Loud engine

Thanks for the suggestion. I'll give it a try when I go camping later this week, if it doesn't get too hot.

A loud roar is usually the cooling fan. The circumstances of loud noise are being in lower gears when engine is hot, so that the fan is engaged, and when the engine is cold and you are starting from a standstill, so that it has not yet declutched.

If your engine fan is spinning full load all the time, the fan clutch needs to be replaced. These are designed to make "engage" the failure mode, to ensure a flow of cooling air when you ate not moving. Thermostatic fan clutches operate based on temperature of air flowing past the clutch, so often may not come on until after you've climbed the hill and raised the temperature in the radiator.

tatest description is accurate for those with thermostatic fans such as on diesel Sprinters and many cars nowadays. But for the 360 engine on donrebcyt vehicle I would be surprised if it has the free wheeling clutch system but likely the fan connected to the flywheel with no clutch.

Back in the 80's the thermostatic fan clutch failed on my first Class B, which was a 1979 Ford E250 with the 351 Windsor engine. That vehicle didn't have a tach so, at first, like others, I thought the extreme roaring noise (which didn't go away) was caused by high engine revs due to transmission slippage. But I finally figured out that the fan clutch had failed. I was on the road at the time so purchased a new clutch to put on when I got home. But since I still had over a 1000 miles to go and I couldn't stand the constant roar anymore, I ended up changing it out at our campsite. As others point out, it's normal for the fan clutch to engage for a short time when the engine is cold or kick in if the engine temps get on the higher side.