Originally Posted by jbrew

Very easy to bleed - ALWAYS fill exspansion tank with top hose OFF thermostat housing. When coolant makes it's way to the thermostat, THEN connect hose and continue to fill to the line.

Then Start- warm up with heat cranked and with expansion tank cap removed - It's bled.

BTW - T-stat spring MUST be pointing toward the ground.

Originally Posted by Foe

Thermostat is 195

Going to break down and take it to the dealer Monday. I believe there's air trapped in the system and I've been unable to bleed it. will let you know what they find out.

I hate going to a dealer not knowing exactly what needs to be done/replaced. Puts you at the mercy of the parts department....

Originally Posted by code58

Brew- have you seen the fill systems that they have now that threads the fill hose to the lowest point (either radiator or wherever the factory overflow hose goes to, down low), and pulls a vacuum on the system and you close vacuum valve and open fill valve and it sucks it very quickly to the lowest point and eliminates any chance of air pockets to say nothing of a quick and spill free fill. Pretty neat, especially for those troublesome systems with no bleed valve.

Originally Posted by CNY98F150

Well Im just offering my thoughts as my experience is identical to the symptoms that foe has experienced and my head gasket/cracked cyl head is now bad. Strong smell of antifreeze out tail pipe. Bubbles in coolant tank etc..Slightly rough idle when cold to slightly warm. Once its up to operating temp and gets all the air out it runs like new with great heat. What else can it be? I have changed everything as it sounds foe has. Radiator, t-stat, waterpump, several engine flushes etc...My money is on what I said earlier. I guess we will find out soon enough..Foe if you do have it fixed and it is not either a bad head gasket or warped or cracked head PLEASE let me know. I would like a nice easy fix..
My truck has been doing this for quite some time but only a few thousand miles as I drive 2.5 miles to work and drive another vehicle as well. I posted here a while back about this problem as I was perplexed as well..
Gerald

Originally Posted by CNY98F150

code58 yes it cycles a few times ,engine gets warm, gets cold, heater blows cold, blows warm etc...It takes about 10 to 15 miles before thing seem to return to normal and the temp guage and the heat become normal..One thing I forgot to mention and this is something I believe you mentioned. With the exhaust leaking into the cooling system and pumping up the cooling system until the engine warms up, I have to be easy on the engine or it will knock pretty easily. Hot spots(lack of cooling) from the trapped air and hot exhaust I guess. I have thought of trying a block sealer..To cold and snowy for me to be pulling heads here outside today, garage is full..

Originally Posted by code58

Just a suggestion but I would try the Barr's leak for head gaskets that I mentioned. They make stuff that works- I have never tried this but I would if I had your situation. The great part is you just put it in with the anti-freeze and forget it.

Originally Posted by Foe

I believe it is the left hand head because I recently had the left hand exhaust manifold replaced and the mechanic told me the manifold had a "weird" expansion condition on one of the flanges on that side. Maybe...that condition was due to localized overheating?

Anyway, looking at the left side bank it appears that removing the head will be nothing short of a nightmare due to limited access at the rear of the head. Is it even possible to pull the head without doing anything special (as in lifting the cab)? At first glance I am worried that there isn't sufficient clearance to remove the head bolts. Please tell me I'm mistaken

EDIT - I saw another post on here that said the engine had to be pulled to replace the gasket. So I guess I'll just drive her until she dies...

Foe

Originally Posted by Foe

Thanks for the input and this may be the route I will pursue. Just got off the phone with Ford and the problem is a leaking head gasket or cracked head. There is compression (pressure) entering the coolant. Bad news, but what I suspected all along....Just didn't want to think about it ;-)

Originally Posted by Foe

I have a 1997 F150 4.6L with 183k miles and the engine is overcooling

Little background:
- Coolant has been flushed
- New Theromostat(s)
- New fan clutch
- Heater core relaced 50k miles ago

I've read similar topics on the net concerning this problem, but none of the topics cover my exact problem.

The engine temp never reaches normal range. Heater used to make your eyes water. Engine operating temp on the temp gage is 1/3 cooler than the motor ran previously. Now temp only climbs about 1/4 of the way into the normal range.

Temp can be verified by grasping top radiator hose which is only warm after 20 minutes of driving.

Coolant reservoir holding pressure after 24 hrs of idle time

Now here's the perplexing part; I removed the plastic cowling to get to the radiator and slid a piece of cardboard between the radiator and the evaporator as a shadetree test.... The cardboard is tight against the radiator. The cardboard covers 7/8ths of the radiator surface area. 30 miles of driving...ZERO change in engine temp. Zero

After the cardboard test, I can still place my hand on the top radiator hose and hold it there. Engine doesn't make any tinking sounds associated with the cooling of a hot engine. The engine is only warm to the touch.

Here's another tidbit....when I FIRST run the engine for say 3-4 miles and heater begins to blow slightly warm air then come to a stop, the heater will blow cold air. The temp gage falls back to cold and will sometimes slowly rise back to lukewarm and actually blow lukewarm air. Other times the temp gage drops, heater blows cold then the temp gage spikes to super hot. Shut engine off for a few seconds and lukewarm temp returns thru the heater and temp gage reads warm....This is an indication of trapped air in the system.

So how in the heck can I have trapped air (which woud make an engine run hotter) and still have an engine I can touch with a bare hand after running it for miles....?

If any of you brainiacs can figure this out I'd really appreciate it...

Originally Posted by jbrew

You CAN do it in the truck, it's just awkward as hell and more of a PITA.

BTW - Use passenger side and drivers side to designate right and left. People think of right and left differently on the motor. Not saying your wrong - Left is Drivers side / Right is passenger, - We don't know if you know that..

Originally Posted by Foe

Thanks

It is the drivers side (I believe), but that's only based on the bad exhaust manifold flange I spoke of earlier. We'll at least it will be a 50/50 shot

I was wondering if you can extract and/or insert the head bolts in the back part of the head if I chose to go the PITA route of pulling the head without removing the engine.

I confirmed it definitely is a bad head or head gasket today. Took the oil filler cap off and saw a water/oil mix on the bottom of the cap...Changing oil in the AM.

Will let you all know how this goes...thanks for the help