Tech
Member
- Joined
- August 4, 1999
- Messages
- 30
- Reaction score
- 1
- City, State
- CA
- Year, Model & Trim Level
- 2002, 1991 Explorer XLT's
This is just an FYI post: Several months ago I noticed that my '91 Explorer was using about 1 cup of coolant per week. There were no indications of any external leaks and the oil level seemed to remain constant; at least, it was not increasing. Also, the oil never appeared to be contaminated. Eventually, I noticed a small amount of moisture on the underside of the oil-filler cap and PCV valve -- bad sign. So, I pulled both cylinder heads. I couldn't see anything wrong with either head so I took them to a specialty shop. They found that one head had an internal crack in one of the passages and it was junk (not repairable).
Since I am really happy with my Explorer and plan on keeping it indefinately I decided to replace both heads with factory-new units. It's note-worthy that the replacement heads are for a '93 or '94 Explorer and are allegedly improved over the crack-prone '91 heads. I also used all new Ford gaskets as they are of an improved design over the originals (no more leaky valve-covers!)
My Explorer had 97k miles when the coolant problem reared it's ugly head. Also, it was using about 1 quart of oil every 3000 miles, which really isn't bad. Interestingly, since I installed the new heads, the oil consumption has gone down to about 1/4 to 1/3 quart every 3000 miles. Apparently, the valve guides and/or seals were worn. Another bit of good news you Explorer fans will like to hear is that the cylinder walls looked like new, even after 97k miles -- there was absolutely no ring ridge! Even the factory cross-hatch was still visible! I guess changing the oil every 3k miles has paid off.
If anyone is planning on removing the cylinder heads on their Explorer (the standard, 4.0L pushrod engine) and would like some details on what's involved, please feel free to e-mail me.
[This message has been edited by Tech (edited 08-17-1999).]
Since I am really happy with my Explorer and plan on keeping it indefinately I decided to replace both heads with factory-new units. It's note-worthy that the replacement heads are for a '93 or '94 Explorer and are allegedly improved over the crack-prone '91 heads. I also used all new Ford gaskets as they are of an improved design over the originals (no more leaky valve-covers!)
My Explorer had 97k miles when the coolant problem reared it's ugly head. Also, it was using about 1 quart of oil every 3000 miles, which really isn't bad. Interestingly, since I installed the new heads, the oil consumption has gone down to about 1/4 to 1/3 quart every 3000 miles. Apparently, the valve guides and/or seals were worn. Another bit of good news you Explorer fans will like to hear is that the cylinder walls looked like new, even after 97k miles -- there was absolutely no ring ridge! Even the factory cross-hatch was still visible! I guess changing the oil every 3k miles has paid off.
If anyone is planning on removing the cylinder heads on their Explorer (the standard, 4.0L pushrod engine) and would like some details on what's involved, please feel free to e-mail me.
[This message has been edited by Tech (edited 08-17-1999).]