Cooling problem PLEASE help me!

[KidintheTSi]

I've been having this problem for a while now and it's really starting to piss me off. Almost all of the hoses are brand new, i just put in a new thermostat and radiator cap.

The problem mostly happens on long trips, this is when I first noticed it. After the car has been running for a long time, it starts getting really hot. When I open the hood to check things out, the coolant in the overflow bottle is "boiling". I put this in quotes because I'm not sure if it is actually boiling of if Air from the system is getting pushed into the bottle. When I check the coolant level, most of the time it is low. I dont know if this is because of a leak or if it's just because the sysem is losing it through the overflow bottle for some reason.

I've got one theory that I have a small leak somewhere and after running for a long time, it loses enough coolant to start getting hot due to not enough being left. Is this reasonable?

I haven't seen any oil in the coolant or vice versa, and I did a test that I read somewhere in which I took the rad. cap off and plugged the nipple for the hose to the overflow bottle. I had a friend crank it over, and supposedly if my head gasket was leaking coolant would shoot up and out-it did not.

I think this description is pretty vague as I dont want to make the post really long. If you have a question that would help you answer a problem for me, PLEASE ask. I really need to get this fixed ASAP

-Kevin

 

[supergoat]

My water pump is leaking, not a lot but enough that I have to add about a liter of coolant/water once a week. I know it's time to add when my temp climbs about 2/3 of the way up. It usually stays just under 1/2 way.

So you may want to check your water pump. With my car, I never leave a puddle on the ground but I can look up from under my car and see the water trickling down from the pump. I have a brand new water pump to install, I just have to motivate myself to do it. What sucks is I JUST replaced my timing belt 3k miles ago and could have easily replaced it then, but the pump wasn't leaking. Now I have to do it all over again.

My thermostat is also just fine(I tested it) and my radiator cap is also new.

Also if it's not the water pump you could have somene drive behind you as you give it a good amount of gas to see if you are producing any white smoke. If you are then it could be your head gasket or a turbo seal.(can't remember if a failing turbo seal could cause this or not, but I mention it any way.)

 

[KidintheTSi]

Nah, i did my water pump/timing belt a few thousand miles ago. Thanks tho...

-Kevin

 

[jott5555]

BAD HEAD GASKET ive had it happen a few times, i swear bro its a bad head gasket get a leak down test done.

 

[KidintheTSi]

Yah that's what I'm thinking too. I'm going to try to just tighten the head bolts back up to the torque spec first. Since it's such a small leak I'm hoping that this might fix it. If not, how hard is it to change a head gasket???

 

[jpolizo]

It could be a head gasket; do you see any bubbles appearing in the coolant reservoir when it's at idle? A head gasket leak need not make your coolant "shoot out"; it's usually a lot more subtle than that. When mine went it was just a stream of small bubbles. A leak-down test, as noted, might give you some good information here.

Starting simple, though, I'd make sure you don't have a coolant leak anyplace. Has your cooling system been pressure tested? You can also get some fluorescent dye to put in the system that can help you spot small leaks -- a small leak, as you said, will cause what you are seeing.

Is your radiator in good shape? Has it ever been flushed?

 

[KidintheTSi]

I'm not sure if the radiator's been flushed or not. I have never done it, and Im not sure about the dumbass that had it before me(dont really like the guy, i've found a lot of things messed up ). I'm going to rent a pressure tester from auto zone and do that later today. I'll also flush it out and tighten the head bolts if none of that is conslusive. I'll let ya know what happens.

Thanks
-Kevin

 

[KidintheTSi]

Alright well I ended up not having enough time to tighten the head bolts, but I did rent a pressure tester from auto zone. I tested the cap(which was fine) and the system. It passed w/ flying colors, didn't lose any pressure at all, and I heard NOTHING. I ended up putting a very little bit of that stupid stop leak crap in it and tightened up some clamps(which were already pretty tight, dont think I really did anything).

