yojimbo

Hi. I've been reading this forum for a while but never posted anything because until this point, I've always found the answer I've been looking for. This place is great. I'd really appreciate some advice to get me pointed in the right direction with a mysterious coolant problem I've been having. I have a 1989 4runner, 22RE engine with almost 200k miles. I had a couple hoses burst within the last year or so; at the time I attributed that to the age of the truck and I replaced them. I don't think the engine overheated (at least, according to the temp gauge it didn't).

For nearly a year, I've been going through coolant, but there's nothing pooling under the vehicle and no visible leaks. It's been worse lately so I've been paying closer attention to it. With the engine warm, the overflow is always full and it's usually spit coolant out into the engine compartment. When I pull the overflow cap off but leave the little overflow straw in the coolant, it blows bubbles, so I conclude that the system is over-pressurized and is venting coolant, and then air, into the overflow. When I let it cool just enough to remove the rad cap and peek into the radiator, there's no coolant visible (I put some stop-leak in recently as a quick-fix attempt, and now I see frothy bubbles, but still no coolant). And when it's cold, the overflow will be empty, but the coolant in the radiator will still be very low. It will lose half a gallon or more of coolant in a week of in-town driving.

I replaced the radiator cap but it didn't help, so I figured it sounds like a blown head gasket, which stressed me out 'cause I can't afford to repair it, and I can't have the truck out of commission long enough for me to learn to do it myself. But I digress...

I just pressure tested the system and it held at both 10 and 15 psi for over five minutes. I also pulled all the spark plugs, and while 1&2 had more deposits than 3&4, none of them looked "steam cleaned" as I've read they would in a cylinder with a coolant leak.

There's no white smoke in the exhaust and the exhaust smells normal, no sweet anti-freeze odor. The engine oil looks great, no coolant or anything else in there. It does sometimes surge at idle, which I think is a symptom of the air in the system, but other than that it runs great. So, without any history of overheating, a BHG doesn't sound likely, but then again, I can't think of anything else that explains the pressure in the cooling system and the coolant loss. Is there anything besides a head gasket that could cause this problem? Could there be some leak in the throttle body or vacuum system that's getting into the cooling system? Or have I overlooked something like a water pump or t-stat that could cause this?

One more thing I tried: I put the pressure tester back on, pumped it up to 10, and then pulled the spark plugs one at a time, assuming that the pressure would escape there, and I'd have a BHG caught red-handed. But with all four plugs out, the system held at 10psi. I know it's not an actual leak-down test, but it's the best I could do. Does this little test rule out a bad head gasket, or was it just a dumb idea and I should pay somebody to do an actual leak-down test to be sure?

I know there are a lot of coolant/head gasket threads here, I've read most of them the last few days. Sorry for another one, but for all the symptoms that point to a head gasket, there are plenty that seem to point away from it, and before I go tearing into the engine or my credit card balance, I wanted to make sure I knew what I was getting into. Any advice or hints to diagnosing this problem would be greatly appreciated, thank you.

Rocketwrencher

Sound like you might have a slight leak that is evaporating before any signs are seen. It doesnt sound like a blown HG to me. No oil in the rad, no coolant in the oil, good pressure test= Good HG. The surge could be a vacuum leak. The best way to check for the coolant leak is to get an inspection mirror and flashlight and check everywhere before the engine gets to operating temp. The vacuum leak check is pretty much done by sound. Those can be tough to trace.

dbcx

Are you sure you are getting it full.
Go out when cool enough take rad cap off, see whats in it add if needed then crank it, may suck down add as needed the let it run long enough for the thermostat to open you will see the water start to flow thru add more iff needed.When its full put cap back on.
The only way to know 100% no oil in water is get your oil tested.

toyota4x4907

Are there any quarters in your radiator? Maybe the Coolant Fairy comes to your house every evening and takes your coolant to a happier place.




DO NOT USE RADIATOR FIX A LEAK!! I learned that the hard way, heh....that stuff is horrid....

