stripped tranny inspection hole (308)

The threads on the rear inspection hole of my tranny ('85 308) are somewhat stripped. Does anyone know the thread size and where I might find the proper sized tap? In the meantime, would it be safe to install an expandable rubber freeze plug? Any help on this asap would be much appreciated.

 

Cant help on the thread size but an expandable rubber plug would be my fix until I corrected the problem. Make sure the hole is bone dry before you put in the plug. The box is vented so it wont build up pressure and blow out the plug. My only concern would be how long will it last before the oil swells the rubber and complicates your life.

 

Thanks, Paul--I did install a plug AND... it's too late for a tap. The threads are gone at the opening of the hole, but the plug is too short to reach the threads which are further inside. I'll need a self tapping plug, a heliocoil installed , or possibly a longer plug. Any thoughts/experience with this?

 

Helicoil would be permanent fix. If you pull the pan, maybe you can get away with doing this with the engine in situ...Good luck
Philip

 

Does anyone know if an automotive oversized or self-tapping plug is made for situations like this ?

 

DOC i have used brass plugs for things like this on race cars / drag cars ect. " but" bieng as yours are metric threads and that the plug may need to be removeable, i dont know if i would use brass in this case. i would check with a shop in your area that does cylinder heads and see what sort of plugs / taps they have. if you bring the old plug they should be able to match up something for you. or a shop that does rearends ect on larger trucks, they fix and fabricate on a regular basis , where as most pass. car shop just remove and replace components.

 

Well, I have a semi permanent solution to the problem. I found a drain plug for a BMW at my local NAPA. It is the same thread size, but slightly longer. As such, it was able to mesh with the good threads further into the hole and is tight. However, I'll be iso another one which may be even longer for a more solid bite. Thanks for the assistance, as always.

 

Does anyone know the thread size of this plug?

 

forgive my ignorance, please..... but what is a "tranny" and where is the inspection hole ?
regards, david

 

Dave--I mean transmission, ie gearbox. The hole I'm referring to is the one at the rear which one uses to to inspect the oil level--not the drain plug.

 

thanks doc......that has put my mind at rest......tonight i am to refit the drop gear cover casing and change the gear oil in the 308.....i am flushing the 'box (tranny ?) with the same synthetic oil i am to use, and from what i can see, i have to drain the drop gear case contents too.....is this correct ?......does the main gearbox oil make its' way through to the drop gear casing and vice versa ?
i am familiar with the half cup of oil to go in the drop gear box.
any horror stories ?
many thanks in anticipation.
regards, david

 

Dave--the seqence I used to change the gear oil was as follows:

1--remove the fill plug at the top of the gear case first just to be sure you can get it out. (Some chatters have reported some difficulty in removing it).

2--remove the rear inspection hole plug

3-- drain both the gearcase and tranny pan

4-- reinstall the 2 drain plugs--be sure to use new copper gaskets

5--Refill the gear box through the top hole of the trasfer gear case. I used a thin rubber hose with a funnel attached. During the refill stage, be sure that the car is sitting completely level. (The gear oil does flow through the gear case into the gearbox)

6--Add gear oil in this manner until it begins to run out of the rear inspection hole. Replace the inspection plug once the dripping stops

It's a pretty straightforward procedure. Again use new copper gasgets on all four plugs to avoid leaks. Also be careful not to overtighten the plugs upon reinstallation to aviod stripping the threads

Good luck!

 

It takes a bit more than 4 quarts (about 4 1/3, I think) before it starts dripping out the tranny 'inspection' hole.

 

I have been using metric fiber washers on all my oil plugs, since I had a mechanic strip my engine oil plug. I like them as you can sinch them up without worrying about stripping the threads. I think the F design lends itself to stripping.

 

"1--remove the fill plug at the top of the gear case first just to be sure you can get it out."

I'm about to help a buddy do a gear oil change. Is the 308/328 fill plug easier to see looking down from above the top of the gear case when I open his engine bonnet, or easier to see from below/side?

Anyone have a photo handy?

Thanks.

 

Robert, where would I find/buy metric thread washers?


That's an awesome idea, by the way.

 

You should be able to get fiber washers w/metric openings from either McMaster-Carr:
http://www.mcmaster.com

or Manhattan Supply Co (aka MSC):
http://www1.mscdirect.com/cgi/nnsrhm

They are the 2 largest 'hardware suppliers' in the US, if they don't have something, then you're in for a long search!

 

With the LH rear fender liner still in place, the only option is attacking from the top (and, if the Bonnet is still in place, this restricts the moment arm length of the tool -- which is why sometimes it can't be removed if "tight" );

With the LH rear fender liner out, from the side is probably easier;

With both the fender liner and bonnet off, both are easy.

