I have an '89 Bronco II 4X4 auto, 2.9L V6. Ever since I bought it a couple years ago, the radiator coolant level has been dropping after a long drive or after a couple days of short trips. Of course I check the level when the engine is cool, however there has never been any signs of leakage; nothing was found on the ground, nothing at all...even after adding a blatant neon additive to check for leaks. I've had the system pressure checked twice with no indications of leaks. So to combat this problem, I've been replenishing the radiator coolant level whenever its low to about 2 inches from the pressure cap. As for the overflow tank, there is only a very very slight amount of antifreeze in it (checked when the engine is cool). I don't know if that's the way the tank should be...and i don't know much about cooling systems...so i've never filled the overflow tank with coolant; i've just been filling the radiator for 4 years. Meanwhile, I hear a gurgling noise underneath my dashboard whenever my car goes from 0 to 'round 55 or when traveling up a hill (in both instances my car's in a lower gear). Yet, when I'm crusing around 65 or 75 (in a higher gear), the gurgling noise stops. On a side note, I've had a lot of work done on the engine of this car, and yet this coolant/gurgling problem is STILL haunting me. So the question remains: what is that gurgling noise and why am I loosing coolant? ...also...am I suppose to fill my overflow tank with coolant too?

Another problem: My oil level has been dropping after a long drive or after a series of short trips (kinda like my coolant)...with no signs of leakage; i don't see any oil spots on the ground. This issue began when i took my car from a routine oil change and heard a loud ticking noise after a long drive. After pulling over, i checked the oil (when the engine was cool) and noticed it was incredibly low. Whether my mechanic forgot to add oil or blatantly DIDN'T add it, I now have this mysterious oil loss problem which I never had before this routine "oil change." Any suggestions as to why i'm loosing oil? On a side note, i don't take my car to that mechanic anymore...

Any answers are GREATLY appreciated...Thank you.

Lou

 

Well first off Welcome to FTE, we'll all be here to help ya out in whatever ways we can. I personally don't know how to help you in your situation, but in a few hours people will be waking up to answer your question.

My radiator does the same thing though, I can fill it and I fill the radiator overflow, and I never spot any leaks on the ground, but it seems to disappear. My oil does the same thing, I did however find the leak to it, and need to replace my gaskets and basically do an engine overhaul, not that this is your case, mine just needs some TLC.

 

Lower intake manifold gaskets can be a problem on these engines, and they can leak externally or internally.
How much coolant are you losing? A slow leak may not be readily visible.
The gurgling you here is most likely air being pumped through the heater core as a result of low coolant levels
The overflow should be filled to the marked full line. Then, as the radiator level falls, it should draw fluid from the overflow to keep the radiator full. As the fluid gets warm and expands, it should expand into the overflow.

 

I'm losing about 3-5 inches of coolant in the radiator, depending on how long of a drive. Usually after a 3 hour drive on the highway or after 4-5 days of short trips on stop-n-go roads, I must replenish the coolant.

As for the oil level, I lose about an eighth to a quarter of an inch under the same conditions mentioned before.

You mention about the gurgling in the system and making sure to fill the overflow tank to keep air from getting into the system. However, how do I go about purging the air (that's already in the system) out? ...Or should it dissipate after a while of keeping the coolant levels adequate (aka. filling the radiator and overflow tank levels)?

 

Do you have any smoke from the exhaust?

The radiator should stay full and purge the air if you keep the overflow tank filled.

 

No. There's no smoke coming from my exhaust. I mean...there's some white exhaust when I first start the truck in the morning, but as I drive the white exhaust fades away for the rest of the day. So I'm thinking that's just water vapor that accumulated through the night. Basically, the exhaust is clean...if u don't count the CO, heh heh.

Yesterday (when the engine was cool) I added antifreeze to the overflow tank up to the "cold fill" line, as suggested, and once again I added antifreeze to the radiator up to about an inch from the pressure cap. As I drove, I could still hear water running under my dashboard whenever I went up a hill or went from 0 to 'bout 50 (basically, whenever I wasn't at crusing speed). Today (when the engine was cool), I checked the antifreeze level in my radiator and it dropped about 2 inches. The level of antifreeze in the overflow tank is still the same (at the "cold fill" line). The mystery continues...any thoughts?

I don't know if this helps, but I'm wondering if this coolant problem has something to do with a "gap" in the radiator coolant reservoir thats between where I actually pour my coolant and the reservoir's housing. The gap seems intentional (it doesn't look like the gap was "formed" by expansion/contraction from heat), however, antifreeze DOES get in the gap whether I pour the antifreeze in it or if antifreeze overflows into it due to pressure. Is that gap a problem? Here's a picture to help better understand it...sorry if I sound more worried than I should be, heh heh

 

Okay, try this. Take the cap off the radiator, start the truck and see what it does. If there was an air pocket your temp gauge would show it.

 

Nice diagram.

I'm not familar with that style overflow tank, can anyone comment on the design???

