Fumes

[Hymek]

I cant comment on the voyager engines running when stabled in stations. I know for a fact in the 1980s with the peaks, the drivers were told not to switch them off at St Panc due to the fact they wouldnt be able to get them started again.

One reason for switching 1st Gen units off is to minimize clag from what im guestimating. As sitting around for an hour and with the length of an exhaust on something like a 108 is very long, so the claggy fumes collect in the exhaust, and when the units leave, hey presto, muchos clag!

But yeah, on the voyagers it is probably to keep the electrical systems inside (such as the fridges) cool.

[Kromaatikse]

Wait, doesn't St. Pancras have a decent overall roof? Why would it be more difficult to start a Peak there than in the open air?

The "claggy fumes" on 1st-gen units probably refers to carried-over oil and unburned fuel. When the exhaust system heats up due to the engine coming under load again, this collected gunge starts to burn - *inside* the exhaust. That was also a problem on Westerns due to their two-stroke engines, but not so much on full-sized four-stroke diesels.

This is also why you get a very dirty exhaust from a diesel with a blown turbo. There isn't enough air getting to the engine to burn all the fuel it's being fed, so it burns in the exhaust instead. Modern diesels have an oxygen sensor in the exhaust which restricts the fuel rate to avoid fuel carry-over, even with a blown turbo - hence, much less clag.

It turns out that the Valenta didn't much like being idled forever either, during the hybrid-set runs before the Mk4 DVTs were built, so they started using the extra power from the engine to avoid ruining it.

[AndyUK]

.....That was also a problem on Westerns due to their two-stroke engines.....

Two-stroke diesels in a Western, I don't think so! I assume you mean Deltics.

Andy L

[Hymek]

Wait, doesn't St. Pancras have a decent overall roof? Why would it be more difficult to start a Peak there than in the open air?

The "claggy fumes" on 1st-gen units probably refers to carried-over oil and unburned fuel. When the exhaust system heats up due to the engine coming under load again, this collected gunge starts to burn - *inside* the exhaust. That was also a problem on Westerns due to their two-stroke engines, but not so much on full-sized four-stroke diesels.

This is also why you get a very dirty exhaust from a diesel with a blown turbo. There isn't enough air getting to the engine to burn all the fuel it's being fed, so it burns in the exhaust instead. Modern diesels have an oxygen sensor in the exhaust which restricts the fuel rate to avoid fuel carry-over, even with a blown turbo - hence, much less clag.

It turns out that the Valenta didn't much like being idled forever either, during the hybrid-set runs before the Mk4 DVTs were built, so they started using the extra power from the engine to avoid ruining it.

No, it has nothing to do with the air, Its just that if they shut them down at St.P they couldnt get them started again due to the worn nature of the Peaks at that point