Not sure where to start, when i lift the bonnet on our mk1 Oct'y the underside of the bonnet hasn't been cleaned for a while so is "dirty"

What can i use to clean it up? ie engine and bonnet underside.

Is it safe to just go at it with the jetwash?

Don't have the problem with the mk2, as the underside of the bonnet is clean, so just gets a wipe over with a microfibre cloth after washing.

Use some Megs APC with a detailing brush to agitate it first and soften the worst of it.

Works for me when it gets bad; but thereafter a wipe down with a damp APC soaked microfibre.

.............i have the same problem although my car is nearly a year old i opened the bonnet the other day and realised that it was a bit filthy,cleaned a bit with wet cloth drying up afterwards although there were many places i couldnt get in.

Would blowing with air pressure do any damage????

Not sure where to start, when i lift the bonnet on our mk1 Oct'y the underside of the bonnet hasn't been cleaned for a while so is "dirty"

What can i use to clean it up? ie engine and bonnet underside.

Is it safe to just go at it with the jetwash?

Don't have the problem with the mk2, as the underside of the bonnet is clean, so just gets a wipe over with a microfibre cloth after washing.

For me I jetwash most engine bays on a detail with no problems, key things to remember and what usually works well for me if having the engine running, that way any water gets evaporated off fairly quickly and don't directly wash electrical areas. So a rinse and then following Ste's suggestion an aggitation with Megs APC and a Detailer Brush will do the job followed by another rinse........

Fair few detail links in this section and on DW where you can see me pressure washing the engine bays.........

.............i have the same problem although my car is nearly a year old i opened the bonnet the other day and realised that it was a bit filthy,cleaned a bit with wet cloth drying up afterwards although there were many places i couldnt get in.

Would blowing with air pressure do any damage????

Air pressure is OK but you need to be careful not to blow anything into somewhere it shouldn't go......... :S

Thanks for the answers, will give it a go in the next day or so.