95 7.3 surging after oil change.

Hello all, just did an oil change on my pickup and it now has a horrible surge at all rpms. Was running motorcraft 15-40 with the big Donaldson filter which was running absolutely perfect. Switched to lubrication engineers monolec 15-40 cause I wanted to make the switch to synthetic to start pushing out my drain intervals. Changed oil, put in new Donaldson filter and truck runs fine at idle after start up but run it 1/4 mile down the road and the surge comes in bad. Can feel it when driving and at idle there is a 200 rpm variance. I unplugged the ICP sensor and it smoothes out, didn't try driving it like that though. Let truck sit for about half hour, no surge till you drive it then it comes right back. Is the new oil turning to foam in the HPOP or did my ICP sensor fail? Anything else I could look at to rule a few things out? I do have a 2000 model 7.3 sitting here, are all ICP sensor the same cause I could borrow that one for testing purposes. Thanx for the help guys!

Sent from my SM-N900V using Tapatalk

Are you going to run some micro bypass filter?

I was looking into extended intervals but a very trusted mechanic said not too. He said
just run good oil at regular intervals (about 5000 miles) and be happy for a long time. He
gets extended interval trucks with wear issues he never sees on engines that just
are serviced when the oil needs changing.

No micro bypass planned, was shooting for 7500 miles just so I don't have to change it all the time. Next spring/summer I plan on using the truck to start running some hotshot loads to make a little extra money.

Sent from my SM-N900V using Tapatalk

I would go with icp.
Try driving with it unplugged.

Sent from my SAMSUNG-SM-G935A using Tapatalk

Just swapped the ICP with the one off the 2000 I know is good, same issue as before. Looks like I get to dump this expensive oil out and flush the motor with something else.

Sent from my SM-N900V using Tapatalk

Also took it for a drive around the block with ICP unplugged, idle was choppy and sounded strange when pushing in clutch from cruising speed, also could feel engine surge when driving so this oil is coming out. Really hope it didn't screw anything up!

Sent from my SM-N900V using Tapatalk

Wish you had a pressure gauge for the engine oil and HPO

Did you over/under fill it?

Oil level is spot on the full Mark on the dipstick. I could possibly rig up a pressure gauge, at work we have a set of high pressure gauges for testing hydraulics. Would just need to buy an adapter or two. Would I just be looking for a big drop in pressure when the engine starts surging? One thing I forgot to mention was the oil on the dipstick did have big and small air bubbles in it.

Sent from my SM-N900V using Tapatalk

Drop in pressure or fluctuating pressure.

Ive noticed that every 7.3's dipstick I've ever checked has bubbles on it, including my own.


Sent from my iPhone using Tapatalk

I just don't see this being the oil, unless you received the wrong stuff, and put it in without noticing.

Sent from my SAMSUNG-SM-G935A using Tapatalk

Pail says lubrication engineers 8800 15-40. What else could it possibly be besides the oil? Only thing that was changed was the filter and the oil. Same Baldwin PN on new filter just different oil manufacturer. Engine ran perfectly fine before oil change. I know it doesn't really seem plausible but the oil is the only variable in this scenario.

Sent from my SM-N900V using Tapatalk

A manual gauge is easy to put on to check your high pressure oil. I think I would start there.

Something could have happened to the filter bypass valve.

Sent from my SAMSUNG-SM-G935A using Tapatalk

Mickey427 said:

Pail says lubrication engineers 8800 15-40. What else could it possibly be besides the oil? Only thing that was changed was the filter and the oil. Same Baldwin PN on new filter just different oil manufacturer. Engine ran perfectly fine before oil change. I know it doesn't really seem plausible but the oil is the only variable in this scenario.

Sent from my SM-N900V using Tapatalk

Click to expand...

Id agree, it makes no sense, but it sounds like there is a bunch of air getting pulled in the system. Did you try to empty the HPO reservoir as well or just do a typical oil/filter change?

Do you have the old oil filter still around? Id swap that back in.

Just doesn't make sense to me that it would be a problem till I change oil brands. What other than oil or ICP sensor would cause pressure fluctuations after driving? Ipr? It sat and idled 10 minutes in the yard no problem till I took it down the road.

Sent from my SM-N900V using Tapatalk

I just did a standard oil change. Still have old filter too. I'll pull filter tomorrow and check that valve in the filter mount.

Sent from my SM-N900V using Tapatalk

Mickey427 said:

Just doesn't make sense to me that it would be a problem till I change oil brands. What other than oil or ICP sensor would cause pressure fluctuations after driving? Ipr? It sat and idled 10 minutes in the yard no problem till I took it down the road.

Sent from my SM-N900V using Tapatalk

Click to expand...

I know-- it would have to be nothing short of weird coincidence that the ICP or IPR would fail at same time. Unless the crankcase is full of aerated oil foam, then oil shouldn't be an issue either.

Well due to life happening I finally was able to work on my pickup again. I installed a gauge to measure oil rail pressure the other night. I have found through a few nights of testing my hpop pressure is fluctuating. All pressure readings were done in neutral since I cannot close the hood with the pressure gauge run through. May need to remove my cowel so I can get loaded readings. Stone cold it is rock steady through the rpm range. Go for a drive to warm everything up and at about 140 my problem starts showing up. Idle cold is about 700 psi and warm it is 650 psi. At around 2000 rpms the fluctuation is the most apparent. With icp hooked up pressure dips down about 100 psi rapidly with no set rhythm. Pull connector on icp and pressure seems to rise about 100 psi rapidly with no set rhythm. I unhooked the oil temp sender as well thinking if I was getting fluctuating readings from it, it might change ipr duty cycle for different temps but no change. When I did gauge install the other night engine was warm and fluctuating. When I pulled plug in head I had just shut engine down and oil had no signs of airation, also pulled plug on hpop reservoir. It was plumb full with no bubbles in oil. Does this sound like a bad ipr? My cousin down the road has the latest and greatest snap on computer but I don't get a family discount lol! Was thinking of having him check ipr duty cycle while monitoring icp. If there are any other tests or things you guys think I should check please let me know. I do have a spare ipr here but it's condition is unknown since I got it from a junkyard hpop that came on a timing cover I purchased awhile back. Thanx for the help!

Sent from my SM-N900V using Tapatalk