Bus Conversions dot Com Bulletin Board
July 29, 2014, 01:49:49 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you had an E-Mag Subscription: You will not incur forwarding fees when you are on the road.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: 1 2 [All]   Go Down
  Print  
Author Topic: Oil Pump  (Read 1835 times)
wal1809
Hero Member
*****
Offline Offline

Posts: 1330




Ignore
« on: March 01, 2011, 06:25:35 AM »

How hard is it to get to an oil pump on an 8v71?  My bud has an MCI and he believes the oil pump may not be doing so hot.  I have told him to change the oil to the right oil as the previous owner had 10W-40 (go figure).  I also told him to get another gauge and try that first.  If those fail it is off to the races on a new pump and I was curious how hard that is coming up from the oil pan.
Logged

1984 Silver Eagle Model 10 6V92 Allison auto tranny
www.snakebreaker.com
bevans6
Hero Member
*****
Offline Offline

Posts: 4544


1980 MCI MC-5C




Ignore
« Reply #1 on: March 01, 2011, 06:38:54 AM »

there are two types of oil pumps on an 8V71, as far as I know.  If your front cover behind the crank pulley has what looks like a snail shell cast into the cover, the front cover is the oil pump housing, driven from a reduction gear on the nose of the crank.  If your front cover is smooth, then the oil pump is a gear drive off the middle of the crankshaft and you have to drop the pan to get at it.

My impression is that the oil pump on these is pretty bullet-proof.  It's just two big gears in a cast iron housing.  I think it would be easy to change on an MCI since you can get to the front of the engine easy enough, and the engine mount is on the upper gear cover.  You do have to take the oil pan off as well.

Well, not easy, but doable.  It would be a PITA for all the easy access...
Brian

« Last Edit: March 01, 2011, 06:50:06 AM by bevans6 » Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
bevans6
Hero Member
*****
Offline Offline

Posts: 4544


1980 MCI MC-5C




Ignore
« Reply #2 on: March 01, 2011, 06:53:33 AM »

here is a thought.  On my MCI the oil feed to the alternator is from the same oil port as the gauge manifold.  My alternator didn't have the right reduction orifice in the feed line, so was taking too much oil.  The gauge read low pressure.  As a test I blocked off the line to the alternator, the pressure doubled.  My actual oil pressure was around 55 psi, the reading had been 25 psi, and after I put in the correct orifice in the alternator line the pressure reading was 45 psi.

Brian
Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
luvrbus
Hero Member
*****
Offline Offline

Posts: 12097




Ignore
« Reply #3 on: March 01, 2011, 06:56:42 AM »

Original 8v71 engine in a MCI 8 or 9 the oil pump is in the pan 

good luck
Logged

Live each day like it was your last,one day it will be
wal1809
Hero Member
*****
Offline Offline

Posts: 1330




Ignore
« Reply #4 on: March 01, 2011, 11:26:19 AM »

I believe he has an MCI9!  Yall reckon a person can get to the pan without taking a lot of other parts off? 
Logged

1984 Silver Eagle Model 10 6V92 Allison auto tranny
www.snakebreaker.com
bevans6
Hero Member
*****
Offline Offline

Posts: 4544


1980 MCI MC-5C




Ignore
« Reply #5 on: March 01, 2011, 11:35:22 AM »

Yep, nothing in the way at all.  Check for that scroll on the front cover, if it's there you have to pull it as well, which means taking the bumper off.  My MCI engine has the pump in the front cover.  My industrial engine has the pump in the pan.

Brian
Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
Len Silva
Hero Member
*****
Offline Offline

Posts: 4083


Angle Parked in a Parallel Universe


WWW

Ignore
« Reply #6 on: March 01, 2011, 12:27:36 PM »

I am most certainly not an expert here, but I think if I had low oil pressure on an 8V-71, the oil pump would be the last thing I would suspect.
Logged


Hand Made Gifts

Ignorance is only bliss to the ignorant.
luvrbus
Hero Member
*****
Offline Offline

Posts: 12097




Ignore
« Reply #7 on: March 01, 2011, 12:34:25 PM »

Len, it would be nice to know what his oil pressure is he may be expecting more than the DD is willing to give up lol the DD oil pump does not ever cause much of a problem the valves on each of the block inside the pan do give a few

good luck
Logged

Live each day like it was your last,one day it will be
JohnEd
Hero Member
*****
Offline Offline

Posts: 4571




Ignore
« Reply #8 on: March 01, 2011, 05:46:41 PM »

This may be a blessing in disguise.  With big block V8s, the bearings having significant wear will drop oil pressure when hot.  Aren't we supposed to replace the bearings in the 8V71 every so often?  If the PO was using 10W40 I would expect accelerated bearing wear.  The bearings are easily measured for wear with a mike or calipers but I would use plasti-gauge on a rod and main bearing.  That's my inclination, anyway.  I have never looked up a 8V71s skirt so I can't be quoted.  Sound good to the experts?

