No Oil Pressure

[denverd1]

Had a blast wheeling with the lady and another friend and his girl. The Jeep performance was amazing even when I eagerly drove into mudhole that was easily 2 ft deep. But I just backed up a bit and went back at it. She crawled out of it no problem!! New tires are great too.

Only issues were mildly overheating. 210 was max. Cylinder 3 miss for about 30 seconds then it cleared up. Time for hood vents.

Also lost pressure at the dash. Had plenty of oil so I just took it easy on the way home. Sending unit go out frequently on these? 98 w 200k miles. About to do new RMS and oil change. Not sure about losing pressure... ill clean it up and go from there, its covered in oil.

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[4.3LXJ]

Yes, you can loose the sender. But check your connection first and then ground the wire to it. Should peg the needle.

[Carves]

If anyone has been a bit careless getting the filter off ... the sender can get a whack.

Could also just be just loose / dirty connection ... thats all mine was the other day.

210* overheating ?? ... some people would die to have only 210* guestimated by the dash gauge - as being the max temp ... :D:D

The vapourising issue which may sometimes cause misfires, shouldnt be rearing its ugly head at those coolant temps .. or in your current weather ??

1/2" or 3/4" spacers on the hood hinges - raising the rear of the hood ... are a good test to see whether butchering your hood might be useful at low speeds.

[stanger351]

Yes, they are somewhat notorious for oil pressure sender failure. One problem is the position near the oil filter which almost guarantees its going to get knocked around during an oil change if the oil filter is even remotely tight.

[BlueXJ]

I am on my third sender but I suspect that the last was just a bad connection. I have completely changed every component in my cooling system and now can barely get to 210* on a hot day sitting in line at the drive thru. High flow pump and aluminum radiator included.

[OrangeXJ]

If anyone has been a bit careless getting the filter off ... the sender can get a whack.

Could also just be just loose / dirty connection ... thats all mine was the other day.

210* overheating ?? ... some people would die to have only 210* guestimated by the dash gauge - as being the max temp ... :D:D

The vapourising issue which may sometimes cause misfires, shouldnt be rearing its ugly head at those coolant temps .. or in your current weather ??

1/2" or 3/4" spacers on the hood hinges - raising the rear of the hood ... are a good test to see whether butchering your hood might be useful at low speeds.

Good call Carves

[denverd1]

yea I guess I wouldn't call it overheating, just noticed that temp was rising while we were out there compared to the trip down but thats a given. I heard the fan kick on and off a few times so sounds like its working right. I noticed from the forum that overheating was a common problem and just thought I'd get it knocked out. I also thought about a bigger/better radiator but the vents seems like a cheap and easy fix. I'll definitely test out the hood spacers before I decide to do it.

are the oil pumps solid on the 4.0? I don't think thats the problem, sounds like the sender. But I'm doing RMS tomorrow prolly so if I need to replace the pump I'll be in there soon anyway. PO said it was rebuilt at 150K, i would have replaced the pump then a preventative measure but not sure if thats the case on this one.

Curious what caused the miss if it wasn't heat... I was in a fairly deep mudhole but dont' think anything got wet enough to cause it. All plug wires are tight on plugs and distributor.

thanks for the replies

[bigjim350]

It will be easy to replace the pump while your doing the RMS. If i were you I would just replace it with a new factory style pump. But I also think its just a sensor. 210* is the normal temp for your jeep. The older ones seem to run a little cooler, but every 96 and newer one ive been in runs 210

[Showtime3492]

This is just my experience. I had pressure loss and all the symptoms pointed to sending unit but when replaced still had pressure issues. Turned out to be a faulty Fram oil filter.

[Carves]

The older ones seem to run a little cooler, but every 96 and newer one ive been in runs 210

Yep that wonderful 210* :rolleyes:

Good for keeping ya tootsies warm in winter but ... :thumbsup: .. :D

Come on down for a ride in my '97 update ... and get bored watching the scangauge flicking a coupla degrees either side of 195* ... with a 195* t'stat fitted ...

