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Index > Engine/Drivetrain > Thread: why is my oil tuning black?
Thread: why is my oil tuning black?
benzrx2


1st Gear
Posts: 28
posted January 04, 2005 07:55 PM

why is my oil tuning black?

I recently had an oil change and after about 50 miles the oil turns black, I noticed this happen after i disconnected and reconnected the oil lines from the metering pump. could i have made a mistake putting it back?
any input on this would be appreciated.

       
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Brad


Rotorhead
Posts: 1672
posted January 04, 2005 08:08 PM
Edited By: Brad on 4 Jan 2005 23:09

Are we talking pitch black after 50 miles?

Hmmmmmm.........OMP lines won't affect oil in the pan. OMP draws oil out of front cover and pumps into carb.

Good chance there is sludge on bottom of oil pan. I flush the pan with ATF before filling, and have found that Amsoil Engine Flush run in motor before draining works wonders. All kinds of crud comes out.

Most people don't drain oil from the oil cooler or lines during an oil change, so a certain amount of old tired oil will be in there and mix with the fresh stuff in pan.



____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Jeff20B


Moderator
Posts: 661
posted January 05, 2005 02:51 AM
Edited By: Jeff20B on 5 Jan 2005 06:02

Brad, please don't pour ATF in your engine ever again, even if it's just to sort of stir up the leavings at the bottom of the pan. Not all of it drains out because the drain plug is not actually on the bottom of the pan. You'll have a little pool of ATF just waiting to contaminate your nice fresh oil.

The ATF myth has been floating around rotary forums for a few years now and a few of us have decided to try to put a stop to it. ATF is garbage and should never be put into a rotary; in the combustion chamber, or otherwise. Who cares if it's an old (piston) engine builder's trick? I wouldn't even pour it into an engine that I knew needed to be torn down. Know why? I wouldn't want to have to deal with it during disassembly (I prefer a lightly carboned oily rotor, actually).

Pour an extra quart of oil through your filler tube if you must, although 'flushing' your pan that way doesn't do jack if you ask me (unless you dump a couple gallons of something through there fairly slowly or whatever), but please keep the ATF out of the engine and in a slush box, or whatever the kids are calling those stupid automatics these days. Please... for me. :)

benzrx2, a little MMO added to the oil can help clean interior surfaces, but your oil will get nice and black in the process. Even a fresh oil change on an engine that hasn't had one in a long time will result in blackened oil shortly thereafter. The blackness means it's doing its job. Change it again in 1500 miles, and then every 3000 after that. Just make sure to follow a maintanance schedule and you'll be ok.

The oil in the cooler, lines and rotors not being drained during a routine oil change is perfectly normal. It really doesn't matter, IF the oil is changed at regular intervals. Rotaries don't pollute their oil with contaminates like piston engines do. Rotaries tend to dilute their oil with gas though. No biggie.
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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Brad


Rotorhead
Posts: 1672
posted January 05, 2005 12:03 PM
Edited By: Brad on 5 Jan 2005 15:08

quote:
Brad, please don't pour ATF in your engine ever again, even if it's just to sort of stir up the leavings at the bottom of the pan. Not all of it drains out because the drain plug is not actually on the bottom of the pan. You'll have a little pool of ATF just waiting to contaminate your nice fresh oil.


Understood Jeff and respect your view and

a) ATF or oil poured in after oil change does flush out residual old oil in the bottom of the pan. By the time the fresh quart is done pouring, the old oil coming out of drain plug is no longer black, it's fresh and new colored.

b) How many ounces are left in the pool of ATF in the pan, mabye eight ( a cup )? Probablly less because my drain plug is in the front of my moroso pan and I back my REPU into my steep driveway to drain almost all of the oil out. I put 7 quarts of fresh oil in my repu during oil change (moroso deep sump 6.25 qt oil pan, -10 lines, Rx4 cooler, Mobil1 filter) so 32oz per qt x 7 = 224 oz total capacity. 8 / 224 = 3.57% ATF solution.

c) ATF is widely known to be an excellent cleaner and detergent. It is also a lubricant, albeit low viscosity. Is 3.57% solution (max) in my oil really going to be an issue?

quote:
ATF is garbage and should never be put into a rotary; in the combustion chamber, or otherwise. Who cares if it's an old (piston) engine builder's trick? I wouldn't even pour it into an engine that I knew needed to be torn down. Know why? I wouldn't want to have to deal with it during disassembly (I prefer a lightly carboned oily rotor, actually).


I've cleaned many engines, trans, and diff's with ATF; from GEO 3 cyl to rotormotor to V6. It really does do a great job de-greasing and loosening sludge. Especially once it's warmed up to operating temperature. Not sure about the dirty oily rotor preference. Just more scrubbing to do.

quote:
Pour an extra quart of oil through your filler tube if you must, although 'flushing' your pan that way doesn't do jack if you ask me (unless you dump a couple gallons of something through there fairly slowly or whatever)


I have flushed with oil before but wasting a quart of Mobil1 or Royal Purple gets expensive especially on the race car where I change the oil after every weekend of racing. I've seen first hand how my flush process does get rid of dirty oil in the pan, resulting in cleaner fresher oil. And when I dissassembled motors, there was a lot more residual oil left in the pan, after drained when in the car, than I imagined. With one overrevved 12a with spun bearings and severe rotor to iron contact, there was a ton of shavings on the bottom of the pan. I'm sticking to it.


