Rebuilding the 4.0 OHV

[KEbert]

While I'm home from school, my dad and I have sacked up and began to fix a long standing lifter problem/noise. With intentions of doing a full rebuild (i.e. all vavle train, bore 20 or 30 over, pistons, strighten rods, surface heads, ect.) we bagan yesterday to tear down the engine. I dont really have enough time to do a full write up, but if anyone has any questions or comments, feel free to post or email me at kpe69@yahoo.com I'm mainly going to post pictures with details of each in sequence of our progress. Sorry about the pic quality, I have to reduce them inorder to meet the file size requirement. If anyone is interested, I have them in larger sizes and higher detail.

This first pic is after we removed everything down to the lower intake manifold. Fairly easy going. The only conflicting thing was having the freon evacuated.

 

[KEbert]

This is during the extraction of the engine. The crane on my dad's trucks looks like overkill pulling out this little engine, but it worked quite well. The only problem here was loosening the pass. side engine mount. Its hidden under the exhaust manifold and there is no way to get it from the underside because of the drop bracket for the I-beam.

 

[Alec]

That's a great engine hoist, every shop needs one!

LOL, that's cool

 

[KEbert]

After reomving the heads we were stunned to find the cylinder walls in such great shape. The cross-hatching from the initial bore are still very visible, and with 168k miles, it is quite suprising. After discovering this, we decided to for-go the overbore and focus more on the vavle train. The pushrods and rockers had very noticeable wear, and a few of the lifters were collapsed; as we had suspected. As far as parts go, we're not yet sure as to what all is in order. A good friend of my dad's has a machine/repair shop and he focuses mainly on performance rebuilds, and he can get parts to us as needed. I'm looking into the Comp cam, but I'm afraid it will affect my emissions too much. Anyway, more pics to come.

 

[KEbert]

2

 

[KEbert]

3

 

[KEbert]

We removed one bearing to look at its condition, and like the cylinders, it too was in great shape. Although they will be replaced since we have access to do so.

 

[KEbert]

The valves looked to be a little hot, but not too bad none the less.

 

[Alec]

New (stock-sized) pistons? Not a bad idea. But you're right that the bottom end looks great. These are damn fine motors.

 

[KEbert]

No, I dont think we'll replace them at all. If we do anything, we'll do rings and just hone it out. But I dont really see even that necessary.

 

[Stealthcb]

How long has it taken you to get to the point you're at right now?

 

[Runnin'OnEmpty]

Kyle, it's amazing that the cylinders and bearings look that good after that many miles. Tell us about the oil that was used in it, and how often it was changed?

 

[KEbert]

To answer Stealth's question, we've put in about 5 or 6 hours so far. Nothing has really been to difficult to do. My dad is a heavy equipment mechanic and with his truck avalible we have every tool known.

I got the Explorer from my uncle 3 years ago as a 16th birthday present. It was in need of a new timing chain an tensioner at the time, and when we did it, the engine didn't look to good. There was a lot of sludge around the valves and rockers; a sign of poor maintinence. Since I have owned it, I have changed the oil bout every 2800 miles with Castrol GTX 20w-50 and in the coldest part of the year, 10w-40. I think this has helped to clean everything up, but yes it is amazing to see the cylinders and bearsing in such great shape.

 

[Shagnasty]

I think I'm going to keep my exploder. I've got 60,000 miles on it, having ragged it hard, and this thread makes me think it just may last forever. I just need to make it a bit more of a work truck.

 

[KEbert]

I believe that taking care of any engine will prolong its life. I'm really glad that I have a manual tranny and I dont have to worry about all the problems the automatics are plagued with.

I took the heads into the machine shop today. They'll return to me on Monday or Tuesday with ported heads, new vavles, springs, and slightly surfaced. We are thinking that since there is no visible wear on the cam or the rollers on the lifters, the cam is in a condition where it can stay. My dad and I both came to this conclusion with the additional advise of the friend at the machine shop. Most parts should arrive tomorrow, and I will post as progress is made.

 

[KEbert]

Also, I'm thinking about getting a chip as well. Perhaps Apten or Superchips. I want to be able to gain the most amount of torque without sacrificing any mileage.

 

[Rick]

See all the golden varnish and beginning of sludge in the lifter galley... The engine out of my parts truck with 75,000 looked like that.

However, the engine out of my '93 with 140,000 miles on it looked like brand new... Quite amazing actually. There was no varnish at all and no sludge. the difference I beleive is that I ran synthetic oil in my motor since it had 5,000 miles. My bottom end is still going strong. I just replaced my heads with a set of rebuilds.

Just thought I would throw that in here since I'm now convinced Synthetic is worth the extra $$.

 

[KEbert]

I do think that Castrol GTX kinda adds to the 'golden varnish'. I think now, after the rebuild, I'm hoing to use synthetic. I agree, I think it is well worth the money.

 

[Towerman101]

KEbert, I have a lightly used set of stock sized pistons still connected to the rods if you need them. I will be pulling them from the engine either Saturday or Sunday, so if you want em give me a holler. They have less than 20k on them.

Also, if you can do so without causing too much damage to them, remove the wheelwells when doing this. It will give you easy access to the passenger side engine mount and makes it easier to reach the bolts holding the engine and trans together.

Joe

 

[KEbert]

Since the cylinder walls were in such good shape, we will not be removing the pistons. But thank you for the offer.