351M oil pressure problem - Pirate4x4.Com : 4x4 and Off-Road Forum
 
Pirate4x4.Com : 4x4 and Off-Road Forum  

Go Back   Pirate4x4.Com : 4x4 and Off-Road Forum > Brand Specific Tech > Ford
Notices

Reply
 
Share Thread Tools Display Modes
Old 03-21-2006, 07:53 PM   #1 (permalink)
Registered User
 
MX500's Avatar
 
Join Date: Oct 2005
Member # 56088
Location: Mid. Cal
Posts: 23
351M oil pressure problem

I am purchasing a 1978 Bronco with a 351M, and the oil pressure gauge indicates that the pressure is very low (nearly no pressure). The engine started up perfectly, and runs like a top, there is no fluctuation in idle speed, or no hesitation to rev. There are no abnormal engine noises, and the engine was cold before I started it up, so I should have been able to hear a rod knock if there was one. Could the oil pressure sending unit or the pressure gauge be the cause of the low oil pressure reading, or would something internal, such as a worn out oil pump, or loose engine tolerances be the cause of the apparently low oil pressure?

Thanks in advance
__________________
1978 Ford Bronco, warmed over 351M, C6, NP205, 6" lift, 35x15 TSL's, D44 front, 9" rear.
MX500 is offline   Reply With Quote
Old 03-21-2006, 08:14 PM   #2 (permalink)
Registered User
 
Join Date: Mar 2005
Member # 44042
Posts: 49
351M's are notorious for low oil pressure, I've owned two and both had good pressure at startup (with an aftermarket guage) but die down to 5psi or less at idle when they warm up. Something about narrow oil passages in the block.. Anyway both ran fine, in fact the one in my 81 F250 is my daily driver at the moment.
jacko is offline   Reply With Quote
Sponsored Links
Old 03-21-2006, 10:36 PM   #3 (permalink)
Registered User
 
Join Date: Jul 2005
Member # 50360
Location: Mount Carmel, PA.
Posts: 1,634
Send a message via AIM to NetBSD Send a message via Yahoo to NetBSD
get used to it, mine has been that way since i got it, even got worse since i spun the main bearings but it still runs strong and gets enough oil to keep it going i guess, from what im told this thing ran with low oil presure almost its whole life and it has about 350k on it right now. gunna try to improve my oil presure when i rebuild it this summer. but dont be scared of it
__________________
89 Ranger, 2.9, 6" lift, 35" baja claws
92 Silverado, 6.2L, GM-3 Turbo at 10PSI
NetBSD is offline   Reply With Quote
Old 03-21-2006, 10:53 PM   #4 (permalink)
Registered User
 
MX500's Avatar
 
Join Date: Oct 2005
Member # 56088
Location: Mid. Cal
Posts: 23
Thanks for the replys. I was hoping it wasn't a problem, and now I won't have to worry about the engine.

Now for an off-topic, newbie question, are the "genuine gear" (I think that's the company) lockers any good? I'll need to tear down the rear axle eventually to replace some leaking seals, and I'd like to get a locker or a true-trac type device in there when I do. I've only got about $4-500 to spend on the rear-end seals and modifications, so I need to make a good choice.
__________________
1978 Ford Bronco, warmed over 351M, C6, NP205, 6" lift, 35x15 TSL's, D44 front, 9" rear.
MX500 is offline   Reply With Quote
Old 03-21-2006, 11:03 PM   #5 (permalink)
Registered User
 
Join Date: Jul 2005
Member # 50360
Location: Mount Carmel, PA.
Posts: 1,634
Send a message via AIM to NetBSD Send a message via Yahoo to NetBSD
i got a mini-spool and chromoly pin (pin was never used) for a ford 9" if thats what ya want, ill sell it for $40 + shipping, mini-spool is 31 spline and only has maybe 700 miles on it
__________________
89 Ranger, 2.9, 6" lift, 35" baja claws
92 Silverado, 6.2L, GM-3 Turbo at 10PSI
NetBSD is offline   Reply With Quote
Old 03-22-2006, 07:51 AM   #6 (permalink)
Axes of E-ville
 
Aces'n'8s's Avatar
 
Join Date: May 2005
Member # 48097
Location: West TN
Posts: 3,596
You will learn not rely solely on those factory gauges to indicate certain levels. They are good at providing approximate settings. Also, if you ever have to perform lower engine work, you might want to install a high volume oil pump for security.
Aces'n'8s is offline   Reply With Quote
Old 03-22-2006, 11:57 AM   #7 (permalink)
Registered User
 
