I am finishing installing the 1991 B230FT in the 1988 760T which suffered the broken connecting rod. I don't know where to connect the large vacuum hoses for the ACC and vacuum reservoir, and if there is a vacuum reservoir and/or vacuum boost pump.

This later style 760T has a vacuum hose routing which I am unfamiliar with and my 740T and earlier 760T experience doesn't help. As shown in the picture below, the intake manfold (this is the one from the original engine) has a short vacuum line with a tee on it, and a check valve on one branch of the tee. The vacuum line coming from the ACC also has a check valve as shown in the picture. I need another vacuum line to connect to the tee, and I don't understand the purpose of two vacuum check valves. The earlier 760Ts have a vacuum pump which provides vacuum for the ACC when necessary. Also, the earlier 760Ts have a vacuum reservoir either behind the front bumper (1987), or just in front of the front suspension crossmember (1986 and earlier).



Unfortunately I didn't get to remove the intake manifold and vacuum hoses. that was done by the person who owned the car before me.

Who can help the stumped Volvo jock?

John,

My 90 765 has the same set up. The check valve with white hose goes to firewall passenger side. Other check valve has black hose (same size as white one) and goes into firewall next to white one. I'll look under dash to see where it goes. I suspect to a vacumn canister.

There are check valves because with a turbo there is not always vacumn. When in boost conditions there is actually pressure in intake not vacumn.

Joe

John
your setup looks like my 89 745gl, the hoses you have upfront there, the one with the T is the vacuum system, you should be able to find the vac canaster in the front bumper guarded by a plastic casing which you have to rip out and even see it, they may have moved it to the inside of the car on the 90 760 model, the T should branch off to the canaster and should have large hose which will then have a connection to a very small hose which since when i looked i couldnt see but it headed towards the back of the block area, the other hose with the check valve looks like someone added that in when trying to chage hoses, since that it a typical volvo hose that they used on the Cruise Control, that should be pugged in with a adapter J shaped to the very bottom connection on the manifold there cloest to the front. this is how mine is setup anyways and it looks like yours would be set up the same even though its a turbo, my center vac connections are blocked off, yours wouldnt be because you have a turbo. i hoped this might have helped you in some way.

Unfortunately the 1988 760T did not have vacuum cannister behind the front bumper like the 740s do. It must be inside the car, as you suggested.

Dick Reiss sent me a picture of his wife's 1991 940SE. The tee is totally stock and there is a black vacuum line and check valve which also connect to the tee. The 940SE is essentially a 900 version of a 760T.

The cruise control has its own vacuum pump and is not connected to the engine manifold vacuum system in any way.

Your input is appreciated. Keep it up.

Looking at wife's 940 SE, there are two check valves and the whole mess is on a T. with only one manifold attatchment. No vac pump that I see and the car is a 91, so should be similar. If you want I can shoot at pic and email it.

dick

I could use the picture. Thanks.