In the gear pumps for a medium truck they were finicky.  They wanted very little depth to the signature from the gear in the side plate.  They had a new spec of .0005 inches clearance on each side for a new item and they tolerated only a few thousandths wear.  I would certainly look up the clearance spec in DaBook on and open the oil pump.

Given that you are working with a pretty old engine I think you would check as much as you could in this maint adventure.  I was shown a 8V71 or 6V92, I don't know which, and it had sheared the teeth off of the cam timing drive gear.  I was told that it "might" only need a couple valves.  That was closely followed by a really deep chuckle.  The engine had had new bearings rolled in a short while prior.  How does one go about making sure of the gear lash limits?

That was some superb info about the oil cooled alternator.

Clifford,

What are the valves up inside on the block all about?

John
Logged

"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla
chart1
Sr. Member
****
Offline Offline

Posts: 267





Ignore
« Reply #9 on: March 01, 2011, 06:06:16 PM »

What is the normal idle oil pressure suposed to be ?
Logged

1976 MCI 8
8v71/740auto
8" roof raise
Jriddle
Hero Member
*****
Offline Offline

Posts: 653





Ignore
« Reply #10 on: March 01, 2011, 06:20:12 PM »

What is the normal idle oil pressure supposed to be ?

Having pressure at idle is good. Mine runs about 25 to 30 at idle and at 1000 RPM around 55 to 60.
Sure all differ some but that is what mine does with Delo 100 30 wt. If you have 15-40 you will find pressure to be less. I did Send PM to you on injectors let me know.

John
« Last Edit: March 02, 2011, 07:02:36 AM by Jriddle » Logged

If It Can't Be Grown Then It Has To Be Mined
John Riddle
Wells NV
1984 MC9
luvrbus
Hero Member
*****
Offline Offline

Posts: 12097




Ignore
« Reply #11 on: March 01, 2011, 06:23:03 PM »

5 to 7 lbs @ 500 to 600 rpm the 6v92 will have more as they use a 8v92 front mounted oil pump the 6v92 with the old pump carried around 5 to 7 lbs also nothing to worry about with 5 lbs at idle when hot

good luck
« Last Edit: March 01, 2011, 06:33:28 PM by luvrbus » Logged

Live each day like it was your last,one day it will be
chart1
Sr. Member
****
Offline Offline

Posts: 267





Ignore
« Reply #12 on: March 01, 2011, 06:35:45 PM »

Luvrbus... Thanks , that's what I thought everyone was beginning to scare me. I have a rebuilt motor with less than 4000 miles and my oil pressure is about 8-9 back at the motor at idle.
Logged

1976 MCI 8
8v71/740auto
8" roof raise
wal1809
Hero Member
*****
Offline Offline

Posts: 1330




Ignore
« Reply #13 on: March 01, 2011, 10:04:54 PM »

His pressures are 30 lbs at 55 mph and nothing at idle.  It could be his guage.    Mine has  a lot higher pressure than that, running near 60 lbs at 55 and 30 at idle.  Heck, it could be my gauge is off!!! 
Logged

1984 Silver Eagle Model 10 6V92 Allison auto tranny
www.snakebreaker.com
chart1
Sr. Member
****
Offline Offline

Posts: 267





Ignore
« Reply #14 on: March 01, 2011, 11:50:55 PM »

I have a gauge back at the motor because they say it is more accurate. 40 feet of wire from the sender to the gauge in the dash has to have some drop in accuracy.
Logged

1976 MCI 8
8v71/740auto
8" roof raise
luvrbus
Hero Member
*****
Offline Offline

Posts: 12097




Ignore
« Reply #15 on: March 02, 2011, 06:14:30 AM »

I would say your gauge is off a little Wayne the DD have a relief valve inside the engine that dumps the oil back into the pan set at 50 lbs you can shim it an get another 5 or so lbs but hot you get 5 to 50 lbs of oil pressure so there is nothing wrong with your buds oil pressure
Logged

Live each day like it was your last,one day it will be
wal1809
Hero Member
*****
Offline Offline

Posts: 1330




Ignore
« Reply #16 on: March 02, 2011, 06:34:40 AM »

I believe your right Luvrbus.  I do believe his motor would have tanked by now anyway as that pressure has been constant for a year.
Logged

1984 Silver Eagle Model 10 6V92 Allison auto tranny
www.snakebreaker.com
Pages: 1 2 [All]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!