MX500's Avatar
 
Join Date: Oct 2005
Member # 56088
Location: Mid. Cal
Posts: 23
Quote:
Originally Posted by NetBSD
i got a mini-spool and chromoly pin (pin was never used) for a ford 9" if thats what ya want, ill sell it for $40 + shipping, mini-spool is 31 spline and only has maybe 700 miles on it
I need something that will let the wheels have a little speed difference, since this will be my daily driver, so the spool wouldn't work for me, Thank you for the offer though.
__________________
1978 Ford Bronco, warmed over 351M, C6, NP205, 6" lift, 35x15 TSL's, D44 front, 9" rear.
MX500 is offline   Reply With Quote
Old 03-22-2006, 08:58 PM   #8 (permalink)
Registered User
 
jopes's Avatar
 
Join Date: Nov 2001
Member # 8469
Location: Douglas, Wyoming
Posts: 3,188
Send a message via ICQ to jopes Send a message via AIM to jopes Send a message via Yahoo to jopes
ford issued a tsb on these engines for oil pressure problems. don't worry about it unless it starts sounding like is diesel, then rebuild it.
__________________
408ci SEFI, 70mm throttle body, 90mm mass air, stang harness, tweecer R/T waiting on a home.
jopes is offline   Reply With Quote
Old 03-22-2006, 09:16 PM   #9 (permalink)
Registered User
 
Join Date: Mar 2006
Member # 69301
Posts: 27
As others have said, the oil pressure is a problem. THIS IS BECAUSE THE BEARINGS ARE WORN OUT- IN MOST CASES. I have serviced many of these. I recommend using a mechanical gauge first to confirm the low oil pressure, THEN REPLACE THE MAIN AND ROD BEARINGS AND INSTALL A HIGH PRESSURE, HIGH VOLUME OIL PUMP and check the screen for cleanliness. If you do nothing it will blow up as others have mentioned. Many of those engine will go 300,000 miles if the bearings are replaced when needed... which may be every 60k to 80k on a 3/4 or 1 ton rig w/manual trans, cause they go fast when the engine is lugged.
Bulldog Bob is offline   Reply With Quote
Old 03-22-2006, 09:42 PM   #10 (permalink)
Registered User
 
Join Date: Jul 2005
Member # 50360
Location: Mount Carmel, PA.
Posts: 1,634
Send a message via AIM to NetBSD Send a message via Yahoo to NetBSD
Quote:
Originally Posted by MX500
I need something that will let the wheels have a little speed difference, since this will be my daily driver, so the spool wouldn't work for me, Thank you for the offer though.

whats the problem with a mini-spool in a DD? my rig is a DD and i just welded up the 14b im dropping in, only ever hear a lil tire chirp when going around 90* turns
__________________
89 Ranger, 2.9, 6" lift, 35" baja claws
92 Silverado, 6.2L, GM-3 Turbo at 10PSI
NetBSD is offline   Reply With Quote
Old 03-26-2006, 08:11 PM   #11 (permalink)
Registered User
 
Join Date: Jan 2006
Member # 65643
Posts: 1
I have run a 351m for 12 years and about every 2 years put in new main and rod bearings in it. The oil psi just keep getting lower and lower. The Cam bearings are the problem. The high valume oil pump will wear out the distor gear with in 3 years, I've been there. This is what I've learned with my motor.
73 F250 434 is offline   Reply With Quote
Old 03-26-2006, 08:18 PM   #12 (permalink)
Registered User
 
Join Date: Jan 2002
Member # 9381
Location: Corning, CA
Posts: 759
You only get 2 years out of the bearings? Wouldn't it be easier and cheaper to pull the whole engine out and fix the problem in the first problem?
Coors is offline   Reply With Quote
Old 03-27-2006, 04:04 AM   #13 (permalink)
Registered User
 
Join Date: Jul 2005
Member # 50360
Location: Mount Carmel, PA.
Posts: 1,634
Send a message via AIM to NetBSD Send a message via Yahoo to NetBSD
Quote:
Originally Posted by 73 F250 434
I have run a 351m for 12 years and about every 2 years put in new main and rod bearings in it. The oil psi just keep getting lower and lower. The Cam bearings are the problem. The high valume oil pump will wear out the distor gear with in 3 years, I've been there. This is what I've learned with my motor.

you got bigger issues, my buddies 351m was rebuilt top toi bottom 4 years ago and his oil pressure is normal with a hiugh volume pump. we just did a new cam in it and bearings looked fine.

#1 main reson for really low oil pressure is main bearings, once they are shot the oil just runs thru them and decreases the oil pressure (as im told) and i believe this is right cuz right after i spun my main bearings by my ex running the motoro hot when a freeze plug blew my oil pressure went to shit, i just have yet to fix the problem. but as stated before once it starts sounding like a diesel its time to rebuild, mine has about 350k on it and sounds like my bosses mack when im at crusing speeds above 2500RPM but im just to lazy and short on money to pull the motor yet
__________________
89 Ranger, 2.9, 6" lift, 35" baja claws
92 Silverado, 6.2L, GM-3 Turbo at 10PSI
NetBSD is offline   Reply With Quote
Old 03-27-2006, 06:44 AM   #14 (permalink)
Registered User
 
Join Date: Sep 2005
Member # 54152
Location: Rapid City,South Dakota
Posts: 897
Hay NET,run straight lucus oil.I have and it helps.Dont throw a rod in that 400 or your stuck with that 300/6 forever.
__________________
2008 F250 CC SB Lariat 4x4. 700HP on fuel.
93 F150. 01 F350. 97 Ram 1500.

