Allison Transmission Questions Notlost, This is not normal. I would take your MH in as soon as possible to have it checked out. It can either be the engine having heat issues heating up the trans, it could be the trans heating the engine or it could be a lack of cooling or blocked cooling hoses or cooler. Sometimes when hoses are built, they cut the inside rubber and this blocks cooler flow. Let me know and have a great day!