Air getting into coolant

[red_devil]

Im getting a lot of pressure in my coolant system still and im not sure why. Flushed coolant system, over flow tank is full, then left cap off to get the air out but it keeps on letting air out and will not stop. So I did a compression test and im 176,175,176,180 with no leaking or burning of oil or water. When I free rev the engine it seems like it getting more air in the system. Could it be water pump? Turbo? (which does not smoke btw)

Thanks

 

[99gst_racer]

The only time this has happened to me, it turned out to be the head gasket.

There was a small crack in one firing ring. It wouldn't show up as a leak when doing a compression test on a cold engine, but when the engine was at opperating temperature, it would push compression gasses past the HG and into my coolant passages.

Does it do it all the time - like at idle as well? Or just at WOT?

 

[red_devil]

At idle there are some bubbles but when you give it some throttle it starts to get almost foamy and then coolant over flows.

 

[black91awdturbo]

I am with the other guy it sounds just like other blown head gaskets I have seen...

 

[red_devil]

I am with the other guy it sounds just like other blown head gaskets I have seen...

But how is it that compression is perfect, no oil in water, not water in oil, and no smoke?

 

[EagleTalon1993]

I have to agree small damage to the head gasket in just the right place will allow pressure to bleed into the cooling system from the combustion chamber/s. Unfortunately the only way I know of to test this is a visual inspection of the gasket.

Before removing the head I would have a pressure test done on the cooling system with the engine off and see if any coolant leaks out that may also indicate where air could get in.

Good luck

 

[Calan]

But how is it that compression is perfect, no oil in water, not water in oil, and no smoke?

Do you have a blown head gasket?



A compression test can be misleading. Your motor is dynamic and things change inside it as operating conditions change. Do a leak down test and see if air shows up in the coolant.

 

[Ill-EagleTSi]

Okay sorry to thread jack...but I have this same coolant pushing problem. Only thing is I just rebuilt my whole engine with a new MLS Head gasket and a Machine shop surfaced head.

My question is...why would my brand new gasket do this?
I used arps studs torqed to 95ftlbs and I went in stages 10 lbs, 30 lbs, 60 lbs, 95lbs. in the RIGHT tightening sequence.

I even used copper spray. So what is the problem? is it cause I dint get the block decked

should I just get a composite gasket?

 

[Calan]

What lubricant did you use on the head studs? Different lubes require different torque values. I believe that if you use the thread lube that ARP supplies, they recommend torquing the studs to 120lbs...but I still need to confirm this. (About to torque the head down on my new block as well).

And yeah... the deck has to be surfaced as well as the head for a good MLS seal.

EDIT:

My ARP instructions say 80 ft. lbs. for ARP Moly lube, 120 ft. lbs. for 30wt oil.

 

[Ill-EagleTSi]

I used the ARP moly lube that they give with the stud kit. It said in the instructions to torque to 85lbs I think with the ARP MOLY lube and 115ft lbs or so if using 10w 30 oil as lube.

The other mistake I think I made was buying a MLS gasket off ebay... I was being a cheap ass...It looked good tho.

But now when I go WOT I push coolant into my overflow bottle. Compression was fine and exactly the same on all cylinders.

 

[red_devil]

I'll try a leak test.

Another note is that it does not push any coolant when running at wot the over flow has stayed the same its just when I rev the car with the cap off it over floes and has alot of air in it.

 

[Calan]

its just when I rev the car with the cap off.

The radiator cap or overflow tank cap?

Just to be sure we are on the same page here...

Your coolant system is a pressurized closed loop system. As the engine gets hot, pressure will increase and the radiator cap will let excess coolant escape into the reservoir, and it's level will rise. As the car cools down, the coolant is drawn back into the engine/radiator through the cap. (Ever notice that there are different level marks for both a hot and cold engine?)

Is it possible that you are mistaking this for a pushing coolant issue? Is the car overheating, or are there any other problems?

Have you thrown a new radiator cap on? If the cap is clogged, you could have a pressure build up since it isn't letting the coolant "overflow" to the tank.

 

[red_devil]

The radiator cap or overflow tank cap?

Just to be sure we are on the same page here...

Your coolant system is a pressurized closed loop system. As the engine gets hot, pressure will increase and the radiator cap will let excess coolant escape into the reservoir, and it's level will rise. As the car cools down, the coolant is drawn back into the engine/radiator through the cap. (Ever notice that there are different level marks for both a hot and cold engine?)

Is it possible that you are mistaking this for a pushing coolant issue? Is the car overheating, or are there any other problems?

Have you thrown a new radiator cap on? If the cap is clogged, you could have a pressure build up since it isn't letting the coolant "overflow" to the tank.

The radiator cap

The car does not over heat and the reservoir never over flows. Its just that when I take the radiator cap off to get the air out of the system it will not stop bubbling, and after I turn the car off you can hear bubbling. If I try to remove the rad cap after a drive it has a lot of pressure in it.

 

[knochgoon24]

You need to do a leakdown test.

 

[Calan]

Does the level in the coolant overflow change between when the car is hot vs. when it's cold?

 

[red_devil]

Does the level in the coolant overflow change between when the car is hot vs. when it's cold?

It changes a little

I was messing with it again today and I noticed that with the rad cap off the coolant level will rise and fall now and again, isnt this a good sign that its the HG? Still need to do a need leak test though.

Been a while and I need to update. I had a hydrocarbon test done which indicated nothing in the coolant. I replaced the thermostat and cap with oem ones and re-flushed the coolant. I am still getting air in the coolant. I have been keeping an eye on the overflow tank and there is no signs of overflowing. What could be causing this?

 

[jrohner]

If I try to remove the rad cap after a drive it has a lot of pressure in it.

It's supposed to have a lot of pressure. You're not supposed to remove the cap when it's hot, you'll get burned doing crap like that. Try something else if you're looking for a dangerous extreme sport.

I would say if it bubbles quite a bit after you shut the car off, you may have a loose hose, which can allow it to suck air in. Yeah it sounds messed up that it could suck air in and not spray out coolant but it does happen. My cousin had this happen recently and it ended up blowing his head gasket in just a few days. Do a pressure check and wiggle, pull, and push on all the hoses and see if you can see or hear any issues.

 

[Ill-EagleTSi]

I posted earlier in this thread with a similar problem. And sure enough it was my Head gasket. I replaced it and the car is fine now!