Loss of power

[duncancompton]

I've got a 1999 SWB diesel transit, 145,000 miles on the clock. It has a mechanical problem, which is:

When it's been running fast for a while (motorway), about 2/3 hours, it starts to lose power. The other day, it broke down. The mechanic said it was only firing on three cylinders and there was air in the fuel. He eventually got it firing again and I made the hour back to london without problems. This loss of power occurs every time I drive it at high revs/fast for 2/3 hours, but it has only broken down once.

It struggles to maintain 80mph at all (even if i've just started a journey), but when it starts to lose power 65 on the flat is a good speed. The worst it gets is struggling uphill (motorway grade) at about 40. All this is without a load.

The temperature looks normal (just below half on the guage) throughout.

Does anyone have any ideas? I've asked quite a few people, but they've never heard of it. I thought, well, this is a forum populated by experts. If no-one here knows, I'm screwed. But someone will, won't they?

Cheers,

Duncan

[gazza]

http://fordtransit.org/forum/viewtopic.php?t=747

quite common it would appear

[gazza]

http://fordtransit.org/forum/viewtopic.php?t=611

and this, you will be impressed at the difference ir makes

[duncancompton]

Thanks gazza, I was starting to get worried the problem was going to cost me a lot of cash.

I'm pretty new to transits (read: has never done anything more ambitious than check the oil level), and that second topic on cleaning the inlet was straight over my head. To be honest, even the first one has got me on the ropes. It doesn't say newbie under my name for nothing.

Perhaps you could recommend some sort of guidebook to the engine? Some way I can see what people are talking about so I can fix it? I tried to get a heynes manual, but they said my transit was too new and they havn't published one yet. Maybe the engine is the same as the one before?

Thanks again for your help,

Duncan