Glazedham42

iTrader: (4)

Hey guys,

Finally starting to make some serious progress on the reassembly of my FB. Succesfully changed the rear main oil seal on the engine tonight and decided that I wanted to tackle some other problems while I was feeling confident.

A while back before disassembling the car I was working on some other project and broke a fitting off where the oil pressure sensor goes. I decided that it was hopeless to try and fix it with the engine in the car so I just plugged it with JB weld. I ended up putting a mechanical oil pressure gauge in the car using the banjo bolt on the back of the beehive. Well, for some reason it didn't ever work right because the gauge was pegged all the time. Ripped out the crappy mechanical gauge, leaving me with no oil pressure gauge. Not good IMO. I would like to go back to using the stock oil pressure gauge or even change over to a nice electric aftermarket gauge. Here's the problem.



I used my dremel to sand off the JB weld that I initially put there to plug the hole after the fitting broke off. The stupid fitting is still stuck inside the rear plate, and you can see it inside. I tried using easy outs, and slotting the thing, and everything else. It is just plain too tight in there. I don't think that it is ever going to come out again. So my question is, Is it safe for me to re-drill and tap this hole? I'm not sure if there is enough "meat" in there for me to do this. If I did drill the hole out, can I use a regular bit or would I have to bore it out so the bottom the hole is flat? I'm wanting to use a standard to metric adapter on the end of the stock oil pressure sensor, and then screw that into the new hole that I would make.

My other option is to just plug the hole with JB weld. I am going to be changing the beehive out for a front mount oil cooler. I thought about getting somekind of a block to put under the oil filter pedestal like RB makes, and then run an oil pressure gauge off of that. I don't really like this idea much because it would junk up the engine bay IMO. I want everything to look nice and clean. But if this is what I have to do to keep from destroying the engine, then so be it.

Please let me know what you think about this guys. I am really having a hard time trying to decide which route to take. Thanks.

Jamie

kettlman

iTrader: (2)

looks to me like you might be able to drill the hole thats there out bigger and get an easy out in there. if not i'm sure you could drill it out and re-tap it. but you would have to find the right connector to connect to the original fitting and tap the hole to that. the original is a standard 1/4 fitting. noting metric. i would try to get it out first cause to re-tap it might become too wide.

RotorMotorDriver

iTrader: (1)

DONT TRY AND PLUG IT WITH JB WELD! Ask me how I know, it doesnt work, lol. I tried 4 or 5 times to get mine sealed up when I had a similar problem, but it didnt work, no matter how much prep work I put into it. My solution would be to try and drill and tap it, theres quite a bit of meat there for you to work with there, at least Im pretty sure. If nothing else, you can drill and tap that last little bit, put a plug in there and go down lower towards the bottom and theres another place you can get in there and put the sender, at least on some blocks. Good luck with it though man, I went through the EXACT same thing.

~T.J.

Rx7carl

Well drill and tap for 1/8" npt. Then you can use either an aftermarket gauge, or get another stock sender. Yes I know the stocker isint metric, but I used a 1/8npt fitting on my racecar and it works and fits fine, no leaks or anything like that so the threads are really close in size, and since they ar both pipe thread, it will seal. Only problem (and TJ will remember this) is how to not get shavings into the oil gallery, or at least be able to clean out the passages afterwards. Maybe remove the bottom plug and flush the whole thing from the top down maybe?

Supper

I would either say use an easy out like stated above. Or find yourself a set of left handed drill bits. Use them all the time at work to get out screwed up set screws. They work like magic, just keep drilling until they catch on something then use the torque of the drill to force the skrew/fitting/whatever loose.

Glazedham42

iTrader: (4)

Thanks guys, this helps a lot. As far as using an easy out, or a drill bit, I already tried that stuff. The fitting actually just gets ripped away like I was using a drill bit. It is so tight in there that you can shave off the inside of the fitting before it will break loose. Unfortunately, there is no way its gonna come out.

