Head gasket or Intake gasket?

Hello, heres what I am experiencing. In my 94 3.1 I am getting some air bubbles in the recovery tank only at idle though which I would suspect would be caused by a leaking head gasket. I am not seeing any water in the oil, or steam in the exhaust, no external coolant leaks, but my vacuum seems to be dropping off under less load than normal. I noticed this by when the heat is on the floor it will go to the defroster as load is increased, then back down again as the load decreases.
I do see some fluctuation on the temperature gauge and have had some air bubbles in the cooling system, most obvious by the cold air coming across the heater core.
I recently went through the cooling system replacing the thermostat, water pump, and hoses. I thought I had purged most of the air out of the system and had everything running pretty good until the other day I started the car and the tension pulley assembly blew apart on me. (which probably explained the occasional dead battery due to not enough tension on alternator, but thats a whole different story).
Well after replacing the tensioner assembly, started motor and started experiencing the air bubble effect again. Cold air across the heater core, ect. ect. After this is when I started noticing the bubbles in the recovery tank, but like I said its only at idle, shouldnt it increase with engine rpms?
Also will a head gasket affect the vacuum? I would think that would indicate intake gasket problems. Also I have replaced and checked any bad vacuum lines that may be contributing to the vacuum problem.
I dont have a problem changing head gaskets but wondering if maybe it could be just the intake and there fore would not have to tear it down as far.

Also one other thing that crossed my mind was if its even possible, with the weak tension pulley would it have been possible that the water pump wasnt pumping as hard as it could have been due to less tension on the pulley and when I changed it out it started pumping like it should and sucked the level down in the radiator causing air to get back in the system and creating the air bubbles again???
Any suggestions would be appreciated and thanks in advance.

dd

Is there any misfire or engine roughness? Also did the bubbles in the jar occur after the work was done. You can get a kit to check for combustion gasses in the cooling system to confirm if a head gasket may be the issue, air in the cooling system can cause your symptoms except the low vacuum issue. Any signs of coolant on the plugs?

I have a blown intake gasket on mine. I can see coolant coming out of the top of the intake mani, I was loosing a fair amount of coolant and stuff. I put some liquid silver or whatever in there and works fine. have you been loosing any coolant?

I have been losing some, but I havent been able to see anything real obvious. I have tomorrow off so I plan on pulling the plugs to see if there is any evidence there. I am not sure if the drop in leve is due to a leak or because of the air being bled off.
I thought of using the "bars leak" type stuff as most everyone I have talked to has had good luck with it. But this is my carpool car and leaving me on the road is one thing, but being responsible for several others is different, so I will be changing out the gaskets. If after pulling the intake gaskets I dont see anything real obvious I will plan on pulling the head gaskets. From what I am reading sounds like they're going to go sooner or later if it hasn't yet. So if I'm that far into it i might as well go all the way.

Are you llosing it to the ground or to the combustion chamber? If its on the ground then I would check around the intake mani, heads, valvecovers etc, thats how I had found my leak. I had used a sealer like liquid silver or something like that, filled the colant, and havent had a problem since, this waas about a month ago. Good luck though.

If your getting bubbles it could be a compression leak in the head where the fired cylinder forces into the coolant system.

Sometimes a good nose can tell if its exhaust gas or just air.

If it continually happens it proubably is a crack or a gasket leak.
It often takes a bit of time before all the air is burped from a coolant system.

An engine doesnt have to use coolant for a gasket leak to occur.

Well, got home tonight and pulled the plugs and all were good, I did have some white build up on one of the plugs. There is no external leaks or am I losing any coolant any where. While it was bubbling into the recovery tank I did stick my nose in and it does have an exhaust odor to it. So I believe bassasasin my be correct. The oil looks good but I do have the scummy build up on the filler cap and the pcv valve. :banghead:

Well, a mechanic freind looked at it and yes it is the head gasket starting to go. So I went and got the gasket kit, had to order the head bolts, and flange gasket. I will let you know how things turn out. Pulled heads before but never on these little cramped motors always been the older 350's and such so it should be a learning experience. :)

Update, I pulled the intakes last night and am down to pulling the exhaust manifolds then heads. Problem is I cant seem to figure out how the motor mount at the front of the block is attached to the head. Do I need to drop the a/c to find a hidden bolt some where? Also I did find my lower intake gasket did have a crack. Hmmm..