# Whats the real deal with oxygen sensors?



## naes.sdrawos (Jun 25, 2014)

o2 sensors get weaker over time, as long as you have no drivability issues, your fine. and yes faulty o2's may not set a code for the o2 even though the underlying cause of but not limited to, catalyst failure (sulfur smells) misfires, lean conditions (to much air), or rich conditions (to much fuel).


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## Windows on Wash (Aug 30, 2011)

+1

As long as there are within specifications and are putting out the correct voltages for the computer to adjust the fuel tables, you are fine.


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## noquacks (Jun 5, 2010)

good to know, naes.


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## noquacks (Jun 5, 2010)

Windows on Wash said:


> +1
> 
> As long as there are within specifications and are putting out the correct voltages for the computer to adjust the fuel tables, you are fine.


Thanks, wash, so One just kinda has to assume they are puting out the correct voltages if it doesnt trip a code, right? otherwise, can one measure the voltage with a meter?


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## Windows on Wash (Aug 30, 2011)

noquacks said:


> Thanks, wash, so One just kinda has to assume they are puting out the correct voltages if it doesnt trip a code, right? otherwise, can one measure the voltage with a meter?


Once it is out of range, it will throw and MIL light (i.e. check engine).

No need to check it or replace it until it is failed. Some never fail.


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## originalhandy (Nov 26, 2012)

My bank 2 downstream sensor got tore off in a snow storm three or four years ago. Throws up a code every now and again, I just clear it. Passes inspections too.

Sent from my SCH-I545 using Tapatalk 2


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## ukrkoz (Dec 31, 2010)

OP, you heard the wisdom:

DON'T FIX IT
IF IT AIN'T BROK
IF IT'S BROK
FIX IT RIGHT AWAY.

OF COURSE *they* want to you to believe that you MUST replace all kinds of components on REGULAR intervals. Right? Like with any "scientific research", always look who sponsored it.


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## Marqed97 (Mar 19, 2011)

Huh. Never heard the 'regular maintenance' excuse for replacement of oxygen sensors before (wink wink). I've had people come in and ask about it over the years, sometimes recommended by a different dealer, sometimes by an independent shop. Since I worked for a Ford dealer, I'd show them the recommended maintenance guide (oh wow! It's in their owners manual too!) where it never mentions the o2 sensors. 

The new 6 wire sensors should theoretically last forever...we shall see. They don't use external air as an oxygen reference like the 4 wire sensors do so they're completely sealed.


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## cjm94 (Sep 25, 2011)

They will get lazy over time, but as long as they are in spec any performance or economy effects will not be noticeable. I have seen cars come back though from just changing one side on high mileage cars due to the old sensor not switching as fast as the new one, which is why in school they recommend replacing all at the same time. Maybe if they were $25 a piece instead of $125


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## ddawg16 (Aug 15, 2011)

Replacing those sensors is right up there Transmission flushes at 50K miles.....


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## noquacks (Jun 5, 2010)

Wow, I feel much better now (wiping sweat from forehead with back of right hand)! 

yeah- so many out there spread so much myths- this one, I had to run by the guys here whom I know would be looking out for me!! Thnaks, people!! Now, time to change my tranny fluid as its been a whole 6 months (sarcasm/joke).......


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## rusty baker (Feb 13, 2009)

noquacks said:


> Wow, I feel much better now (wiping sweat from forehead with back of right hand)!
> 
> yeah- so many out there spread so much myths- this one, I had to run by the guys here whom I know would be looking out for me!! Thnaks, people!! Now, time to change my tranny fluid as its been a whole 6 months (sarcasm/joke).......


Don't forget to change your blinker fluid and rotate the air in your tires. :whistling2:


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## toolaholic (Jul 31, 2011)

ddawg16 said:


> Replacing those sensors is right up there Transmission flushes at 50K miles.....


 I wouldn't ever flush a transmission but I did change my toyota yaris trans fluid at 47k. It even had a drain plug. Replaced 2.6 quarts. New fluid was deep red. Old fluid a deep purple. Shifts better now.


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## cjm94 (Sep 25, 2011)

Nothing wrong with changing trans fluid. It won't ruin a trans. If it fails afterwards there was something wrong with it. Like bad seals that sludge was sealing up.