... be quick tho ... coz Im about to drop a 190* or 192* back in it ... as 195* is imho ... a bit close to the boiling point of the coolant mix ratio Im using ...

:D

[seu83]

Just a thought on the mis. Do you have the heat shield between the intake and the fuel rail? I've seen heat soak cause similar problems.

[Jarlaxle]

My 97 runs 200-210 all the time...doesn't seem like a big deal. I have driven vehicles that ran hotter without a problem.

What temp is the T-stat on the 4.0 rated to open at, anyway?

[denverd1]

seu, I'll take a look and see if its there. Thanks for the tip.

[Carves]

My 97 runs 200-210 all the time...doesn't seem like a big deal. I have driven vehicles that ran hotter without a problem.

What temp is the T-stat on the 4.0 rated to open at, anyway?

Getting a bit offtrack from oil issues but ....

a 195* should typically, be starting to open a bit before 195* and be fully open by at least 200*

Have read in some early XJ FSMs where t'stat specs were still provided ... that 220* was the fully open position .... but that would be a broken 195* t'stat IMHO ... or a 210+* t'stat .. ;)

High temps up to the liquids boiling point are fine ... apart from heat damage to engine bay components ... as long as the radiator is efficient enough to ensure that temp is not exceeded ... in all driving conditions.

... and therein lies the 4.0l XJs issue ... ;) ... not too mention that 50/50 boils at about 225* ... and many think temps above that are OK to keep driving at.

[Jarlaxle]

It boils MUCH hotter than that due to the 14+psi in the cooling system! I have seen engines that ran hotter...offhand, a Chevy C35 with a TBI 454 that had a 205 degree (!) thermostat. It ran 215-220 degrees all the time, and would touch 230 pulling a hill with a heavy load on the hook (it's a wrecker). It ran 290,000 milees on the original engine & is still going with about 170K on the replacement (a Jasper).

[Carves]

It boils MUCH hotter than that due to the 14+psi in the cooling system!.

:D

Forgot to add in the 3* for every psi the rad cap is good for ... didnt I ... ;)

I tend to do that .... as I dont rely on the cap to make up for inadequacies in a cooling system ... but rather as a bonus, above the 225* temp - when everything is in perfect condition.

[denverd1]

since we're on engine temps and keeping them down, I noticed the aux fan only covers about half of the radiator where the trans cooler is. Why couldn't I add a 12v fan to the other side? surely there isn't enough current draw to prohibit running two... and I could tie into the existing one that kicks at 210'ish and really get some air moving across the radiator, even at idle...

anyone done this? doing rear hood bushings first, but this seems like a simple way to cool things down.

Also, is tranny temp something else I need to worry about? Seemed like the console was getting hot on the way back last time.. just curious if its underdesigned for our purposes as well.

[denverd1]

So after 5 days of rain and cold temps in temps in Texas, I finally got a chance to work on it yesterday. Got the oil pan, girdle and old oil pump taken off. Cam and crank look good as does the distributor gear and what I could see of the pistons. New pump today. Then new RMS, filter and finally new sending unit. Maybe ill see how far a cleanup gets me.

Anything else I should do or look for while I'm in here?
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[denverd1]

Seal is in. About to install pump. Press fit with no vice. Thx YouTube
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[denverd1]

New pump is in and I noticed there wasn't much clearance b/w the crank and the pump housing. So I turned it over once or twice and noticed a scuff on the pump. wiped it off, repeat. same thing.

I could put a grinder bit on the dremel and take the housing down a little. Just curious if this is common.

thanks in advance

[denverd1]

Did I piss you guys off?

Anyway I decided on shaving down the housing. There were a few deep scratches on the housing from the leading point on the counterweight.

http://img.tapatalk.com/a6cd08f0-a99f-1f78.jpg
After grinding on it
http://img.tapatalk.com/a6cd08f0-a9ed-af89.jpg
Works like a charm! Tested it out w a few cranks and no contact between them. Just FYI for anyone else considering this job.


