I have a '90 F-150 4.9. Just put her back on the road after nearly 3 yrs of sitting around. Motor seems to run good most of the time but occasionally a lifter will start to tap really bad. Twice when this happened it got to the point that the engine started to miss and the oil pres dropped to 0 then came back. After turning off the engine and checking oil level the lifter quieted down and engine seemed to run fine when I cranked it back up. Is this something that could be a result of it sitting so long? Is this a bad lifter or maybe an oil port getting stopped up? How much of a PAIN is it to replace lifters? I've never been inside an I6 before.

 

id pull that valve cover asap and take a look see

 

i want to say this carefully. the drop to zero oil pressure is very troubling .H aving said that, sometimes an engine that has not been run for awhile will form varnish, gums, that sort of thing that can cause plungers in pumps to stick and then release. hyd are very effected by these old gums and such. you could try 1 can of motor flush, some greybeards swear by a can of atf, But you must follow directions to the LETTER. no high rpm tweaks, it will not make cleaner (quote work better). its ex, but i take it further to be sure all cleaner is gone when done. buy 2 filters one elcheapo and your good one you like to use. buy 12 qts oil. 6 absoulete no name bottom line, and 6 of your favorite. flush motor per can directions. replace with cheap filter and oil. run for awhile. do not drive or rev motor. get plenty warm though. dump this mess. good oil and good filter and listen and observe. still issues, then you have an issue that will require an internal look see. best i can offer you with facts provided. post back if want/ remember no high revs with cleaner, paul

 

I assume the I6 has hydraulic lifters. I'm thinking one of them may be collapsing. I'v heard about running some ATF through the engine but was scared to try it. Can't think of anything that would make it collapse then work again unless it had some blockage somewhere.

 

atf in an attempt to clean passages will not hurt you in the driveway idling. never been hurt by the gunk engine cleaner either Provided followed to letter. the whole point of this exercise is to see if it is full of sticky varnish. this is not an insult to you. you sound sharp on mechanics. but i do not recall if you said you changed the old oil. it could be just so thinned out it is leaking past the internals clearences in your hydros and preventing pump up. anyway, this is your best bet to obtain one diagnose in the driveway and you will know in an hour or less. listen 2 4 8 second op,s do not offend me at all. maybe more of the fellas will weigh in. its not about me. i want to see your truck run thats my goal. let me know okay/ i care. paul

 

the atf,s use 10 20 wieght quality base oil with huge detergent packages among other additives. the shelf engine cleaners are more high quality solvent based. this is the reason you do not drive the motor or rev it high. all it has to is circulate.

seriously, .in the day it was very common to flush engines with kerosene. in the artic, some guys run small % kero in there crankcase so they can get the oil to flow atall.

seriously, i would never dink with a man and his transportation never, paul

 

it is POSSIBLE that you have a valve stem sticking slightly in the bore from built up varnish , a little slow returning , that would beat a lifter to death and could explain why it tis only one. it is possible. paul

 

I had an 89 4.9 that wore a hole in the bottom of one of the lifters, it acted just like that, until it poped a pushrod out from under the rocker arm. then I had to fix it. I replaced 1 lifter, and 1 pushrod, and ran that truck for another 100,000 miles.

 

2 to 1 for pulling covers now. that,s what you should, db, been at it a long time, his advice is good and the goal is to save your motor, will you post back if you find it so we all can keep on learning . i,m very interested in whats wrong with the old girl. paul.md

 

My .02 worth: Has that thing been over-heated lately? Are you loosing any fluid? Do you have bubbles coming in rad.?

What do your s.plugs look like? Fouled?

Could your ticking be a cracked head? Isn't that pretty common with an EFI? Isn't ticking like that systematic of a cracked EFI head?

 

Talked to one of my buddies who has a repair shop. He seems to think that maybe the oil pan has some gunk in it and that the screen on the oil pump is getting stopped up thus starving the top of the engine of oil. Guess that will be my project this Sat if it's not raining. Will let you guys know what I find when I pull the pan.

 

Isn't it easier to pull the v. cover and check? Or drain the oil and shine a flash light into the drain hole and look?

 

You mean look through the drain hole in the oil pan?? I doubt that you would be able to see if the screen was gunked up by looking through that little hole. I don't think it will hurt any thing to pull the pan and clean it, so I will start by doing that. If I don't find any thing I will dig deeper.

 

I will start by doing that.
AND let us No...

 

I had a ranger one time that was gummed up so bad, when I pulled the oil pan off, it looked like a sheet cake still sitting there. was the perfect shape of the oil pan. can't believe the truck was still running.