Still No Oil Pressure

All buttoned up... cranks right over... no oil pressure still.

On the plus side... no spare metal bits in oil pan when I dropped it.

I installed the new Hi Flow pump from Summit Racing

http://store.summitracing.com/partdetail.asp?autofilter=1&part=DCC-4529241&N=700+4294924385+115&autoview=sku

The pump instructions say to prime... the factory service manual (as well as a few forum posting I ran across http://www.jeepforum.com/forum/showthread.php?t=601124 ) say NOT to manually turn the pump once it is installed because the Cam Position sensor will loose its timing, and then needs to be calibrated by the dealership.

So...

Don't want to throw in the towel yet... but I am not sure how to proceed...

I know the pump works... I dumped oil into it before installing, and stuck the pick up in oil... then spun clockwise and watched it pull the oil up...

When running (for VERY short time) the gauge starts to build pressure, then drops out almost immediately (which is when I kill the motor)...

I am pretty sure it just needs to be primed.

As a last resort I was thinking of disconnecting the coils, then just cranking it over with the starter...

Is there a way to tell if oil is flowing to the valves without pulling the valve cover?

For now I have finished off the hot wire job the kids started on my Dakota, so I can at least get around... I'll just have a lot of explaining if I get pulled over...

How does the pressure sensor and guage work and on this motor? Is it a mechanical sensor or electric?
I'm wondering if it's possible that the pressure is actually OK, but the sensor or guage is lying to you... maybe i's flaky and responding/no responding to teh heatup of teh engine compartment?

It is an electric sensor... like the MAP sensor... as pressure is applied it changes voltage state (0 to 5 volts)... more pressure = more voltage.

I can tell the gauge is accurate because you can hear and feel the lack of oil...

At this point I am positive there can be only a few problems...

1) Oil pump is not primed (most likely)

2) Oil pump seal broke when I put oil pan back on. (Maybe... oil pan went on tight... but no excessive jarring to get it on...)

3) Oil pump drive not meshed properly... but since it slid all the way in, and bolted tight I doubt this is the problem... the slot was a good 1/4" deep, I can't imagine it not meshing and still bolting up flush.

4) The drive mechanism internal to the engine is broken... (doubtful). It is a theoretical problem... but I think if this is the case I would see and hear more evidence to that... plus he old pump built pressure at RPM

5) clog in the system... there was a lot of sludge in the old oil pan... the old screen was pretty clear though... so I am not sure.

I really... really had OBD II. No codes kicked for this VERY important problem... if you are going to monitor... monitor something vital.

If it had a distributor... no problem... all these stupid electronics....

Tony,

Where the oil pressure sending unit is screw into the block you need to take it out and put in a machanical gauge and read the oil pressure that way you will know for sure if you have oil pressure.

Alright... round 3...

I went back to basics... oil was a quart low... I put 5 quarts in, but I guess priming the whole system ate a quart or so...

Added a 6th quart and was back in line.

Pulled fuel pump relay for good measure, and used starter to prime for about 5 minutes (not continuous because didnt want to kill new starter, and til battery was almost dead...)

Gauge had no activity thru this, which was disheartening, but a quick call to Alex and we verified this is the case with no engine running (he pulled relay on his and duplicated).

So... a bit reassured, I installed the relay and... IT LIVES...

I was jumping with joy.

A lot of smoke from the seals setting and still water in exhaust, but it ran quite and smooth as could be...

For about 20 minutes... Just like at Rausch on Sunday... at idle after 15 - 20 minutes it just bottomed out, and the knocking lifter noise returns confirming the gauge.

I will try to pick up a mechanical tomorrow, but I am sure judging by how the engine reacts I am assuming it is accurate enough.

For now I will let it sit... tomorrow pick up a few more quarts of oil... Initial dip stick reading right after was dead center between the 2 dots...

I did notice the new pick up is a little shorter, so it might need just a bit more oil to keep it in the mix...

So technically still at square 1... except making progress...

OK... several hours of research later...

A few people have had the exact same problem with this motor...

All the replies said to replace the oil pump (which I did), and the sending unit (thanks Paul )...

I still don't think it is the sending unit... but at this point it doesn't hurt to change it out.

I will also pick up a mechanical gauge for the roll bar so I have a number to look at... not a guessing game.

All the posts regarding the 4.0L say as long as it builds 10 psi per 1000 RPMs then all is well... so that is what I am shooting for.

Is there a way that I can connect both the electrical sending and mechanical so I can run the mechanical gauge but not have CHECK GAUGES on all the time?

Tony,
Normally the sending unit is 1/8" pipe thread, you can go to the Depot and get a brass nipple and a T fitting. Screw the nipple in the block and the T on top then you have two outlet one for the mech gage and one for the factory gage.