As far as the stock pressure sender I had no idea that it was standard thread. Carl, you said to drill and tap for 1/8npt. How do npt sizes compare to whatever the stock sending unit is measured in? I have no experience with npt sizes or fittings. Call me crazy but 1/8 is smaller than the 1/4 of the stock sending unit. Wouldn't I be drilling air? I know this sounds really stupid, but I don't understand how the npt fitting works.

I already have a sending unit in great shape. The fitting that is broken off in the engine is actually part of a "T" that I had between my mechanical gauge and the stock sender, so that I could use them both simultaneously. At this point I really just want to find some kind of adapter to put on the stock sender, and then drill and tap my engine to match it.

Does anyone know what the smallest adapter I could get that would go on the stock sender is? I think the one I have is 1/4" to 1/2". This is an awfully big jump, and I don't want to have to drill a hole that big. Is there such a thing as a 1/4" to 5/16" adapter? I don't want to make that hole any bigger than I need to, as you can well understand. Thanks again guys. Hopefully I can get this fixed without it becoming too much of an issue.

Jamie

Glazedham42

iTrader: (4)

Ok, i'm an idiot. haha. NPT fittings are just the regular old brass fittings that you can find about anywhere right? I still don't understand how I could drill to 1/8 to fix it though....

Supper

all pipe has NPT threads on it unless otherwise specified (such as EUE, ACME, and a couple others i can't think of off the top of my head).

And if you are tapping to 1/8" NPT you don't drill 1/8". You find a pipe tap chart and see what size of drill bit it says you should use and drill it that size. You then, and only then, tap it. If you drill too big you won't have enough metal left to get good clean threads when you tap it.

kettlman

iTrader: (2)

yeah. 1/8 sounds more right than 1/4. sorry about that. but also if you try and be carefull enough. you can drill it almost the width it is and then try the easy out. but at first i was thinking the engine was going to be apart. so make sure you have a vacuum suckin the shavings out as you drill. it will be better in the end. and flush it out someway before you start it. good luck.

rob81gsl

iTrader: (3)

use a "screw extractor", it's kinda the same principal as an easy out but instead of reverse threadind it in you have to drilll it out to a proper size hole and then beat in the extractor. then just twist it out. it doesn't apply outward pressure on the threads like an easy out does. i just fixed mine yesterday with one and i got it out in like 2 minutes

Glazedham42

iTrader: (4)

OK,

I found a tap chart and I am ready to hammer out the ugly details. Here we go....



Here is my list of remaining questions:

1) If I use a 1/8" NPT fitting then I am going to want to use a 21/64 drill bit right? Do I need to specify any certain type of tap when I go to buy it? Or do I just tell them that I want an 1/8" tap? The reason I'm asking this is because I figured that certain taps may have different thread counts. If I get a tap with the right diameter, but wrong thread count then I am going to have problems with leaks, or the fitting may not even go in. The chart says 1/8-27, so 27 threads per inch? Is this the right tap? Someone please help me out here.

2) When I get my 21/64 drill bit, is there any special kind of bit I should get? I am assuming I can just use a regular V-bottom drill bit, right? I believe they are 108 degrees if I'm not mistaken.

3) How far should I drill in before tapping? I obviously want to get out all of the old brass fitting that's stuck in there right? I want to make sure that my hole is deep enough to get a good hold on the fitting that I'll be putting in. Is it going to hurt anything if I go in too far?

I think that is it for right now. I'm hoping to get this taken care of pretty quickly, so if you guys can help me out with my questions I'd appreciate it.

Thanks,
Jamie

Rx7carl

1- 21/64 correct. Just ask for a 1/8"npt or pipe thread tap.

2- Yea a regular bit will be fine.

3- thats a good question. I'd say go slow. Keep checking the depth till you get the brass drilled out. That should be deep enough. Grease on the bit will help catch some of the shavings. Still my concern is how your going to flush out any chips that do manage to fall in.

rob81gsl

iTrader: (3)

i'm tellin you dude try the screw extractor. it works man, i'd try it before you drill and tap it out.

Rx7carl

Couldnt hurt. Less chance of getting shavings in the engine. Your talking about the straight flute type right?

anthrax

Is that not an Esay out??

If it is not what is the difference?

