cooling issues..., fine when driving, spikes when stopped. Options

[Mike Bellis]

So, yesterday I tried getting all the air out of the system. I indeed do have a air bleed nipple on the radiator in the front and I just jacked the front end up a little bit to make it the highest point in the system. I pulled a vacuum and followed your steps. I then took it for a drive. It helped, but the car still tends to slowly climb when Im stopped after driving. I am going to try again today with the vacuum and see if it will help.

any other ideas of maybe why it is overheating? cooling systems are really NOT my expertise, so I am kind of in the dark here. Thanks guys.

peter

sent you a PM

[Phoenix-MN]

So, yesterday I tried getting all the air out of the system. I indeed do have a air bleed nipple on the radiator in the front and I just jacked the front end up a little bit to make it the highest point in the system. I pulled a vacuum and followed your steps. I then took it for a drive. It helped, but the car still tends to slowly climb when Im stopped after driving. I am going to try again today with the vacuum and see if it will help.

any other ideas of maybe why it is overheating? cooling systems are really NOT my expertise, so I am kind of in the dark here. Thanks guys.

peter

sent you a PM

You say the temps climb when at idle, if you idle up the engine to let's say 2000 - 2500 rpm and hold it there does it start to cool down? if so then you are not pumping/flowing enough water at idle speeds. I sort of see this effect with my V6, it doesn't over-heat at idle but will cool down a bit if the idle is brought up.

[malaga_red75]

So, yesterday I tried getting all the air out of the system. I indeed do have a air bleed nipple on the radiator in the front and I just jacked the front end up a little bit to make it the highest point in the system. I pulled a vacuum and followed your steps. I then took it for a drive. It helped, but the car still tends to slowly climb when Im stopped after driving. I am going to try again today with the vacuum and see if it will help.

any other ideas of maybe why it is overheating? cooling systems are really NOT my expertise, so I am kind of in the dark here. Thanks guys.

peter

sent you a PM

You say the temps climb when at idle, if you idle up the engine to let's say 2000 - 2500 rpm and hold it there does it start to cool down? if so then you are not pumping/flowing enough water at idle speeds. I sort of see this effect with my V6, it doesn't over-heat at idle but will cool down a bit if the idle is brought up.

yes, this does happen. If i hold the rpm up it does start to cool down. maybe the thermostat isn't opening enough?

[malaga_red75]

and mine will and does begin to overheat at idle if the rpm's are not brought up.

[charliew]

You must not be moving enough coolant if you need to idle the motor up. I tried the stock 02 wrx radiator in my 914 and it will not fit standing up inbetween the headlight boxes, course it's not a crossflow, it needs to be layed in at a angle that uses much more space. you are not making wrx power though so what you have may work. Are you sure the fans are turning the right direction? I think I read where the exhaust openings need to be 30% bigger than the inlet of the radiator. You can google it. If you use several 90 degree bends in the coolant lines you will get more restriction in the system and you will need bigger diameter lines to overcome the flow restriction. There is is a chance the thermostat is not seeing the bypass flow subys require to send the hot coolant to the thermostat to make it operate right. The stock suby has a heater, a oil warmer/cooler, and the reservoir bolted on the intake the third bypass to the thermostat thats what makes it open and close properly.

When it's idling open the hood and see if it cools ok.

I'm not sure how well you know subys but they do blow headgaskets pretty easy if they get hot very often.

[malaga_red75]

You must not be moving enough coolant if you need to idle the motor up. I tried the stock 02 wrx radiator in my 914 and it will not fit standing up inbetween the headlight boxes, course it's not a crossflow, it needs to be layed in at a angle that uses much more space. you are not making wrx power though so what you have may work. Are you sure the fans are turning the right direction? I think I read where the exhaust openings need to be 30% bigger than the inlet of the radiator. You can google it. If you use several 90 degree bends in the coolant lines you will get more restriction in the system and you will need bigger diameter lines to overcome the flow restriction. There is is a chance the thermostat is not seeing the bypass flow subys require to send the hot coolant to the thermostat to make it operate right. The stock suby has a heater, a oil warmer/cooler, and the reservoir bolted on the intake the third bypass to the thermostat thats what makes it open and close properly.

When it's idling open the hood and see if it cools ok.

I'm not sure how well you know subys but they do blow headgaskets pretty easy if they get hot very often.

I am running a 1996 era 2.5l N/A so, i was comparing my radiator size to that of a 1996-1998 legacy.