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## toolaholic (Jul 31, 2011)

cjm94 said:


> Nothing wrong with changing trans fluid. It won't ruin a trans. If it fails afterwards there was something wrong with it. Like bad seals that sludge was sealing up.


 I changed trans fluid on the old 99 chevy lumina my teenage daughter drives . Dropped the pan and put a new wix filter in. Changed at 96,000 miles(gm calls for 100,000) despite urban legend to leave it be. Has 102,000 on it now and still shifts fine.


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## iamrfixit (Jan 30, 2011)

Any kind of lubricant breaks down over time; heat and cool cycles cause moisture to get into the lubricant. Transmissions are full of bearings, plates and gears that create lots of heat, shear and friction breaking down the lubricant. Worn particles from the clutch friction material gets into the fluid and tiny particles that can pass through the filter continually circulates through the transmission, and what the filter catches can also restrict the fluid flow. Friction, heat and clutch wear can be greatly accelerated by towing, stop and go or an aggressive driving style. 

Do you really believe you might not need fresh fluid after 50K miles? Compare fluid with 50k on it to new and you will see a difference. Just because transmission fluid does not turn black does not mean that it's still as good as new. After 50k miles a fluid change is absolutely necessary, sooner is even better for more extreme conditions.

A transmission for my F250 is over $4000, a 15 quart fluid change every 30k costs me a little over a hundred bucks, I like my chances better with the fresh fluid. At 120k now even with thousands of miles of heavy towing, snow plowing and my driving style, it's going strong.

One of the most often neglected items on a vehicle is the coolant. I have seen thousands in damages done by "saving money" not servicing the coolant. It doesn't just become contaminated and wear out, it actually becomes acidic. It will begin to corrode the components from the inside out. On some vehicles it can cost over $1000 just to change a heater core due to a leak or because it becomes plugged with internal corrosion. That's just one item in a list of dozens that bad coolant can destroy. Three years 50k for green, five years 100k for extended life and it's out of there.

Regular maintenance of fluids is not a myth. As for O2 sensors, they get nothing until the computer says they are out of range.


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## Windows on Wash (Aug 30, 2011)

cjm94 said:


> Nothing wrong with changing trans fluid. It won't ruin a trans. If it fails afterwards there was something wrong with it. Like bad seals that sludge was sealing up.





ddawg16 said:


> Replacing those sensors is right up there Transmission flushes at 50K miles.....





iamrfixit said:


> Any kind of lubricant breaks down over time; heat and cool cycles cause moisture to get into the lubricant. Transmissions are full of bearings, plates and gears that create lots of heat, shear and friction breaking down the lubricant. Worn particles from the clutch friction material gets into the fluid and tiny particles that can pass through the filter continually circulates through the transmission, and what the filter catches can also restrict the fluid flow. Friction, heat and clutch wear can be greatly accelerated by towing, stop and go or an aggressive driving style.
> 
> Do you really believe you might not need fresh fluid after 50K miles? Compare fluid with 50k on it to new and you will see a difference. Just because transmission fluid does not turn black does not mean that it's still as good as new. After 50k miles a fluid change is absolutely necessary, sooner is even better for more extreme conditions.
> 
> ...



+1

ddawg and I don't often disagree but I wholeheartedly believe in fluid changes.

The most overlooked fluid is power steering and it gets abused more than anything.


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## ddawg16 (Aug 15, 2011)

Windows on Wash said:


> +1 ddawg and I don't often disagree but I wholeheartedly believe in fluid changes. The most overlooked fluid is power steering and it gets abused more than anything.


I should have qualified my statement. I was alluding to the practice fast fluid chains like Jiffy lube have of trying to convince you to get a tranny flush on a low mileage veh. 

I'm a fan of prompt maint. But unless your working a tranny hard as in towing....50k is a little early. Transmission flush? GMA_B. At most drop the pan, change the filter and put in a few quarts. 

I used to work in a transmission shop. Hardest thing on a tranny is heat.....and chunks of metal from broken parts.


