Oil Pump GeRotor

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
Well you say your running 60 wt oil. 70 wt is a gear oil. There’s lots of problems with running oil that thick. Your just compensating for really loose clearances.
 

Spark6

Well-known member
Oct 31, 2020
127
40
New Hampshire
Nope, Liqui Moly is a motor oil made in Germany primarily for high performance engines. Whatever it takes to keep this old girl on the road.
I switched to Liquimoly at the last oil change. Spendy, but made a massive difference in smoothness and engine noise. Buy from FCP Euro, and they’ll exchange the oil for new for free for life…
 

reelsretreat

Member
Jul 10, 2021
14
0
North Texas
Well you say your running 60 wt oil. 70 wt is a gear oil. There’s lots of problems with running oil that thick. Your just compensating for really loose clearances.
Shouldn't be loose clearances, just had the engine completely rebuilt by a reputable mechanic here in N. Dallas. Maybe the fact that the front cover is obsolete so I may be losing pressure there since I can't find one in any better shape?
 

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
Shouldn't be loose clearances, just had the engine completely rebuilt by a reputable mechanic here in N. Dallas. Maybe the fact that the front cover is obsolete so I may be losing pressure there since I can't find one in any better shape?
Ok so you have to run 60 wt oil but your still happy with it?
 

Blueboy

Well-known member
Apr 20, 2004
3,205
459
Back in the USA; Rockwood, PA
I switched to Liquimoly at the last oil change. Spendy, but made a massive difference in smoothness and engine noise. Buy from FCP Euro, and they’ll exchange the oil for new for free for life…
Use it (5-40) in my 2004 Audi A4 Avant. Made a huge difference in the engine smoothness. Very bizarre green color though when pouring it in. Sticking with Rotella 15-40 for the D1.
 

Flyfish

Well-known member
Oct 29, 2004
1,402
212
52
St. Louis
Well you say your running 60 wt oil. 70 wt is a gear oil. There’s lots of problems with running oil that thick. Your just compensating for really loose clearances.
10w-60 isn’t gear oil. 10 is the weight, like 10w-40. 60 is the viscosity.

Gear oil is 75w-90 or 75 weight.
 

p m

Administrator
Staff member
Apr 19, 2004
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10w-60 isn’t gear oil. 10 is the weight, like 10w-40. 60 is the viscosity.
Seriously? You should know better.
An oil's viscosity increases exponentially with decrease in temperature, but a straight-30 oil will still be x amount thicker than a straight-20 oil across the entire temperature range. The oils for which two numbers are given have a modifier added to them that allows them to appear (in a 10w40 example) as a 10-weight (or viscosity) oil when it is very cold and as a 40-weight (or viscosity) oil when it is hot.
"w" stands for Winter.
Stew is correct - 10w60 oil behaves as a 60-weight oil at normal operating temperatures. 70- or 75-weight oils are already gear oils.
Running an oil _this_ thick in an engine is exactly what he said - trying to mask up underlying low-oil-pressure, high-clearance, issues.

 

Jimmy

Well-known member
Apr 10, 2006
740
64
Aurora, CO
Well you say your running 60 wt oil. 70 wt is a gear oil.

Crankcase oil and gear oil are apples and oranges when it comes to viscosity:

image-asset.jpeg
 
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Flyfish

Well-known member
Oct 29, 2004
1,402
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St. Louis
Seriously? You should know better

I may have replied without being specific enough.

As for my 10w-60 comment, Stew asked if we’re using gear oil to keep the light off. I should have clarified better what I meant. The 10w is the “cold” weight. So if there’s a real problem, that probably wouldn’t keep the light off at startup until it got closer to operating temp. I doubt most of us would let the engine run that long with the light on waiting for it to get up to temp.

Also, admittedly, 60 is definitely thick but I didn’t consider it in the gear oil category. Really never gave it much thought.

So certainly didn’t mean any disrespect towards Stew whatsoever.
 
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reelsretreat

Member
Jul 10, 2021
14
0
North Texas
Ok so you have to run 60 wt oil but your still happy with it?
It's better than seizing the engine while sitting at a stop light or in heavy traffic when it's 100 degrees outside. Yes, my mechanic has put a oil pressure gauge on it to make sure it's oil pressure and not a bad sensor. Like I said engines been rebuilt, twice actually since they tore it down a second time trying to figure it out. Only thing we can figure is front cover is scored so oil pump can't produce proper oil pressure with anything less. Can't find a better one since they are obsolete. If you have any suggestions I'd be happy to hear them, but everything seems to be running fine for the time being. And I love the truck. Only D1 I've seen in North Texas, although I'm sure there are others around.
 

Flyfish

Well-known member
Oct 29, 2004
1,402
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St. Louis
Can't find a better one since they are obsolete. If you have any suggestions I'd be happy to hear them
Have you checked with Will Tillery? He’s always getting new inventory and rarely can’t help. And more importantly, he won’t tell you something is good, unless it’s good. You should check with him.
 

Knightspirit

Well-known member
Sep 22, 2019
251
84
Mount Shasta, CA
I am interested in this thread - as I also am in the middle of a teardown and rebuild of my 4.0. I have heard this before about the front cover - and I would like some clarification as to what actually gets worn? What am I looking for? Also - is there a need to "deck" the cover so it is absolutely flat? I am about to take the block, crank and both heads to the machine shop just for an initial evaluation - I guess I should include the front cover as well?

Also - if anyone has any tips for getting the seal out of that thing - i could use some ideas. I tried punching it out from the back with a screw driver and then a chisel - but was afraid of damaging the cover - so didn't try too hard. Doesn't look like there is anything to push against if using a press either....
 

reelsretreat

Member
Jul 10, 2021
14
0
North Texas
I am interested in this thread - as I also am in the middle of a teardown and rebuild of my 4.0. I have heard this before about the front cover - and I would like some clarification as to what actually gets worn? What am I looking for? Also - is there a need to "deck" the cover so it is absolutely flat? I am about to take the block, crank and both heads to the machine shop just for an initial evaluation - I guess I should include the front cover as well?

Also - if anyone has any tips for getting the seal out of that thing - i could use some ideas. I tried punching it out from the back with a screw driver and then a chisel - but was afraid of damaging the cover - so didn't try too hard. Doesn't look like there is anything to push against if using a press either....
Mine is a 4.0 gems. The inside that houses the oil pump gears gets grooved or scored if you will. The front cover is obsolete and we couldn't find one in better shape. Had I known what I know now, I might have looked into an engine swap.
 

Flyfish

Well-known member
Oct 29, 2004
1,402
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52
St. Louis
I guess I should include the front cover as well?
Sounds like a very good idea. The machine shop would definitely be able to point out any issues or confirm all is good with the cover and pump. And you could have them fit a new pump so everything is perfect. That’s the heart of your engine!

Leave the seal in, they can remove it.
 

p m

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Apr 19, 2004
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It is not a matter of a sleeve. The cover is aluminum, the gears are steel. The cover can get scored or simply worn out.
It was endemic for Buick, AMC, (and probably Ford) V engines with aluminum timing chain covers.
There are oversized (taller) oil pump gears for older engines, but I don't know if there is an option for a crank-driven pump.
Technically, one can raise the worn surface by electrolysis and then machine it.