Yes, the fans are turning the correct direction. when the turn on, i can feel the air being pulled into the front trunk.

I do know about the headgasket issues, especially with the series motor. I actually do think this might be a possiblity because after driving it one day, i came back, let it sit for an hour, went and fired it up, and a big plume of white smoke came out the exhaust. Will a bad headgasket cause it to overheat at idle, and not while moving?

-Peter

(p.s. Mike (kg6dxn) stopped by yesterday in his sweet 914 -8 and we talked about cooling systems, we talked about different ways of getting the air out of the system, and finding a good high point to pull a vacuum from. Thanks Mike!!)

[ArtechnikA]

Will a bad headgasket cause it to overheat at idle, and not while moving?

In my case, it'd idle all day just fine and overheat within 10 minutes on the road.
I'm not saying your scenario isn't possible, 'cause I donno - but I did have the Subie bad head gasket issue. Idle fine, overheat on the road...

[realred914]

You could try the the Bong method to get the air out and water in to teh cooling system the Bong is a tall pipe, maybe three feet, of PVC pipe, maybe 2 inches diameter, it is attached to the top of the filler hole via a rubber plumbing sleave with two hose clamps to make a tight seal to teh Bong. the bong can now be filled with coolant, becuase of teh tall sixe of teh bong, it will give the filler head pressure to help force air out.

this works great on a vanagon, which are well known for trapping air no need to jack up the van nor hybrid 914 with the bong.

the bong idea is compliments of the samba.


for my 914 Buick car, before I had the bong, I used a steep, very steep driveway to help get the radiator higher and got the air out, took several trys


give the bong idea a try, cheap and easy to make, and it does work very well on vanagons which have simular probelms with high spots trapping air.


good luck

[budman5201]

I had the exact same problem in 2 of my sub conversions. And both turned out to be a stock subie thermostat that opened up a very small amount and very very very slowly. Take your stock subuaru thermostat out, go buy a cheap aftermarket one, boil some water in a big shallow cooking pan that is high enough to cover both thermostats completely in the water and watch the reaction time of both.

I guarantee the stock subaru thermostat has a slow reaction time and gets suck from time to time. Air bubbles are not that hard to burp.

Oh also the other thing I messed up with on my first subaru conversion is that I eliminated all recirculation lines except for to the turbo and back to the water pump inlet. This isn't sufficient and it causes extremely high temps when stopped combined with the slow opening thermostat.

One way to test if it's thermostat or non enough recirculation lines is to gut out the thermostat and run it gutted wide open but with the rim still there so it will seal.

Best setup was to run a new thermostat whichever brand but new, with one small hole in it to let some air pass buy but definitely small or else it will cool too much in the winter.

That will test if your front radiator is enough and if cruising at highway speeds it should run cold if now at 160 degrees all day in 70 to 80 degrees weather. That's what mine does with thermostat gutted.

[malaga_red75]

I had the exact same problem in 2 of my sub conversions. And both turned out to be a stock subie thermostat that opened up a very small amount and very very very slowly. Take your stock subuaru thermostat out, go buy a cheap aftermarket one, boil some water in a big shallow cooking pan that is high enough to cover both thermostats completely in the water and watch the reaction time of both.

I guarantee the stock subaru thermostat has a slow reaction time and gets suck from time to time. Air bubbles are not that hard to burp.

Oh also the other thing I messed up with on my first subaru conversion is that I eliminated all recirculation lines except for to the turbo and back to the water pump inlet. This isn't sufficient and it causes extremely high temps when stopped combined with the slow opening thermostat.

One way to test if it's thermostat or non enough recirculation lines is to gut out the thermostat and run it gutted wide open but with the rim still there so it will seal.

Best setup was to run a new thermostat whichever brand but new, with one small hole in it to let some air pass buy but definitely small or else it will cool too much in the winter.

That will test if your front radiator is enough and if cruising at highway speeds it should run cold if now at 160 degrees all day in 70 to 80 degrees weather. That's what mine does with thermostat gutted.

So, your saying literally drill a hole in the thermostat to allow flow even when the thermostat is closed? I just want to make sure I understand this right before I go about drilling holes. Thanks budman.

This is what I was thinking too, I actually just called Kohlweiss to see if they had thermostats. I am kind of thinking this might be it because of the fact that I have now pulled vacuum several times from several ports in the system. And also that when revving the engine (forcing more water through the engine) it cools down. Off to kohlweiss to pick up the thermostat and gasket! Ill keep you guys posted.