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## Chokingdogs (Oct 27, 2012)

ddawg16 said:


> I should have qualified my statement. I was alluding to the practice fast fluid chains like Jiffy lube have of trying to convince you to get a tranny flush on a low mileage veh.
> 
> I'm a fan of prompt maint. But unless your working a tranny hard as in towing....50k is a little early. Transmission flush? GMAFB. At most drop the pan, change the filter and put in a few quarts.
> 
> *I used to work in a transmission shop. Hardest thing on a tranny is heat*.....and chunks of metal from broken parts.


me too, many moons ago. 

we would advise against a flush/fluid change if the vehicle had high mileage and the trans was acting up with no obvious signs of what the issue was - e.g. plug disconnected or a TV cable broken/unhooked. of the customers that insisted on doing that, 3 out of 5 would be back a few weeks later with the thing toasted.


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## cjm94 (Sep 25, 2011)

Chokingdogs said:


> me too, many moons ago. we would advise against a flush/fluid change if the vehicle had high mileage and the trans was acting up with no obvious signs of what the issue was - e.g. plug disconnected or a TV cable broken/unhooked. of the customers that insisted on doing that, 3 out of 5 would be back a few weeks later with the thing toasted.


. Absolutely right. The trans that fails after a service or flush. Was failing before it. We always inform a customer who want a trans service. It will not fix 95% of any shifting concerns. It is preventative maintenance not a repair.


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## noquacks (Jun 5, 2010)

Right on periodic fluid changing. Ignore the tranny fluid- especially in Florida, etc, and your AT will leave you stranded. every 2 years down here, if you drive in Tampa/St pete/orlando/miami/Jacks. Highway- not as big a problem, but city- giive me a manual transmisison I know will never leave me stranded and cost me 2-3000$$ to fix, depending. 
If its not red/pink, its no good.


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## iamrfixit (Jan 30, 2011)

noquacks said:


> giive me a manual transmisison I know will never leave me stranded and cost me 2-3000$$ to fix, depending.


Manuals come apart too, less often for sure but when they do they can also be very expensive to fix. They can certainly leave you stranded. Had to haul my moms little 5 spd ranger pickup home last fall. 

She was getting on the interstate in heavy traffic, doesn't drive it much and sometimes gets flustered with traffic and in the process she took a wrong turn. She was shifting into 5th but somehow, I don't even know how, she got it in 3rd and dumped the clutch. That was it, done, no noise, no movement, nothing. Figured it for busted input shaft as that is fairly common with that transmission. Luckily it wasn't, but she shredded every bit of clutch lining off both sides all at once, all of it right down to the metal. All the shredded friction material went out and packed into the springs on the pressure plate.


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## rusty baker (Feb 13, 2009)

But that wasn't trans problem, that was driver error.


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## Doc Holliday (Mar 12, 2011)

4r100 on my 2001 7.3 went over 400k miles, original fluid. hellz no, trans fluid lasts forever.


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## Windows on Wash (Aug 30, 2011)

It is worthy of note that transmissions today are more sensitive to degraded fluids than some of the oldies and goodies of days gone by.


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## hyunelan2 (Aug 14, 2007)

Especially now that you have cars with 7/8/9 speed automatic transmissions. It's just foolish not to replace it at the interval stated in the owner's manual. 

If you have a new car, change it from the beginning at regular specified intervals = best option. Always use the correct proper specified fluid, avoid universals and snake oil brands. Some of the Chrysler/Mitsu/Hyundai transmissions of the early 2000s would not last long if you used the wrong fluid.

If you have an older/high-mileage car that's never been changed, better to leave it be. 

If you have a Chrysler automatic transmission from about pre-2005, immediately sell it and buy something else.


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## noquacks (Jun 5, 2010)

iamrfixit said:


> Manuals come apart too, less often for sure but when they do they can also be very expensive to fix. They can certainly leave you stranded. Had to haul my moms little 5 spd ranger pickup home last fall.
> 
> She was getting on the interstate in heavy traffic, doesn't drive it much and sometimes gets flustered with traffic and in the process she took a wrong turn. She was shifting into 5th but somehow, I don't even know how, she got it in 3rd and dumped the clutch. That was it, done, no noise, no movement, nothing. Figured it for busted input shaft as that is fairly common with that transmission. Luckily it wasn't, but she shredded every bit of clutch lining off both sides all at once, all of it right down to the metal. All the shredded friction material went out and packed into the springs on the pressure plate.


