Brake servo pipe keeps blowing off

[joshs90]

Hi, I have a 1982 T25. 2 litre air-cooled. Just got it road legal after six years in the garage. Starts easily, idles good and drives well. Or so I thought. Once the engine gets up to temperature and you are driving the van struggles for power and then the brake servo vacuum hose blows straight off the inlet manifold and the van dies. I have replaced the one way valve to see if that is the culprit but unfortunately not. Any suggestions what the problem could be and how to fix it?

[bigherb]

It is backfiring back through the carburettor pressuring the manifold and blowing the weakest link off (the servo pipe). Usually caused by incorrect timing or the fuel mixture is too weak.

[joshs90]

Ok I will have a look, I have a suspicion there could be a small air leak on the inlet manifold on that side. This could be contributing?

[Mr Bean]

Cor bigherb I just noticed your Ariel Arrow! Back in the days of black and white 405 line TV and turn ups my mate used to have one of those fitted with a dustbin fairing. He worked at Raymond Way in Kilburn. As I remember it had an interesting pressed steel frame and leading link front forks. We all thought the dustbin was a bit heavy for the Arrow but it went like SFAS. Ah! Memrories...

CS