League of Legends (LoL) Question: Hecarim mana issues

I tend to buy Hunter's Potion on Hecarim. Alternatively, you simply make sure not to use Spirit of Dread for sustain unless you currently have Blue buff. Also Hecarim is a carry jungler so if you are doing well and you don't trust your Mid laner or they aren't doing well you can choose to not hand it off to them. And of course if you can steal the enemy blue buff safely then that helps as well. Also make sure you are using your Q, Rampage, after you auto so you don't accidentally cancel your auto attack reducing your damage output, which slows your clear and results in your taking more damage.

Mana is designed as a power limiter so that you can't just spam skills unless you build accordingly. As Hecarim, that means you can:

A) Buy an early Sheen. IDK if this is advised anymore, but some months ago a viable build path was Smite upgrade item -> Trinity Force before even finishing the full jungle item. With the current lethality meta triforce is possibly not a first buy though.

B) Go hybrid with Enchantment: Runic Echoes. It was a viable build some time ago. Then again, this means you wouldn't be doing the lethality build so it's probably not meta.

*If you want to go A or B make sure to look for an updated build and not one from the past season.

C) Learn to limit your skill usage. Hecarim can spam his skills quite often, which may be the reason why you're running out of mana. You may want to avoid using too many skills, especially if you're close to full health. You can see it as "trading a bit of hp for a bit of mana" whenever you hold onto a skill during your jungle clear.

I think C is the advised option currently, so you might want to minimize skill usage as much as possible. Don't use Spirit of Dread on single monster camps, don't spam Devastating Charge during your clear to use it without charging the movespeed, make sure to use Rampage right before hitting your Devastating Charge to make maximum use of the AD gained by the movement speed... There's probably more tips in guides, you should ask there if these aren't doing the job for you.

You can buy some mana items. I recommend you just look for a Hecarim guide and see how they counter the mana issues. But, you can always just buy a Manasomething. Trinity gives 250 mana, so that's something you should probably have (I definitely didn't just look at a guide and say that).
And besides, the jungler item gives a lot of mana regen in jungle, so that shouldn't be a real big problem.

Hope I've helped.

so ultimately hecarim's biggest limiters are early game dueling weakness and mana, general what I do on hecarim is do a clear of everything but gromp (always start blue) and go back once I have 1450 gold, get sheen+boots (minimum sheen) and then later get a hunters potion, asap, and remember you wanna rush trinity before even buying your smite item, further helping mana problems