Ok, fair enough- things CAN happen with a MT, although, very rare, but regarding your above repair- no way a new clutch even with a new pressure plate and shaft repair bill will be near an AT repair. Your descriptuion of "very expensive" in my opinion is not accurate. A "very expensive" tranny bill/expense is a german car's AT job. $3-4000. Thats "very expensive". Clutch on a MT- $600, depending. 

Most DIY'ers can do that in a weekend, but an AT- kinda requires a pro as most of us do not have the knowledge for taking apart an AT.


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## noquacks (Jun 5, 2010)

Whew- anyway, Im not buying a new O2 sensor, thanks to the guys here. LOL


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## Doc Holliday (Mar 12, 2011)

I hate 'em. In Texas diesels have no emissions testing so I had new injectors and a new turbo installed on my 7.3 F250, giving her another 200hp. But with that, when I step on gas hard and "roll the coal" as they say the service engine light immediately comes on due to oxygen sensors. 

hate 'em.


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## triz (Jul 22, 2014)

One thing i'll never ever do;flush any tranny i own!! 
I just always change my filter&drain trans oil in pan&put on new gasket.
I do this every 3yrs whether oil is miled out or not and never had problems or burning issues..tranny flushes seem foolish,risky and just begging for a "if it ain't broken,let's break it" to manifest with something dislodging from a flush.


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## Windows on Wash (Aug 30, 2011)

Triz,

I would suggest that you look at some of the new transmissions. These aren't 700R4 and C4 type bulletproof.

They are much more sensitive to fluid contamination and breakdown.

Whether a fluid looks smoked or dirty can have little to nothing to do with its lubricity and health.


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## triz (Jul 22, 2014)

Windows on Wash said:


> Triz,
> 
> I would suggest that you look at some of the new transmissions. These aren't 700R4 and C4 type bulletproof.
> 
> .


 You are assurdly right!! (oops)I should of mentioned i don't buy anything newer than 99!


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## noquacks (Jun 5, 2010)

Windows on Wash said:


> Triz,
> 
> 
> 
> Whether a fluid looks smoked or dirty can have little to nothing to do with its lubricity and health.


I dunno about this, Windows. I wouldnt go so far as saying it has little to do with [effectiveness]. I believe it has much to do with it. You didnt mention smell though- smell can be very telling. 

The "paper towel test" is a well kep secret of the tranny fluid circuit. Even some pros dont know about it sometimes. You can tell by the blank stare they give you when you mention it to them (I can, anyway).


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## Windows on Wash (Aug 30, 2011)

noquacks said:


> I dunno about this, Windows. I wouldnt go so far as saying it has little to do with [effectiveness]. I believe it has much to do with it. You didnt mention smell though- smell can be very telling.
> 
> The "paper towel test" is a well kep secret of the tranny fluid circuit. Even some pros dont know about it sometimes. You can tell by the blank stare they give you when you mention it to them (I can, anyway).


I am not saying that dirty fluid is good. My point is that the fluid can look (visually) fine as well as not smell and you can still have issues.

Trust me. 

The newer units are extremely sensitive to fluid condition and chemistry.


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## bilug (Apr 16, 2014)

All this talk about transmissions....how about differentials....same story??? Is it not necessary to change the fluid??


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## triz (Jul 22, 2014)

bilug said:


> All this talk about transmissions....how about differentials....same story??? Is it not necessary to change the fluid??


 Has to be changed periodically, when/how often?
should be in owners manual..usually change mine every three years though.


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## r0ckstarr (Jan 8, 2013)

triz said:


> Has to be changed periodically, when/how often?
> should be in owners manual..usually change mine every three years though.


324,000 miles (all by me and my gf) and never changed it once in my Ranger. :laughing:


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## triz (Jul 22, 2014)

r0ckstarr said:


> 324,000 miles (all by me and my gf) and never changed it once in my Ranger. :laughing:


 Most probable sight in that diff case=
grey, milky, watery, mix of oily ooze..lubrication at a complete minimum.


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## r0ckstarr (Jan 8, 2013)

triz said:


> Most probable sight in that diff case=
> grey, milky, watery, mix of oily ooze..lubrication at a complete minimum.


:laughing: Probably been that way for the last 224k miles.

I got a better one for you. My 1966 Buick that I recently sold, 27k original miles. Differential fluid hasn't been changed in 20yrs.


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## BigJim (Sep 2, 2008)

If you have a positive traction rear end, you best not let the fast change oil chains top it out. They ruined two of my trucks rear ends by adding the wrong stuff, even after I told them.


