Power Brake Vacuum Assist Failure on Diesel Vehicles

[calebmogul]

I replaced my second vaccum pump in east LA last fall. The first blew about 10k before. In both instances, the brakes were really hard, but would gain pressure again after the engine was under load for a while, then go hard again after being used again. Turns out my brake booster was broken, which explained the early burnout of the second vaccum pump.

I pulled in to Covina Diesel on a Friday afternoon at 3:00, just getting started back to colo from Jalama Beach. The guy was slammed, but was able to get me on the road nonetheless. Apparently the shop who replaced the first vac pump didn't check to make sure it was pressurizing correctly.

If you ever get stuck near LA, Google Covina diesel. Brake booster, vaccum pump, and labor was about $750, off the top of my head. But it was super cool that he squeezed me in, as he set him self up for a late night working on a previous customers box van that had to be ready in the morning for deliveries.

[Jeffrey]

My vac pump went out on my 6.0L in Boron, CA on my way to the Grand Canyon on a Sat. I limped back to Lancaster and finally decided, after a few test runs, that I could drive back to Santa Barbara without power brakes. It was dicey, but I made it safely. Monday morning I was waiting at my ford dealership service gate and they were able t get the part and install before 5PM. I left right away and got to Needles by midnight. Been fine since.

But, this brings up an idea… Can anyone find a 12v. vacuum pump that equals the pull of the mechanical one, that could be connected to the hose coming from the original in order to restore all the vacuum assisted systems (brakes, ventilation, etc.) while on the road?

[Viva]

Just curious if this is similar on an E-350/V-10 gas? I know my E-350 has the vacuum vs. the hydraulic boost on the E-450, but is there some reason it is less of an issue on a gas rig vs. a diesel (even if it is the same system as the diesel - if it is)?

I don't mean to derail the thread, but of course this made me wonder, since it sounds diesel-specific, and yet I am pretty sure I have vacuum boost brakes too (V-10).

Thanks.

[unimogdave]

One disadvantage with hydraulic boost on both brakes and steering is if you have a pump failure you loose the brakes and steering. Now that sucks!

Dave

[UJOINT]

We replace a lot of them. 7.3's are much easier than the 6.0's.

Since we do a lot of engine work we generally replace if we're in there. Nothing worse than being right there and not replacing it!

[carringb]

Originally Posted by Viva

I don't mean to derail the thread, but of course this made me wonder, since it sounds diesel-specific, and yet I am pretty sure I have vacuum boost brakes too (V-10).

Thanks.

Vacuum is inherently generated by gas motors due to the throttle body which diesels don't have.

[Viva]

Aha, thank you! Now I understand why it was more of a "diesel owners take note" thread, even though I have the vacuum boosted brakes on the V-10. Sorry to interrupt, but maybe someone else wondered too...

(Somehow I feel as though I should have known this Well, now I do, anyway!)

Viva

[photographix]

Originally Posted by BogusBlake

Are there detectible symptoms which could indicate an impending failure?

Not on mine. It was working when I pulled into the space in the parking lot, then not when I went to leave again. No banging or any other funny noises. Pulley turned freely when I had the old one off the engine.

[jaclindavis]

I am on my third vacuum pump on a 1996 7.3, 180,000mi. The first failure was at 105,000mi, without noise or warning going down a steep grade and it took all of my 200lbs and both feet on the brake pedal to slow it down. Kind of scary. The brakes returned to normal long enough to get to a Ford dealer. The dealer replaced the vacuum booster and 100mi later brakes fail again. This time the dealer replaced the vacuum pump, total price for the two, $2,100.

All goes well for 10,000mi, then leaving camp, the smell of smoke brings us to a stop. The vacuum pump has seized up and the fan belt is slipping on the pump’s pulley. At idle the pump stills turns, above idle the pump freezes up, power brakes inoperative and steering affected. We limp at 10mph to a ford dealer 20 miles away. It takes 2 days for the part and one day for repair under warranty.

The last failure was in Las Vegas last week(3-12). Started to hear an strange noise, similar to a ratchet wrench. Took it to Ford and R&R the vacuum pump. Another $600+. Headed for Death Valley and about 20mi from dealer the lower radiator hose blows off. Upon inspection it appears that the mechanic took the pump out the bottom and in the process pushed the hose off its seat. Replaced the hose, filled radiator with onboard water and headed for NAPA parts for replacement coolant. The shop manual for this year says removal is out the top with removal of upper radiator hose, pulley, fan and shroud. A special puller is needed to remove the pulley to gain access to the mounting bolts
I will carry a spare pump and the puller in the future. New pumps do not have pulleys mounted.
So there you go vacuum pump fans.
Add this event to the list in the on going topic of "field repairs".
Jack

[daveb]

I don''t see this as a field repair for my 6.0 with my skills. However if there was a way to put a valve to hook in a temp 12v pump like Jeffery's talking about just to get me out of the back country, I'd be willing to have that set up. Mine didn't freeze up and as long as the majority of these failures simply kills the vacuum, I wouldn't mind packing a backup pump. I guess the question is if you could install some kind of a remote port would the factory pump keep a portable pump from making enough vacuum to keep the brakes working? As long as the pump would be cheap & small enough to pack I'd haul one around. Would you have to regulate the vacuum pressure?
When mine went out, I opened the hood and had a hard time seeing if the belt was even intact. Mechanic I'm not.