1994 Cougar- Overheating Problem(s?)

1994 Cougar- 97,000 miles
I've noticed lately that something has been dripping onto the oil filter, eroding the red "Motorcraft" logo right off it. Upon closer inspection, there is a white (and partially green) chalky residue all over the water pump, which drips onto the oil filter and crank pulley. I'm guessing coolant, and just topped it off recently. No overheating problems yet, but time for a new water pump maybe?

For your diagnosing pleasure--
I drove it this morning, and it actually did start to overheat this time. The needle stayed in the "normal" range, but was definitely climbing towards the red zone. I switched heater on to full hot, but cool air came out.

I accelerated (~3,000 revs), and hot air started coming out, and the water temp went down. But the heater started blowing cool again, so I accelerated from the next red light, and it blew hot again, as the water temp went down further.

Is my acceleration forcing free a blockage somewhere? Are the overheat, leakage, and heater problems linked?

I replaced the thermostat, it runs fine now.

But it seems the leakage is from some kind of weep-hole on the top of the water pump. What makes it weep out and how do I stop it from shedding coolant?

I am planning to flush the cooling system and maybe replace the water pump.

I found that the weeping of the water pump indicates its failing. I replaced the water pump, and the problem is fixed.
However, the water temp gauge never leaves the blue cold area, into the normal range, and the heater only ever blows cool/warm air, never hot. I think it's cooling too well.

Replaced thermostat under part warranty, problem solved! It was stuck open, though brand new.

:banghead:
But the low temperature problem seems to have returned after driving it a bit more. I hope this one hasn't stuck open too. The thermostat has little tabs that lock it open, so that if it fails, it won't fail in a closed position. However, the spring needs to compress itself enough for that to happen. Is it possible something is causing these thermostats to fail?

I think I need a new thermostat, but I don't want to replace it until I know there's not something in the engine causing it to fail.
Today it was acting up more; here's what I encountered.

My heater blew warm air (not really hot) for most of the way to work. The water temp showed below normal, too.

On the last 10-15 minutes of my 50 minute drive, it blew cool air only. Also, the water temp rose into the "normal" range, and crept towards overheat. It climbed high enough to trigger the "check gauges" light. I wondered if it was a blockage, so I shifted into neutral and revved the engine. The water temp quickly fell back down into the normal range, but soon crept back up again. Am I freeing up a blockage somewhere when I rev the engine?

Once I got to work, I popped the hood, but couldn't find any obvious problems. The upper rad hose was hot, the lower one was merely warm. Coolant level in expansion tank was fine.

When I left work, the "low coolant" light was on, and I drove it for a few miles. This time, the heater was working again. After driving a few miles, I stopped and checked the coolant level. It was fine, and air was bubbling up into the reservoir. I turned the engine off and restarted it to make the "low coolant" light turn off.
I made it almost the rest of the way home, when the heater stopped blowing warm air again, and the engine started trying to overheat. I again revved the engine to make the water temp go back down.

What is going on? Can a bad thermostat do this?

You've all the symptoms of a blown head gasket. Combustion gas is getting into the coolant forming gas pockets that are keeping the transfer of heat low. Revving it up will temporarily make it transfer heat again. Take it to a radiator shop and they can test the coolant for exhaust gas with a simple test. When it's hot you shouldn't see bubbles forming in the overflow tank. Also, it may have oil in the coolant or coolant in the oil. Either way you are going to have to fix the head gasket and change the oil and the coolant.

Rats. I knew the 3.8 had the potential to do just that, and hoped I might luck out.

This morning, once I got to work, (after fighting the car to keep it cool again) I popped the hood to find bubbles coming up into the reservoir, just like you said. I thought I saw a little "rainbow sheen" on top of the coolant, too.

D**n.

From what I hear, it's about $1000 for a shop to do, but closer to $150 to do myself (lots of labor). The closest I've ever gotten to engine work is tune-ups and electrical equipment, but I'd like to do this myself if I can. Any pointers would be much appreciated.

What causes these HGs to blow? Is the design itself at fault, or did Ford just put crappy gaskets in these?

I had to leave it at a gas station tonight. The overheating was getting harder and harder to fight. I'm sure it's a head gasket now, and probably burning coolant. The reservoir smells of exhaust fumes, and the coolant level has dropped.

So let me get this straight; the blown gasket allows the exhaust and coolant to trade places, explaining the overheat. But does this really account for the "under-heating" problem i was experiencing? I don't understand how that works.

I had hopes that I was wrong, also. I didn't mean to be confusing. The way I see it, the combustion gas is leaking into the coolant system through a blown head gasket. What I meant to say was that the coolant is being displaced by exhaust gas. Gas doesn't transfer heat as well as a liquid does. So....that was the reason for the temperature to go up on your guage. By the same token, the gas in the coolant is keeping the heat from transferring in your heater core. Hence, no warm heater. When you rev it up the surge in coolant pressure makes it transfer heat in the engine and the heater core. The engine runs cooler and the heater runs warmer.

A head gasket will take a while to do, but there isn't anything very high tech with it. The important thing is to torque the head evenly and at whatever specs call for as far as torque settings. You ought to get a Haynes repair manual at the local parts place. It will tell you what to do step by step with really good pics. It's about $20 and will pay for itself the first time you use it. Basically, you unbolt the exhaust manifold, unbolt the intake manifold, take the belts off and pull bolts out of the head. Its not that hard to do. I think you can do it. I will play the devil's advocate though. If the head is cracked and it's not the head gasket you will have to deal with that if you do the work. If you have someone else do the work and replacing the head gasket doesn't solve the problem then they are stuck with doing it over again and you are spared any additional labor.

What makes the gasket go? Thats a good question. I think that if the coolant has never been changed it gets corrosive and along with the heat and pressure it eats the gasket up between 2 cylinders. There's not much gasket to blow out between the 2 cylinders.

The only problem I see if you do it yourself is the exhaust manifold bolts. Usually they frozen in the head and the only way to get them out without breaking them off is to heat them with a torch and use an impact wrench. If you aren't comfortable with doing it yourself it would be better to have it done at a shop. I'm thinking it would be about $500 labor and $100 for the gasket. Look at it this way. It's ALWAYS cheaper in the long run to pay for repairs rather than make car payments. The dealer will give you next to nothing for your trade and will overprice his end of it 200%. Then you've got higher insurance, sales tax to be paid and no guarantee that the same thing won't happen again.
Make sure you get the work done someplace that will give you a guarantee. That way, if it ever needs to be done again, it will fall back on them and not on you.

I trailered the car to a friend's house, who has graciously offered his (heated) garage. Unfortunately, I will be out of town for a couple of weeks, unable to work on it.

Until then, I'll be researching stuff for the job so I can start right away when I get back. I'm looking for a good gasket that will hold up better than stock.

I'm taking my time tearing it apart; just have to get the heads off now. I should have unbolted the header-to-pipe connections before I got this far. There's almost enough room to unbolt the heads without taking the headers off. I think I will go with Fel-Pro gaskets after I get the heads surfaced.