with.