-Peter

[malaga_red75]

well, new thermostat installed. no change... well, id say maybe a 5 degree difference while driving, now around town I am probably steady at around 195-200 moving a littler faster it drops to around 185-190. stopped, it goes to about 215. my local shop said that they can sniff for hyrdocarbons at the radiator and determine if there is exhaust leaking into the cooling system. I will be doing this on tuesday morning.

One other note:

I have been reading online and on other forums and it seems that normal engine operating temperatures are between 180-220. But most of you guys say that you are running between 150-160 while driving. just curious what some thoughts are on this.


-Peter

[Mike Bellis]

well, new thermostat installed. no change... well, id say maybe a 5 degree difference while driving, now around town I am probably steady at around 195-200 moving a littler faster it drops to around 185-190. stopped, it goes to about 215. my local shop said that they can sniff for hyrdocarbons at the radiator and determine if there is exhaust leaking into the cooling system. I will be doing this on tuesday morning.

One other note:

I have been reading online and on other forums and it seems that normal engine operating temperatures are between 180-220. But most of you guys say that you are running between 150-160 while driving. just curious what some thoughts are on this.


-Peter

having temp fluxuations is fairly common with a conversion car. Some go as far as removing the thermostat. Removing it will keep the tamps more consistant, instead of up/down. It will take longer to warm up in the winter if removed. Since everybody has a different cooling system, even with the same engine. It's hard to say exactly why you have a problem. I could be as simple as you needing a new water pump. There are electric in line pumps that can be fitted if flow is your problem.

Since your car does not overheat while moving, your problem is either flow or air. 90% of the time it will be air. When you have all the air out, the problem is flow. Here's where it gets tricky. You can have a problem with both too much and too little flow. Too little, the water does not get cooled fast enough and hot water is returned to the engine. Too much and the heat exchanging effect will not work and hot water will be returned to the engine. At this point, you should try removing the thermostat and see if it helps. This should increase flow. If the system cools down, your system has too little flow. If the temp goes up, you may have too much flow. At that point try to pinch the hose aome to restrict flow. I would suspect too little flow is your problem.

To cure to little flow... Remove thermostat... or... Inline Water pump... or... Smaller pully on the water pump... or... larger pulley on the crank. Also look for any natural restrictions in your hose, kinks, bends etc...

[budman5201]

one question, how many return lines do you have that recirculate water around the engine when the thermostat is CLOSED?

What happened when you did the boiling test with thermostats ? old vs. new?

[budman5201]

the basic design of the water pump housing on a subaru needs ALL these recirculation lines so the Tstat will open. It has cool water trying to enter the Thermostat from the inlet and hot water on the inside of the thermostat. If the hot water is NOT recirculating around the inside side, the thermostat will try to open and then close itself once cool water has entered.

With ALL recirculation lines intact, which i think on your N/A motor there are two inlets. The tstat will always have a hot supply of water to stay open if hot.



On my first conversion i was like, cool i will clean up the way the engine looks,etc. So i eliminated all these recirculation lines, heater ,etc. which was a major fault.

[malaga_red75]

budman-

First, when i did the tstat test, the new thermostat opened much quicker than the old. However, once both were open, they looked like they had opened the same amount. so, despite realizing that the thermostat was fine, I installed the new one anyways.

re: recirculation lines
I guess my answer is that no, I do not have any return lines to the engine while the Tstat is closed. My expansion tank is connected to the heater return line (just on the inside of the thermostat) and then there is the incoming radiator line on the outside of the thermostat.

Basically, I fill the system via gravity through the expansion tank into the heater return line... then the fluid goes through the engine, out to the radiator, then back to the thermostat.

So, how would I setup the system to have a recirculation line? If I used the heater return line, say connected to a port at the top of the crossover pipe, where would I run my expansion tank?

I only know of 1 recirculation line, which is just on the inside of the heater return, which is where my expansion tank is currently hooked up. where is the second?

Thanks budman, I know you know your subaru stuff. especially cooling, living in AZ.