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[denverd1]

http://img.tapatalk.com/a6cd085f-d428-4967.jpg
And here's the problem. Sadly the new one doesn't look any stronger. They should've spent more time engineering the unit rather than the impossible to remove plug that goes on the end.
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[denverd1]

Got it all buttoned up with fresh oil and filter. I didn't see anything mentioned about priming the oil pump. Any thoughts?

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[stanger351]

I poured some oil into it and rotated it a few times by hand, until it was squirting out a bit, but that is quite messy and obviously can't be done after you put it all back together. You could pull the center wire from the distributor (to prevent it from starting) and then use the starter turn the oil pump; that way you'll at least (hopefully) pull some oil into and get it primed before putting a load on the engine bearings. The biggest risk is going to be a dry sump (where it won't prime), but with mine, I think there was enough grease inside it from the box to prevent this (this is also why a lot of guys recommend packing them with vaseline or petroluem jelly before installing them; mine pulled oil in pretty readily when hand turned).

[stanger351]

Is that a Melling? I used a Melling high volume. I had been warned that because the body was longer that there could be interference issues with the pickup bottoming out on the oil pan. That wasn't my case (but I bought the Melling pickup along with the pump; the thought of trying to get a thin metal tube pickup out of a 100k+ mile oil pump didn't sound like a winning proposition to me!). I did have baffle interference with the new pickup tube though, which was solved in about 20 seconds with a pair of snips (probably 45 minutes overall though with maneuvering the pan into and out of place while test fitting).

[denverd1]

it is a Melling. I'm pretty sure its the high volume pump too, I'll check it out.

How did you know it bottomed out? low pressure?

[stanger351]

I was just warned by several people that the body of the Melling high volume pump was longer than the stock pump. I measured them up against each other and this was true. However, I bought the Melling pickup tube that was a matched part for the Melling high volume pump. It was shorter than the stock one (by the same distance that the body was longer), so the net effect was no difference in distance between the pickup tube screen and the bottom of the oil pan. If you would try to use the stock pickup with the Melling pump, you would bottom out on the pan (and you'd need to massage the bottom of the pan with a mallet to make it work). Melling should really just sell the pump and the pickup tube/screen as a package; but I suppose then it would look like the price of the pump was way more than the stock replacement pump, which also doesn't come with a pickup tube/screen. For me, it just makes more sense to replace both, as I've had a few that just fell apart, but most of the time the oil pumps and the pickup tubes are so tight that by the time you get them separated the pickup tube is so mangled its not usable anyways.
I did have to make about a 1/2 inch notch in the oil pan baffle to clear the new pickup tube. It was pretty easy to tell as that things weren't fitting together nicely and I could see marks on the edge of the baffle where it was hitting the pickup tube. I just snipped the baffle back and rolled it down with a small plastic mallet and everything worked fine.

[denverd1]

I'm using the new pickup that came with the pump. They did come in the same box and the stock bolts held it back in place.

Gotta return the 1 prong sender and look at a new melling pump to compare size



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[stanger351]

I should mention that I too was having oil pressure issues, it turned out to be a combination of bad sender and crappy (STP) oil filter. I switched to the bigger Wix filter (15151) ... its longer than the stock size but has the same mounting dimensions. Wix makes the "Napa Gold" filters also.

[denverd1]

Pulled the dizzy and primed pump. Got it all back together with dizzy in close to where it was in its rotation. My research shows that timing doesn't matter, computer controlled.... its acting like it has timing issues. Is it correct that it sets itself??

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[denverd1]

Thought I had the rotor 180* from where it should be. Flipped it, no love.

What am I missing? I have a timing light and know how to use it. Can't see any marks on balancer....

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[denverd1]

Ok so this "setting itself" is a load of shit....

http://www.jeepforum.com/forum/f12/timing-4-0l-508405/index2.html

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[Showtime3492]

Try unhooking the battery and reseting the computer. Seems simple but are the plug wires on the proper order/on all the way?

