Low oil pressure on a 258 - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Low oil pressure on a 258

Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineDan's Old as Dirt Birthday Sale!GEARSHADE Pocket Tops in stock and available at ROCKRIDGE

Reply
Unread 01-29-2009, 05:48 PM   #1
81cj7id
Registered User
 
Join Date: Jan 2009
Location: Idaho
Posts: 23
Low oil pressure on a 258

I have a 1981 Jeep cj7. It has the 258 which was recently rebuilt. The problem is it only holds about ten pounds of oil pressure at idle. Is this right? A brand new oil pump was installed when it was rebuilt. I also get a tapping noise that sounds like valves/lifters. Any ideas? Thanks.

81cj7id is offline   Reply With Quote
Unread 01-29-2009, 06:19 PM   #2
crusty75
Registered User
1975 CJ5 
 
Join Date: Oct 2004
Posts: 424
FSM spec for my 75/258 is 13lbs @ idle (600 rpm). Given the accuracy of most OP gauges, I'd say you have nothing to worry about. Mine runs an indicated 5lbs at idle, been that way for years and years, not a problem.

You're more than likely OK with the noise also, the 258 is a noisy thing, even when in good shape. But I'd have to hear it to say for sure....
__________________
But what do I know? I'm old.
crusty75 is offline   Reply With Quote
Unread 01-29-2009, 08:23 PM   #3
CrazyHorse6
Registered User
1979 CJ7 
 
Join Date: Jun 2006
Location: Irmo, SC
Posts: 1,056
Quote:
Originally Posted by 81cj7id View Post
I have a 1981 Jeep cj7. It has the 258 which was recently rebuilt. The problem is it only holds about ten pounds of oil pressure at idle. Is this right? A brand new oil pump was installed when it was rebuilt. I also get a tapping noise that sounds like valves/lifters. Any ideas? Thanks.
Put your hand on the valve cover while its running - do you feel tapping or pinging? Pull the valve cover off (pick up a replacement gasket first- autozone and Advanced Auto has 'em) and inspect each rod - one may have slipped out from underneath a rocker. If the rods are all still set beneath the rockers, wiggle each rod to see if there is play- you want them all tight. If you have a loose one you might have a bad lifter, a broken rocker, or the torque on the rocker is incorrect. You mentioned it was rebuilt - I'm assuming they replaced the lifters and camshaft though? If you get a tapping noise from the front of the engine it may be the timing chain slapping the timing chain cover - mine does the same thing. Good luck
__________________
CJ7, 258, Dana 20 T-case, Dana 30 & AMC 20, TFI Ignition upgrade, headers, MC 2150 carb, YJ tub mod w/Family Style roll bar...


Are you military or former military? Take a look at militaryjeepers.com!

Last edited by CrazyHorse6; 01-29-2009 at 08:28 PM.. Reason: Update
CrazyHorse6 is offline   Reply With Quote
Unread 01-30-2009, 07:53 AM   #4
careyfl
Registered User
1986 CJ7 
 
Join Date: Jan 2009
Location: Daytona Beach
Posts: 57
I have 20 to 40 psi at 600, 40 to 65 at 2000. 91,000 on the engine. I do have a faint tapping and some occasional blue smoke. When I get around to it I'll do your check crazyhorse6 thanks. Ive been told my timing chain is due for replacement just based on miles but I doubt 81cj7id would have that issue unless he got a dubious rebuild. Something to think about 81cj.
careyfl is offline   Reply With Quote
Unread 01-30-2009, 09:38 AM   #5
CrazyHorse6
Registered User
1979 CJ7 
 
Join Date: Jun 2006
Location: Irmo, SC
Posts: 1,056
You'll see some garage guys use an automotive stethscope for locating ticks, pings, etc. Its not always significant enough to feel with your hand, but its definitely an inexpsensive test.
__________________
CJ7, 258, Dana 20 T-case, Dana 30 & AMC 20, TFI Ignition upgrade, headers, MC 2150 carb, YJ tub mod w/Family Style roll bar...


Are you military or former military? Take a look at militaryjeepers.com!
CrazyHorse6 is offline   Reply With Quote
Unread 01-30-2009, 11:38 AM   #6
crusty75
Registered User
1975 CJ5 
 
Join Date: Oct 2004
Posts: 424
^ +1 on the stethoscope. Picked one up at Harbor Freight for 1.99 a couple of years ago. It is amazing what a LOUD symphony of noises a motor can make when you poke around in there with one.

They are so good a transmitting sound, that you can give yourself many sleepless nights by listening to your engine. 99% of the time, unneeded worry from too much audio information, in my experience.

But they sure can come in handy when you need one. You just gotta keep the fear factor in mind.
__________________
But what do I know? I'm old.
crusty75 is offline   Reply With Quote
Unread 01-30-2009, 12:20 PM   #7
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 6,351
If minimum spec from the FSM is 13 and you got 10 it's hard to say.

A fresh rebuild for me netted 20 to 25 at idle when the oil is hot. Also a strait crank and tight cylinder bores made the engine idle so quietly, with a stock exaust, my mother in law thought it stalled a few times.

