Oil pump probs

4649 Views 31 Replies 8 Participants Last post by Junkie, May 14, 2003

Racefiend

Discussion Starter · Apr 3, 2003

I'm in a bind. I bought a new 7m pump to throw into my 7mgte. Of course one prob is redoing the pickup. However, ,due to the pumps different orientation, it does not clear the arp main studs. And even if it did, it looks like the crank counterweight will hit it, if not it would only have a fraction of an inch clearance. The 5m pump fits like a glove. I like the 7m pump cause its new. Would it be possible to transfer the guts from it into the 5m pump? Also how thick of a washer would I use to up the oil pressure, ,and what would that new pressure be?

TIA

Christian

1 - 20 of 32 Posts

WadeT

· #2 · Apr 4, 2003

The '85-'92 pumps all have the same displacement. They are infact the same pump except for the pickup feed and exterior changes.

I'd take the 7mgte pump back (if you can) and get a '85 pump to save your self some headaches with fabricating a custom pickup tube down the road.

The '82 to '84 pumps have smaller pump gears and the pans are not as deep as the '85+. I think where the whole 7m vs 5m pump difference debate started with Reg comparing his '82 pump to the 7mgte pump.

Go with the '85 pump and pan if you can.

-wt

Racefiend

Discussion Starter · #3 · Apr 4, 2003

OK, never mind. I took the two pumps apart and found that they shortened the pump body, ,and elongated the pump cover on the 7m. This allowed them to shorten the gears and have an exposed shaft to fit into a recess on the pump cover (now that it's taller and can have a recess). They must have done this to give better support to the shaft, for more longevity. So no, the innards are not interchangable.

I did notice that the parts/function of the two pumps are almost identical. I do not see any reason to switch to the 7m pump as they should perform identically. I will be using a 5m pump now. Way less hassle.

Christian

Racefiend

Discussion Starter · #4 · Apr 4, 2003

whoa, looks like we posted at the same time, Wade. Yea, thats pretty much what I came up with.

As far as the gears, I found the opposite to be true. The 7m pump had smaller gears and a deeper pump cover compared to the 5m I have. I don't know what year it is, though.

I already have the 85 pan (got it from autozone for only $55). I will be exchanging the 7m with a 5m hopefully. Unfortunately I've had it for about 1 year

I'll find out tomorrow. I checked part numbers for the pumps for an 82 and an 85 and they are the same at the auto parts stores. Are you sure they're different?

Christian

WadeT

· #5 · Apr 4, 2003

Yes sir they are not the same. The oil pump out of my '84 is smaller that the of the '85 and of course the gears are shorter (less displacement). Check with Toyota on that one because the pumps/pans are NOT the same.

On a side note, I'm using a 7mgte pump in my '85 with a custom pickup tube. It took about 4 hours of cutting a scribing on the stock tube to create a pickup that would fit the '85 pan. Add $25 for a welder to piece it together.

Good luck,
wt

williamb82

· #6 · Apr 6, 2003

christian, whats this about putting a washer in the pump to raise the oil pressure? im interested in that as im about to start on a new 7mgte for my 84. im going with forged pistons and race prepped rods. i will be buying a new 5m oil pump and would like to modify it to run ~10psi oil pressure at idle if its possible. i remeber someone saying you could put a stiffer spring in it but dont remember what the spring was from. i guess adding a washer would stiffen the current spring like on the turbo xs bov's? lmk. thanks

82TURBOSUPRA

· #7 · Apr 6, 2003

Oil pump shim

I shimed my 5mgte oil pump about 1/8" ,back in 1987(40,000 miles on motor never been rebuilt since),pressure at idle is 16 to 22 and never goes beyond 65 psi. normal driving :wink: is usually 35 to 50.Thats using 15/50 synthetic oil.

williamb82

· #8 · Apr 6, 2003

ok, this may sound stupid, but ive never pulled an oil pump apart. which side of the spring did the washer have to go to and what diameter washer was needed? also, for an 1/8th in that is what, maybe 2 washers? lmk. thanks.
william

82TURBOSUPRA

· #9 · Apr 6, 2003

I placed washer on relief plug it doesn't have to an exact fit,this will not cure low oil pressure at idle,will only increase your max oil relief pressure.
In a high mileage engine, low oil pressure is often due to a combination of worn main and rod bearings and crankshaft journals. The oil pump itself does not create pressure. It produces flow and the resistance to that flow produces pressure. Resistance is created by the orifices in the engine block through which the oil flows, and the amount of clearance between the bearings and crankshaft journals. As the bearings wear, clearances increase allowing increased flow which reduces pressure.

The pressure relief valve, located on the pump body can be yet another cause of low oil pressure if the valve sticks open or is held open by a small piece of debris. The relief valve is designed to limit oil pressure as engine speed increases. The valve opens when pressure reaches a preset value (typically 40 to 60 psi). This vents oil back into the crankcase and limits maximum oil pressure in the engine. The reason for doing so is to prevent oil pressure from reaching dangerous levels. Too much oil pressure can be just as bad as too little because excessive pressure can rupture the oil filter or even blow out pressed-in oil galley plugs in the block.

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Joseph

· #10 · Apr 7, 2003

WadeT said:
The '85-'92 pumps all have the same displacement. They are infact the same pump except for the pickup feed and exterior changes.

Are you sure about this? There was a discussion about this back on the yahoo list, and if I recall correctly it was determined that the mk2 & na mk3 pumps were high pressure/low volume and the mk3 turbo pumps were high volume/low pressure. I'm not positive on this, just asking.
If you're right I definitely may go that route and just get an '85 pump and pan. Might end up being more expensive than modifying the 7M pickup I have though.

