Ford Thunderbird 3.8 Engine Cooling 'Heater Problem

I have a 1992 Ford Thunderbird and have taken care of it since I have purchased it new in 92. After a couple of years I learned of the Head Problems that can happen with these engines. One of the reasons is design and the radiator sets lower than some of the cooling in the heads in the engine. I tried to take care of this car and just recently blew the heads and emptied the radiator thru the exhaust as I was traveling on the highway after 216,000 miles on original heads.. Here is what I know after owning this car for 13 years.

  1. When checking the coolant level check the overflow level in the overflow bottle. Do not remove radiator cap for a coolant level check as air most likely will enter the system as the Radiator fill is below the water level in the heads. Can also check top radiator hose by touching it carefully as to see if it is hot if engine is just started it will take a few minutes for the hose to get warm and the bottom of the hose will heat up first as flow will be slow at first and that means coolant is should be flowing thru the system. The radiator cap is below some of the head cooling and this coolant in the heads will drop down to the level of the radiator fill cap as it spills out the fill cap opening..

  1. If radiator cap is removed then the vent on top of the engine most likey will have to be removed and the radiator topped off. To do this I have found if the front of the car is elevated compared to the rear (I can tell if the front of the car is at the correct height as the vent water level will be the same as the Radiator fill Cap opening) I can top off the radiator till I see the fluid in the vent. There will be some bubbling as the air is purged with the water moving in to the voids. If you have the proper Thermostat with a small check valve or bleed valve and it is located at the top of theThermostat in the housing then the next time the engine is run the radiator may sippon fluid from the resorvor to the radiator. And the vent can be loosened and vented. This does not always get the air pockets out from my experience as afterward when driving the thermostat will cycle and the temp gauge will go from 1/4 up to half way up with spikes higher to near too hot. 3 Get the correct thermostat and that can be hard at times and I have a hard time to get a mechanic to listen to me to install the correct thermostat.. The correct Thermostat has a little bleed or some call a check valve and this is important in removing any airt or steam pockets in the heads. The Thermostat is mounted with the air bleed or check valve at the 12 o clock position), I just had my heads worked on and I asked for the Thermostat with the vent in it and they put a stat in with out the bleed I knew almost right away it was wrong or they did not vent the cooling system correct. I also had asked for Prestone the Yellow Anti Freeze that will mix with any anti freeze and they put in the green stuff they get in 55 gallon drums for little nothing. I also knew I had a air lock or vapor lock in the heads as when I filled up my gas I only got 16 miles to a gallon and so I knew the water at the sensor was too cool and I was not getting correct circulation, The temp sensor kept the car computer in closed loop and that made the gas milage bad. Steam or vapor or air lock will prevent correct circulation and cause cool spots or even worse hot very hot areas on the heads that can warp or crack the heads or blow the head gaskets.

An early sign that something is wrong is the heat output of the heater just won't be as hot it will seem like the car will never quite get warm enough this can be the begining or the head or heads going bad. If heat output is down get a pressure test before the problem gets worse and may cost even more money.

This is what I have found to work for me on my 3.8 Thunderbird. With a little care they will last and a understanding of the cooling of the heads.

I post this as someone may search for this problem and this may be of a help to them.

chil

Reply to
ep_zz
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I'm sorry... but I've had 2 3.8 93's and my son a 90 3.8 cougar... and all that you write is pretty much wrong.

I dont care how long you've had it..

  1. The position of the rad has nothing to do with the head gaskets blowing. The composition of the gaskets and

  1. Look close... there's a bypass from the Thermostat area to the water pump. That eliminates the need for a bleed hole in the thremostat.

  2. you only open the vent with the cap on... having it 'level' makes no difference and DOES NOT mean there isnt still air in the heads. Helps to bleed it out a few times after a refill

  1. opening the rad cap when it's cool, and bleed vent closed, doesnt let air in

Reply to
Backyard Mechanic

Dont mix colors.. it might work... but why bother!

Reply to
Backyard Mechanic

Just because there's coolant in the reservoir doesn't mean there is coolant in the motor.... thankfully, later systems have gone to a pressurized "degas" bottle to eliminate errors.

If the cooling system develops a slow leak that goes unnoticed, air (which is composed of much smaller molecules than coolant) can be drwn into the system as it cools... leaving a reservoir containing coolant and a cooling system too low.

Our cars are simply machines and machines require attention.... smart money is on spending a few minutes each week taking a good look at these machines... after a cold soak, check the coolant level, check the underhood fluid levels, check the FEAD belt (fan belt for the unFordists - is that a word?), check the tire condition and pressure... and for Gods sake - check your lights!!!! Doing these simple things can reduce the possibility of our machines leaving us stranded at the most inopportune times

The 3.8 is almost famous for puking head gaskets... part of the reason is it's inability to withstand excess heating in the cylinder heads.... many of these motors have seen a long and troublefree lifespan simply because the owners visited shops that paid close attention to detail or were painstaking in their own servicing....

Reply to
Jim Warman

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