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Ford F350 hydroboost issues


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So, the real race for us at VIR is to see if we can work on the truck more than the car, so far the truck is 'winning'.

 

Situation as follows:

 

- Drive to vir, uneventful for once. Noticed brake pedal got hard a few times (like, out of power assistance) but nothing major. 

 

- Friday in South paddock for tech, unhook truck to go to lunch. Big problems. Had to two-foot drive it to keep rpm's off idle so I could steer and brake. Fun. Drive straight to Napa and get a pump. Truck was off, restart truck, no issues on the way back to track. We're thinking check ball or something similar. Decide to change pump to be safe. 

 

- pump changed, fire up truck, everything perfect. Leave south paddock, 1000', we are back to no brakes no steering. Must be the actual booster behind the master, so we change that today. Nada.

 

Only thing left in the system (I think) is the gear box. Is there a procedure for bleeding the system after a parts swap? 

 

See @Team Infiniti, should have brought you along, ironically enough not for a broken racecar :lol:

 

As it sits, this thing is interrupting my beer drinking for Sunday afternoon. Unacceptable. Or the other option is we move to VIR, which is more acceptable. 

 

 

Edited by pintodave
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5 hours ago, pintodave said:

See @Team Infiniti, should have brought you along, ironically enough not for a broken racecar  

 

Ha, let me guess,  I would get to drive the truck?

 

Your choices are a defect pump (possible but unlikely) Or air turned to foam.

 

From what you describe it is air.

 

After verifying there is return flow in the reservoir.... Every couple of hours you need to hit the starter (borderline not letting it start)to stir the fluid releasing trapped air, be sure to keep it topped off as to not get more air sucked in.

 

 

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Procedure I've used to bleed ps systems on hot rods after a build (not a hydroboost, never had any issues with one) is to jack up the front end and cycle the steering stop to stop about twenty times, keeping the level up like Infiniti says. Let it sit for a bit to de-aerate the fluid and repeat until there's no air left.

 

You should get an audible response (whine) from the pump each time you hit the stop and the internal pressure spikes. Don't turn hard against the stop, just enough to know that it's there and working a bit against the stop.

 

Mercon V synthetic seems to be the recommended fluid, not ps fluid.

 

Hope that helps.

 

P.S. Just found this:

After installing a steering gear or pump in a vehicle with a hydraboost braking system, you may discover odd problems after bleeding the system in the normal way. The problems would be lack of power assist in your brakes, lack of power steering or some combination of the two. The reason is air in the system. Air in the system can cause all kinds of strange problems with the hydraboost system.

A manual will tell you to use a vacuum bleed system which is very complicated and requires tools that many shops do not have. Another alternative that we find works well is as follows:

  1. Jack the vehicles up so the tires are just clear of the ground.
  2. Make sure the steering wheel is centered and start the engine.
  3. SLOWLY turn the steering wheel to the right half an inch from center and then left half an inch from center. Continue to do this SLOWLY increasing the amount you turn the wheel half an inch at a time until you are going lock to lock. This process should take at least a half hour.
  4. During this process, it is important that the fluid level in the pump remain above the pump casting so you do not introduce more air in the system.
  5. If you get small bubbles appearing in the fluid, you have to shut the vehicle off and walk away until the bubbles are all gone. If small bubbles re-appear, you need to shut the engine off again and take another break. There is no way to speed this process.
  6. Once you have gone through this process the steering and brakes should work.
Edited by mender
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So. It still isn't bled perfectly. It was good enough to get on the road. Fine at speed but gets iffy at idle. 

 

It got us on the road long enough for the trans temp sensor to go bad and put the trans in limp mode. Can't make this stuff up. 

 

The good news is we got one at the Ford dealership and we found the local Walmart to get busy.

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1 hour ago, pintodave said:

So. It still isn't bled perfectly. It was good enough to get on the road. Fine at speed but gets iffy at idle. 

 

It got us on the road long enough for the trans temp sensor to go bad and put the trans in limp mode. Can't make this stuff up. 

 

The good news is we got one at the Ford dealership and we found the local Walmart to get busy.

At this point you should just stay up there and wait for next year's race. 😄

S. 

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