NissanDiesel Forums

I am now starting the turbo on my sd22. I want to get rid of the diesel alternator and replace it with a different one. The problem would be the power brakes. If I mounted a vacuum line on the intake of the turbo would this creat enough for the brakes?

bacho wrote:If I mounted a vacuum line on the intake of the turbo would this creat enough for the brakes?

No.

If Nissan could have left off the vacuum pump, I think they would have

There is insufficient vacuum at the intake manifold to operate the brake booster.

You'll need another vacuum pump. A belt-driven or an electric drive. A couple of common belt-drive ones are pictured in this post.

There are nice electric ones too. They are not cheap. This one's $320 .

What about a hydroboost braking system? I guess you'd need to have power steering for that to work though...don't know if you have that or not.

steve a

I just had a thought (it doesn't happen all that often). GM had an electric booster on some cars in the 80s. I know this because a friend of mine had three fullsize GM Wagons and I had opportunity to keep several of them running for a number of years.

1986 (and only 1986) Buick Estate Wagon used it. 1985 and 1987 both were conventional vacuum boost.

They are very expensive to replace, and when one of them burnt up I called several places to investigate having the motor rebuilt, nobody would touch it.

Eventually, I converted two of his Wagons back to vacuum boost, using 1985 LeSabre parts in one case.

(Note for anyone here due to a search engine: the brake pedal has to be replaced, because the master cylinder rod has a different diameter hole where it mates to the pedal. And get the vacuum line and fitting for the intake manifold and the check valve.)

NAPA NBB529700, $581 + $85 core:


While this wouldn't be cheap if you had to buy one new, if you happen across one of these in an old GM car, it could be adapted and fabricated into your truck.

Is That what that is?

I see them on the 80's jeep cherokees and wranglers, 90's ones too, anything with the shoebox style from the 80's (cherokee classic, cherokee sport). Also I spotted one in a 90's astro van, and a mid 80's bmw 5-series

If you need a set of dimensions/specs for one from a 93 ish wrangler, I can check it up for you tommorow, I got a friend that has one.

Yes, that high pressure bulb that says Warning! High pressure stumped me for the longest time, I never knew it was electric and not vacuum powered, but then again I havnt spent enough time under the hood of those cars to look or care enough to look.

Would you need some kind of computer system to run those?

I'm not sure that the black plastic reservoir is always a tip-off to having the electric pump below the MC.

No computer is required. It's a simple pressure switch, IIRC. And it's mondo expensive to replace the thing if you need one. My friend bought one new replacement, after that one went, I converted it back to vacuum boost.

Oh, in that case I take that back about those cars, but ill check it up on the jeep wrangler tommmorow and cherokee box

OK ok, the 90's wranglers and jeep Cherokee sports dropped the electric booster, but the 80's ones had them.

I think the electric booster on the 80's Cherokees seem to include the brake proportioner as part of the assembly, and with everything it seems very bulky, ill get measurements whenever I get off my ass and venture out into the world

But just eyeballing it, the unit seems about a foot wide, 7 inches deep, and I think it had a 4 pin connector on it

Give or take it seems to be twice as complex looking as the GM unit Al put up earlier

do you get peugoet diesels in the states??they use an easy bodgeable belt driven vac pump..

zen wrote:do you get peugoet diesels in the states??they use an easy bodgeable belt driven vac pump..

Peugeot vacuum pump pictures here, as well as other vacuum pump discussion.

Add this one from evparts.com

evparts wrote:Most passenger vehicles built in the last 40 years use vacuum assisted braking. If your EV was originally manufactured that way, then it is likely to be hazardous if their functionality is not maintained. This Thomas vacuum pump is both quiet and efficient. Its 12VDC permanent magnet motor is rated at 1/10 HP. Vacuum performance is up to 22.9 in. Hg. We also include rubber shock mounts with threaded studs. Measures 7.34"L X 4.25"W X 4.7"H and weighs 4.5 lbs.

Note: Use with brake vacuum switch item number BK2785

Click here for Specs.

Price: $ 249.56
Weight: lb. 5.30

evparts wrote:This simple lightweight vacuum switch turns pump on only when needed. Adjustable vacuum setting. Has COM, NC and NO connections. The switch comes from the factory set with a cut off at 18 to 22 inches of mercury. The hysteresis is 15% to 20% of the 20 inches nominal so it's about 3 to 4 in/Hg

Contact Ratings: 4 amps @ 15 vdc, 1/2 amp @ 125 vdc

Measures 2.25"L X 1.5"W X 1.5"H and weighs 0.8 oz.

Price: $ 23.50
Weight: lb. 0.05

Reading a Dec-06 Northern Auto Parts catalog today (I'm a bit behind in my reading), I found a SSBC electric vacuum pump. It's no longer available from Northern (according to their website). Northern had it in their catalog last year for US$250. It's SSBC's No. 28146.

AutoAnything and Jegs have it for $280 now.



One sold on eBay recently for $180.



eBay seems to have a bunch of IRUNA electric vacuum pumps that looks substantially like the SSBC unit, at $100 a pop, which seems like a steal.

I recently worked on a 1992 F-700 that had an electric booster with pretty simple wiring. Its probly too big for the 720 but if anyone sees one of those trucks in the JY it might be worth looking into. That part may be a little rare though as most of those trucks seem to have air brakes.

asavage wrote:

bacho wrote:If I mounted a vacuum line on the intake of the turbo would this creat enough for the brakes?

No.

If Nissan could have left off the vacuum pump, I think they would have

There is insufficient vacuum at the intake manifold to operate the brake booster.

Al,

I was surprised to read your statement saying it has insufficient vacuum at the intake of the SD22. Are you saying the vacuum pressure is insufficient or the volumetric flow rate, capacity is insufficient. I can see the pneumatic governor and throttle body combo not wanting an additional air intake to run a vacuum brake booster, but I find it hard to believe the SD22 does not pull enough vacuum pressure to run a brake booster.

ecomike wrote:SNIP-.... but I find it hard to believe the SD22 does not pull enough vacuum pressure to run a brake booster.

Mike: If the SD22 could provide vacuum on the average to keep up the brake booster .... don't you think Nissan would elimate those little oil/vacumm pumps?

The pneumatic governor can be moved the fuel rack full retarded by 5-6" vacuum. The engine would die.

TEST: Using one of those little MityVac's, and with the Mity's vent open, at engine idle speed, the reading was 8" vac. With the Mity's vent close, the vacuum reading passed 25" vac.