Constantly have air in my cooling system

[CyFi6]

Thats the problem. I don't know if combustion is forcing air into the system thus pushing coolant out or if its just not getting sucked back in. I checked the piping and its perfectly sealed. I even put a different piece there for a day and no change. But then i also did the block test and had 100% no change in color it stayed perfectly blue.

 

[gaboonviper85]

I vote for a pressure test myself....that will bring out all the weak spots..

 

[jetjock]

ok so i could not find an adapter for less than 30 bucks for the pressure tester

Stant #12027. Around 18-20 bux from lots of places. Rock Auto comes to mind or here:

http://tinyurl.com/3kyxfp

The cap adapter is a Stant #12021

 

[iwannadie]

I think you misunderstood....what he is saying is when it gets hot it pushes water into the overflow....but when it cools its not sucking it back in

Mine would still bubble out(mostly air not coolant) After I shut the motor off. Coolant would spray out while I drove leaving my radiator soaking wet. Im guessing the exhaust gas just pressurized the cooling system that much. With the motor off the Tstat doesnt just close suddenly so the pressure is still pushing past the radiator cap. Coolant never seemed to suck back in from the overflow bottle either, too much pressure? Id drive loosing coolant and come home park it and look for leaks, never found them.

Again, Im just going from my experience when I had coolant problems and BHG.

Replace the rad cap, Tstat, pressure test. Drain the coolant into a clear container and let it sit over night, check for sludge at the bottom(or remove/clean you overflow bottle, check for sludge in it). Do all the cheap easy stuff first, then go from there I say.

 

[CyFi6]

UPDATE:

Pressurized the cooling system. 100% held pressure. Pressurized the overflow tube, 100% pressure held. Replaced cap, same problem.

Basically air is getting in, combustion is not getting into the coolant, everything is air tight according to all my tests....what am i left with? The only thing i can think of is something is leaking when the car gets hot, and thats a time when i cannot use the pressure tester. What do you guys reccomend i do? I also used a four gas analyzer just in the radiator opening above the water with the car running and no hydrocarbons showed. I really have run out of ideas!

 

[GrimJack]

Do us a favor and replace the line that goes to the bottom of the overflow tank, will you? It's only ~6 inches long anyway. I've seen this get crusty and leak, and most people overlook it because it isn't meant to hold pressure anyway.

Problem is, it needs to suck coolant back into the system when you are cooling down. Ever try to use a straw with a split in it? All you get is air.

 

[CyFi6]

I have visually inspected it and its fine, and I pressurized it to over 10 psi and it held just fine, so I dont see a reason to replace it. I pressurized the whole tube btw, from the radiator nipple to the end of the tube in the overflow, which includes the connections on the overflow lid etc..

 

[jetjock]

For coolant to be sent to the tank the radiator must start out full enough so there is no room for expansion. If that's the case then as the system cools it *must* draw coolant back in unless there is a leak or the cap is faulty. If the system were airtight the upper radiator hose would collapse. Therefore you have a leak, either in the system or the cap, or too much expansion space in the radiator. Neither you or your cooling system are exempt from the laws of physics you know.

Pressurizing the hose is an indirect check. Instead prove there's no vacuum on it. After shutdown put a short piece of hose with a vacuum gage on the radiator neck nipple. Or pull the overflow tube out of the tank, remove the suction screen, and gage it there.

You can do the same on the radiator itself after it cools enough to remove the cap. Think about how the thing is supposed to work, formulate a hypothesis for why it doesn't, and then formulate a method to directly prove or disprove the hypothesis. If unsuccessful move on to a new one. I'd also go to Auto Zone and buy some coolant dye.

 

[Nick M]

Fascinating....

Isn't it?

orly? This is how I do it when I do cooling system work at my job at Nissan. (Minus the watching tv and sandwich parts)

Spoken just like a lube rack employee.

 

[GrimJack]

For coolant to be sent to the tank the radiator must start out full enough so there is no room for expansion. If that's the case then as the system cools it *must* draw coolant back in unless there is a leak or the cap is faulty. If the system were airtight the upper radiator hose would collapse. Therefore you have a leak, either in the system or the cap, or too much expansion space in the radiator. Neither you or your cooling system are exempt from the laws of physics you know.

Pressurizing the hose is an indirect check. Instead prove there's no vacuum on it. After shutdown put a short piece of hose with a vacuum gage on the radiator neck nipple. Or pull the overflow tube out of the tank, remove the suction screen, and gage it there.