-Peter

[drive-ability]

IMO a blown head gasket would be much worse under load and show the least troublesome with no load (Idle, coast etc). If your not getting enough flow at idle, bring the rpm up to 2k. I would assume you have done this, you sound like you have done your homework ! I have found most often with cooling problems that have you scratching your head end up to be a radiator issue.. (IMG:style_emoticons/default/smile.gif)

[malaga_red75]

IMO a blown head gasket would be much worse under load and show the least troublesome with no load (Idle, coast etc). If your not getting enough flow at idle, bring the rpm up to 2k. I would assume you have done this, you sound like you have done your homework ! I have found most often with cooling problems that have you scratching your head end up to be a radiator issue.. (IMG:style_emoticons/default/smile.gif)

I have thought about this too, and realized that my radiator might be to small. although I am running a engine from a 96 era subaru, I am making about 40 more HP due to the EMS stinger. I am thinking that I may need a new, bigger one. but I don't want to do this until I sort out any other issues, because well, re designing the front shroud is a little more time intensive than some other fixes.

-peter

[budman5201]

budman-

First, when i did the tstat test, the new thermostat opened much quicker than the old. However, once both were open, they looked like they had opened the same amount. so, despite realizing that the thermostat was fine, I installed the new one anyways.

re: recirculation lines
I guess my answer is that no, I do not have any return lines to the engine while the Tstat is closed. My expansion tank is connected to the heater return line (just on the inside of the thermostat) and then there is the incoming radiator line on the outside of the thermostat.

Basically, I fill the system via gravity through the expansion tank into the heater return line... then the fluid goes through the engine, out to the radiator, then back to the thermostat.

So, how would I setup the system to have a recirculation line? If I used the heater return line, say connected to a port at the top of the crossover pipe, where would I run my expansion tank?

I only know of 1 recirculation line, which is just on the inside of the heater return, which is where my expansion tank is currently hooked up. where is the second?

Thanks budman, I know you know your subaru stuff. especially cooling, living in AZ.

-Peter

Peter YOU NAILED IT! congrats! Get that recirculation line back and your problems will be SOLVED!!

There should of been two tubes that go to the stock subaru heater core when it was in the stock subaru car. These are at the rear drivers side of the engine when you have the subie in the 914. Just put those back, put a loop so basically you loop the coolant back to the thermostat. Whatever way you get the top manifold on the engine (hot water) to loop back and feel to the inside engine side of the thermostat is the route. You can T into this line for your expansion tank. When flowing it will just run past your T in the line and back to the water pump. The T in the line will be good for filling and expansion to the overflow etc.

[budman5201]

here is a stolen pic from STI progress thread. shows the route of a turbo recirculation lines. You just need the one the runs from the manifold top and back down the top of the block, through the front area of the engine and to the water pump.

[malaga_red75]

budman-

First, when i did the tstat test, the new thermostat opened much quicker than the old. However, once both were open, they looked like they had opened the same amount. so, despite realizing that the thermostat was fine, I installed the new one anyways.

re: recirculation lines
I guess my answer is that no, I do not have any return lines to the engine while the Tstat is closed. My expansion tank is connected to the heater return line (just on the inside of the thermostat) and then there is the incoming radiator line on the outside of the thermostat.

Basically, I fill the system via gravity through the expansion tank into the heater return line... then the fluid goes through the engine, out to the radiator, then back to the thermostat.

So, how would I setup the system to have a recirculation line? If I used the heater return line, say connected to a port at the top of the crossover pipe, where would I run my expansion tank?

I only know of 1 recirculation line, which is just on the inside of the heater return, which is where my expansion tank is currently hooked up. where is the second?

Thanks budman, I know you know your subaru stuff. especially cooling, living in AZ.

-Peter

Peter YOU NAILED IT! congrats! Get that recirculation line back and your problems will be SOLVED!!

There should of been two tubes that go to the stock subaru heater core when it was in the stock subaru car. These are at the rear drivers side of the engine when you have the subie in the 914. Just put those back, put a loop so basically you loop the coolant back to the thermostat. Whatever way you get the top manifold on the engine (hot water) to loop back and feel to the inside engine side of the thermostat is the route. You can T into this line for your expansion tank. When flowing it will just run past your T in the line and back to the water pump. The T in the line will be good for filling and expansion to the overflow etc.

Cool, I think I understand. I actually removed on of the pipes, but the other one (the one that comes directly off the crossover pipe) will work just fine. I will get a T fitting, and basically run from there down to the tstat and have it T off up to the expansion tank.

But will this help after the tstat is open? Or are you saying that because there is no circulation, it is constantly trying to open then close then open...etc.?

-peter

budman, i got your message, i might call you tomorrow, but i think i got it figured out.