Probbly impossible to answer

[Pdwight]

I have a 94 Explorer Limited witht eh 4.0 engine. The other day the oil pressure went to zero and I heard a soft knock. I stopped and had it towed. the dealer put a new oil pump and screen on. Now when I start it up it sounds fine , after it warms up there is a soft knock, I mean if the radio is on you cant hear it. The oil pressure stays in the mid to high range and it has plenty of power....actually going down the road you hardly hear it at all. The engine has 67K miles on it, my question is one of best guess please.

Drive it untill it it gets really bad or the oil pressure drops out more

Rebuild the engine or get one from a junk yard

Try to drop the oil pan and replace the bearings on the pistons ???

I know this is a very difficult question to answer, but any thoughts would be greatly apprecieated.

Dwight P

 

[Glacier991]

soft knock. Rythmic, varies with RPM ?

 

[rookieshooter]

This is not impossible to answere. One thing is certain.
Went to zero, that most likly means It went to zero well before you noticed it. You heard the knock then noticed it was on zero, right. The question is not, did you damage the bearings, but how much you damaged the bearings. No oil pressure means the air space between the soft bearing and the journals are not filled with oil but with air, other then the film oil that remained on the bearings. It is so critical to keep that air space filled with oil. Thats why I have an oil pressure cut off device on my Poject B11, I fill the oil filter up as much as possable when doing oil changes, put Moly on all bearings when building engines and then use an adapter to turn oil pump before starting new rebuilt engine so oil is allready starting to flow before the crank starts to turn. Even if the knock turns out to be something else, I would rebuild including main bearings because the bearings did recieve damage.
Hardly hearing it is like hardly pregnant. It will be more noticable later.

 

[Pdwight]

Thanks

It varies with RPM, this is not a daily driver...I drive it to the Shooting range and gyn...usually less than 10 mile round trips....I will probbly leave it untill spring unless it get noticably worse. A rebuild is usualy around $1200 ??

Thanks again
Dwight P

 

[Billy177]

i would just change the oil to some 20w50 see what happens

 

[Pdwight]

Thanks

I apprecieat everyones advise. I will probbly use the thicker oil 20-50 and drive it untill spring. Then I will probbly try to find a decent milage engine and do a changeout. I have a "X" in my VIN so am I correct in understanding that newer 4.0 engines will not fit or work ??. If I am going to change it , it would be nice to get an engine with under 50K miles on it.

Thanks and a great board BTW, If I can help answer any shooting questions please ask me....especially if it involves rimfires...my speciality

Dwight P

 

[Glacier991]

I'm guessing a spun bearing.... either main or con rod big end, but more likely con rod.

 

[Runnin'OnEmpty]

I have a "X" in my VIN so am I correct in understanding that newer 4.0 engines will not fit or work ??.

Dwight, you have the OHV type engine, and Ford used them up through the 2000 model year (along with the SOHC). The electronics were a bit different on the newer ones, but you could use the sensors, etc off your old engine.

 

[Green98XLT]

Damage is done to the bottom end.... time to pull it and put bearings in or just swap it out for a low mileage motor. When that factory oil pressure gauge reads 0 it is too late..

 

[Pdwight]

Thinking out loud here

How about dropping the oil pan and putting new bearings on the connecting rods ?? How difficult is the oil pan to get off....I put bearings in a Honda prelude back in 85. Like I said the oil pressure never drops now that I have a new oil pump in it. If I went with a newer engine say a 2000 OHV model would it be a bolt in job ??

Thanks
Dwight P

 

[Pdwight]

Runnin on empty

"Dwight, you have the OHV type engine, and Ford used them up through the 2000 model year (along with the SOHC). The electronics were a bit different on the newer ones, but you could use the sensors, etc off your old engine"

Hi I really apprecieat your post. I think the engine is gone or past the point of repair. Do you have any information on what you posted ?? I have changed out a couple of engines in the past but they were straight changeouts. Is there a web site that will give me more information or could help me with this ??

It seems much easier to find a say 98-2000 engine with low milage than a 91-96....I really dont want to change it out twice...I want to do it right when I do this.

Thank you for taking the time to respond to my post

 

[Runnin'OnEmpty]

Dwight, here's a good resource:TheRangerStation That being said, there's many people in this forum that have lots of experience in changing engines, and can help with any problems you might have.

The last model year for the 4.0 OHV was 2000, and the motor mounts and bellhousings were the same for all years, so any model OHV should bolt into your vehicle. Ford made changes in the valvetrain, crankshaft, pistons, flexplate, and block strength over the years, so a later model would be more desirable.

There were lots of electronic differences in the later models, mainly transmission controls, so you'll need to use your old electronics with the new engine.
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First I'd make sure you're indeed hearing a rod knock. A rod will make noise when you let off the gas slightly after accellerating, and kind of 'feathering' the throttle. I'd make sure it was really needed before changing out the engine. If it's a 2WD, the oil pan might come off fairly easily. Might be a good idea to pull the pan and take a look at the crank journals; you might get lucky....