Vacuum diagrams/lines

[MPCAuto]

I've seen people ask about the vacuum diagrams countless times and I always see the same pic. We're working on an 86 Grand National and some of us were not there during the tear down, so the vacuum routing is giving us a lot of trouble. Two things specifically: In the picture below marked in green, where is the boost gauge sensor? What part of the engine bay is it located in? And marked in red: On our Vac. Block there is an opening right there which is not marked on any diagram I've seen. Should we just plug it? What is/was it for? Thanks in advance from the team at MPC Auto.

 

[Sal 87WE2]

Easy, on the pass side fender there is/should be a plate where the hood strut would rest when closed. Under the plate is the Map sensor which has a vacuum nipple and a weather pack connector.

The other nipple on your vacuum block may be pointing to the drivers side and if so it is for a vacuum brake setup. Cap it off if you are not using vacuum brakes because you may decide to use them later when your powermaster fails...

See here for MAP sensor or 'boost gauge sender":

 

[MPCAuto]

Ok thanks a lot! I thought that was where it should go but didn't want to hook it up and be wrong when we tried to start the car . The other opening in the vacuum block is on the same side as the other 5 lines though, but I guess we may just block it off anyways. That seems to be what people think it looked like 5 years ago when it was still in one piece lol.

 

[just plain john]

So you're saying there's 6 ports on the passenger side? Is the vacuum block metal or black plastic?

 

[MPCAuto]

So you're saying there's 6 ports on the passenger side? Is the vacuum block metal or black plastic?

our vacuum block is made of black plastic

 

[just plain john]

How many ports does it have? As far as I know, the OE blocks are the only plastic ones and they only have 5 ports.

 

[MPCAuto]

The black plastic vacuum block, which is mounted to the top of the throttle body, has 6 vacuum ports on the passenger side, 0 on the driver side. This car was donated to the school straight from the factory with 8 miles on it.

From left to right the vacuum connections are PCV, Boost gauge, Mystery port, and the clustered 3 of egr vacuum, evap can, and fuel pressure reg. I'll see if I can post a pic, the school computers don't like outside peripherals though.

 

[MPCAuto]

 

[GNVenom]

That vacuum block is a prototype part, not a production turbo 3.8 pod. Also, the steel lines attached to it are prototype, not production. The production steel tubes were not triangle-clustered like yours.

Still, the hookup to the ports can be managed using the available illustration, but you would have to use individual hose pieces and you'd need to flatten the triangle cluster. Also, you won't be using the pipe threaded brass fitting.

 

[MPCAuto]

That vacuum block is a prototype part, not a production turbo 3.8 pod. Also, the steel lines attached to it are prototype, not production. The production steel tubes were not triangle-clustered like yours.

Still, the hookup to the ports can be managed using the available illustration, but you would have to use individual hose pieces and you'd need to flatten the triangle cluster. Also, you won't be using the pipe threaded brass fitting.

Everything is hooked up, except that brass fitting. The question I'm asking is what should the empty vacuum line (brass fitting) be connected to.

 

[MPCAuto]

Bump for any guesses as to what that vacuum line is for. I know the brass fitting isn't supposed to be there, we're just plugging it for now.

 

[GNVenom]

I'd guess someone had a nylon hose attached to it, and ran it to a boost gauge in the cockpit.

That's a brass compression fitting for 1/8" nylon tubing. It definitely does not belong there as it's not a factory style fitting. I'd pull it out, and plug the threaded hole with a 1/8NPT pipe plug.

Or, put a line on it and run a boost gauge.

 

[just plain john]

Factory stock vacuum blocks have only 5 ports. Plug it, or as already mentioned put a boost gauge on it.

 

[MPCAuto]

Thanks guys, I guess we'll just plug it. Far as I know it never had any owner other than the factory since it has no VIN.

 

[Sal 87WE2]

Thanks guys, I guess we'll just plug it. Far as I know it never had any owner other than the factory since it has no VIN.

You said it was donated? From which Factory? No VIN??

Can you post more pics of everything?

:biggrin:

 

[MPCAuto]

You said it was donated? From which Factory? No VIN??

Can you post more pics of everything?

:biggrin:

we will work on getting more pics up. The car was donated by the local Buick dealership many years ago. It was their showroom car and used as their sorta flagship. I do believe it has a vin but the plates are not on it due to the total body restoration that the local highschool did for us while we worked on the motor.

 

[Trick Or Treat]

hey guys im new on here i was wondering if you could help me out on my project i have a 83 ttype and i cant figure out the vaccum lines to the turbo if you could help i would really appreciate it

 

[just plain john]

Trick Or Treat, try the hot air section