97 4x4 short cab. Short bed. 4.0L automatic, 104,000 miles. Now that thats out of the way, here is my concern. Over the past year my trucks performance has been slipping. Sluggish acceleration, loss of power, sputtering/almost stalling, difficulty maintaining RPM, and a whining noise. During the summer i ran seafoam because i had a valve knock. Afterwards I took the throttle body off because the gas pedal would get stuck in the UP position. To my dismay, the intake manifold was full of a tacky black substance i assume is oil sludge, which was causing the throttle to stick closed. I cleaned it and no more stick. As far as i know, the intake manifold shouldn't have anything in it. The oil pressure guage has been dropping out lately, which is exactly what my last truck did just before the engine locked up. That was a 3.0L which the previous owner had not changed the oil for a while. My concern is that the same thing is happening to my current truck, and it may not be long for this world. Any suggestions on what to do/check? Been running synthetic oil since i got the truck 10,000 miles ago. Changed oil every 5,000 miles w/new filter.

 

Do you know if the previous owner beat the crap out of the truck? casue thats what it sounds like, seafoam should have cleaned out most of that junk.

 

I think all of the black stuff in your intake is EGR residue which is normal. Sounds like you just need a good tune-up.

 

sounds like you need intake gaskets

 

From what i can tell, and the grocery list of $Hi+ I've had to do on this truck, i can say beyond the shadow of a doubt, the truck was beat. senselessly.

 

Rangers take beatings VERY well.

 

Is there an issue switching from regular oil to synthetic? A friend said that is a no-no.

 

There should be no issue in the switch but as a precaution I'd go to a synthetic blend for a change then go full synthetic even though you're supposed to be able to go back and forth with these new oils. I pick pennzoil ultra synthetic but the platinum should be plenty for you.

 

NO do not switch to synthetic or a synthetic blend if you have only used regular oil previously. just my opinion. I tried synthetic after using regular oil for the 4 years I've owned mine and it caused an oil leak from the main seal and oil filter adapter. Not sure if the same would happen to you, just thought I would share.

 

Early and cheap synthetics have a reputation of doing that the new ones shouldn't do that.

 

The supposed danger is if there is sludge built up in the engine switching to synthetic loosens it up, thereby creating quite a mess. So i hear. Any truth to that?

 

I switched to synthetics at 128k. No leaks yet and I haven't had to add any oil after my last change which I used to have to do with my conventional. This time I am running synthetic blend but next change I am going full synthetic.

Like red-headed step children.

 

Ditto. I switched to synthetic blend at 65k, at 70k i switched to synthetic... No issues.

 

Any other clues as to what may be causing it to run so crappy? My gas mileage has reduced over 4 mpg!

 

Nothing? The whining noise is getting louder, and it feels like I'm dragging a boat anchor. Thinking i might take it to a shop.

 

found the squealing noise. turned out to be the idler pulley. also put a quart and a half of oil in it yesterday. i have no clue why its losing oil. it doesnt smell like its burning it and its definately not leeking at the pan or anything. still running crappy. any help at all is appreciated.

 

Just an update, because i know you're all dying to know, need head gaskets, or have a cracked head. gotta pull it apart to be sure but the mystrery is solved.

 

Clean it top to bottom and get new gaskets in there is what I'd do.
Pull the intake off, split the heads and clean her good, drain oil, pull bottom end and check to make sure there isn't sludge build up down there, if there is clean it out and run synthetic.

 

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Good thing about synthetic is you don't have to change your oil as often. I run synthetic blend and change mine every 5000, but with full synthetic, you should be able to go 7500 between changes...