My wife's 86 4-cyl's oil pump recently took a crap. I will be ordering a replacement, but was wondering if it is worth getting a high-volume oil pump. What are the benefits? Are there any potential drawbacks?

The only drawback I know of , if you are installing this in an engine that is sludged up you may pump all of the oil out of the oilpan. therefore starving the motor for oil. especially since this motor holds such a small amount of oil t begin with. A friend of mine did that in a boat with a 383 stroker, he was fine when running lower rpms but he would lose oil pressure if he went above about 4000 rpm, since that motor would turn about 8000 that was a real problem, so he went back to a stock volume pump.

Edit; the benefit, better oil pressuire on a worn motor

[This message has been edited by mferrell (edited 03-04-2012).]

Primary benifit is better oil pressure at lower RPM.

My understanding is the reason they are not installed from the factory is that they fractionally reduce gas milage, due to extra load on the engine. This number is so tiny you will NEVER be able to detect it, like a gallon every thousand miles or more.

On a differant note: It is almost unheard of that you have nothing wrong but an oil pump.

[This message has been edited by Electrathon (edited 03-04-2012).]

quote Originally posted by Electrathon: On a differant note: It is almost unheard of that you have nothing wrong but an oil pump.

Meaning that the damage is already done, internally? Or something else?

quote Originally posted by fierobear: Meaning that the damage is already done, internally? Or something else?

On a Duke, I have never heard of just an oil pump going bad. Usually if it actually does, it takes the whole engine with it. Or something else.

A Duke is a Low RPM engine, sees maybe 4500 rpm tops, it won't empty the pan. you should ALWAYS run 4 QTS of oil in it anyway ! forget what the stick says. 3 is a joke.

If this engine goes, I would be seriously tempted to yank the 4 cylinder and just put in a V6. I've found the V6 to have less problems, are easier to diagnose and fix problems and are easier to work on.

quote Originally posted by fierobear: Meaning that the damage is already done, internally? Or something else?

Yes, if the preasure is that low you generally have bearing issues too.

Well, the pump failed pretty quickly. I shut off the engine right away when I noticed the oil pressure light. Funny thing, it was in the middle of a smog check, so the car wasn't even moving.

quote Originally posted by fierobear: Well, the pump failed pretty quickly. I shut off the engine right away when I noticed the oil pressure light. Funny thing, it was in the middle of a smog check, so the car wasn't even moving.

A pump is rather basic. Just two gears and a blowoff valve. Not much there to just fail. Look carefully when you pull it for other issues.

Aaron

The oil pump is run off of the crank, not the cam, right?

quote Originally posted by fierobear: The oil pump is run off of the crank, not the cam, right?

Not on an 86, only 88's had that along with a balancer system that tends to blow up. Pre-88 Dukes use the Cam for the oil pump, pretty sure. Just like the 2.8 is.

The oil pump on 84-87s is driven by a shaft that has a gear on it that interfaces with the cam.

Often times, the roll pin that holds that gear on the shaft will shear, letting the gear spin without turning the oil pump.

To check this, you don't have to take hardly anything apart- just the two bolt cover down on the block and pull the oil pump drive gear, shaft, and upper bushing out.

quote Originally posted by KurtAKX: The oil pump on 84-87s is driven by a shaft that has a gear on it that interfaces with the cam. Often times, the roll pin that holds that gear on the shaft will shear, letting the gear spin without turning the oil pump. To check this, you don't have to take hardly anything apart- just the two bolt cover down on the block and pull the oil pump drive gear, shaft, and upper bushing out.

What Kurt said ^. The cover Kurt is talking about is located above the camshaft centerline on the block, above where the oil filter sits. It's unlikely that the pump internals failed, I'd be it was the gear/roll pin that is the problem.

A high volume oil pump on a modest rpm engine will increase your oil pressure. Not good on an old motor.

The stock oil pump does the job well.

Arn

My 1990 Pontiac 6000 with 3.1 cleared 200K miles and started lighting the oil pressure light at hot idle. I swapped in a HV pump (but kept the original regulator spring) and the light stayed off.

Iron Dukes are much easier t fix and diagnose than V6's.

out of the 13 Fieros I've owned, I can honestly say I enjoyed working on 4 cylinders more bcause of how easy they are.
not the most powerful engine,but very reliable, and if taken care off, will out last te 2.8L V6 (the Fiero one)

just my $0.02

as for your problem, I've never had oil pump problems. I'd say check the oil pump shaft. it may have bent or snapped (never seen one snap though...)

The first question that should have been asked before anyone gave an opionion -

What kind of oil pressure did the engine carry prior to the problem?

And then -

How many miles on the engine?

Answer these two questions first, and then we can give you advice - everything prior to this is only opinion, not based on fact.

Joe

Well, he said it was an 84 4cyl which means it has no gauge, just an idiot light. He also said it stopped working, which most of us took as meaning zero oil pressure.

I've heard pro and con regarding my ls4. Some said that I could pump the oil pan dry and some said don't worry about it. I'm not building a high rpm engine, just boosted, so I don't think I'll have a problem, but I'll be watching it.

quote Originally posted by TONY_C: Well, he said it was an 84 4cyl which means it has no gauge, just an idiot light. He also said it stopped working, which most of us took as meaning zero oil pressure.

No, he said it was an 86.

My questions are valid, and needed to answer the OP's question in a factual manner.

always use the stock oil pump,performance pumps use more horsepower,neither the duke or V6 has any HP to spare,if you have a 160 HP or higher V6,then use a hi performance pump..

..On duke & V 6 with worn engine & low oil pressure add a bottle of STP oil thickner ,,this will redeuce oil consumtion & increase oil pressure,it simply thickens oil so it does not flow as easily thru valve stem oil seals ,rings & there is a better "pad" between worn bearings.. this is old schoolstuff been working on worn engines for 55 years,,do not wait till the engine is about to blow

quote Originally posted by olejoedad: The first question that should have been asked before anyone gave an opionion - What kind of oil pressure did the engine carry prior to the problem? And then - How many miles on the engine? Answer these two questions first, and then we can give you advice - everything prior to this is only opinion, not based on fact. Joe

FYI, I added the GT-style gauge pod to this car, so I had a zero-pressure on the gauge *and* the oil light. The oil pressure was dropping low at idle (like at a stoplight). It is an automatic, so I was questioning the stall on the torque converter (rebuilt tranny).

Miles on engine - good question. I bought it from a forum member who said he did the head and valves. Don't know how many miles on that. My buddy and I plastigauged the crank bearings before we put it in. All the bottom end looked good. I can't remember if I put in a new oil pump or not, it's been a few years.

[This message has been edited by fierobear (edited 03-09-2012).]