Hi. I recently converted my 914 to Ej25 power, and love it but i am having issues with air bubbles in the radiator and it wont cool very well.

Can someone please give me a diagram or maybe just tell me their hose routing and radiator cap pressure and tell me if the bubbles ever go away.

Symtoms while driving....I gun it and then close the throttle and coast and i get water coming out of the radiator reserve tank ( i have it routed in a tube so it doesnt splash around) and i see a stream on the road when i do this. Then when i get home i can bleed the top air bleeder screw on the top of the renegade radiator and a ton of air comes out, then i go to the back and i can fill the fill cap with another pint of water. This NEVER stops. Always needs water and their are no leaks apparent other than this squirting symtom.

My radiator cap is a 16 lb cap. The routing goes from thermostat through the engine block up , out the mainfold on top to the highly mounted aluminum housing that i bought from Renegade that i fill the water from( this has the radiator cap part), then down underneath the car to the radiator up front then back to directly into the thermostat/ water pump again. I drilled the thermostat also like instructed with 3 small 1/8 inch holes in diaphram.

I am lost why it still needs water all the time. I know why it does because of the spurting, but dont know why it does this....arrggH!!

Any help is appreciated. thankyou very much.

back of engine compartment

Nice looking conversion.

when the cooling system cools, vacuum sucks water from the bottom of the purge tank, back into the system.
that said, check your purge tank and make sure the rubber hose that goes to the rad cap thingy picks up water from the bottom of the purge tank.
also make sure the little (usually brass) return pressure spring in the center of the radiator cap is free and working properly.

Yep that line to the purge tank is fine, tank full too. The radiator cap spring looks fine. I press up on it and it goes up with about 16 lbs force. I am not sure what else to check on the cap.

There is a subaru conversion forum on www.clubnarp.com. Someone was having the same issue as you - here is the suggestion

"I leave the upper radiator hose loose, and burp air out there until it's full, and then use one of the heater lines to burp the remaining air out." (from Crazyhippy)

When you say the "top air bleeder on the radiator" do you mean the top petcock?
If so, that is not an air bleeder, if you open that and anything but water comes out
you don't have a full system. (at least if it is the same as on my v8 renegade radiator).
My method is to park with the back higher, open the top petcock in the radiator and
start filling through the radiator cap. When water starts to come out of the top petcock, close it and keep adding water. When it won't take any more, wait a bit
and you will usually see a few bubbles and the level will drop. Add water. Squeeze
any hoses you can and this usually moves a bit of air. Let it sit, and do it some more. At this point I fire it up and let it idle and add water as the air bubbles come
out. Mine won't overheat at this point, but sometimes the fans come on. Keep at
it until you get bored, and drive it. MAKE SURE your overflow bottle has water in it,
cause as stated above, it will suck water to replace the air as it heat cycles after
shut down. A few drives like this and you will have the air out and should be fine.
(obviously just personal experience, no expert)

patrick

By the way, I've got a turbo baja and I thought that motor would be the very
best conversion possible for a 914.

patrick

I don't have a SUBI but do have a water cooled engine in my car and it sounds like there too much water pressure. I guess it can be a combo of vapor and flow force from the pumping system. They are present is all water cooled cars but maybe you are building more pump pressure in just that portion of the pluming. My car will do this a little from time to time and I have to have been running at a higher rpm for it to happen. I don't have the problem to the extent you do but I think its the water pressure driven by the water pump. Maybe a you have a restriction down stream of the pressure cap?

I think i have an idea of what it could be.

I have the aluminum bottle like yours mounted in the exact same location as yours in the pic, but my subaru shoots the water from the bottom directly at the cap, so this i think is the problem. At a good throttle pressure is hitting the cap making it unstick and shoot water to the expansion tank when the pressure isnt even built up, then i have less coolant and then the boiling point isnt as high due to the fact that now i have less coolant.

I am changing the system to go directly to and fron the radiator without any bleeder there....instead i am running a wrx expansion tank and running the heater core lines in the back of the subie motor which are smaller 1/2 inch lines in and out of the expansion tank, and that will be my new expanstion location. this way the actual flow of the water will not be pressing directly at the cap and the only thing that will be making it surge up and loose coolant through the expansion tank will be pure coolant pressure itself and not current of the water during hard acceleration......hopefully this is my problem ...seems logical, a new tank and we will see.....
thanks so far...hopefully this weekend it works!!

Good to see another AZ 914.

Make sure you sign up for the Yahoo group that we have. It'll make sure you get the word for dinners & such.

Click Here

i mounted my overflow bottle in the front trunk high enough to be obove the engine. When i had first began trying to bleed my system, i had crazy air that i couldnt get out and the overflow would do about the same as you.

So i pulled the upper rad. hose off of the motor and refilled my system from there, then filled it again, with the hose remounted, in the front trunk... Ever since then it has worked great.

give that a try, it may help..

pankopp

I'm using a VW coolant tank on the heater bypass line with the exact same engine. Sounds like that should do the trick for you.

my 29 page long conversion thread:
http://www.914world.com/bbs2/index.php?showtopic=31579

-Tony

The best place to bleed the Subie engines is at the top throttle body heater tube. (about a 1/4 in black rubber coolant hose attached to the throttle body) Disconnect this hose and fill it with water then re-attach. Also parking it on a slope really helps when bleeding the radiator. Check for kinks or high spots in the hoses that could collect bubbles. These conversions are generally a pain in the ass to bleed, believe me i know. Welcome to the world!
Dana.

PROBLEM FOUND!!!! Bad head gasket. I was almost going to do it the subaru warranty way and put their "subaru conditioner" in, but I am not like that and I love knowing things are done correctly.

TORE IT DOWN! Found.........Head Gasket leaking into coolant, easy FIX!!

I am going to bring the heads in, resurface them, new gaskets everywhere. new h2o pump and upper coolant manifold gaskets..... Whew GLAD I FOUND SOMETHING!!!

Here are the pics. look at the shiny parts of the gasket near the piston, Shiney from piston to coolant passage. Definately leaking into coolant and causing expansion!

another..black area between piston and coolant passage on head!

I sprayed down with water to wipe off the surface stuff so you can see the exhaust trail between the piston and the coolant passage.

You sound a little to be happy about a busted head gasket...