[stanger351]

Yes. Cylinder 1 has got to be at top dead center when the rotor is directly under the distributor post for the first cylinder. Its a mechanical relationship between the position of the piston, intake/exhaust valves and the introduction of the spark into the combustion process. The computer adjusts the timing advance/retard ("dynamic" timing when the engine is running), but can't compensate for the "static" timing. The valves and position of the piston are tied together with the timing chain and since you haven't disturbed that, its the distributor/rotor position problem. When you primed the pump, you moved the slot where the distributor slides into the pump from its correct position. You'll need to adjust the pump slot that so when you slide the distributor back in, it meshes together correctly. The tricky part is remembering that the distributor gear that meshes with the camshaft gear isn't straight cut, so you have to compensate for that twist when the distributor meshes with the camshaft. It sounds harder than it is, but may take a few adjustments before everything clicks back into the right spot. :o

[stanger351]

I guess earlier, I should have said this was the reason I advised pulling the plug wire from the center of the distributor (from the coil to the distributor) and using the starter to prime the pump ... so the static timing wouldn't get disturbed (and if the pump didn't prime, at least the engine would not start running with no oil pressure). But I've done things way worst ... whatever you do, don't use an extension with a little socket on the end of it to find top dead center for cylinder 1! Yeah ... I did that, and the socket fell off inside the cylinder ... its a miracle that I managed to finally fish it out through the spark plug hole with one of those magnets on a steel rod (which would have been a much better choice for shoving into the spark plug hole in the first place!) :smiley-laughing021:

[denverd1]

Thanks for the help stanger. You too show, but yes all wires in correct order. Whew. Had a few drinks with the lady last night. Now I'm calmed down and ready to do this.

I did pull coil wire and fuel pump relay and tried to crank for 20 sec 3 times but got no pressure so I thought I'd do it right and prime it.


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[denverd1]

Socket on an extension!! :p You funny Stanger!! :D sounds like something I'd do... turn a bad sending unit into 15 hours of work! haha!! :bang:

So a physical check of the piston is how to find TDC... I found the timing mark on the balancer (could it be any more hidden??). silly jeeps..

[denverd1]

is there a 2:1 cam/crank relationship like V engines?

[denverd1]

Good stuff. We're back. Took few shots but its 100%. I'll be damned if those manuals are useful after all.
:):beer::):beer::):beer::D:D:thumbup:

My thanks to stanger, 4.3, bluexj, carves, showtime, seu. Thanks for putting up w my rants and stupid questions.
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[denverd1]

Seu83 mentioned a heat shield b/w block and header and I don't have one... thanks for the tip

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[stanger351]

is there a 2:1 cam/crank relationship like V engines?

Right. Its a four cycle engine, so the piston will be at TDC twice during a single cycle, once with the exhaust valve closing and the intake valve beginning to open and once with both valves closed ... that's the TDC you're looking for when setting the distributor (on the end of the compression, beginning of the power stroke). I've pulled valve covers before if I couldn't find the timing mark (to make sure the valves were closed and I had the correct TDC)

Glad you got it going again! We can't have any Jeeps sidelined. Need them all out there representing!

[Mudderoy]

I guess earlier, I should have said this was the reason I advised pulling the plug wire from the center of the distributor (from the coil to the distributor) and using the starter to prime the pump ... so the static timing wouldn't get disturbed (and if the pump didn't prime, at least the engine would not start running with no oil pressure). But I've done things way worst ... whatever you do, don't use an extension with a little socket on the end of it to find top dead center for cylinder 1! Yeah ... I did that, and the socket fell off inside the cylinder ... its a miracle that I managed to finally fish it out through the spark plug hole with one of those magnets on a steel rod (which would have been a much better choice for shoving into the spark plug hole in the first place!) :smiley-laughing021:

Man I bet your pucker factor was high just after and for the duration of that fishing expedition.

[stanger351]

I spent about 40 minutes fishing around trying to get it out with a coat hanger and thin screwdriver and the magnet thing. Just as I gave up and said "f' it, I'm going to pull the head off", the magnet thing caught the socket on the edge and it pulled right out. I learned a lot of lessons that day including "never drop anything down a spark plug hole that comes apart or doesn't have a handle on it that's at least a foot long" :wink:

[denverd1]

pucker factor say the least!

forgot muddy and cantab too...