Hello Schwmh,

I recently an owner of 1990 740 turbo. Yes. When you apply the gas pedal, the turbo needle goes up to turbo boost and goes back down. However, according to my experience, the turbo needle never stays in the turbo mode unless you hold until you after applying the gas. For example, if I am driving the freeway and I am traveling at speeds of 40 mph and the press the gas to accelerate to 55 mph, my turbo need would go up then come back down. It does not hold in turbo mode. The needle showed be going up and down, up and down, as you apply the gas to accelerate. Historically, the volvo 7 models are very good cars, but the turbos are the may the most problems and are muck faster during acceleration.

cherronb

If you are not familiar with how a good running turbo performs, try to bring someone along who is. If that is not an option, take the car to a good independent Volvo shop to have the car checked out. Even if the car looks well cared for and has all the service records, you should still have it checked out by a mechanic who can find potential problems. This way you can negotiate a fair price and not have any nasty surprises...

Good luck,

JJ

My first thought is that the turbo's wastegate actuator rod has fallen off the wastegate. It happened to mine. The turbo gets EXTREMELY hot so do this when the engine has cooled completely. Standing next to the right front wheel, reach under the turbo and feel for the rod that goes from the actuator to the wastegate. It should be secured there with a clip or cotter pin. If you find the rod just hanging loose thats your problem. With the car on ramps, jackstands or a lift you can reattach the rod and put a cotter pin through the hole in the WG lever. With the rod disconnected, the wastegate will flap open and you'll have no boost.

If this isn't the problem, check all the hoses from the turbo to the intercooler and on to the throttle body for tightness and or splits. You may have a leak.

Hope it helps.
--
Erwin in Memphis, '88 745t 183,000 miles, '95 855t For Sale

When the boost gauge is right of center you should be able to feel a noticable boost in power. If you don't feel it something is probably wrong IMO and may or may not be expensive to repair depending on what it is.
--
1988 760Tic - 155,550 1966 M-B 230 sedan - 98,000 - Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us. - Bill Watterson

On a 940T, the boost gauge needle is straight up at the crossover point between vaccuum and boost. At wide-open throttle, the needle should go maybe 15 or 20 degrees to the right of dead-center... and you should be getting quite a kick in the pants!

I know the gauge setup is different on a 740, but either way sounds like a problem if you're not feeling the boost.

- Brian '93 945T