He said he tried an easy out already...

Soak the thing in penitrating oil over night and then see what happens...

rob81gsl

iTrader: (3)

it's the straight flute type. they work a hell of a lot better than the reverse thread tapered type. since the flutes are straight instead of tapered when you put it in it doesn't put outward pressure on the theads, hence not making it tighter. trust me i did the same thing like two days ago and a regular easy out wouldn't work either but with the screw extractor i got it out in like no time. i wouldn't drill and tap it out until i absolutely had to, to many metal shavings that could get in only god knows what parts of the engine

Glazedham42

iTrader: (4)

It doesn't really matter if I can get it out at this point or not. Even if I did manage to get it out somehow, there are no threads left in the hole. The ensuing battle with the fitting has basically annihilated the majority of the threads inside the hole. So I don't really have a choice at this point. I am going to have to tap the hole regardless.

Anyway, I went back out and did some checking and I don't think that 1/8" is going to work. My hole is already bigger at the opening than 21/64. The drill bit actually fits inside the hole already at the opening. I think i'm going to have to go up to 1/4" and use a 27/64 bit.

Carl, do you think there is enough bulk there to do a 1/4" fitting? I know you went with 1/8", but I think my hole may be too large already. Looking at the the back of the engine, I'm worried that the plate isn't as thick there as it looks like. You can see a raised area where the sensor goes on the back engine plate, where they beefed up the casting. If you have access to the back of an engine you'll know what I'm talking about. I'd hate to take off at it with a 27/64 bit and come through the back of the casting.

Let's say hypothetically that I want to try using a 1/8" NPT fitting first, just to see if it will work. I drill and tap and it doesn't work because the hole is too big at the opening from all the battle scars. Is this going to cause problems with the 1/4" fitting, or could I go ahead and drill it bigger? I hope this is making sense. Basically, if I've only got one shot at this I think I'm going to try 1/4". But if I could do 1/8" and then if that doesn't work, step it up to 1/4" without any complications then I would do that. I have posted a side profile drawing below of what the hole looks like.



Above is basically what the hole looks like. I have really butchered it pretty bad trying to get the dumb fitting out. I would really prefer to put a 1/4" fitting in there if possible. Below is a picture of the setup that seems ideal to me. I have the adapter, which i'm pretty sure is 1/4", on the end of the stock sender. I'd like to do this to get everything back to a nearly factory setup. I'm just worried about making a hole that large.



Also, are the threads on the outside of that adapter the right type of threads? They look rather coarse to me compared to the stock sending unit. Is the adapter I have on there an NPT fitting?

Finally, here is a picture of the adapter I'm wanting to use right next to the hole. I did this so you guys can get a perspective on how they measure up in size. I'm thinking that it would be okay to use this fitting, but I'll admit I don't know much. Let me know what you guys think.



Thanks.
Jamie

lovintha7

I was just going to say, use a 1/4 NPT tap, and screw in a 1/4 to 1/8 npt adapter. This will work absolutely fine, just use teflon thread tape. But, before you put them in, GET THE METAL OUT OF THE HOLE. I doubt your oil filter will catch all that crap, and that oil may not even go to the oil filter, it could be coming from it, which means all that metal will go inside your engine.

Glazedham42

iTrader: (4)

Thanks lovintha7. Glad to hear that someone is so positive on this working. Just out of curiosity, have you had to do this before? How do you know the 1/4" fitting isn't too big? I'm not doubting you at all, just interested to know how you found out.

Ok, here is the current battle plan then. We are nearing completion on this pain in the butt project, and I owe all of you the credit. Let me know if you see any flaws in the plan, or have any suggestions.

1) Drill out the broken fitting in the engine using a 27/64 drill bit. I will continue to drill into the hole until I see that the old brass fitting has been totally drilled out from the hole. Some type of grease or oil will be used to try and contain the amount of metal shavings going into the engine. However, it is going to have to be flushed out somehow as it is impossible to keep all metal shavings out. (I know there is some in there now anyway after last night's battle.) There will be no fitting left inside, only a nice clean hole. With metal shavings inside my engine.

