workings of vac pump - 13BT (1 Viewer)

[jblueridge]

I have put my BJ74 back together only to find that I have either a vacuum leak or vacuum hoses incorrectly routed/plugged in.

The dash brake warning light never goes off. When I plug/block the 2 large lines leading into the pump from clutch booster and brake booster reservoirs, there is no change.

When I turn the ignition key off, there is a 10 second delay until the VSV butterfly actuator shuts the engine down.

Air is sucked in by the pump, but I don't know where it goes after that.

I have the vacuum line diagram from the a parts catalog, but it is not a hi-rez image and I find it hard to read, much less understand.

Any advice would be appreciated.

 

[jblueridge]

Anybody with some advice or wisdom?

I'm thinking of taking the vac pump off and apart this weekend.

 

[ozcrusier]

Sounds like a vacuum leak to me because of the 10 second delay when shutting the engine down.

 

[roscoFJ73]

You need to test the pump and then test the vacuum at another end from the hose. Does increasing engine rpm increase vacuum?
Vac test guages can be bought cheaply. The pumps also have a regulator that opens when the vacuum gets to a certain level. On some landcruisers it is 6 hgz? (I forget the unit of measurement for vac)

 

[lowenbrau]

I looked and looked for a diagram for my BJ74 and didn't have any luck. I, too think that the slow shutdown in is an indicator that you've got a significant leak somewhere or perhaps a vsv installed backwards. It is easy to confuse the boost compensater system at the IP for vacuum too. The lines look the same.

 

[jblueridge]

Thanks guys. I now have a vacuum test gauge. I need to get some adapters to let me attach to the larger brake and clutch booster lines. A quick imperfect test of the smallest line that comes out of the pump shows at least 16 inches of Mercury (the Hg Roscoe was aiming at.)
I read some other posts/threads where the values 16 and 20 are considered good.

I disconnected the brake and clutch booster lines and plugged them. It still took 10 sec for the engine to shut down. When I plug the line to the VSV and leave the brake and clutch boosters connected normally, the dash warning light remains on. So either I have more than one leak or the dash light is staying on for other reasons.

I hadn't meant to change anything related to vacuum lines during this last re-furb of components except the rebuilt clutch booster. Either I did not get things back correctly or there's a true leak somewhere. I did not touch the VSV and it is rather new.
Thanks Lowenbrau as I could not figure out where al the extra lines came from on that side (fuel line side) of the motor.

 

[Greg_B]

Found this in my computer after a search. Can't recall where I got it, but might have been mud a while back. Hope it helps and is a better resolution.

gb

 

[roscoFJ73]

Was it getting good vacuum before you put it all back together?

 

[jblueridge]

GregB! That diagram is about 17.4 times better than the one I have now! Thanks so much!

Roscoe, I am not sure. It seemed to make pretty good vacuum before I took things apart. I looked inside the vac pum and measured the carbon blades; no detectable wear. I glass-blasted the turbo oil pipes and replaced all sorts of hoses + an alternator rebuild. When I ran the engine to do a turbo oil supply leak test, I had some vac lines disconnected. Also, I had to jack the engine up to replace motor mounts and to get the starter in and out for rebuild. I am thinking I crushed something or popped something loose raising the motor. I sure can't see anything obvious.

I made up some vacuum test gauge adapters out of mini-brass tubing. I have some extra vac hose. If it ever stops raining I'll try to track this thing down.

 

[roscoFJ73]

If you cant remember ,there was probably nothing to alert you of a problem. What happens when you select 4wd?

 

[jblueridge]

I did not think to try 4wd. The dash warning light and the lack of power steering at low RPM blew my mind.

I'll try that 4wd vac actuator this afternoon. Good idea, Thanks!

 

[jblueridge]

Some progress in the rain.

4wd vac actuator does work correctly.
Disconnecting the leads of the brake MC fluid level sensor/switch makes the dash warning light go out.

I'll search for the smallish leak that must be there tomorrow.

 

[jblueridge]

Vacuum pump is making 23-27 inches of Hg. Depends where I measure.
I could not find a leak.
I think maybe the shutoff actuator has a torn diaphragm.