Vehicle : 1991 Ford Ranger 3.0L 151,000 miles

Recently I have been having a problem with the cooling system in my '91 Ranger. The truck was getting up there in age, and still running well so I decided to go ahead and go all out on the cooling system. (I had a stuck open thermostat also, so I figure it is time to put some money back into the Ranger) I went ahead and replaced the following:

Radiator
Radiator Hoses Upper and Lower
Heater Core
Thermostat
Waterpump

It drove great for the first day, and she started overheating. So I figured that maybe the Thermostat I got was stuck closed. ( I used some Bars Leak a bit back to try and seal up the heater core awhile back, and I noticed it gunked up the system when I did the previous work) So I decided to remove the thermostat to see if that was the culprit. It is still overheating, and smoking a bit (Which it smoked a little before, but hey its an older vehicle they do that), and I am losing coolant.

I went out and bought a Compression gauge to take readings on the cylinders and got the follwing results. On the Passenger side of the Block starting closest to the radiator was 137, 145, and 145 psi. On the Drivers side of the block starting closest to the radiator was 125, 140, and 101. Now I took those readings when the motor was cold, and the 101 it was struggling to get there. When I drove it I noticed the smoke goes away a bit when the motor gets up to temp. I rechecked the compression in the lowest valued cylinder, and got a reading of 120. The cylinder in front of that still read 140.

The Truck is sputtering pretty bad and I probably lost about 10 ounces of collant test driving it yesterday and this morning. Its going somewhere, and there are no visible leaks under the truck. With the Chilton's or Haynes (can't remember which I have atm) the lowest value it said I should have is 101 psi in the cylinders. I didn't see anything in the write up on a certain % or tolerance it had to be in relation of the other cylinders. Am I in right thinking I need to replace the Head Gasket on that side? Any advice would be welcomed towards this. I have had this truck since '96 and it does hold a certain value to me. Even though people say they need a Tetnis shot after standing next to it. Thanks once again.

 

Try changing your oil - does it come out black/brown, or does it come out milky? Any puddles if you let the truck sit for a while? Hows the exhaust smoking?

 

The Oil was recently changed. There is no Chocolate Milk look too it. The oil on the dipstick still looks brand new. It was done under 700 miles ago.

The smoke is white, and if I step on the accelerator while she is cold it will put out some pretty heavy smoke. If I let it idle it will occasionally blow a perfect smoke ring. It is kind of humerous, but not funny in the same thought.

 

I used to have a fitting with a schrader valve on it that would screw into the spark plug hole.After removing the valve cover and making sure the valves were closed on the suspect cylinder I would put this in the plug hole and hit it with about 30lbs of air.With the radiator cap off I would listen for any air bubbles in the coolant system.
Does your coolant have any oil spects floating around on the top? White smoke out the tailpipe most always means head gasket , cracked head ,or cracked block.
Anybody know if that engine came with aluminum heads?They are known to warp.
Hopefully you just need a head gasket.

 

I am hoping it is just a head gasket. It has been a very durable truck the whole time I have owned it. I am going to get all the gaskets I need on order this week, and probably start the tear down on her next week sometime. If this doesn't fix her it may be time to upgrade to a newer Ranger.

 

While you've got it apart you might as well do the valve seals too.May help to cut down on the smoke issue.