M1 Abrams trivia question!

It is/was the air vent intake for the crew heater. Originally, it looked like a little mushroom shaped vent with a small grill around it. Later it was removed and air from inside the tank was used to supply heat. This was because once the tank became common to both the Marines and the Army, it would allow water to enter the hull when the Marines did their deepwater fording. Sea water and the crew heater did not mix well.

So you'll see it on XM1, M1IP and early M1A1s. On early M1A1 heavy commons, it might just have the spot welded over. On later tanks it could be invisible or not even there at all. There are several variations of the welded over spot depending on if the spot was elimintated at the factory (Lima) or during the depot remanufacture (Anniston).

On M1A2 and AIM tanks, these are remanufatured earlier tanks. So if the original tank had that spot, there might be evidence of the spot on the remanufactured tank. If the tank being remanufactured didn't have the spot originally, then the later tank won't have evidence of the spot either.

Here is an old photo of one of my tanks, one of the first of the M1A1 tanks produced circa 1989. You will sort of see the actual vent standing proud. I've also added a couple of photos of the welded over holes.

I believe the exterior holes were blanked off and the heater drew from within the crew compartment when the overpressure system was added in M1A1s.

HeavyArty

I believe the exterior holes were blanked off and the heater drew from within the crew compartment when the overpressure system was added in M1A1s.

 

Ok, I see it now.  At first I thought you were just showing the blanked off area. 

How can you remember such a small detail from a tank you were on over(?) 30 years ago?  I can hardly remember what I had for lunch last week.

Well, for one, you can see it in the picture. Two, it was one of the things we had to cover if we went thru the bird baths, the other being the pre-cleaner intake.

High pressure water doesn't play well with air intakes.

HeavyArty

How can you remember such a small detail from a tank you were on over(?) 30 years ago?  I can hardly remember what I had for lunch last week.

 

LOL! I can't remember either, but now and then, certain arcane detail things regarding vehicles that I served on long ago pop into my mind. But lunch last Friday, forget it.

Gotta say, I am glad we have members here who have crewed, maintained and fought in these vehicles to know the answers to the sometimes random questions we ask. 

Thanks for your service.

Heck, I can remember the pain in the butt it was when we went from regular diesel fuel to JP8. Fuel filters had to be changed and the smoke generators had to be disconnected. On an Abrams tank, smoke is (was) generated by the tank spewing diesel fuel onto the hot exhaust grills. With JP8, it supposedly would shoot out a flame instead of smoke. There was also a modification done to the crew heater because it ran off of the left front fuel tank. It had to be worked on to burn JP8 instead of diesel as well. I don't recall that being as big a deal as the fuel filters though.

I do remember at least two meals* I had last week; it was my birthday last Thursday and we got subs from Penn Station East Coast subs. That Monday was a snow day at work/school/most of the state and I ordered a pizza from Papa John's and picked it up in my new Outback I bought myself for my birthday.

*for me two meals actually equates to four meals on many days. I normally eat half a meal at lunch and the other half at 8 PM for my work dinner break. For instance, if I get a foot long sub, I'd eat half of it at noon and the other half at 8.

With commute, I'm gone from 2 PM to 2:30 AM, so my bedtime is approximately 3-3:30 AM to 10:30-11 AM. I wake up, get a cup of coffee (sometimes) and then eat lunch around noon. Yes, just two meals a day, and my two meals would equate to many people's one meal.

Wow, thank you for this! Now I finally know.