Go Back   Ford F150 Forum - Community of Ford Truck Fans > Pre-1997 F150 > 1987 - 1996 F150
Sign in using an external account
Register Forgot Password?


Welcome to F150 Forum!
Welcome to F150 Forum,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


Reply
 
 
 
 
Thread Tools Search this Thread Display Modes
Old 10-15-2010, 09:05 AM   #1
Senior Member
 
Pine Barron's Avatar
 
Join Date: May 2009
Location: NJ
Posts: 171
Mentioned: 0 Post(s)
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Default oil pressure for a 4.9 L6

What is the ideal oil pressure for my 88 straight six? My manual is pretty vague.

I installed a mechanical oil pressure gauge last night and here's what I got for oil pressures.

Cold idle: 55psi
Hot idle: 25psi
Hot driving @2000rpms: 45

The reason I ask is because my truck has a knock on start up thats been getting worse. It seems to go away when it warms up but when stop and idle for a minute I think I'm starting to hear it then too. I've read some posts that say not to worry about this sort of thing on a straight six, but I had a small block chevy that sounded like this and it died shortly thereafter.

It's got 142,600 with a recent oil change and a motorcraft filter.
__________________
1988 Ford F150 4x4 - 4.9L I6 - 5 spd
2001 Hyundai Accent L - 1.5L I4 - 5 spd
Pine Barron is offline   Reply With Quote
Old 10-15-2010, 10:09 AM   #2
April 2010 TOTM Winner
 
1987 F-150 XLT 4x4's Avatar
 
Join Date: Jan 2010
Location: Panama City, FL
Posts: 516
Mentioned: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Default

You have normal oil pressure for a 4.9L.

My 65K rebuilt and balanced 4.9L shows 42 psi at 2500 RPM and 25 psi at idle
on a aftermarket electrical gauge after warmed-up.

What is the weight of the motor oil you are using?
I use straight 30W year-round in Florida.

No engine should knock on start-up, the Main Bearings on the Crankshaft are worn.

As long as the low knocking sound quits after a few seconds after a cold start,
the 4.9L should last for years!
1987 F-150 XLT 4x4 is offline   Reply With Quote
Old 10-15-2010, 11:00 AM   #3
Senior Member
 
Pine Barron's Avatar
 
Join Date: May 2009
Location: NJ
Posts: 171
Mentioned: 0 Post(s)
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Default

Normally I run straight 10w30, but right now 2 quarts of it are 10w40 because I was low on oil and thats what I had at the time. It just leaking from the drain plug in the pan though...when I do my next oil change I'll put some teflon tape on the threads and that should fix it up.

If its got worn main bearings are there any additives worth using to make my engine last longer? I drive it like an 80 year old, but I occasionally tow a 4,000 pound trailer. Is that ok?
__________________
1988 Ford F150 4x4 - 4.9L I6 - 5 spd
2001 Hyundai Accent L - 1.5L I4 - 5 spd
Pine Barron is offline   Reply With Quote
Old 10-15-2010, 11:39 AM   #4
We'd do it
 
Just call me Sean's Avatar
 
Join Date: May 2008
Location: Orlando,Fl.
Posts: 31,044
Mentioned: 2 Post(s)
Thanks: 29
Thanked 360 Times in 320 Posts
Feedback Score: 1 reviews
Send a message via Yahoo to Just call me Sean
Default

I drove my truck with the I6 for over a year knocking. The knocking didn't even kill it, the blown head gasket did but even then it still ran.
__________________
Quote:
Originally Posted by Early Cuyler
Fights begin, fingerprints are took, days is lost, bail is made, court dates are ignored, cycle is repeated.
Just call me Sean is online now   Reply With Quote
Old 10-15-2010, 09:04 PM   #5
April 2010 TOTM Winner
 
1987 F-150 XLT 4x4's Avatar
 
Join Date: Jan 2010
Location: Panama City, FL
Posts: 516
Mentioned: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Default

No, there are no additives to help worn main bearing.

I have owned several I6 300ci 1V from the 70's,
couple of them had a low knock on cold start-up,
but held normal oil pressure at highway speeds;
I used 20W50 motor oil and run the engine for years with no problems.

Tow your trailer, it won't hurt it, just keep checking your oil level regularly.

Yeah, Teflon tape is good stuff,
but for a few bucks you could buy a new drain plug with a new gasket;
either way, as long as it stops the oil drip.

-----------------------------------------------------------------------------------------------
I went back and re-read your first post again-

If you hear the knock after it's warmed up now,
you can buy the engine some time running a thicker oil, it will last longer.
Seriously,
you will not hurt your engine running 20W50 oil in it!


