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post #1 of (permalink) Old 05-30-2002, 08:04 AM Thread Starter
 
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High volume oil pump for 4.0L

Hey All

I am looking for a high volume oil pump for the Jeep 4.0 I-6.
Watching the oil pressure gauge, I don't like how the pressure dips badly at idle. That pressure dip is from insufficient volume to pressurize the system -- the relief valve should control oil pressure, not the lack of pump volume.

I have a 2002 TJ Sport if that info helps.

Is anyone here running one of those high volume oil pumps in a TJ or YJ with 4.0? If so what do you think and where did you get it?

Thanks

John
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post #2 of (permalink) Old 05-30-2002, 08:25 AM
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Re: High volume oil pump for 4.0L

Is it out of warranty already? If not, is the dealer not wanting to do anything about it?
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post #3 of (permalink) Old 05-30-2002, 11:02 AM Thread Starter
 
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Re: High volume oil pump for 4.0L

well, the Jeep is like 2 months old and I don't have an FSM yet. I don't know what the spec on oil pressure is.

What it is doing is dropping down to like 38psi at idle when the engine is nice and warmed up. At speed, it runs 55-58 psi.

If that is below the spec, I will certainly take it in for warranty, but I have this feeling that it is in spec.

I am guessing that the best solution is to put a higher flow oil pump in there and let it do its work.

Any info about oil pressure at idle? Specs?

Thanks

John
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post #4 of (permalink) Old 05-30-2002, 12:15 PM
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Re: High volume oil pump for 4.0L

It's better than my 5-10 psi at idle with my 360.
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post #5 of (permalink) Old 05-30-2002, 12:15 PM
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Re: High volume oil pump for 4.0L

That pressure sounds about right to me. But I don't know the exact specs.
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post #6 of (permalink) Old 05-30-2002, 12:53 PM
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Re: High volume oil pump for 4.0L

thats way more pressure than your engine needs at idle..
it doesnt make any sence to me to put an aftermarket part in a warrantied engine and void the warranty. 38 is fine.. better than fine..its good.
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post #7 of (permalink) Old 05-30-2002, 01:44 PM
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Re: High volume oil pump for 4.0L

My 99 TJ had approx 42 lbs at cold start up around 24 lbs at warm off idle ...and around 12-13 at hot idle. The idle pressure would drop somewhat if I was just done accellerating hard.

I installed a high volume oil pump. Most here don't see the sense in it ...but if you go to Jeggs or Summit 9 out of 12 pumps offered are HV ..very few HP or OEM volume.

You can get a HV oil pump for the 4.0 right from MOPAR. It has a warning sticker attached saying that it is illegal to install it on an emissions controlled vehicle. This is, I assume, a legal technicality dealing with "packaged factory certification" since I've had superb emission results with the HV pump and the MOPAR roller rockers (that carry the same prohibitive warning).

I didn't buy the MOPAR oil pump. I bought one from QualCast. It's a heavier unit then the MOPAR ..and was a little more expensive. I would have preferred the MOPAR ...but I was unaware of its existance until after I did the swap.

With a HV oil pump you will have PLENTY of pressure under all modes of driving. You will be up against the pressure relief springs at virtually any road speed . You will have more pressure at idle than your current pump delivers at cold start up. You will have a hard time getting below 38 lb of pressure even if you idle it in 90 F. traffic for hours on end.


The liability of the HV pump is in energy consumption. The trend to lighter weight oils is to consume less energy to pump them through the engine. There is also additional stress on your distributor to drive the added volume You're sending this in a totally different direction. I personally don't feel that the costs outweigh the benefits ....but that's just me. I also think that most people, especially in this forum, don't consider it a topic worth spending much thought upon. If this was an "engine longevity forum" ...that would be another issue.

...a little side note

Although my 99 4.0 had "normal' oil pressure (as many here have indicated 12-14 idle etc.)...my 2002 SE with the 2.5 already has a HV oil pump installed. It evidences the same characteristics as my 4.0 w/HV pump ...almost to the lb.

So .... if your unhappy with the oil pressure ...go buy a HV oil pump...but don't ask the dealer to install it. Do it yourself or get a reasonable wrench to do it for you. Most here don't bother with this sort of thing because they're geared toward performance and not longevity. Given the expense of most of the mods here ...the engnie is probably the cheapest and most durable item on the jeep ...even in stock form. A swap every year or two of hard use is ok for them. To them it is just another cost involved with running with the pack.

So unless it's totally paid for ...I do everything to make it last longer. BTW- if you want to get obsessive like I am about lubrication you can graduate to the 9.5 qt. capacity system and never worry about oil fatigue ..it does get expensive at oil change time however [img]images/icons/wink.gif[/img]
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post #8 of (permalink) Old 05-30-2002, 04:32 PM Thread Starter
 
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Re: High volume oil pump for 4.0L

Gee,

Thanks

No wonder the chrysler engines wear out so fast -- 12-15 psi at idle is terrible. I bet they would last forever with a nice constant 50 psi (not high pressure -- that is close to the relief pressure of the stock pump.) People swap out engines every 2 years because they are slap worn out after 20,000 miles of 5 psi oil pressure. I wonder if that is what the typical "Jeep Rattle" is from? Fords and Chevy's only do that when they are really low on oil.

I am used to vehicles where the oil pressure just stays rock solid at whatever pressure it is supposed to be (toyotas.) I get kinda nervous when I see them just start dropping off. Engine rebuilds are expensive, and an oil pump costs nothing compared to one. As for fuel milage, I am sure it is not even 1mpg difference with the higher volume pumps.

I was looking for a source to find those pumps. I tried Jegs and Summits websites but they were really not too helpful. I guess I should just give them a call. Any brands that I should look for? I would trust Mopar, and I know Melling too, and you mentioned QualCast but I have not heard of many others. Any suggestions?

Where did you find the extra capacity for the 9.5 (or so) quarts? Was it some sort of deep sump oil pan? I know my oil pan hangs down pretty low as it is. I am not sure I would give up another 2" for an extra quart or two of oil. I would love to be able to run the extra oil in the system. I really don't care about a couple of extra quarts at oil change, but the engine would last worlds longer with oil that stays 20 degrees cooler.

Thanks

John
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post #9 of (permalink) Old 05-30-2002, 04:48 PM
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Re: High volume oil pump for 4.0L

I had 152k miles on my original 304 with no problems. I only swapped it out because I had a 360 I wanted to replace it with. I have 40k miles on my 360 that I rebuilt 4 years ago and except for problems with the pro-jection, has been trouble free. No noises that shouldn't be there.
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post #10 of (permalink) Old 05-30-2002, 05:07 PM
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Re: High volume oil pump for 4.0L

To start out: the 4.0 is an AMC engine that chrysler stuck its badge on. External block dimensions are the same as the Venerable AMC 199-232-258. you look at the inside the journal sizes and journal to journal distance is the same. heds will interchange between most AM sixes and Cranks will interchage for all 232 based motors. (199 is a destroked 232, 258s are stroked)
With one exception all the 258s ive ever run or driven or been around (there have been a few) have started clicking about 1- 1 1/2 quarts low on oil. If memory serves AM inlines should 13 psi 650 rpm and anywhere from 35-75 psi at 3000 rpm.

Jesse

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