MGExp

MGB & GT Forum

Low oil pressure

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

Zimbo1967 Bob Duggan
Port Alfred, Eastern Province, South Africa   ZAF
Hi Tyler, I can't fault any replies which you've had but doubt whether you'll damage the crank in the short term carrying on as you are until you feel like having a proper engine rebuild. Just restrict your revs and drive sympathetically.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
spikerj Avatar
spikerj Josh Spiker
Provo, UT, USA   USA
1973 MG MGB MkIII "Little Red"
Ya you should be fine for the short term. I drove my MG with the low oil pressure for about eight months before I rebuilt the engine and the crank shaft was still in good shape when I inspected it, albeit I did not drive the car hard and I was very easy on it.

Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
Drive it cautiously. Listen for any "rattling" sounds from the engine especially at throttle lift. Rattling indicates excessive clearance on the crank/piston rod bearings.

This prgresses to spinning a bearing and then the crank needs to come out for a grind and maybe scrap. Ulimately can lead to rod failure.



The goal - Reliable summer driver interspersed with mechanical tinkering...
Motto - "Driving fifty in the twisties..."
On Mods - It's your damn car - Do what you want. Haters gonna hate...
On SUVs - Drive your B like a soccer mom is texting her friends about how she wants to kill you...
Red Betty - http://www.mgexp.com/registry/GHN5UH418165
Bart - http://www.mgexp.com/registry/GHD4U146898G

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
What Dan said...

Dick



In reply to # 3553374 by Ex-Calif Drive it cautiously. Listen for any "rattling" sounds from the engine especially at throttle lift. Rattling indicates excessive clearance on the crank/piston rod bearings.

This prgresses to spinning a bearing and then the crank needs to come out for a grind and maybe scrap. Ulimately can lead to rod failure.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

Camper66 Avatar
Camper66 Silver Member Tyler Smith
Columbia, SC, USA   USA
1980 MG MGB
So I would need number 25 on this Moss website. Anything else I would need? Would it be worthwhile putting in the uprated oil pump?

I have replaced the head before, but never attempted anything in the lower part of the engine. So are there any gaskets (other than oil pan gasket) or other parts that I should replace while I am in there?

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36454

dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
Item number 25 is indeed the set of connecting rod bearings. You'd need to confirm whether the bearings in your engine are standard or undersize, which would depend on whether the crankshaft had been machined undersize in a previous life. That is easily determined by inspecting the back of one of the bearing shells once you have it apart. The bearing shells will be stamped "STD" for standard size or 0.010, 0.020, etc. for the appropriate undersize.

It is common and desirable to replace the three center main bearings at the same time, since they are readily accessible once the oil pan is down. The front and rear main bearings cannot be accessed with the engine in the car. It is unusual to see oil pump wear like that shown in post number 15 in this thread. Most often the original pump is not scored and is fully serviceable, and is re-used. The uprated pump is not a good choice for a street engine, for a variety of reasons. If your inner and outer gerotors are damaged but the oil pump housing is not, you can buy and install a repair kit. If the housing is damaged, then a stock replacement pump would be a good choice.

Do bear in mind that replacing the rod bearings, three accessible main bearings, and possibly the pump, is a repair, and not a substitute for a full rebuild. There are other considerations, like worn camshaft lobes and tappets, the need for cylinder head service, the need for new piston rings, etc., which indicate that a full rebuild might be an option. And a full overhaul would afford the opportunity to incorporate some modest performance upgrades in the process...

Dick

In reply to # 3553507 by Camper66 So I would need number 25 on this Moss website. Anything else I would need? Would it be worthwhile putting in the uprated oil pump?

I have replaced the head before, but never attempted anything in the lower part of the engine. So are there any gaskets (other than oil pan gasket) or other parts that I should replace while I am in there?

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36454



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
If you are pulling the engine there are lots of things you can do and need.

If doing it from below you pretty much need

- Crank bearings
- Main bearings - you will only use 3 of the 5
- Oil pan gasket

I (personally) would not like to do this laying on the floor and would pull the engine but it is possible.

Do you know what size bearings you need? I didn't so pulled the engine on a Sunday afternoon, pulled a crank and main bearing and ordered the replacements. Finished up the following Saturday.

I also installed a stock rated replacement oil pump.



The goal - Reliable summer driver interspersed with mechanical tinkering...
Motto - "Driving fifty in the twisties..."
On Mods - It's your damn car - Do what you want. Haters gonna hate...
On SUVs - Drive your B like a soccer mom is texting her friends about how she wants to kill you...
Red Betty - http://www.mgexp.com/registry/GHN5UH418165
Bart - http://www.mgexp.com/registry/GHD4U146898G



Edited 1 time(s). Last edit at 2017-07-17 09:39 AM by Ex-Calif.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Camper66 Avatar
Camper66 Silver Member Tyler Smith
Columbia, SC, USA   USA
1980 MG MGB
I replaced the head last year and the tappets were in great shape. It does not burn any oil so the rings are probably fine. The only thing I have not checked is the camshaft.

In reply to # 3553515 by dickmoritz Item number 25 is indeed the set of connecting rod bearings. You'd need to confirm whether the bearings in your engine are standard or undersize, which would depend on whether the crankshaft had been machined undersize in a previous life. That is easily determined by inspecting the back of one of the bearing shells once you have it apart. The bearing shells will be stamped "STD" for standard size or 0.010, 0.020, etc. for the appropriate undersize.

It is common and desirable to replace the three center main bearings at the same time, since they are readily accessible once the oil pan is down. The front and rear main bearings cannot be accessed with the engine in the car. It is unusual to see oil pump wear like that shown in post number 15 in this thread. Most often the original pump is not scored and is fully serviceable, and is re-used. The uprated pump is not a good choice for a street engine, for a variety of reasons. If your inner and outer gerotors are damaged but the oil pump housing is not, you can buy and install a repair kit. If the housing is damaged, then a stock replacement pump would be a good choice.

Do bear in mind that replacing the rod bearings, three accessible main bearings, and possibly the pump, is a repair, and not a substitute for a full rebuild. There are other considerations, like worn camshaft lobes and tappets, the need for cylinder head service, the need for new piston rings, etc., which indicate that a full rebuild might be an option. And a full overhaul would afford the opportunity to incorporate some modest performance upgrades in the process...

Dick

In reply to # 3553507 by Camper66 So I would need number 25 on this Moss website. Anything else I would need? Would it be worthwhile putting in the uprated oil pump?

I have replaced the head before, but never attempted anything in the lower part of the engine. So are there any gaskets (other than oil pan gasket) or other parts that I should replace while I am in there?

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36454

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1967 MG Works MGB GT Racecar

Text Size

Larger Smaller
Reset Save

Sponsor Links