2) Clean out the inside of the new 27/64 hole as good as I can. Use a 1/4-18 pipe tap to begin cutting new threads into the block. I will cut slowly, and back the tap out occasionally to remove shavings. I will not break the tap off inside the hole.

3) Clean the shavings out of the hole and find some way to flush the engine. __________________________________________________ __________________________________________________ _____________________________________________. (The blank space is for everyone to submit their ideas. I have no clue on how to get the metal shavings out of there. Maybe blow it out from the bottom hole on the engine with an air compressor? Take out the bottom bolt on the engine and start dumping in oil from the top to rinse it out? Flush it out from the top with water? I'm open to anything. PLEASE MAKE SUGGESTIONS!)

4) Put some new teflon tape on the fittings and carefully screw them into the block without overtightening. NEVER overtigthen the fittings again as long as I live.

PLEASE help me by figuring out how to clean out the inside of the engine. I don't know how the oil is routed through, so as as result I can't make too many suggestions. While I have seen inside one, I'm not entirely familiar with the internals of the rotary. I understand the basics, but don't have enough knowledge to troubleshoot something like this.

Thanks again fellas, I'll be sure to post pics of this when I do it.
Jamie

RotorMotorDriver

iTrader: (1)

Too much teflon tape will interfere with the stock sender ground and wont let it work, be careful.

Oh, and what I did to keep the shavings out, is I made some plugs for the ends of my oil cooler lines, one had a quick disconnect for an air compressor and I used an external PSI regulator from the compressor and sent ~10 PSI through the oil system so as I was drilling it was pushing everything out, as well as sticking to the oil/grease on the bit.

~T.J.

RotorMotorDriver

iTrader: (1)

By the way, it looks like youre still running the water/oil cooler, so the bottom hole is unused. I realise that since your drilling and tapping anyway, you might as well put the sender there, but if you cant get the adapters you need or whatever, like I said WAY earlier, plug that hole with a fitting, and go to the bottom hole thats not used on the engines with the water/oil cooler and just drill and tap there for whatever size you want/need. This is also a good spot of you want to add another gauge and not T the hole again. Just take the plug out and drill and tap the damn plug.

Thats the way my car was when I first got it, hence me knowing all about the JB Weld not working where you want to put it, and yadda yadda yadda.The only problem you will have is if you ever want to go with a front mounted air/oil cooler, your rear hole is taken, but this is solved with one of those adapter blocks that goes under the oil filter for gauges and junk, which once again is what I did. Or, you could make a spacer to go from the block to the line to the cooler and put a fitting in that spacer. Either way, that only matters if you plan on going with the FMOC.

~T.J.

EDIT: This fitting

Rx7carl

DONT DO IT! I just looked at a rear housing and its iffy drilling a hole that big (for a 1/4" npt fitting). It might break thru on the backside!

Rx7carl

Loks like the drill is wobbling on you or something. Try a 5/16 bit. Its .3125 so its a little undersize. If it wobbles a little, youll still have a decent hole for the pipe tap. Im gonna go see if I can mic the hole and measure a stock sender.

Rx7carl

Ok heres the deal. First off, the threads are only about 1/4" deep. A 5/16 bit is just smaller than the hole so it should only drill out the brass. After that you might be able to clean up the threads and just screw in the stock sender. Of course youll have to flush the passage. Looks like if you remove that bottom plug on the housing, you should be able to flush downwards with solvent and get it clean hopefully. Also the brass is soft and should drill rather easily so go slow. Good luck man, I hope you get this in time.

Jeff20B

iTrader: (13)

I drilled and tapped an R5 rear plate which has nothing but a cast surface there ('79-80 engines are similar). I had to guess where to drill. Well, I hit the drilled oil 'galley' perfectly left to right, but as for up and down, it's 1 or 2mm lower than dead-center (I'm not a CNC machine, heh). Since the oil galley runs vertically, it's just fine. Yes, centering it left to right is very important as problems can come up, such as what Carl said. Oh, and the engine was disassemble. There are so many metal shavings produced that I'd never attempt this on an assembled engine.