Higher gear, uphill, flooring it = hissing?

Flatulentoldgoat

peter3hg said:

Flatulentoldgoat said:

ontheroad1970 said:

Flatulentoldgoat said:

Friends van does this and I've always wondered what it was. I 'thought' it was a very slight vacuum leak but I can't find or see anything obvious. You only really hear it / pronounced when you're going up hill in say 4th/5th and flooring it. It's like a very mild, muted sound like a pressure cooker. Could a slightly slack/loose fan belt be a likely candidate. The only other thing I can think of is a Turbo going bad but it's been like this for ages and I think he'd have known if that was the case by now!!

Why would you go uphill  in 5th?  Or even in 4th?

Speed > 50 = 5th gear. Do you drop down to second?

If you are "flooring it" to maintain 50mph then you are in the wrong gear. Speed should not be what determines gear selection, engine load should be.
Very simplistically you want to be in the gear where you need the smallest amount of throttle applied to maintain the speed. That may well be 3rd on a hill at 50mph.

I try and keep my revs between 1.6-2.5 x1000. Ideally around 2.0 and I use the gears to maintain that ratio.

Even if I'm at 2000 RPM (and not flooring it) as soon as I hit a hill the hissing gets audible. Obviously the more gas I give it the more I hear it. In practise I almost 'never' floor it - I drive like a granny (most of them)

AdrianC

Flatulentoldgoat said:

I try and keep my revs between 1.6-2.5 x1000. Ideally around 2.0 and I use the gears to maintain that ratio.

Why be so prescriptive and restrictive?

Use whatever revs are required by the situation.

If it's struggling up a hill to maintain speed, needing to be floored, change down. Yes, you might be using a few more revs... but you'll be in far better control of the vehicle.

photome

Flatulentoldgoat said:

peter3hg said:

Flatulentoldgoat said:

ontheroad1970 said:

Flatulentoldgoat said:

Friends van does this and I've always wondered what it was. I 'thought' it was a very slight vacuum leak but I can't find or see anything obvious. You only really hear it / pronounced when you're going up hill in say 4th/5th and flooring it. It's like a very mild, muted sound like a pressure cooker. Could a slightly slack/loose fan belt be a likely candidate. The only other thing I can think of is a Turbo going bad but it's been like this for ages and I think he'd have known if that was the case by now!!

Why would you go uphill  in 5th?  Or even in 4th?

Speed > 50 = 5th gear. Do you drop down to second?

If you are "flooring it" to maintain 50mph then you are in the wrong gear. Speed should not be what determines gear selection, engine load should be.
Very simplistically you want to be in the gear where you need the smallest amount of throttle applied to maintain the speed. That may well be 3rd on a hill at 50mph.

I try and keep my revs between 1.6-2.5 x1000. Ideally around 2.0 and I use the gears to maintain that ratio.

Even if I'm at 2000 RPM (and not flooring it) as soon as I hit a hill the hissing gets audible. Obviously the more gas I give it the more I hear it. In practise I almost 'never' floor it - I drive like a granny (most of them)

In your OP you say you are flooring it , now you  say you almost never floor it , you also say it’s your friends van…note to self…stop replying