how do you get the air out of the system. I just did a heater core on my truck and I have intermittent heat.

 

With the radiator cap off, start the engine and let it run until the thermostat opens (the top radiator hose will get hot), the coolant level should go down as the air bleeds out of the system. Add coolant as needed to bring it up to the proper level. That's the way I've always done it, unless there's something else about the expedition I don't know. Then have a beer.

 

With the amount of coolant I've been adding daily (two gallons +) if the head gasket was blown, wouldn't I have gallons of coolant in the oil?

 

there isn't a radiator cap per say... The only cap there is, is the overflow bottle. I'll give it a shot this evening.

Thanks!

 

Two gallons, holy cow. You could have a cracked head or bad gasket leaking coolant into one of your cylinders instead of in to the oil. Does your exhaust look steamier than normal, if so that's probably your problem ?

 

Yes, that's what I meant. Did you do it, and if so did it work for you ?

 

If there was that much antifreeze flowing into the cylinders (2 plus gallons a DAY) you would DEFF know it, but its either internal or external and if it was external you would DEFF see it leaking onto the ground, so id have to say this thing is in pretty bad shape. How does it run???

 

Typically its about a half gallon a day. The two gallons today may be due to the flush I did in the morning after I replaced the thermostat. The exhaust is more noticeable and a puddle forms below the tail pipe.

I did a pressure test of the coolant system and loss about 2 psi over a ten minute period. When I drained the coolant yesterday, there were no signs of oil in it. I'm thinking about draining the oil for a closer look. The dip stick didn't show anything.

I put the expy at an incline so the resevoir is at the highest point. After running the engine to operating temperature (with the resevoir cap off) I still didn't feel coolant flowing through the upper hose, but I am getting interior heat. The lower hose also didn't feel like there was much flow. Both hoses did not feel hot. After squeezing the upper hose with the engine stopped, I did see air bubble into the resevoir.

Also, it runs very smooth (except when the 1bank1 O2 sensor acts up)

I'm not sure where to go from here. Is there a way to check the water pump while still on the engine? I'd like to be absolutely sure if I have a cracked head or blown head gasket before I start tearing things apart.

 

I would say that because your upper hose didn't heat up that either your thermostat isn't working or it's in backwards, or your pump isn't pumping. However that doesn't explain the coolant you're loosing. If it's actually a 1/2 gallon a day you're loosing, and you're not leaking anything to the ground, and your oil isn't creamy looking and you don't notice coolant on your dip stick I'd say it's not going there. I'm still thinking you could be loosing it through a leak off the head. It could be small enough that you don't really notice it in how the engine runs but large enough to cause the coolant loss. I wonder if that could be causing your O2 sensor problems also because usually when these sensors go out they go out, they just don't act up intermittently . There's no way to check the pump on the vehicle that I'm aware of. Usually when the pumps go out they'll start leaking coolant out the weep hole on the bottom of the pump. I'd think it's unlikely your impeller isn't turning but you never know. Also when your engines cold your cylinder pressure leaking through the head gasket could be going into your cooling system until the system pressures up which could explain your system gasing up, then when your cooling system pressures up the coolant to flow the other way out your cylinder and the tail pipe. Thats why I had you take the cap off, start your engine then put your hand over where the cap was to see if you could feel any indications of pressure. When this is done if everythings normal you shouldn't feel any pressure at all. A two pound drop in pressure in 10 minutes on your pressure test isn't much but it tells me it is leaking somewhere, slight though it may be.

 

I'm a little late in mentioning that I replaced the intake manifold gaskets last week. I thought the addition of the more than usual coolant was due to the evacuated intake manifold. I drove it for a week with just adding about a quart a day until the over heat two days ago. I'm not leaking at the water pump but someone earlier in this thread mention cavitation of the pump due to excessive air. I'm thinking about removing the thermostat and watching the coolant in the resevoir, feeling the hoses for flow, etc. This should rule out the water pump. I can also due a compression check but I'm not sure if "bad" results will indicate a problem with the head gasket. I believe a compression check needs to be done with the engine as close to operating temperature as possible. I'd love to meet the person that can remove all the plugs and run the compression test in less than 30 minutes!

 

Awww, now the truth comes out. Did you have this problem before replacing the gaskets ? If not I bet that's your problem, you might have a leak from the intake gaskets into the cylinder (at least I think the intake on these has coolant flow through it). I think doing a compression check would be a pain in the you know what.

 

Ok to eliminate confusion what services with the cooling system have been performed in the last two years?

 

I had a coolant leak coming from the pipe that runs under the intake to the water pump. You have to pull the manifold to get at it. The two o-rings on the pipe were shot. So, while in there, I cleaned up the intake and replaced all the gaskets. Yes, coolant does flow through the intake manifold. But prior to pulling the manifold, I would have to add about a quart a week. It had been that way for about a year. I thought the coolant loss was due to the bad o-rings. Prior coolant maintenance was not very intensive. I would simply drain and refill the coolant about every 60,000 miles. I've also replace both radiator hoses. The heater hoses are original but don't show signs of any wear. I did replace the quick disconnects with hose clamps when I reinstalled the intake manifold. I never did a thorough flush. I examined the intake for signs of leaking and don't see any.

 

Ok so you didnt suspect an intake leak, just had to take it off to get to something else. Have you checked for puddling in and around intake? Look all over the motor VERY well and look to see if you find any dried coolant or if its setting somewere and its burnin off or something. You should not be puttin a half gallon of antifreeze in this thing everyday. Get a compression check done also. Easy way to tell if a head gaskets leakin internally is if you have a way to measure HC's take your coolant cap off after you let it cool down and test to see if theres any HC's in there. Also make sure everywere you turned a bolt that it is correctly tightened and in place (including gaskets properly sealed ect...)

 

I'll do the compression test tonight. What do you mean by HC's?