Vacuum pump or brake booster?

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T

thx3232

10 Year 15 Year
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Jun 18, 2009
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Location
cawston, b.c.
I just purchased a /84 diesel wagon. The brakes work, but they have to be pressed very hard. Feels like 'power brakes', missing the power.
Would this be a non-functional brake booster? I believe they run on vacuum, not hydraulic. Correct? Is there a vacuum pump that may not be working?
When I hold my foot on the brake and then start the engine, the pedal does not depress at all. Before I go and purchase a new brake booster (expensive), I should make sure that it's not the vacuum pump?

Any pointers would be appreciated,
thx3232
 
thx3232 said:
I just purchased a /84 diesel wagon. The brakes work, but they have to be pressed very hard. Feels like 'power brakes', missing the power.
Would this be a non-functional brake booster? I believe they run on vacuum, not hydraulic. Correct? Is there a vacuum pump that may not be working?
When I hold my foot on the brake and then start the engine, the pedal does not depress at all. Before I go and purchase a new brake booster (expensive), I should make sure that it's not the vacuum pump?

Any pointers would be appreciated,
thx3232
Click to expand...

All brakes in LC are hydraulic. Vacuum only provides assitance.

Check for vacuum at the booster first. If there is no vacuum there, then check at the pump. If you vacuum at the pump, then you have a broken hose or a cracked/rusted vacuum resevouir. Its just a simple process of checking connections from the booster back to the vacuum pump.
 
thanks, i'll try working backwards.
is the vacuum pump driven off the motor? this is my first vehicle with a brake booster, i'm trying to understand how it works. why did toyota not just use 'power' brakes? is there an advantage?
 
The term "Power Brakes" refers to the vacuum assistance from the brake booster. Cars prior to mid 60's were not usually fitted with brake boosters, or dual circuit brakes for that matter. So they made a bit of hype to sell the new safety feature.

In petrol driven cars the vacuum is bled from the inlet manifold of the motor. In diesels the usual thing is that there is a pump grafted onto the back of the alternator. There will be 3 or 4 hoses going to it, two from the motor which are oil lines. One from the brake booster and the other may go to the air cleaner (this is the pumps exhaust).

If you don't have any vacuum applied to the Booster follow the hose to the alternator. If there is no pump, then it may be that the previous owner replaced the alternator with one off a petrol motor which doesn't have a vacuum pump.

They do get a bit expensive. The pumps are usually no fuss, but have been known to have oil seals fail causing the engine oil to be pumped through the alternator.

Follow the hose from the brake booster to the pump, you may also have a vacuum reservoir. Any leaks from any of the hoses or fittings will mean no boost assist for your brakes.

If this is your first diesel/Landcruiser do youreslf a favour get the factory workshop manuals, you can download them from the mud website.

Cheers
Perry
 
thanks for the in-depth explanation.
looks like the vacuum pump.
you are right, it is attached to the back of the alternator.
if it likely just a seal, is it possible to rebuild the existing pump? or should i just bite the bullet and try to find a new pump?
 
Short answer is yes it can be rebuilt.

Longer answer, quicker to replace the alternator/vacuum pump assembly with a replacement unit. Either a second hand one from the wreckers(auto dismantlers) Epay, or a generic replacement unit. Then rebuild your old one at your leisure as a spare. Don't do a half job, rebuild both the alternator and the pump.

Not having your general location makes it a bit hard to advise ( you can put a general location as part of your profile) with regards local conditions.

Cheers
Perry


The factory workshop manual has the proceedure to do the job
 
thx3232 said:
thanks for the in-depth explanation.
looks like the vacuum pump.
you are right, it is attached to the back of the alternator.
if it likely just a seal, is it possible to rebuild the existing pump? or should i just bite the bullet and try to find a new pump?
Click to expand...


Do you know that the pump is not sucking air for sure? If so, you need to take the alt out, and remove the pump from the back of it. often the threads that drive the pump are stripped, then you need a new alt-pump combination.
Make sure the setup is correct. There should be an oil-in and an oil-out line, then a vac line to the vac canister, then a line to the booster.
cheers,
J
 
Tobugrynbak, you said,:
"The pumps are usually no fuss, but have been known to have oil seals fail causing the engine oil to be pumped through the alternator."

Could this be blowing oil all over the side of the engine? Today I am going to degrease/wash the motor to see what seals need to be ordered, but I had been thinking that it looked like something was actually spraying oil. It's in the same area as the back of the alternator, and directly above the alternator area on the inside of the hood. The cooling fins on the front of the alternator have no oil on them though.

Jan-78FJ40, I have pulled off both of the intake and output vacuum lines from around the pump and there is no air movement. Otherwise it does look like the setup is correct.

I am going to call around today and try to get some quotes on replacements.

Thanks for everybodys input!
 
Looks like you need some help. I suggest you connect with your local TLCA club: CA.BC- Okanagan-Similkameen Land Cruisers - IH8MUD Forums

Goldboy, (AKA Simon) is near by in Hedley.

Make sure you confirm that there is no vacuum at the pump. If there is no vacuum, pull the alternator and remove the pump to see if it is the spline or the vanes. You can get used parts from Greg and Sheldon at G&S Cruiser Parts in the Fraser Valley or Steve at EBI in Port Moody. They can have parts to you overnight on the bus. Also, check the Vancouver Craigslist. A number of our club members always seem to have parts for sale. You can ask on our club section: CA.BC- Coastal Cruisers - IH8MUD Forums
 
Thanks.
Oddly enough, I think I have met 'Goldboy' before. I think I got a welder off him a couple years ago. I forgot he drove a LC.
Small valley up here.

You guys have been super!
 
magnus_heydoc said:
3b alternator

I upgraded my power system to a high output alternator so I have the stock alternator with the vacuum pump for sale if you need one. Send me a pm if you like.
best
aaron
Click to expand...
Hi Aaron,is the stock unit still available and at what price,would you also mind to place a photo
 
I ordered the carbon vanes or blades.
I compared them to the old ones. Almost zero detectable wear.
I put the new orinfs in and calld it good.
 
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