In the booklet that came w/ the pressure tester it said you could test for internal leaks(ie combustion/compression and head gasket) by hooking the tester up, starting the car and getting it up to normal temerature. It said that if the pressure rose quickly the HG was leaking and if it sat there and pulsed or vibrated you had a compression leak-it did neither! I filled it back up and 'burped' the system. The highest it got in the trip back home(hour to an hour and a half at about 70-80 MPH) was 206 deg. I have a 185 thermostat so I was pretty happy that it stayed down, figured I fixed the problem. But after it was cool enough to open the cap, I saw that it was still low on coolant! What the hell!?!? Did it just stay cool because it was night time now, and probably 60 somethig degrees outside?? Where could my coolant be going?

I guess maybe a leakdown test would be more accurate than doing it w/ the pressure tester, maybe I'll find somewhere that can do that, how much will that cost? Any more ideas guys? Im still gonna play w/ it to see if Im still losing coolant today...

 

[jpolizo]

How did you measure the 206 peak temperature? That sounds fairly precise, do you have an aftermarket gauge? Have you checked that with another thermometer of some kind? It also sounds a bit high to me, for a cool night at 70 MPH. Before you had this problem, what was the usually temp under these conditions?

Are you getting good coolant flow when the thermostat is open (it should be moving pretty good)?

Another thought, is how much boost were you pushing when you did the drive home; you may be getting a head gasket leak only under high boost conditions; it might be fine, or too slow to measure, at idle. When mine went, it started out real slow but got worse over time. In fact, it did pretty much what yours is doing.

An HG change is a good bit of work; in fact, it's so much work it makes sense doing lots of other stuff too (like valves, head porting, and etc.). I'd definitely cross off all the easy things first.

 

[KidintheTSi]

I measured that temp w/ my datalogger. It probably is a little high because the coolant was low afterall. I think it just didn't overheat b/c of the fact that it was so cool out. Im not sure what it would have been before i had any problems b/c Ive only had the logger for a couple weeks now.

On the drive home it is all highway driving so I'm under vacuum almost all the time; you could be right about it only causing problems under boost. Yes, it does have good flow when the thermostat is open. I changed the water pump along w/ the timing belt just a few thousand miles ago.

One of the main reasons this is all such a problem is b/c Im in college, have no money to be fixing this POS and home is that hour and a half drive away, so its really a pain in the ass!

 

[jpolizo]

You have my total sympathy; I hate stuff like this.

First, I'd double check the temp with another thermometer -- just to keep everybody honest.

Next, I'd flush the radiator.

Next, recheck the belt tension on the waterpump.

Is the thermostat an aftermarket or OEM? I'd go with an OEM and make that little dongle thingy on it as at 12 o'clock high; if it's not, you'll trap air.

Finally, I would consider your religious life because whomever/whatever you are praying to ain't working.

Let us know if you find anything else out.

 

[hose101772]

Tighten zee head bolts..ol

 

[jpolizo]

Originally posted by hose101772
Tighten zee head bolts..ol

If you do this, you should probably pull the damned things out and make sure they aren't stretched out of spec before you tighten them back down.

 

[KidintheTSi]

Alright. So I have yet to do a compression test still, but I am as soon as I get a chance, probably in a week or two. I've loosened and re-torqued my head bolts and I replaced the hose that goes to the overflow bottle b/c the one that was on it was way too big. Well yesterday I had to drive from San Antonio to Austin (hour and a half or so) and back and it never once got above 199*F(w/ 185 thermostat), even driving around downtown in the mid afternoon w/ a/c on. I didn't even check the coolant level until today, after it has been sitting all night, here's what I found.

In Austin: I didn't open the rad cap when it was warm, while in Austin, but I was squeezing/shaking the upper hose and it felt/sounded like it was still full. When the car was hot, the overflow was full to the top, like it should be, and as the engine cooled off it was sucking it back out of the overflow and into the system. At one point I looked and it was to the full mark on the bottle like it should be when cooled.

Back in San Antonio today: I looked in the overflow bottle and it was FULL up to the top(as if the engine were hot or something). Then I opened the rad. cap and heard a little bit of pressure escape(not losing pressure, holding it in there all night and half of today) but the upper rad. hose is very low if not empty now!

So what the hell is going on?!? Im so confused, I have no idea whats happening. Please help

 

[Sotarts]

What's your water/coolant mixture %?

 

[KidintheTSi]

Umm this is really old. I've since figured out the problem. It was the head gasket. I changed it and had the head rebuilt and it's all good now.