Last edited by Fordtrucks; 03-27-2006 at 06:44 AM.
Fordtrucks is offline   Reply With Quote
Old 03-27-2006, 03:05 PM   #15 (permalink)
Registered User
 
Join Date: Jul 2005
Member # 50360
Location: Mount Carmel, PA.
Posts: 1,634
Send a message via AIM to NetBSD Send a message via Yahoo to NetBSD
Quote:
Originally Posted by Fordtrucks
Hay NET,run straight lucus oil.I have and it helps.Dont throw a rod in that 400 or your stuck with that 300/6 forever.

400 and 300 were both pulled today, i managed to get the 300 running after 4 years of it sitting, ran strong but rear main seals leaking, but i think it swelled back up and stopped. the 400 is getting totally redone and bored .030 over and hot tanked, scoped, heads are getting ported and polished, then i gotta find out what ima run in it
__________________
89 Ranger, 2.9, 6" lift, 35" baja claws
92 Silverado, 6.2L, GM-3 Turbo at 10PSI
NetBSD is offline   Reply With Quote
Old 03-27-2006, 03:57 PM   #16 (permalink)
Registered User
 
Join Date: Sep 2005
Member # 54152
Location: Rapid City,South Dakota
Posts: 897
Well,dont build it to much.I overbuilt my 466 and now regreat it.I am going from a 6k pound mud truck to a jeep for rock crawling.Before I put the 460 in the jeep,ittl get a smaller cam and some things like that to settel it doun a bit.Its hard to crawl rocks with a lopy idle.
__________________
2008 F250 CC SB Lariat 4x4. 700HP on fuel.
93 F150. 01 F350. 97 Ram 1500.
Fordtrucks is offline   Reply With Quote
Old 03-27-2006, 04:45 PM   #17 (permalink)
Registered User
 
Join Date: Mar 2006
Member # 69721
Location: Little Chute WI
Posts: 199
Send a message via AIM to Nitrofueled14
Hmm... I've got the 351M and my oil pressure never goes below 40.
Nitrofueled14 is offline   Reply With Quote
Old 03-27-2006, 06:55 PM   #18 (permalink)
Registered User
 
Join Date: Jun 2005
Member # 48716
Location: Virginia
Posts: 989
Send a message via AIM to VerticalTRX
The 351M thats currently in my '79 has virtually no oil pressure. The mains are completly gone, infact it knocks so bad that it sounds like the crank is hitting the block. These motors seem to wear main bearings out fairly bad, I've heard of many doing it.

I'm going to try putting straight 50w oil in mine and see what happens, hope it runs long enough to get me through this next trail ride. Then I'm ripping the piece of crap out, throwing it in the land fill, and getting this GT-40 351w built up thats sitting on my engine stand. Can anyone tell I despise modified series motors?
__________________
Kickin' it old school: '79 Ford, Q78 TSLs and a Q-jet
VerticalTRX is offline   Reply With Quote
Old 03-28-2006, 05:47 AM   #19 (permalink)
Registered User
 
BUZZISCRAZY2's Avatar
 
Join Date: Feb 2003
Member # 17399
Location: oxford wi
Posts: 1,530
Send a message via AIM to BUZZISCRAZY2 Send a message via Yahoo to BUZZISCRAZY2
Quote:
Originally Posted by VerticalTRX
The 351M thats currently in my '79 has virtually no oil pressure. The mains are completly gone, infact it knocks so bad that it sounds like the crank is hitting the block. These motors seem to wear main bearings out fairly bad, I've heard of many doing it.

I'm going to try putting straight 50w oil in mine and see what happens, hope it runs long enough to get me through this next trail ride. Then I'm ripping the piece of crap out, throwing it in the land fill, and getting this GT-40 351w built up thats sitting on my engine stand. Can anyone tell I despise modified series motors?

A good "m" is just fine.........even for Abusers like me

__________________
[FONT="Comic Sans MS"]Catch your Dreams, before they slip away........[/FONT]

[FONT="Arial Black"]Current vehicles[/FONT]

67 Bronco
69 Bronco
81 Bronco
81 Bronco
75 F-250 (highboy)
77 F150
78 F150
70 F100 (2wd)
93 F350
95 F350 (Blown Crazy")
95 F350 ("Crazy Too")
87 Ranger (2wd)
00 Excursion
04 Navigator
BUZZISCRAZY2 is offline   Reply With Quote
Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 04:19 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0 ©2011, Crawlability, Inc.