I even had the rebuilder increase the oiling to the timing chain a little over stock and it still has the 20 psi.
86cj74.2L is offline   Reply With Quote
Unread 01-30-2009, 12:40 PM   #8
texasdave
Senior Member
 
texasdave's Avatar
1980 CJ7 
 
Join Date: Dec 2007
Location: Killeen, Texas
Posts: 917
You can also use the old mechanic trick of holding a long screwdriver on the valve cover and hold the hande to your ear. It will transmit the noise through the metal blade and you can isolate it that way.
texasdave is offline   Reply With Quote
Unread 01-30-2009, 03:19 PM   #9
Bubba Ray
Registered User
1984 CJ7 
 
Join Date: Dec 2005
Location: SC
Posts: 1,658
Mine has read 0 at idle and 20 at speed for years.
Bubba Ray is offline   Reply With Quote
Unread 01-30-2009, 04:23 PM   #10
careyfl
Registered User
1986 CJ7 
 
Join Date: Jan 2009
Location: Daytona Beach
Posts: 57
As custy75 said given the doubtful accuracy of OP gages I wouldnt worry. But if mine started reading like bubba ray's I'd freak out.
careyfl is offline   Reply With Quote
Unread 01-30-2009, 05:54 PM   #11
Fjguercio
Web Wheeler
1978 CJ7 
 
Join Date: Dec 2007
Location: Burnsville, MN
Posts: 2,814
Napa and other locations will have 1/8 NPT to 1/4" NPT brass adapters so you can put a mechanical gauge in the oil sensor port. When you start a new engine I woudl ALWAYS do this. You need to know the oil pressure is up ASAP or a problem. IN your case need to verify the pressure with a 0-100 or 0-160psi gauge.

We had a lot writen about the OIL we use. The FLAT LIFTERS/CAMS and the new emissions complient oils are not doing so well. Recommend using the offroad and diesel oils they still have ZDPH, zincPhospate, and helps make the metal slipery. New engine you need a oil change right away and then at 200 miles again. Shell Rotela is what I am using and there area few others if you do a search.

Filters. I was using Frame, and this one lets the oil drain back out and causes dry starts. So use a good premium filter like a WIX. Can search that also if you like. When you change your first filter might want to cut it apart with tin snips or utility knife to see what is in it.

After changine oil and Wix or other good filter if still tapping.. I like the idea of taking off the valve cover and cking.

For your first start?????? did you pour oil over your valve train, springs, guides, down pushrods & on cam, etc, Make your oil pump so it primes fast with vaseline or similar on the pumps gears, ie open it up??? Then the engine needs a the pump/oil PRIMED with drill, rotating engine 2 full revolutions at 1/4 turn intervals so all lifters get pumped up and oil comes out each push rod before you start engine. Did you do this proper work prior to starting up you new rebuild???


I would try these action items before taking off your valve cover:
Tell us what your start up process was like???
Get a 2" liquid filled gauge installed 0-100 psi
Tell us about your oil prime work
Change your oil & filter with materials above
Give us gauge pressures

Fred

Last edited by Fjguercio; 01-30-2009 at 06:06 PM..
Fjguercio is offline   Reply With Quote
Unread 01-30-2009, 06:25 PM   #12
careyfl
Registered User
1986 CJ7 
 
Join Date: Jan 2009
Location: Daytona Beach
Posts: 57
Then again remember that even mechanical gauges are only acurate to +/- 2% of there range.
careyfl is offline   Reply With Quote
Unread 01-30-2009, 06:40 PM   #13
81cj7id
Registered User
 
Join Date: Jan 2009
Location: Idaho
Posts: 23
thank you all for the help. the motor had its original start in the shop before i picked it back up, but i got a three page detail of all work that was performed, what oil was used for break in procedure, and how it was done. According to the paper work, the break in was done basically how Fjguercio described it being done. And i have changed oil four times since rebuild and there is only maybe 6000 miles on the new motor. I will pull the valve cover off as suggested and check and make sure all of the rods are still connected to the rockers and torqued properly. Its not terribly loud, but annoying enough after a $2000 rebuild. Previous owner was VERY hard on the engine and it had high miles. Shop said it looks like it had lost at least one head gasket recently. He said it looked like previous owner tried to resurface the head himself with a angle grinder!! This might just be as good as it gets for this old six cylinder. Thank you all once again.
81cj7id is offline   Reply With Quote
Unread 05-22-2011, 05:01 AM   #14
johnnykind
Registered User
1988 YJ Wrangler 
 
Join Date: Mar 2011
Location: Lucerne Valley, CA
Posts: 53
did you ever figure out what the problem was ???
I have the same problem New Motor No Oil Pressure, new oil pump still no pressure 10-15psi at 2000rpm MAX
would like to know what the fix was if you ever got it fixed ????
thanks
John...
johnnykind is offline   Reply With Quote
Unread 03-17-2012, 05:30 AM   #15
OldTexas
Registered User
1984 CJ7 
 
Join Date: May 2011
Location: Houston, T E X A S
Posts: 166
Same Problem

Same problem here. Pressure is 10-20 lbs. Kindy scary but it uses no oil. Going from 10w30 to 20w50 next oil change to see if the increase in viscosity helps. Not new though, 173,000 miles and still hanging in there.
OldTexas is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.