____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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benzrx2


1st Gear
Posts: 28
posted January 05, 2005 06:08 PM

thanks for the input but...

thanks for the input brad and jeff but my motor is newly built w/ 800 miles in it ( doubting that there is a sludge build up) and even after i took out the oil pan (no sludge found) and put new oil ,it is still turning black. 1) could it be because i put a tiny bit of motor oil into the carb every 100 miles(recommended by the mech. who built the engine)? and 2)i also put a little part of mystery oil into the fuel tank?(just experimenting)3)is it normal to see bits of metal shavings on the bottom of the oil pan despite being watchful during the break in period?

       
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Brad


Rotorhead
Posts: 1672
posted January 07, 2005 09:54 AM

new motor explains it

the oil rings in the rotors have not completely introduced and become acquainted with the iron plates. so combustion gasses are leaking into the oil. this is normal ona new motor. it will stop after motor is broken it, say 2000 miles on it.

even my 12a j bridge with brand new plates, housings, rotors, and cryo oil control rings had dirty oil during break in and i doubt your motor is that new.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Jeff20B


Moderator
Posts: 661
posted January 07, 2005 11:37 AM

Brad, I misunderstood what you meant in your earlier post. I though you were talking about actually cleaning the bottom of the pan with ATF rather than simply pouring something in there to dillute the old stuff sitting below the level of the drain plug. I've seen a film at the bottom of every oil pan I've ever cleaned manually (removed from an engine) and it didn't matter whether the oil was changed regularly or not. It was the bearing material which is soft like lead and probably nearly as heavy.

Pouring in some oil to dillute what's there is actually not that bad of an idea if your oil hasn't been changed at regular intervals or is otherwise really black. Of course it still can't drain the oil from inside the rotors etc, so again, it doesn't really do very much good in the end. Well, maybe a little. ;) I don't see a reason to do it with my oil change schedule.
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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benzrx2


1st Gear
Posts: 28
posted January 07, 2005 06:30 PM

correct jets

thanks for the input Brad, i was getting worried that my engine was not correctly built. do you know the correct jets for a 13b bridge used with a weber ida down draft?
i have been having problems of running it too rich. and it seems like the more mileage I put in the lesser fuel input it needs.

       
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Brad


Rotorhead
Posts: 1672
posted January 07, 2005 07:47 PM

quote:
Brad, I misunderstood what you meant in your earlier post. I though you were talking about actually cleaning the bottom of the pan with ATF


Well......... this is what I do: Drain oil. Pour a quart of ATF into the filler neck to flush old oil out of pan. Drain as much ATF out as humanly possible without dropping pan.

quote:
rather than simply pouring something in there to dillute the old stuff sitting below the level of the drain plug.


Well there will be some ATF left in the bottom of the drain pan, but not a lot per my earlier post.

quote:
I've seen a film at the bottom of every oil pan I've ever cleaned manually (removed from an engine) and it didn't matter whether the oil was changed regularly or not.


Certainly!!!!!!!! Agreed!!!!!!!!!!!!

quote:
It was the bearing material which is soft like lead and probably nearly as heavy.


I try to flush sludge and metal particles out of the oil pan during oil change. That's the ideaer.

quote:
Pouring in some oil to dillute what's there is actually not that bad of an idea if your oil hasn't been changed at regular intervals or is otherwise really black. Of course it still can't drain the oil from inside the rotors etc, so again, it doesn't really do very much good in the end. Well, maybe a little. ;) I don't see a reason to do it with my oil change schedule.


I've found putting a 3 foot long 3/4" heater hose onto the oil filter pedastal threads and pouring oil down there flushes oil out of the bearings and e-shaft, and into the oil pan. I do that before starting every new rotormotor and like to do it during oil changes sometimes. There's not a LOT of oil in those components, mabye a 1/2 quart at most. But better prelube it with a new motor.

Also been known to drain oil cooler and oil lines during oil change. And refill them with fresh oil. Might be a little overkill but when I put new oil in the motor, I want NEW oil in there! And since my new 13b in the REPU is done with break in, I'm switching to Royal Purple 20/50 this weekend. Which with topping off and Mobil1 filter changes every 3,000 miles, that oil should last 10-15,000 miles before changing. Not a bad idea to put some extra time into prepping the motor since won't need to do another change for almost a year?

:)

____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Brad


Rotorhead
Posts: 1672
posted January 07, 2005 07:50 PM

quote:
thanks for the input Brad, i was getting worried that my engine was not correctly built. do you know the correct jets for a 13b bridge used with a weber ida down draft?
i have been having problems of running it too rich. and it seems like the more mileage I put in the lesser fuel input it needs.


http://www.mazspeed.com/carburetorfacts.htm

Almost half way down the page:

Weber 51IDA on bridge ported 13B with headers and open exhaust

Venturi 45mm

Main fuel jet #235

Air Jet #165

Emulsion Tube #F-11

Use larger #300 float needle valve

Need less choke and fuel jet with street exhaust. So you can use this info to develop a starting point.

____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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benzrx2


1st Gear
Posts: 28
posted January 08, 2005 09:23 AM

thanks!

thanks a lot for the info, I almost given up and thought about switching to efi. this brought new life to the project. I'll be picking up the correct fuel/air jets and w/ a little patience start enjoying all the hard work put in it.
Ben

       
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