Hole in my Allison?

AXett · 10-08-2022, 04:53 PM

Possibly a very stupid question but I was under my bus today and noticed there's a large open port on my transmission. I can see a spur gear of some kind in there... Pictured.. Normal? Am I missing a rubber plug?

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magnakansas · 10-09-2022, 01:49 AM

you are looking at the gear teeth on the engine for the starter. flywheel ring gear teeth. maybe there was a plug.

william

cadillackid · 10-09-2022, 08:09 AM

yep magna has it right.. that is the starter ring gear..thats the inspection hole and fluid weep escape if a leak occurs... there is usually a little metal plate over the hole but mine was missing long before i got the bus and I dont worry about it..

nothing to be worried about there unless you have gobs of oil pouring out of it or pieces of metal are being ejected

AXett · 10-09-2022, 02:13 PM

Thanks folks! No fluid or chunks coming out at the moment. I'll look maybe at printing a high temp plug for it...

cadillackid · 10-09-2022, 03:35 PM

Quote:

Originally Posted by AXett

Thanks folks! No fluid or chunks coming out at the moment. I'll look maybe at printing a high temp plug for it...

dont plug it.. plate it..

magnakansas · 10-09-2022, 04:47 PM

Think of that hole as being helpful for early warning. the leak from the hole is the warning before a really bad leak happens.

If you plugged it, then you fill up the case. That is not how it is intended to work.

a cover to keep debris and things like mud daubers nests out. This can also be a good inspection hole

william

Asylum · 10-10-2022, 06:57 AM

Quote:

Originally Posted by magnakansas

Think of that hole as being helpful for early warning. the leak from the hole is the warning before a really bad leak happens.

If you plugged it, then you fill up the case. That is not how it is intended to work.

a cover to keep debris and things like mud daubers nests out. This can also be a good inspection hole

william

I've got the same open plug-hole. I was told it was an inspection port for the rear main bearing. However, I do have some oil that seems to seep out of it...there is fresh oil in about a 4" diameter around the hole, just after an oil/filter change and a drive.

Is this a concern?

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