The photo shows an '84 with the transfer gear reservoir fill plug having an internal (female) hex drive feature -- IIRC, on my ex '78, that same fill plug had a large (19mm AF?) external (male) hex head drive feature.
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Doc,
Helicoils or other spiral wire replacement thread inserts tend to leak a bit. There are solid metal thread repair inserts such as the Tim-Sert that are made from solid metal & don't have this problem.

Alternatively, any transmissioin rebuilding shop can build up the heads with welding, then drill & retap the hole. They routinely do things even more amazing than this when rebuilding transmissions. Given the large number of japanese cars out there, there's a good chance that they'll have the proper tap.

BTW, you can just measure the thread OD & round it up to the nearest mm to get the thread size. Most shops have a thread pitch gauge that can measure the threads. Or take the plug to Sears & use one of their pitch gauges. It'll eighter be on the display with taps & dies, or most of the tap & die sets have them.

 

Steve, Verell,

Thanks for your thoughtful help. Branko and I were able to change the gear oil in his Euro 308 to RedLine's 75W90NS.

That's great gear oil. He's never been able to shift into 2nd gear (when the engine is cold) until today after the gear oil change.

He drove me around for 15 minutes prior to the oil change to warm up the tranny, and he avoided 2nd gear like the plague (wouldn't go in).

Upon changing the gear oil, he immediately noticed a difference between Reverse and 1st. It was just natural for him to immediately shift into 2nd, and when he did his face lit up as he yelled "Chris! I've got 2nd gear now!"

Too cool.

Oh, the prior owner to his 308 failed to use a washer on the tranny inspection plug. What a nightmare to remove! Branko had a brilliant idea to place a brick under the handle of his socket and lower the car in order to break the plug loose. That was clever and worked like a charm.

Neither of us are mechanics so we've only got little hand tools, but that trick made up for it. Lowering the car moved the socket-handle and broke the plug free. No thread damage, either. It was a smooth play.

Mmm...one other thing:

To get to the rear tranny inspection plug, you've got to first remove a four-bolt (10mm) heat shield back by the exhaust. This step is not optional on his Euro 308.

I don't know those cars so I can't say if that's normal or not for other variants.

 

For the benefit of Searchers coming to this thread later, the transfer fill plug is at the top left of the illuminated silvery transfer case in your photo. For Branko's Euro 308, it took a male 12mm allen to remove that female plug.

The transfer drain plug is a male 19mm (on this Euro 308) just out of sight at the bottom right of that silvery transfer case, requiring a female 19mm socket to remove.

The bolts to remove the inner fender liner were all 10mm, so you'll need a 10mm female socket for them. Ditto for the four bolts (all 10mm) on the heat shield that covers the rear gear oil level inspection plug. That inspection plug itself is a female 12mm, so you'll need a short 12mm allen wrench or a long extension 12mm male socket/allen.

The transmission drain plug is a 10mm female, so you'll need a male 10mm allen or socket to remove and re-install it. It is closer to the rear of the car, and closer to the rear inspection plug, than another drain plug nearby (engine oil on that other one, perhaps?).

Since we were jacking up the rear of the car, which is where the parking brake goes, and where the transmission would lock the rear wheels, we placed bricks around the front tires since nothing was preventing them from turning.

Due to location, we didn't have protective jack stands, so we had to place the wheel under the car as an emergency backup if the floor jack failed, as well as stacked 3 bricks from the ground up to the rear frame rail for a third level of safety if the jack and wheel both broke.

Even when "making due" in life you should still play it safe. Don't do this job with only a jack preventing a ton and a half from crushing you.

Better yet, be prepared and have/use multiple jack stands. That's what they're for.

 

Could you or another Euro 308 owner post a pic of this heat shield? Mine is a Euro and my inspection plug is easily removed without having to remove anything else. Appreciate the help. Didn't mean to highjack the thread.

 

If you mean transmission cover, it is easily seen on drivers side. If you mean the plug under the car for the transmission fluid, a Euro does not have it covered and it is the one closest to the rear of the car. If you mean the side bolt for the engine transmission oil to 'leak out' when refilling, that is not covered by a heat shield on my 85 Euro.


BRB to add photos... going to take pics of all right now...

 

Steven,

I guess it was a head-scratcher for me as well. The rear-most gearbox fluid inspection plug on my car is not obstructed with any type of shield. In fact, I've never noticed any bolt holes that would indicate a shield would / should be attached.

Maybe the heat shield on Branko's Euro is not original?

 

Owens, forget everything i said pretty much. i KNOW what you are asking now that i took a look. There is a heat shield held on by four 10mm bolts. i red pointed two of the bolts. There is one in the middle i think and also one to the far right that holds the passenger side shaped thingie (technical aint i ). Note, that large silver sway bar IS NOT stock, odds are yours is blackish and much smaller.

Geeze, musta removed that darn thing 100 times in my lifetime, pounded it with a soft mallet a few times to reshape it... and you'd think i'd know wtf it is.

If you car is missing this shield, it seems to basically shield heat and also scoops some air going under the car upward to the lower part of the engine for cooling.
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