Hope this helps!
1987 F-150 XLT 4x4 is offline   Reply With Quote
Old 10-15-2010, 09:24 PM   #6
We'd do it
 
Just call me Sean's Avatar
 
Join Date: May 2008
Location: Orlando,Fl.
Posts: 31,044
Mentioned: 2 Post(s)
Thanks: 29
Thanked 360 Times in 320 Posts
Feedback Score: 1 reviews
Send a message via Yahoo to Just call me Sean
Default

The oil drain plug should have a nylon washer that seals it.
__________________
Quote:
Originally Posted by Early Cuyler
Fights begin, fingerprints are took, days is lost, bail is made, court dates are ignored, cycle is repeated.
Just call me Sean is online now   Reply With Quote
Old 10-15-2010, 11:12 PM   #7
Hi-Rev Motorsports
 
dr_bowtie's Avatar
 
Join Date: Aug 2009
Location: Northern Indiana
Posts: 4,841
Mentioned: 0 Post(s)
Thanks: 0
Thanked 48 Times in 48 Posts
Feedback Score: 0 reviews
Default

just run it....

It is typical of Fords to have a Main rattle when cold....the oil drains back to the pan when cooling and the rattle is the lack of oil for the few short seconds until it pumps back up....

even the cheap motorcraft filters dont stop drain back...you need the better 10.00 dollar filters...

Mine started doing it the very first oil change I did when I got the truck at 79,000 miles when I put on a 3.00 dollar motorcraft filter....and I even use good Royal Purple oil
__________________
Rule#1...NEVER argue with an Idiot...they only drag you down to their level and then beat you with experience...!!!
Chevrolet....the only thing faster than my zipper...!
Quote:
Originally Posted by ymeski
Not a spankable offense...unless "raider" does it.
dr_bowtie is offline   Reply With Quote
Old 10-18-2010, 07:55 PM   #8
Senior Member
 
Pine Barron's Avatar
 
Join Date: May 2009
Location: NJ
Posts: 171
Mentioned: 0 Post(s)
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Default

I'd say the knocking takes about 5 minutes to stop knocking, not until the truck is totally up to normal operating temp it seems like.

Also mine is missing that nylon washer...have to pick one up.

I guess I'll just run it until it gets too bad and then maybe learn how to rebuild a straight six.
__________________
1988 Ford F150 4x4 - 4.9L I6 - 5 spd
2001 Hyundai Accent L - 1.5L I4 - 5 spd
Pine Barron is offline   Reply With Quote
Old 10-18-2010, 08:21 PM   #9
We'd do it
 
Just call me Sean's Avatar
 
Join Date: May 2008
Location: Orlando,Fl.
Posts: 31,044
Mentioned: 2 Post(s)
Thanks: 29
Thanked 360 Times in 320 Posts
Feedback Score: 1 reviews
Send a message via Yahoo to Just call me Sean
Default

It'll still run forever knocking away.
__________________
Quote:
Originally Posted by Early Cuyler
Fights begin, fingerprints are took, days is lost, bail is made, court dates are ignored, cycle is repeated.
Just call me Sean is online now   Reply With Quote
Old 10-18-2010, 11:38 PM   #10
Member
 
Join Date: Oct 2010
Posts: 31
Mentioned: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Default

Is it a low knock or a light tap? These engines are known to tap alot cuz of the rocker arms. Gotta retorque them.17 to 23 ft lbs. Try that first. I gotta do mine. They are tapping alot.167000 miles.... Id say it was time LOL. Besides I need to put a new valve cover gasket on her anyway. I been slackin...
Kubb 147 is offline   Reply With Quote
Old 10-18-2010, 11:38 PM
 
 
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
oil pressure jgrathoff Maintenance Shop 1 07-04-2010 09:41 PM
Oil Pressure and 4.2 Hvymtl 1997 - 2003 Ford F150 2 06-17-2010 07:40 AM
No Oil Pressure DGrant11 1997 - 2003 Ford F150 1 06-01-2010 08:48 PM
Low Oil Pressure jwelsh86 1987 - 1996 F150 15 01-28-2010 11:08 AM
Oil Pressure Nikdob 1997 - 2003 Ford F150 2 12-16-2009 06:12 PM

 

The Mustang Source
All times are GMT -4. The time now is 09:20 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.5.2
Copyright 2006 - 20011 F150forum.com
This site is in no way affiliated with the Ford Motor Company.