 

The diagram is not the overflow tank; it's the reservoir on the radiator where I pour my coolant (I don't know the actual name for it). The pressure cap isn't shown. I drew the diagram myself, so it's not entirely accurate. I was illustrating a gap in the reservoir...I wanted to know if anybody knows the purpose of that gap, 'cause antifreeze gets in there. It looks like the gap was manmade/intentional...but maybe it has something to do with the coolant problem I've been having (and describing throughout this entire thread).

Anyway...I now have correct coolant levels (the radiator and overflow tank levels are correct when the engine is cool) and I'm still losing coolant after a long drive or after a series of short trips. Also, the gurgling sound still exists whenever I accelerate...yet, when considering the intake manifold issues on Bronco II's, as mentioned by mrshorty, I'm beginning to think that could be the source of the problem. I recently discovered how the intake manifold works; it establishes air-fuel mixtures. Seeing how air is involved, it is possible that air is somehow getting into the cooling system through a problem with the intake manifold. I believe this since the gurgling sound occurs whenever I accelerate, in which case more air is pumped into the air-fuel mixture and (if my assumption is correct) is also being pumped into the coolant system. Air in the coolant system could result in slight overheating of the engine, which in turn burns off some antifreeze. This subtle overheating may be why I'm losing 2-3 inches of coolant over extended periods of driving (it would be more inches if I didn't replenish it periodically). Of course, the overheating should be indicated by my temp gauge, but I've never seen it go into the red or even jumped past the midway point...then again, I'm not sure if the temp gauge is accurate in the first place. But anyway...does anybody else think that a problem with the intake manifold could be responsible for the problem with my coolant system?

 

Thats the auto tranny cooler, everything is normal there.

I don't recall the coolant passages related to the intake manifold but if your leaking coolant there it would either end up in the oil, end up on the outside of the engine or get drawn into the compustion chamber and burned. Maybe mrshorty can comment on this. If it is getting into the combustion chamber you might see white, sweet smelling smoke and the spark plugs would look very clean, steam cleaned. Also burning coolant will trash the O2.

 

Here's some new stuff about my coolant system problem:
I checked my overflow tank this morning (when the engine was cool) and it was entirely filled, all the way up to the lid...way past the "cold fill" line. I also checked the coolant level in the radiator reservoir and it was very low. Keep in mind that my coolant levels were all fine the day before (the overflow tank level and radiator level were filled correctly before I drove). This is telling me that coolant is expelling into the overflow tank but not being sucked back into the radiator. I'm starting to wonder if the radiator cap is working correctly; maybe it's not adjusted to the right psi...maybe it's not the right cap for my truck in the first place. Can anyone tell me how this overflow tank problem might be related to my coolant system problem?

 

You could have a small hole in the hose that runs from the radiator neck to the overflow tank. This could allow coolant to flow into the overflow tank at atmospheric pressure, yet suck air back into the radiator as the system cools back down.

I'd check that hose very carefully for leaks.

 

Well...I did forget to mention that after noticing all that extra coolant in the overflow tank, I knew I couldn't drive around like that. So I took off the hose (from the radiator neck to the tank) and emptied the coolant from the tank into an empty jug. I inspected the hose and found no holes or cracks, but I was concerned if the hose clamps were tight enough. So I reconnected the hose, tightened the clamps thoroughly, and filled the radiator reservoir and overflow tank levels with the coolant collected in the jug. I did a bit of driving today, so I guess I'll see how the radiator and overflow tank look in the morning. But seeing how there were no holes/cracks in the hose and no visable antifreeze stains, I can't say that air is getting sucked back into the radiator. The problem seems more complex than that...after all, I hear the gurgling noise whenever I accelerate; the noise stops immediately whenever I let my foot off the gas or when I'm crusing. I'm thinkin about tellin my mechanic to check the intake...or at least find a way to purge the air out of the system.

 

I would suggest that you test your radiator cap as it may not be operating properly.

Unfortunately you may have another problem and that is that you may have a cracked head or leaking head gasket. In this case the combustion gas in the cylinder is leaking into the water jacket and pressuring the cooling system up. This causes the coolant to be blown into the overflow tank. Because of the process that occurs, the coolant from the overflow tank is not pulled back into the radiator as the engine cools as it should be. The fact that your overflow tank is empty at times is another possible indicator of this. If you drive long enough, the combustion gas will eventually blow the overflow tank dry. You can get a tester to check for combustion gas in the radiator.

If this leak exists you won't often see any antifreeze in the combustion chamber as it is the cylinder compression that forces the gas into the cooling system by higher pressure. Generally there is not enough pressure in the cooling system to force coolant the other way.

I currently have this problem with my BII 2.9 V6 and I have been trying to deny it but I know I am going to have to overhaul the engine. I have the same problem with my 1991 Ranger 3.0 V6 as well but it has almost 400K miles on it. It blows the coolant out big time though.

 

Have you check your heater core?If its good I would get a new radiator cap.If you get the right pressure on the system you might find your leak.Just remember that the 2.9 does not like heat!!! So keep the coolant in it till you find your leak.