D1 no oil pressure

Nich_in_uscg

Member
Mar 1, 2018
12
0
New Jersey
1995 D1 with 3.9 210k miles
Just did the timing cover gasket and oil pump. Initial start up oil pump went out and the oil sensor started to leak and then I lost pressure. I replaced the sensor last week and changed the oil from 10w30 to Rotella 15w40. With this my oil light went out. I had good pressure for about 30 minutes then my oil light would come on under 1100 rpm. Now I have no oil pressure. I?m thinking probably going to need to replace bearings. But I am interested if anybody has a direction that I should look into. Possibly stuck oil pressure relief valve? I haven?t dug into that yet. I am contemplating having the 3.9 rebuilt or swapping to a 4.0. The truck was running fine until the timing cover gasket started leaking.
 
Apr 20, 2004
6,926
223
Floyd, Virginia
I have seen those come loose (actually come detached)or not seal well against the block.

Of course they can suck up trash as well and depending on what got stirred up...

Keep in mind if you swap to a 4.0 you still have to use your timing cover/pump or source another.
 

Leadvagas

Well-known member
Jun 10, 2010
232
2
Leadville CO
TA performance down in Tuscon, IIRC, has all the front cover, oil pump etc parts. They are Buick guys, not really Rover guys, but I have picked up a few things from them. They have a large knowledge base on the small block, and give an alternative to D&D.
 

Vegas99D1

Well-known member
May 5, 2009
187
9
Plano, TX
I'm kind of experiencing a low oil pressure as well. What parts would work on the 4.0 from the TA Performance parts list?
 

Leadvagas

Well-known member
Jun 10, 2010
232
2
Leadville CO
The 4.0 non dizzy motor has a different style pump than the 3.9 dizzy motor. The 4.0 is a Gerotor, the 3.9 is a gear type pump. IIRC
 

Nich_in_uscg

Member
Mar 1, 2018
12
0
New Jersey
Update. Pulled the pan today and I guess I might have been a bit overzealous in my application of RTV on the reinstall. Lots of rtv bits in the bottom of the pan. Cleaned out the pickup and pan. Installed new gaskets in both. Will test tommorow and crossing my fingers that this was the problem
 

robertf

Well-known member
Jan 22, 2006
4,778
354
-
The 4.0 non dizzy motor has a different style pump than the 3.9 dizzy motor. The 4.0 is a Gerotor, the 3.9 is a gear type pump. IIRC

This is not true for discoverys sold in the US. They all had the same oil pump
 

robertf

Well-known member
Jan 22, 2006
4,778
354
-
Doesnt sound good. Got rovergauge so you can see the real temp? Hows the fan clutch?
 

ezzzzzzz

Well-known member
Apr 22, 2010
604
7
SE Va
Sticking bypass valve in timing cover comes to mind. The bearings are probably worn too. I suffered this issue on a D2 4.0 until I finally replaced the timing cover assembly with a new one from Rimmer Bros.
 

Nich_in_uscg

Member
Mar 1, 2018
12
0
New Jersey
I haven?t swapped my viscous fan clutch. It was pretty dirty when I did my timing cover gasket and oil pump gears. I cleaned it with a rag, toothbrush and carb cleaner. I didn?t inspect the oil pressure relief valve when I did the pump. Is that something that can be serviced without having to drop the oil pan and draining all the fluids?
 

mearstrae

Well-known member
Mar 15, 2017
143
18
Pennsylvania
Oil filter by-pass? Stuck oil pressure spring or needle? I've used Buick hi-po oil pump rebuild kits to up the pressure and volume on the external pumps on all three of my engines (Rovers 3500S, 3.5 - S3 109, 3.5 - and R.R.C, 4.2) with good results. It can be done in place, without taking the front cover off. The external pumps can have scary low oil pressure, especially at idle. These front covers are like (not the same as) the AMC V-8 ones, and there is a problem with the end plates (and housing) being aluminum and grooves wearing into both. Might be worth a look...



'99 Disco II
'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S
 

robertf

Well-known member
Jan 22, 2006
4,778
354
-
I haven?t swapped my viscous fan clutch. It was pretty dirty when I did my timing cover gasket and oil pump gears. I cleaned it with a rag, toothbrush and carb cleaner. I didn?t inspect the oil pressure relief valve when I did the pump. Is that something that can be serviced without having to drop the oil pan and draining all the fluids?

You'll have to pull the alternator/ac bracket. Then its a snap ring on the side of the timing cover. Then its the plug (with o-ring) spring, and valve. May have to blow some air through the oil lines or filter connection to get the valve part out of the cover.
 

robertf

Well-known member
Jan 22, 2006
4,778
354
-
Oil filter by-pass? Stuck oil pressure spring or needle? I've used Buick hi-po oil pump rebuild kits to up the pressure and volume on the external pumps on all three of my engines (Rovers 3500S, 3.5 - S3 109, 3.5 - and R.R.C, 4.2) with good results. It can be done in place, without taking the front cover off. The external pumps can have scary low oil pressure, especially at idle. These front covers are like (not the same as) the AMC V-8 ones, and there is a problem with the end plates (and housing) being aluminum and grooves wearing into both. Might be worth a look...

That won't work on NAS Discos. They all had crank driven oil pumps.