You can do the same on the radiator itself after it cools enough to remove the cap. Think about how the thing is supposed to work, formulate a hypothesis for why it doesn't, and then formulate a method to directly prove or disprove the hypothesis. If unsuccessful move on to a new one. I'd also go to Auto Zone and buy some coolant dye.

Scientific method FTW!

 

[CyFi6]

BHG FTL! So i figured out its a bhg. Cylinders 5 and 6 are just slightly blown. I did a cylinder leakage test and sure enough when i cranked up the pressure around 90PSI the coolant level started rising. I guess the low pressure from the pressure tester wasnt enough to get past the partially sealing gasket, and for some reason the block tester wasnt getting anything. At least now i know what is wrong and i can start on fixing it. It is going to be tough as this is my daily driver but i think i will be able to work something out. Thanks for the help guys.

 

[supramacist]

Yep. The cool thing is that it should be easier since you didn't blow it
to hell and back. Machine wise.

Start buying all of your parts and get them all collected before you get to the
put it back together phase.

 

[Nick M]

So you pumped the cooling system to 90 psi, or the leak tester?

You know what else is fascinating? The area that seems to give the most fits, stock control, has the fewest questions in the SME section.

 

[CyFi6]

I pumped the leakage tester to 90 psi, so the cylinders, not the cooling system, and then saw the level in the filler opening with the radiator cap off rise/bubble

 

[iwannadie]

...Same as my bhg, right around 5-6.

 

[supramacist]

6 is known for being a troubled spot.

 

[CyFi6]

Ok i have a few small questions because this will be my first head gasket job. I looked up all the prices for gaskets and sets and such and toyota is looking for $350 for a full head set. They want $80 for a head gasket only. Now ebay has a full head set for $37. I was planning on buying a composite head gasket from Toyota, buying felpro valve seals from kragen for 45 dollars, EGR cooler gasket from toyota and buying the full gasket set from ebay and tossing the EGR cooler gasket, valve seals, head gasket and valve cover seals. So in the end i will have
Head gasket from toyota
Valve seals from felpro
EGR cooler gasket from toyota
all other small gaskets from EBAY

What do you guys think about my plans? I have heard the ebay small gaskets are pretty decent for what they are. I also had a question for the valve adjustment. Should i bother getting all of them perfectly? I heard the shims are very expencive and not worth replacing all of them just to get it a little closer to where it should be. Just want opinions on this. I will only be replaceing those things listed above, and lapping the valve and having the head machined. I do not want to do the timing belt at this time so i will leave that alone. Thanks a bunch guys.

 

[AJ'S 88NA]

Ok i have a few small questions because this will be my first head gasket job. I looked up all the prices for gaskets and sets and such and toyota is looking for $350 for a full head set. They want $80 for a head gasket only. Now ebay has a full head set for $37. I was planning on buying a composite head gasket from Toyota, buying felpro valve seals from kragen for 45 dollars, EGR cooler gasket from toyota and buying the full gasket set from ebay and tossing the EGR cooler gasket, valve seals, head gasket and valve cover seals. So in the end i will have
Head gasket from toyota
Valve seals from felpro
EGR cooler gasket from toyota
all other small gaskets from EBAY

What do you guys think about my plans? I have heard the ebay small gaskets are pretty decent for what they are. I also had a question for the valve adjustment. Should i bother getting all of them perfectly? I heard the shims are very expencive and not worth replacing all of them just to get it a little closer to where it should be. Just want opinions on this. I will only be replaceing those things listed above, and lapping the valve and having the head machined. I do not want to do the timing belt at this time so i will leave that alone. Thanks a bunch guys.

Why not get the Felpro HG? In fact why not get the whole set from Felpro?

If you're getting a valve job the machine shop should be able to do the valve lash.

Why not the timing belt? Alot easier to do while you have everything apart.

 

[CyFi6]

With the way i wrote above its a little cheaper than the whole felpro set, and i would rather have a toyota head gasket than a felpro.

 

[Nick M]

With the way i wrote above its a little cheaper than the whole felpro set, and i would rather have a toyota head gasket than a felpro.

I wouldn't be suprised if the head gasket set for Toyota of North America is made by Fel-Pro. I have seen many OEM gaskets labeled for the manufacturer on one side, and Fel-Pro on the other.

My Fel-Pro looks exactly like an OEM gasket. And they may have just built it that way, and are not building for Toyota.