I'm pretty much having the same problem in my 22re: Coolant loss with no tell-tale signs of a bad HG. Keep on posting man!! -Subscribed-

MSR

have a shop check for hydrocarbons in the cooling system or buy the $50 block check dye. with the fact that it keeps pumping out into the overflow sounds like a head gasket. the sealing ring can be broke without getting water in the oil but still consume coolant

yojimbo

I have tried starting it with the cap off, after a bit I can see coolant start to move and then the level rises and it spurts out pretty quickly (like less than a minute after starting it when cool), and so I run and shut off the engine and then out comes the kitty litter. I've been assuming that the spurting is due to the thermostat opening, and that it means it and the water pump are OK, but perhaps I'm misreading the spurting and it's due to something else? At any rate, I don't have much chance to add more coolant because it's a little geyser within a minute.

yojimbo

Well if there is a coolant fairy, she better start leaving something bigger than quarters! Twenties would be nice, in a few weeks I might actually be able to afford the head gasket! I never realized how expensive coolant was until I was buying it every other week...

I don't know why I did the stop leak. I had it in my hand, thinking to myself "this stuff is going to gunk up everything and fix nothing." But I tried it anyway. Some lessons you've got to learn over and over, I guess.

I will see if I can find somebody who can test the coolant for exhaust fumes as MSR suggested, thank you. That makes sense... if it's exhaust and coolant mixing, I should have exhaust that smells like coolant, OR coolant that smells like exhaust. Thanks to all for the suggestions so far!

toyota4x4907

Thats for sure! 12-15 dollars a gallon is pretty bad. I have to fill my reservoir tank every 7-10 days and it takes about 1/3 gallon. a few days before I replaced my radiator, it was leaking enough to be completely empty in 5-6 hours of just sitting.

When I used stop a leak junk, after about a month, it all got dropped into my res. tank. The tube between the rad and tank was completely clogged and there was about an inch of junk in the bottom of the tank.

Question to MSR: Where can I buy the dye stuff? NAPA, Schucks, CarQuest, etc.? Is it called "block check dye," or is there a more specific name? Thanks!

yojimbo

Well, I went ahead and had a leak-down test done, and as I suspected the head gasket is leaking in both cylinders 3 and 4, pressurizing the cooling system with exhaust and forcing the coolant out. I couldn't think of any other reason it would fill with air so quickly, but none of the other telltale signs of a BHG were obvious so I held out a little hope there'd be a quick and easy fox. At least now I know what it was, and what needs to be done to fix it.

The repair place wanted close to $2000 to replace the gasket, timing chain, and water pump, and that's about $1800 more than I can afford, so I've got a project ahead of me! Should be fun. I am certain I can get it apart, I'll probably be back here asking more questions when it's time to put it back together though. Thank you for the responses and the help!

kirkerik

I now this an older thread but, I have been having the same symptoms but just not quite as extreme meaning little less coolant loss and little less pressure.

I found these symptoms last year but it was quite mild, now a little more obvious but still subtle. I hope this helps as this is one of those things a bad HG can do just not as obvious.

When i start my truck from cold and let it run a few minutes (less if ambient temp. is warmer) pop open the hood, I can see and hear bubbles coming from the tube in the overflow. I turn off the motor and still the bubbles keep coming. Since i never let things get warm/hot I open the radiator cap the first turn and all pressure is released in to the overflow suddenly now. So i open the overflow and take a sniff and it surely smells like exhaust!
Inside the radiator it smells of exhaust too!

Im considering renting the coolant pressure test from the auto parts store but it looks conclusive at this point, Huh?

Again, i'm glad to have found someone else with the same mysterious symtoms and i hope bumping this helps

Kirk

Dongskie

I have experienced the same issue, bubbles in the radiator.

Found a very very small crack in the cylinder wall #3 right in the cooling galley.

Sleeved, done and back to 100% condition