Racefiend

Discussion Starter · #11 · Apr 7, 2003

Hey William,
At the end of the pump, near the pickup, there is a cylinder about the size of a battery sticking out of the pump. The spring is inside this cylinder. At the tip of the cylinder is a nut that holds the spring in with a hole in the center to relieve oil. You can put a washer between the spring and that nut.

As far as the discussion on the mk2 list, I remember that one. One of the members (cant remember who) said his dad is a machinist and they pulled both apart and measured everything and they were identical internally. You musta missed that one.

Christian

Joseph

· #12 · Apr 8, 2003

Racefiend said:
One of the members (cant remember who) said his dad is a machinist and they pulled both apart and measured everything and they were identical internally.

Cool, now all I have to do is find an '85 pump and pickup. Will the '85 setup work with earlier oil pans or is the '85 pan special?

Thanks,

Racefiend

Discussion Starter · #13 · Apr 8, 2003

Well, I just sent back my new 7m pump for a 5m pump. They had the same part number for 82-86. We'll see what I get when it comes in.

Christian

jdk_ii

· #14 · Apr 8, 2003

I will try and find the Toyota doc that describes the difference.

It was in one of those rare technology highlights of the late 80s.

WadeT

· #15 · Apr 8, 2003

"Racefiend"

As far as the discussion on the mk2 list, I remember that one. One of the members (cant remember who) said his dad is a machinist and they pulled both apart and measured everything and they were identical internally. You musta missed that one.

Christian

lol, that was my dad and me. We took everything apart and mic'd the gears. The pump gears are interchangeable but the 7m drive shaft bearing is larger than that of the '85 5m. This probably gives the 7m longer pump life. IMO, the '85+ 5m pump might actually flow better because of the straight pickup tube while the 7m has a longer, snakey crush bent style, pickup tube. The flow of the 7m might be compromised somewhat by those crush bends and longer snorkle. I have pictures of both pumps disassembled side by side.

On a side note, I've seen the pressure guage read slightly better a different 7mgte MKII running a '85 pump compared to my '85 7mgte w/ the 7mgte pump. I ran the 7mgte pump because mine was almost new and for me it was cheaper to make a custom pickup tube.

About the shimming, I'd be very carefull when doing this. That valve acts much like a wastegate on a turbo and it's there for a reason. If you exceed the recommended oil pressure your engine will start blowing seals which = oil leaks. It only takes a few pounds over the limits of what your seals can handle before they start going. I know I wouldn't want to replace the crank seal over jury-rigged shim-job, not to mention having to pull the pan to de-shim the pump. :shock:

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williamb82

· #16 · Apr 11, 2003

well, is there any other way to make the pump push a higher pressure at idle? normal pressure at idle is 3-4psi and i would rather have it at ~10psi. i know the bearing clearances play a large role but i dont want to make them to tight as that would cause problems. to bad we cant overdrive the oil pump. that would solve the problem since it would only raise the pressure at idle since the releif valve would regulate maxiumum pressure. would there be a way to overdrive the pump at all besides custom machining a new oilpump drive gear and trying to find a timing belt that is the perfect length shorter?
william

Racefiend

Discussion Starter · #17 · Apr 11, 2003

3-4 psi!? I think there's more there than loose clearances. You may have something wrong with your pump. My mk3, with tired JDM rod knocking engine, puts out at least 10psi at idle when hot.

Christian

williamb82

· #18 · Apr 12, 2003

thats not the oil pressure i have, its what i read was acceptable in either the chiltons or the haynes(dont remebr which at the moment). i just want to make sure when i build my other motor that it will be trouble free for at least a year or 2. i have a lead foot and drive the car very hard day in and day out. you can ask eric, paul, or dave, they will tell you. lol. anyhow, since im about to put the short block in my 84 i will try the shim mod to the oil pump. btw, ,anyone know where i can get a 5m pump cheap. i found one on toyotaparts.com and it was like ~$175. id rather not go broke on a oil pump for this block. i will definatly go oem for the race motor though.
william

Junkie

· #19 · Apr 12, 2003

williamb82 said:
thats not the oil pressure i have, its what i read was acceptable in either the chiltons or the haynes(dont remebr which at the moment). i just want to make sure when i build my other motor that it will be trouble free for at least a year or 2. i have a lead foot and drive the car very hard day in and day out. you can ask eric, paul, or dave, they will tell you. lol. anyhow, since im about to put the short block in my 84 i will try the shim mod to the oil pump. btw, ,anyone know where i can get a 5m pump cheap. i found one on toyotaparts.com and it was like ~$175. id rather not go broke on a oil pump for this block. i will definatly go oem for the race motor though.
william

William,to quote the Godfather of the SBC "Smokey Unick "sp"",any engine needs only 5-7psi of oil pressure per 1000rpm.At idle,many of my old Mopars ran 3-5 psi,and all the manuals of the day called this acceptable,never lost a motor that was not my fault :twisted:

As for your oil pump,I can supply a factory 5m pump ,shipped to your house,for aprox. the same as the one you found on toyota parts.com.They come in an afermarket box,and the the "toyota" is ground off the housing.I just priced them this week,$165 + shipping is what I can sell them for and not have the boss nibbling on my behind

HTH

Racefiend

Discussion Starter · #20 · Apr 17, 2003

Well, I got my new oil pump in the mail yesterday. It's an application for 82-88 5mge. It looks exactly like the one I used to compare to the 7mgte unit (and found they were basically identical). I checked the clearance with my 85 pan and it had ~5mm clearance. Looks good and I'm going to use it. pre 85, post 85, i don't know, but it works.

Christian

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