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High Volume Oil Pumps- Yay/Nay?

Old 04-30-2019, 03:38 PM
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Default High Volume Oil Pumps- Yay/Nay?

Does anyone have any experiences with Melling's High Volume Oil Pumps for their XJ, or any HV oil pump on any car? Specifically whether it increased oil pressure at idle, or if it led to another engine part's failure down the line?

I bought a 2000 Sport in December and it ended up having a blown head gasket that didn't show up on the inspections. Coolant leaked into the oil and worn away some of the bearings. I now have low pressure at idle (if it's warm enough, the "check gauges" light comes on, but at 2,000 rpm, I have about 40 psi. I have thought about using a thicker oil, but the Tech Support guy from Melling said if I have that low of pressure at idle, no oil of any thickness is really going to help me. So I think the HV oil pump is my best bet.

I know I can either rebuild or swap the engine, but I am only a college student now and don't really have the cash, nor can I be without my car for so long. Hopefully the oil pump will kick the can down the road a few years so I can do a proper swap or something later.

If anyone has any experiences with Melling or advice on what I should do next, please share; it'd be greatly appreciated!
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Old 04-30-2019, 04:59 PM
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Not sure if it is stil this way, but back when I was a youngin', you could get a high pressure oil pump or a high volume oil pump.

They each had their purpose.
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Old 04-30-2019, 05:08 PM
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They have a "standard volume high pressure" pump but that is only a new regulator spring that regulates the pressure to say 80 psi, instead of the standard 65 or so. So since my pump can't make above 40-50 psi, the new spring wouldn't do anything for me.

Since I do indeed have worn bearings, the Melling tech support guy said I would be in no danger of even reaching above 80 psi though.
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Old 04-30-2019, 06:46 PM
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I have a high vol. melling pump in mine and have had no problems at all. it does have higher pressure just because of the vol. mine runs about 45- 50 psi when hot and about 80 psi at highway speed. Will peg the gauge when cold may very well buy you some time. you have to take pan off to replace pump why not just replace bearings while your there you can do all rods and mains with the engine in the jeep not a big deal. Pull a main cap and a rod cap and check if they are standard or what they are get new bearings and be done!
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Old 04-30-2019, 06:53 PM
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This conversation always aggravates me . A oil pump if any kind is not a repair of any sort for damaged bearings causing low oil pressure . A hvop for low pressure is the equivalent of adding another cooling fan knowing you have a blown head gasket lol
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Old 04-30-2019, 06:59 PM
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Originally Posted by GreaseMonkey17 View Post
This conversation always aggravates me . A oil pump if any kind is not a repair of any sort for damaged bearings causing low oil pressure . A hvop for low pressure is the equivalent of adding another cooling fan knowing you have a blown head gasket lol
I agree that's why I asked why not change bearings while he is there! Oil pump just a band aid per say!
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Old 04-30-2019, 07:27 PM
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I have had the gasket replaced, but I still have low oil pressure. I thought about replacing the bearings but I won't be able to replace all of them from just taking off the oil pan. Replacing just a few may not solve the low oil pressure problem, as well. At that point, just do a whole rebuild, which is expensive and time consuming.

I know this is just a band-aid; I just want to buy me some time until I make real paychecks and can do the job properly.
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Old 04-30-2019, 08:46 PM
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Originally Posted by markhoff1022 View Post
I have had the gasket replaced, but I still have low oil pressure. I thought about replacing the bearings but I won't be able to replace all of them from just taking off the oil pan. Replacing just a few may not solve the low oil pressure problem, as well. At that point, just do a whole rebuild, which is expensive and time consuming.

I know this is just a band-aid; I just want to buy me some time until I make real paychecks and can do the job properly.
cheaper to buy a good used engine than to rebuild imo .
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Old 04-30-2019, 08:48 PM
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Originally Posted by RockinRonnie View Post
I agree that's why I asked why not change bearings while he is there! Oil pump just a band aid per say!
sorry my comments werenít directed to you . You lose most your oil pressure from the cam bearings according to what Iíve been taught so yeah replacing bearings with low oil pressure is an all or nothing affair .
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Old 05-01-2019, 07:32 AM
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I say give it a try and see what happens.

You'll have to beat on the oil pan to clear the pump. No biggie.
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Old 05-03-2019, 05:53 PM
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I'm thinking of the same thing let use know what you do and how it works out .
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Old 05-03-2019, 10:39 PM
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Originally Posted by tech View Post
I'm thinking of the same thing let use know what you do and how it works out .
I used one on my wife's 88 4.0. Worked just fine. I'm curious what happens if you put one on a vehicle that had a failed 0331 head. My Jeep only had 175K on it.
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