So I just picked up a 2003 2.3L. Guy said it was blown --- didn't know much about cars/engines. Non-running. $200.

I drained the crankcase and it was completely full of coolant. Oil / milk chocolate on top. I ran a magnet thru the milk chocolate and found no metal.

Got all of it out I could, left the plug out, put in maybe a quart of water into the overflow tank .... and it all came out the oil drain -- immediately.

Pulled the spark plugs - Lots of pretty clean oil in the holes, and 2 of the 4 cylinders. Cyl #4 spark plug was bent to heck. never seen anything like it. Not like impact, the diode was bent upwards. like towards the piston.

Cranked it with all holes open -- sounds OK...no big clang or anything. Compression was decent. 90 on the dry hole, even got like 200 on the wet holes, which I can't believe.

Where to start ? I dont think the block is cracked, or a piston broke. I'm betting on a head gasket, but I am dumdfounded by the seemingly good compression. And if a head gasket - then how does the coolant so quickly run out the drain ? I didn't put enough water in to fill the block/radiator.

Previous owner says his daughter ran it out of oil. Not sure he really knows though.

Salvage engine at LKQ is $900 ( 105K miles)

 

This could get expensive really quick.

I would suggest buying a used engine, however I do not trust junkyard engines.

Try and find another Ford Ranger that has low miles and perhaps was wrecked.

The perfect donor truck would be one that still runs and can be run until completely warmed up.

It is a lot of work to save your current engine or replace the engine.

The last thing you want to do is pay good money for machine work to your head, buy all the needed parts and materials put the engine together and find out the bottom end is shot.

The same goes for buying a junkyard engine, they will warranty it for you if it is found to be bad yet you will be out all of your time and money spent on fluids filters etc.

If you prefer a junkyard engine buy one that you can hear run then have them pull it.

 

Have to say I haven't disassembled a 2.3l Duratec engine, so not familiar with all the crossover areas for coolant and oil.

On some engines the water pump can leak into timing chain cover, which leads directly to oil pan

Compression test was a good start but post ALL 4 cylinders pressure, this is not done just to see where coolant may have come from, it is done to see general engine condition, pistons, rings, valves and head.
The "90" would mean a problem, as would damaged spark plug tip

2.3l Duratec engine uses 9.7:1 compression ratio
Usual multiplier for sea level air pressure and mechanical compression on used engine is 18
18 X 9.7 = 174.6

So you would expect 175psi on compression test, but this is with calibrated gauge, good battery and good crank speed.
Point of compression test is not high numbers or in this case 175psi, point is the comparison of the 4 cylinders compression numbers

EaOutlaw is correct that another engine or rebuild might be best bet.
Coolant in the oil doesn't hurt bearings or anything else.
The problem with coolant in the oil is the coolants boiling point
Oil has a very high boiling point(well over 500degF) and doesn't freeze either, lol.
Coolant boils/turns to steam at about 235degF
If you run an engine with coolant in the oil then when that coolant gets pumped into a hot bearing/journal gap it can turn to steam instantly which blows out any oil so bearing is now running dry, which causes wear, and if continued bearing will get hotter and melt, its a soft metal.
When engine is shut off it will seize as bearing metal welds itself to journal.
Worse case scenario, lol.

If engine wasn't run long with coolant in the oil then bearings could be OK, if you don't know then its a roll of the dice since the only test for bearing condition is disassembly and inspection, and at that point new bearings are too cheap to not be used to replace old ones.

So compression test aside I would at least look for replacement engine costs locally to have a backup plan as you disassemble current 2.3l Duratec to see what the damage might be.
Could be you have a top end issue so pulling the head, testing it and then replacing gaskets might be all thats needed.

 

ha ha ha ahha --- OK, so went back again to redo the compression tests. I'm not sure how everyone else does compression tests, but I just crank it until it wont go any higher. Got 180 or above on cyl's 1, 2, 3. Was feeling pretty good. Checked #4 .... 0. Wouldn't even budge the gauge. Thought maybe I didn't have it threaded all the way in, tried again --- 0. Grabbed some bailing wire, stuck it down the hole ..... went down about 24" ... HA. So either the piston is laying in the bottom of the pan(unlikely I guess) ... or the piston has a hole in it the size of jupiter. Just weird that there's no clank or know when turning over.

 

The good news is you have a great start to your Ford Ranger since you have so little money invested in it.

Personally I would not go for a junkyard 2.3 DOHC with what is supposed to be 105K on it. ( $900 ) is way too much when you can get a rebuild 2.3 for anywhere from $1600-$1800

What will drive the cost of this project up is all the little parts that will be wore out.

With this in mind, get a note pad. Inspect the truck from top to bottom front to rear.

Write down all the parts that need to be replaced.

My guess is you will be shocked on how expensive it is to save your $200 truck.

The 2.3 DOHC has more cooling system hoses and maintenance items that should be replaced while you have the engine out that can quickly turn this project upside down financially in a blink of an eye.

It is best to know exactly what your getting into before you spend the first dime on this truck.

Items I absolutely would not reuse on this engine are as follows.

Fuel injectors, Intake manifold, water pump, electronic thermostat, PCV valve and hoses , Spark plugs, Plug Wires, Radiator and heater hoses, heater control valve, radiator, Fan Clutch,Valve cover bolt grommets ( which are no longer being made )
These grommets can be custom made. Ford or Mazda used to sell them with the bolt at a very expensive price per bolt.
You will not need all of the bolts or grommets but pay close attention to any they look worn as you will get a leak from worn grommets.

If you have a manual transmission count on replacing the clutch parts as well

Once you get to know the exact condition of the entire truck, and price all the parts you need.

You can decide if buying another running and well maintained but wrecked truck with low miles may be the best way to save your truck.

I have seen low mileage newer Rangers wrecked sell for much less than it would cost to buy 1/4 of the parts I suspect you will need to repair your neglected truck.

I say your truck is neglected because if it was well maintained I doubt you would have had the opportunity to buy it for 200 bucks.