Volvo: Volvo 740 Turbo, switch repair, volvo 740

Question
I have a 1975 volvo with a 1989 740 turbo engine installed on it, manual, the boost is opening only 0.3 0.4 bar i want to know is my engine has problems? or is it original to open 0.4 bar? if not what it is the original engine boost bar?


Thanks!  

Answer
Mike,
Reading:  50 ±4 kPa (7.1 ±0.6 psi)

If boost pressure is correct, turbo system operates correctly. If boost pressure is incorrect, adjust wastegate valve and retest.


If valve adjustment does not fix the problem, check the following:
Wastegate valve
Turbo charger
By-pass valve
Turbo over-boost pressure switch Repair or replace bad component(s) and retest.
5.80152 psi is equal to 0.4 bar so you are just under the spec.