Losing coolant regularly, but not leaking?

[dd-dd]

I have a 2003 4Runner V6 with 108K miles on it and I am losing coolant.

I noticed recently that my coolant resevior was empty, open the radiator cap and it was low as well. Topped off the radiator, filled the resevior, and with a week the resevoir was empty and the radiator low. Refill both, same deal. Refill just the radiator, same thing. Each time, over the course of a week or two the coolant is always gone from the resevior, and the radiator is down maybe 1/4 of a gallon (maybe a little less) each time I check. It is a consistent level down.

There are no fluids leaking that can be seen on the pavement or anywhere under the vehicle.

Last oil change at 107K did not look milky or smell of coolant. I have not done an oil analysis.

I pulled the spark plugs and they look mostly normal, maybe a white burn on the electrode more than expected.

I have not noticed any moisture/smoke from the exhaust, but I also don't have a good view of my exhaust while I'm driving...

My thoughts are a leak somewhere in the system which burns off before it can drip to the ground, or a head gasket. I'm not sure what to check next, other than take it to a shop for a pressure test of the radiator and a compression test.

I follow the Toyota maintenance schedule, and I have had no other problems except for a few front brake calipers (of course) and one O2 sensor.

If anyone has any ideas on what else I can check before bringing it to a shop I would appreciate any input.

Thanks!

 

[progress4m]

.....

My thoughts are a leak somewhere in the system which burns off before it can drip to the ground, or a head gasket. I'm not sure what to check next, other than take it to a shop for a pressure test of the radiator and a compression test...

I hate to say it but it sounds like the Head gasket… if you are losing ¼ gallon of antifreeze per week and it would be leaking externally I do think that amount would burn off…. you would see it…
Is there any hesitation in idling\start up when engines is cold? If yes, that is just more sign of HD blown..

The only other thing you can check is your transmission fluid: there is a remote chance that transmission cooler inside of the radiator is leaking and antifreeze is getting pushed into trany… This actually was known issue on 3-rd gen 4Runners..

Good luck to you.

 

[FlyZLow]

I hate to say it but it sounds like the Head gasket

+1 You may not see coolant in the oil if the break is between the coolant chamber and cylinder wall. In that case, you'd just burn the coolant in the combustion chamber. Were all of the spark plugs as you described or only 1 or 2?

One thing that you can try is to let the motor run until the thermostat opens w/ the radiator cap off. If you're frequently seeing bubbles rise to the surface in the radiator, then you're probably getting combustion pressure into the cooling system (i.e. head gasket failure between the coolant passage and cylinder wall).

Good luck.

 

[DC runner]

Yep. Mysterious coolant loss that your cannot explain with a puddle on the ground..then, yea it is getting eaten up in the combustion cycle which means the headgasket.

Before we assume that. Take a fresh, clean piece of cardboard and put it under there right after you drive it.

If you have a crack or leak in the system, while it is still under pressure from being heated up - you are more likely to see the leak. If not... then, yea; headgasket.

 

[08T4R]

If it is being burned, the cylinder(s) that are the culprit will be clean(er) than the rest due to the cleaning from the coolant/water being turned to steam. One of the easiest ways to tell if this is the case. Just pull the plugs and rotate each piston to TDC and look into the plug holes with a good flashlight/mirror if needed. I would certainly think the plug(s) would be clean(er) as well.

 

[ClockWork]

Dang...another V6 HG fail......I'll stop.

Hope everything works out for you, though.

 

[NJshadow93]

Dang...another V6 HG fail......I'll stop.

Hope everything works out for you, though.

i was thinking the same thing. but that 4.0L V6 is still a great engine. im sure the ones that did have this issue or similar can be counted on one hand.

 

[slyangel9]

It's happened to me in the past (not on the 4runner though), it was a evaporating from the top of the radiator.

