89 Volvo 740 Turbo Transmission Problem?

Sometimes the car doesn’t engage immediately when I put it in drive/reverse. For example, I put it in drive and press the accelerator then nothing happens for a moment…then it engages. (150,000 miles, auto)

Sounds like old age to me. Leaky clutch piston seals would cause exactly what you are describing.


Forgive my ignorance, but what is a clutch piston seal?

Some of the stuff that needs to be replaced when a complete transmission rebuild is done. It is time for that or a different car.

The transmission piston is sealed by rubber lip seals that seal the hydraulic piston to its cavity. The oil pressure developed by the transmission pump and commanded by the valve body is used to push the piston out when its associated clutch pack is needed to be compressed together to hold or drive a gear set element. If the oil pressure escapes around the seal the pump cannot develop enough pressure to lock the clutch pack so you get no drive or slippage. As the oil warms up, the lip of the seal will finally contact the wall of the cavity; pressure is developed; and the clutch pack engages.

You might try one of the products that claim to swell the transmission seals ala TransDoctor. This might get you a little more life out of the transmission.

Thank you for all the details. I’ve also heard that the problem can be caused by a vacuum leak. My mechanic said a while back ago that the hoses need to be replaced. Thoughts any one?

A vacuum leak is going to cause a poor running engine and will not cause a delay in transmission engagement.
A 19 year old car pushed by a turbocharger is probably suffering from exactly what Transman says it is - trans rebuild time, and especially so if the fluid has never been changed.

You might TRY having the transmission serviced (fluid and filter changed) and maybe a can of additive to “condition” (swell) the seals. If that doesn’t work, the end is near. A rebuild would total the car…

If the car is in good shape at 150K miles, I would do the transmission if necessary. I bet you can buy a good remanufactured unit for about $3K (maybe $4K) for that car, but I would be a little surprised if it needed a rebuild at only 150K (unless it’s been neglected). Unless you can replace the vehicle for the repair cost, it’s worth fixing. Make sure you service the new transmission as recommended and it should last considerably longer.

Do a search here: http://car-part.com/ for a used transmission for your Volvo. I have one in a wrecked '91 740 DOHC, but I have no idea whether it has a crank sensor notch or which model it is, nor do I know how to find out. I’m going to guess that the B230F has no turbo and the B230FT does. My DOHC is not a turbo car.

The tranny is 19yrs/150k old. I think the part has lived its design life + some.

“he tranny is 19yrs/150k old. I think the part has lived its design life + some.”

I hope not, the transmission in my car only lasted 250K miles/20 years due to some abuse by the PO, I will be very disappointed if the replacement doesn’t last considerable longer with the correct maintenance.

I have seen low transmission fluid levels cause the same problem when a seal went out.