Tony,
just running over everything again, sometimes its the little things that cause the most problems
when you put the new oil pump in, was there a seal for the top of it?
Could the pump be pulling up so much oil that it runs itself dry after 15-20 minutes?
Did you change out the oil filter when you did all this?
When the pressure starts to drop, if you rev it, does the pressure go up?

sonofsam02 wrote:

when you put the new oil pump in, was there a seal for the top of it?
Could the pump be pulling up so much oil that it runs itself dry after 15-20 minutes?
Did you change out the oil filter when you did all this?
When the pressure starts to drop, if you rev it, does the pressure go up?

1) Old seal came off with old pump. Cleaned block surface, and installed the new gasket with new pump.

2) New oil filter, and now 6 quarts of fresh 10w30 (still 1/2 way between 2 dots)

3) as pressure drops, revving does rebuild the pressure, however the lifters also begin to knock again indicating lack of oil... so I shut it down to prevent more damage.

There are a couple ideas left before I totally throw in the towel...

A) I will take the old oil pump and put a drill to it... if it pumps oil, then it might indicate this is not a pump/pickup issue, and changed them needlessly (but better safer than sorry since it was all torn down)

B) The new pick up was about an 1" shorter than the old one... I may need to add more oil to ensure the pickup is staying submerged, although it is odd that both pumps had the same symptom.

C) Mechanical pressure gauge to see whats going on with oil pressure.

From the posts I have seen it doesn't look good...

I am not going to jump the gun on this, but from what I have read it points to bearing failure... when it gets hot it opens up...

So the "belt squeal" may not be the belts after all...

I would be willing to accept this theory (although hard to swallow for the pocket book) except wouldn't I see other issues (metal in the oil pan, coolant/oil mixing... blowing smoke... etc).

Like I said... when pressure is good all seems normal... no squeals, knocks, pings, shakes, etc. It ran around 160 to 210 range for a majority of the time... all seemed like job well done...

Then train wreck...

Oh well... I'll take a break from it for now... work 10PM tonight til around 3pm tomorrow... clear my head... maybe check crazy rays for Cherokees just in case.

Golen 4.7L looking real good right about now... too bad that is waaaaaaaaaaaaaaaaaaaaaay beyond this budget.

All the price you have to pay when playing in the mud. Hope it is something simple that you can fix easy.

my jeep was knocking going up hill and would loose oil pressure after getting hot. i had to have my main bearings replaced, and i put stp treatment in the oil. that helped allot. it stays around 4-5 lb at idle now when hot and 40 at high idle. i did the main bearings myself it is not really that hard to do. you can google it, there is allot of pic to look at if you decide to go that route

Lets go back to the original injury. From what I understand you went into the mud and couldn't make it through. Did you leave it running or shut it off? If you left it running then good. If you shut it off then the cold water could have been sucked up through the exhaust and into the head causing damage? If it was still running fine in the mud pit and the damage occurred when you were yanked out then it has to be related to the shot to the oil pan. Oil pump damaged but was replaced and still the same problem. Could there be anything else damaged that has a direct connection to the oil pump? I may be off base here but I think I would pull all the plugs and do a compression test to make sure there isn't any valve train damage.

great idea

at this rate it would of been easier to swap another 4.0 in.

md4wheelin wrote:

at this rate it would of been easier to swap another 4.0 in.

Well I would not admit defeat yet. I'm for Tony trying to figure everything he could do to save it before he starts planning a motor swap.

I love puzzles so I've been reading a Jeep Engines manual that I had laying around. Under oil pump priming it states the following:
1. remove spark plugs in order to relieve the compression in the cyllinders and to prevent the engine from starting.
2 the engine should be turned over with the starter until the oil pressure guage shows a reading of over 10 psi

If it reads pressure then it says to replace spark plugs and start motor and should be at 13 psi at idle 600rpm.
It also says if the guage does not register any pressure when the engien is cranked with the starter motor "DO NOT TRY TO START THE ENGINE."
then says if no pressure make sure ther is sufficient oil in the pan, pickup is connected and that the oil pickup is fully submerged. make sure the pickup tube does not have any leaks where air might be entering the system, and make sure th oil pump is working properly.

also says "caution: do not disturb the position of the oil inlet tube and strainer assembly in the pump body. if the tube is moved within the pump body a replacement tube and strainer assembly must be installed to ensure an airtight seal."

your pump says on the summit web site that "Requires oil pan modification." does the pump directions say exactly what modifications to the pan is required?

OK... I spent most of the overnight inventory and my day off yesterday thinking this over and running through the events in my head trying to make some sense...

I came to the same conclusion as Bill, and seeing his response really built my confidence a little.

The Jeep never shut down or stalled in the mud... I had the hand throttle set to keep the revs up just to prevent that...

When I got out of the pit and up onto the climb out the Jeep stalled... and at that point didn't want to turn back over...

Maybe it sucked water, but at the time the intake was dry... never thought exhaust...

So I was gonna pick up the compression tool and oil pressure gauge tonight on the way home... yesterday I was just too exhausted.

I was also worried about it being the main bearings... so Von's post also made me feel a little better too...

