Ford 4.0 OHV Slightly melted piston. Would you run it?

[Brad J]

I picked up a 92 Ext cab Ford Ranger (4.0, Auto, 4x4, 3" lift springs) as part of a trade. I was told that it would die periodically but would start again. I was hoping it wouldn't be too bad to get it running well and drive it or sell it to make a little money. I replaced the Brakes and ignition lock cylinder and Door lock cylinders and a few other things. It seemed to run decent for me but when I went to change the Oil there was water in it. In looking online these 4.0 OHV engines have bad Heads that crack so I got 2 new complete Heads from ebay for $500. I was hoping to throw these on and call it good but when I pulled off one of the Heads the Center Electrode was gone and the Piston below it looks melted. I am not attached to this vehicle so I don't really want to spend much unless I could get more out of it. How long do you think it would last if I put the Heads on and called it good? I could buy an EngineTech recon kit for $290 or a Master rebuild kit for $585 (camshaft and Lifters included) Dingleball it and throw it back together. Final option is to drop the engine off to have it checked out and bored out and rebuilt. I did that on our 05 Honda Accord 2.4 in 2015 and it ended up being $1,500. The Honda is my wives car and it ended up being a great deal since we got the car for free. I'm sure it would be a lot more now 7 years later. There is so little of room under the hood that I am not wanting to upgrade the drivetrain to something newer. I have enough other projects right now and no room for that. What would you do?

 

[1969honda]

Looks more like valves have contacted the piston to me? The reliefs/contact marks are shiny and clean whereas the rest of the piston is dirty. How many miles are in the engine? Has it ever had a new timing chain and tensioner installed?

 

[Brad J]

Looks more like valves have contacted the piston to me? The reliefs/contact marks are shiny and clean whereas the rest of the piston is dirty. How many miles are in the engine? Has it ever had a new timing chain and tensioner installed?

The odometer shows 26k miles so I don't know if it is 126k, 226k or 336k. The person that I got it from had it almost a year and the only thing that he know is that they ran a snowplow on it at one point. He is not aware of any other history besides that. I do know that the thing is a mess with with a thick coating of Oil, Grease and who knows what else.

I talked to one of our Mechanics at work and he recommended doing the $300 rebuild and calling it good. He said "You're most of the way there" so I removed the bolts from the Bell Housing. I just have the Motor Mounts now to pull it this weekend. Hopefully there won't be any other surprises along the way. The last two wrecked vehicles that I got & fixed I made them my Daily Driver and sell them after a few thousand miles so I know that they seem to be in good shape.

 

[Brad J]

It's been over a year since I updated this. It was a mess but it is done, running great and now on KSL to hopefully clear some space.

I was only able to find 1 single new Piston since all of the rebuilt kits in stock needed the Engine Bored out. I didn't want to add that expense so I just ran a Cylinder Hone in it with new Rings & Bearings.
It was completely gutless and took a couple minutes to get up to 25 MPH. Found out I had 0 Compression on one Cylinder from a failed lifter. Pulled that Head off, replaced the lifter and now had good Compression. It still wasn't running great and the Cat was bright Red and would run worse the longer it was running.The RPM's would not hold steady so the Emissions place would cancel the test the several times that I took it. It would die when I would put it in reverse and struggle to start back up when I would try to leave. I borrowed an old Matco OBD1 Scan Tool that rarely would connect to the computer. When it finally did it showed Engine Coolant Temp was very cold. I realized that a prior owner had installed an aftermarket Coolant Temp Gauge bypassing the computer's Sensor. This caused it to run rich and and worse the hotter it got. Once the aftermarket gauge was removed and the correct Sensor installed the Cat was good but still had idle problems. The Computer is by the Passenger foot area and had water stains on it so I got a used one and a NOS Ignition Control Module and the engine finally could run steady at 3k RPM for the test. It was failing the HC test worse with each attempt. The final failure at 12708 HC ppm (220 standard) 58x what it needed to pass. They said that they had never seen that high of a reading. After the 1st Emissions test failure I had installed 6 Re-Manufactured Fuel Injectors that I got from ebay for $71.81. From reading online forums with HC failures like mine I found that many replaced their Injectors with ebay Injectors and that was the reason. I ordered 6 GB remanufactured OEM fuel injectors for $253.17 from RockAuto. Replaced all 6 Connectors since the clips were broken and the RPM would change when touching the connectors. It now ran better than ever and passed Emissions with 60/220 HC. I got it registered and right on KSL. I have learned my lesson to not trust ebay parts and you get what you pay for.