 

[20034RunnerV84x2]

I hate to say it but it sounds like the Head gasket… if you are losing ¼ gallon of antifreeze per week and it would be leaking externally I do think that amount would burn off…. you would see it…
Is there any hesitation in idling\start up when engines is cold? If yes, that is just more sign of HD blown..

The only other thing you can check is your transmission fluid: there is a remote chance that transmission cooler inside of the radiator is leaking and antifreeze is getting pushed into trany… This actually was known issue on 3-rd gen 4Runners..

Good luck to you.

So in other words its mostly on the V6 right?

 

[08T4R]

Another idea is to do a compression test and leak down test. The gauges aren't too expensive.

 

[norcal2]

i had the same problem, at 100k...water pump leak, the water was evaporating so i never saw a drip until i put it up on my rack...double check your water pump...

 

[dd-dd]

Thanks.

Thanks for the replies, good news - for the most part.

All 6 spark plugs looked the same, no bubbling of the coolant with the cap off with the engine running and thermostat open, not a drip of coolant after the car was running.

Took it to the shop and they didn't detect any combustion in the coolant system. They didn't see any leaks either. Pressure tested the coolant system and found a small leak directly from the radiator, so it was just leaking and burning off.

Will get a new radiator, just glad it wasn't the head gasket!

 

[blaniac22]

Thanks for the replies, good news - for the most part.

All 6 spark plugs looked the same, no bubbling of the coolant with the cap off with the engine running and thermostat open, not a drip of coolant after the car was running.

Took it to the shop and they didn't detect any combustion in the coolant system. They didn't see any leaks either. Pressure tested the coolant system and found a small leak directly from the radiator, so it was just leaking and burning off.

Will get a new radiator, just glad it wasn't the head gasket!

Congratulations...sort of.

 

[simple]

Same problem, maybe? In February I opened my hood and to my surprise my coolant bottle was empty. I refilled and checked it regularly for a few weeks and it hadn't dropped an mm. Maybe 2-3wks ago I was changing a headlight bulb, and I noticed my coolant was down about an inch. I thought, dammit, I'll monitor it. Well today I remembered after seeing this thread and went out there to check and refill, well it wasn't as bad as I remember, it was 1/8th of the bottle, or maybe a visible 3/4in loss of fluid. Put more fluid in, and now its full again. It was steady for months, and it dropped again. What do you guys think? Head Gasket, leak, normal?

 

[achen]

2004 Toyota 4runner coolant leaking?

Hi,
i have a 04 4runner v6 with 94k miles. I have realized that my coolant in the reservoir box get evaporated very quickly. I dont see any leaks under the car. I have to constantly refilling the reservoir. what can the problem be? Please advise.

 

[gshadow325]

holy thread ressurection batman.

sorry but as others have said...dreaded head gasket

 

[achen]

Steve,

how much would the repair cost and do i know it's a dreaded head gasket? any symptoms? what caused the damage?

 

[gshadow325]

Steve,

how much would the repair cost and do i know it's a dreaded head gasket? any symptoms? what caused the damage?

i dont know how much it would cost. i have read prices from $1k to 3500

loosing coolant you can sometimes smell something sweet from the exhaust. you could have a leaking radiator, thats one i hope you have. thats the cheapest problem. problem could be from materials used when it was being built. lots of different factors. no one knows for sure. only thing i know for sure, i am seeing more and more of these threads pop up in recent months from v6 owners.

symtoms are what you descibe, missing coolant. maybe leaking water pump. i honestly dont know for sure.

 

[radlynx]

that's definitely your radiator. I had the same problem around that mileage. leak is coming from the driver side part of the radiator. look in there and check for crust of white/orange stuff.

Hi,
i have a 04 4runner v6 with 94k miles. I have realized that my coolant in the reservoir box get evaporated very quickly. I dont see any leaks under the car. I have to constantly refilling the reservoir. what can the problem be? Please advise.

 

[achen]

so what do i do now? i mean i don't see any leaks on the ground or any check engine light on. what to do now?