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## r0ckstarr (Jan 8, 2013)

BigJim said:


> If you have a positive traction rear end, you best not let the fast change oil chains top it out. They ruined two of my trucks rear ends by adding the wrong stuff, even after I told them.


On the Miata transmission, there's 3 bolts that look like drain plugs. One is to drain the fluid, one is to fill the fluid, the third will require a full transmission rebuild if you remove it.


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## triz (Jul 22, 2014)

r0ckstarr said:


> On the Miata transmission, there's 3 bolts that look like drain plugs. One is to drain the fluid, one is to fill the fluid, the third will require a full transmission rebuild if you remove it.


 Thats so damn hilarious,good thing i don't own one,i'd be a'walking that day of trying to be nice to my trans!


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## triz (Jul 22, 2014)

BigJim said:


> If you have a positive traction rear end, you best not let the fast change oil chains top it out. They ruined two of my trucks rear ends by adding the wrong stuff, even after I told them.


 *Do Not Go Anywhere Near Such Places*..nothing but highschoold type boys whom have playstation&texting on their minds during all working hrs.


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## bilug (Apr 16, 2014)

r0ckstarr said:


> On the Miata transmission, there's 3 bolts that look like drain plugs. One is to drain the fluid, one is to fill the fluid, the third will require a full transmission rebuild if you remove it.


How is this even possible? What kind of engineer would design something where you remove a bolt and the transmission is useless?

Update: I went and verified this. Unbelievable!!


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## r0ckstarr (Jan 8, 2013)

bilug said:


> How is this even possible? What kind of engineer would design something where you remove a bolt and the transmission is useless?
> 
> Update: I went and verified this. Unbelievable!!


Yep. I'll be changing the fluid in my Miata soon. I'm going to take a paint pen and put a red X on that bolt for future reference.


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## Mort (Nov 26, 2008)

I'd throw a tack weld on that b.....d, just to make extra sure.


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## triz (Jul 22, 2014)

Mort said:


> I'd throw a tack weld on that b.....d, just to make extra sure.


 Just round off the nut with grinder or loosely attached vice grips on nut,and turn to strip/round off edges.


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## r0ckstarr (Jan 8, 2013)

I'd probably do such a great job rounding it off, getting it to a perfect circle, then realize I rounded the wrong one. 

Funny. After knowing about it, I am almost afraid to even touch it, lol.


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## triz (Jul 22, 2014)

r0ckstarr said:


> I'd probably do such a great job rounding it off, getting it to a perfect circle, then realize I rounded the wrong one.
> 
> Funny. After knowing about it, I am almost afraid to even touch it, lol.


Can't say i blame you!...and IF you do round it off *make sure* you round it off in *clockwise* direction..imagine if by rounding it off you accidently removed it Yikes!


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## ratherbefishin' (Jun 16, 2007)

C'mon, guys, look at the picture....it's an Allen cap screw, not a hex bolt, good luck making it any more round than it already is....and if you drill out the recessed hex, good luck to you if you ever need to dismantle the trans for repair...you just made it a royal pain in the butt.
The smart thing to do: do your homework beforehand, instead of just pulling plugs and bolts and hoping to find the right ones.
It's not uncommon for internal tranny parts to be secured to the case with through bolts.


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## r0ckstarr (Jan 8, 2013)

ratherbefishin' said:


> C'mon, guys, look at the picture....it's an Allen cap screw, not a hex bolt, good luck making it any more round than it already is....and if you drill out the recessed hex, good luck to you if you ever need to dismantle the trans for repair...you just made it a royal pain in the butt.
> The smart thing to do: do your homework beforehand, instead of just pulling plugs and bolts and hoping to find the right ones.
> It's not uncommon for internal tranny parts to be secured to the case with through bolts.


It's called humor. We're just joking around. :laughing:


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## triz (Jul 22, 2014)

ratherbefishin' said:


> C'mon, guys, it's an Allen cap screw, not a hex bolt, good luck making it any more round than it already is....and if you drill out the recessed hex.."


And if you do decide to round off hex with drill,*make sure* drill is in clockwise setting..:laughing:



r0ckstarr said:


> It's called humor. We're just joking around. :laughing:


:thumbsup:


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