A couple days off has rebuilt my drive to fix this... I thought engine swap, but the only thing in my budget would be a junk yard pull and I would be no better off, so I will just put the time into this one that I know its history of use and abuse.

Worst case 4wd and Quad have a whole head replacement (valves, rockers, etc) for $500...

But we will see once I get compression and pressure numbers and go from there.

Rockn93YJ wrote:

your pump says on the summit web site that "Requires oil pan modification." does the pump directions say exactly what modifications to the pan is required?

It said to place oil pan and check clearance of depth... like the oil pan would not seat fully against the block...

There was a build up I found on another forum using this pump, he had pictures of the process and where it hit...

My oil pan has a different shape, and the pump was no bigger in dimensions than what I took out.

This may be way the YJ-02 TJ oil pan would not work on my engine... The bend for the oil pump is a lot different, and no "reinforment" pieces inside the pan.

Anyway the pan went right to the block before I put the gasket on, and I wiggled it around the studs to see if it hit anything (the pump or something) and felt no resistance to the range of motion, though limited.

There were also no scratches in the powder coating where the pump lives, so I figured there was no clearance issue...

Its hard to explain the pump comparisons... the original pump was shorter in size, but used large headed bolts on the plate at the bottom... the new pump is longer, but contersunk bolts into the plate... so overall they became the same outside length...

The only differance would be the inlet tube screen... once I had that hammered in place I didn't even want to brief on it becasue the FSM said pretty much the same thing (except priming procedure).

Rockn93YJ wrote:

I love puzzles so I've been reading a Jeep Engines manual that I had laying around. Under oil pump priming it states the following:
1. remove spark plugs in order to relieve the compression in the cyllinders and to prevent the engine from starting.
2 the engine should be turned over with the starter until the oil pressure guage shows a reading of over 10 psi

If it reads pressure then it says to replace spark plugs and start motor and should be at 13 psi at idle 600rpm.
It also says if the guage does not register any pressure when the engien is cranked with the starter motor "DO NOT TRY TO START THE ENGINE."
then says if no pressure make sure ther is sufficient oil in the pan, pickup is connected and that the oil pickup is fully submerged. make sure the pickup tube does not have any leaks where air might be entering the system, and make sure th oil pump is working properly.

also says "caution: do not disturb the position of the oil inlet tube and strainer assembly in the pump body. if the tube is moved within the pump body a replacement tube and strainer assembly must be installed to ensure an airtight seal."

I pulled the fuel pump relay so it got no fuel... I thought to pull the plugs, but then decided the new starter could handle the compression too, especially if all the instructions said 1/2" drill... so if a drill could do it so could Mean Green.

The gauge didn't stay in the dead area... it came up just a little so I knew it had some kind of pressure, just no number to go with it... That's why I called Alex to confirm his gauge behaved the same way...

His is the same year, make, and model... only differance is his runs, and mine is jealous.

After that it fired to life and had oil pressure back at its normal range... but only for about 15 minutes as I said...

There is the belt squeal too... every time we ran it you hear the squeal of the belt slipping from time to time... maybe it is not the belt, but the bearings instead.

If this were my jeep I would:
1. prime the system as explained in my post above to check for oil pressure using the starter.
2. if not reading pressure with starter then do a compression test while the plugs are already pulled.
3. if compression is fine then drop the oil pan and remove and reinstall the oil pump to ensure proper installation, maybe there is something that was missed and not getting a good seal.
4. while the oil pan is dropped check the main bearings. visually check for it first and if something looks suspicious then pull that main bearing cap and check the condition of the bearing.(this is very simple and you just need to make sure of orientation going back on and torque to specs.

Either the pump isn't creating the pressure needed because of a poor seal and air is entering the system or 2. there is adequate pressure from the pump but there is no restriction to the oil presssure somewhere else allowing oil to just leak out and prevent pressure from building in the block.
Looking at the oil diagram makes sense with this thinking.

Rockn93YJ wrote:

your pump says on the summit web site that "Requires oil pan modification." does the pump directions say exactly what modifications to the pan is required?

Pump instructions were useless... didn't even mention modifications in the instruction...

1) Remove old pump
2) Install new pump
3) Use 1/2" drill with priming tool to prime engine and pump
4) Start engine and check oil pressure

the priming with the drill the instructions speak of involves removing the distributer and sticking the end of the drill down into the distributer hole to activate the pump so this method will not crank the engine but will circulate oil through the motor.

Bill,

One thing that has been bugging me... simple but sometimes it is the simple things...

The pick up on the new pump is about 1" shorter... could it be getting up out of the oil when the motor is running?

The dots on the dip stick seem to correspond to where the pick up level was... so with a higher pick up should I try more oil too?

Just a thought.

Definately gonna go with your suggestions though... had I known step 4 before I woulda checked that while I had all ripped apart.

On the bright side... I am now a pro at knowing how to get the darn thing off, and all the bolts are freshly broken loose

are you loosing coolant too?