Potential vacuum pump issue.. (3 Viewers)

[Josh NZ]

Hey guys,

So I’ve had a fair bit of oil leaking from my motor for some time, and I finally traced a fairly comprehensive oil leak out of the back of my alternator/vacuum pump area. My clutch has been making wierd scratching noise for a wee while and the pedal is a bit stiff every once in a while. It’s a 1987 BJ71 with the factory boosted clutch.

I can’t really replicate the clutch noise but it sometimes happens when I brake hard suddenly and push the clutch in at the same time.

Is my vacuum pump dying? If so, what’s my best course of action? New vac pump from Toyota is $700 plus shipping so that’s probably out!

Any advice or thoughts are welcome.
Cheers!

 

[jblueridge]

I had mine apart a while ago. I ordered new blades and O rings which Toyota calls Packing.
The old carbon blades showed almost no wear.
I put the new o rings in and bolted it back together.
I had a new oil hose made up for it, it has a banjo fitting.

A vacuum gauge and various tee and adapter fittings for vac lines has proved very useful to me.

 

[ALEXY]

@jbluridge :if the leak comes from the alternator itself with a "dry" look vaacum pump is there anything that can be done?
I assume the leak would be along the alternator shaft then?

replacing the blades made a difference?

 

[Josh NZ]

@jblueridge Thanks for the reply.

What vacuum figures should i be expecting if the pump was healthy? My boost gauge has a vacuum scale so i could tee into the output from the pump.

When i replaced the brake booster, the original one was full of what looked like oil. Can the pumps leak internally?

Cheers

 

[ozcrusier]

Josh the pumps can leak oil into the system gravity normally keeps the system reasonably dry but if the vanes fail they can pump some oil through the system. The pumps normally last for donkey years and so does the alternators on these old girls so something has to give.

 

[nickolai]

13BT has vacuum pump on the back of the alternator right?

If so you might be able to have it rebuilt.

 

[jblueridge]

I did not bother to replace the blades: the ones in place were almost indistinguishable from the new ones. Perhaps PO replaced them.

I can't recall the amount of vac I measured but it was considerable...more than 20 inches of Hg I think. Guys at brake booster shop did not believe me.

Josh I would seek out an auto-electrical shop that rebuilds alternators and that has experience with 24V and big trucks.
I got mine rebuilt as a precaution and the technician must have made sure the shaft that drives vac pump was sealed properly.
Sounds like your leak is in that interface between alternator and pump.

 

[Josh NZ]

@jblueridge Looks like a have some phone calls to make.

@nickolai
I’ve sourced a good second hand unit to keep me on the road and I’ll get my original unit rebuilt and keep it on the shelf as a spare.

I’ll still measure the vacuum produced between the two and post it up for reference just in case someone else has this issue. Will also be curious to see if it helps with my clutch issue as well.

Cheers for all the replies on this so far! Very helpful.

 

[nickolai]

I couldn't find any listings on Trademe for new ones, but is this one close?
Toyota Hilux 2.4 2.8 Alternator Internal regulator type

I got an alternator for a 1HZ i had through Ashdown Ingram - they have a GIANT Catalouge with good pics that might help: Ashdown-Ingram - Alternator & Starter Motor Catalogue 2014 - Page 1

Also if you can't have the alternator + pump rebuilt you could always add an electric vacuum pump - there'd be a bit of dicking about with capping oil lines and stuff but wouldn't be hard.

 

[Josh NZ]

I had actually been looking into an electric vacuum pump as well, but i was stuck on it being 24 volt so options which weren’t a massive pain were limited.

I suppose 12volt isn’t that bad to run with if it came to it..use a step down converter or something. Would need a pressure relief valve once it reached a preset amount of vacuum as well wouldn’t it? Or am I thinking about it wrong?

 

[nickolai]

Most approaches use a vaccuum sensitive switch, so the pump is off at over, say 25inHg and on when vacuum drops below say 18inHg. So this would give you constant vacuum in a useable range. It's common on engines with high lift cams which produce less vac.

Here's a hella one:
HL42808 Hella High Performance Electric Vacuum Pump

but yeah it would need a stepdown converter capable of supplying 10A.

Is your alt internally or externally regulated?

 

[Josh NZ]

Finally got the offending noise on video! It’s not so easy to hear but it happens twice towards the end of the video.



Thoughts on possible culprits? As hard as that might be!

 

[Scopedog]

If your alternator is one with the smaller pump, where the oil enters into a port on the alternator then your leak could be at the bushing on the rear housing. The shaft passes through a soft metal busing with an oil channel. The oil enters into the side of the alternator and flows through a port in the shaft and into the vacuum pump. After a rebuild, my alternator leaked from the seal - it exits a weep-hole just above the alternator bolt. I am not sure if it was a shaft issue, shaft alignment issue or the bushing was damaged. In any event, it did not appear that Toyota sells or ever sold the bushing separately. Perhaps it could be sourced separately.

 

[Josh NZ]

Finally had a chance to test the vacuum pressure from the pump. It appears i have a healthy pump!

However, i think i found the issue. In the video, you will see the vacuum drop by a couple of increments after it reaches full pressure. That's me pumping the pedal to the floor each time. Next it drops quite quickly to 0. That's me quickly pushing the pedal in, just until it resists slightly, several times.

I think my booster/cylinder rod is adjusted wrong and is emptying the vacuum reservoir when pressed to take up the free play in the pedal.

I probably have explained this poorly but hopefully somebody will chime in with their thoughts?



Cheers

 

[Rubiclone]

Finally had a chance to test the vacuum pressure from the pump. It appears i have a healthy pump!

However, i think i found the issue. In the video, you will see the vacuum drop by a couple of increments after it reaches full pressure. That's me pumping the pedal to the floor each time. Next it drops quite quickly to 0. That's me quickly pushing the pedal in, just until it resists slightly, several times.

I think my booster/cylinder rod is adjusted wrong and is emptying the vacuum reservoir when pressed to take up the free play in the pedal.

I probably have explained this poorly but hopefully somebody will chime in with their thoughts?



Cheers

Did you ever figure out the reason behind your issue?

 

[Josh NZ]

Did you ever figure out the reason behind your issue?

Yes… in a sense. It turns out I had a few different problems all manifested in 1 area. My vacuum issue was not poor adjustment from the pedal but a failing clutch booster. I swapped my original one out for an identical looking Chinese copy and the vacuum issue was sorted. The original one was full of oil!

The intermittent noise coming from my clutch/gearbox area was a bolt which some idiot (me) had forgotten to tighten and had come out, and was whizzing around/catching on things in the assembly as it was operating. Which ultimately ended up jamming the whole assembly one rainy night on my way home. One new clutch and machined flywheel later that’s all fine.

The oil leak from the back of the alternator is still happening but I’m just living with it for the mean time. I had the original alternator fully rebuilt at considerable cost but it still leaks from the oil line. So some carpet under the truck and a top up of oil every once in a while is fine by me.