hydroboost troubleshooting help

[mblaney]

I put hydroboost in my truck (with stock MC). It works well but I have never had the "lock all wheels" stopping power that I expected. I also have a problem with it running very hot, causing power brake failure and no power steering. This does not happen with city driving (low rpm) but on the highway pulling a load it heats up. Loss of power does recover after a few minutes at slower speeds.

I do not have an auxiliary cooler (will add one) but I am worried why this is heating up while driving in a straight line (highway) and not using brakes. I would think everything should be cool unless there is some restriction causing back pressure.

Should I change the HB?

 

[Thewespaul]

What kind of fluid are you running in the power steering? You won’t get the full benefit of the hydro without going to a newer larger bore mc.

 

[Snowmanw900]

What kind of fluid are you running in the power steering? You won’t get the full benefit of the hydro without going to a newer larger bore mc.

Which part numbers are the newer MC? I want to do this conversion on my 1990 f250 soon.

I'm still gathering up all the latest and greatest part numbers tho.

 

[Thewespaul]

Theres tons of different mc that will work, just make sure youre getting one with a 1.25" bore and youre golden. The 1 1/8" bore (factory) takes more travel to displace the same amount of fluid as the larger bore mc, you will get a stiffer pedal with the larger mc, but I kinda prefer that.

 

[ifrythings]

Theres tons of different mc that will work, just make sure youre getting one with a 1.25" bore and youre golden. The 1 1/8" bore (factory) takes more travel to displace the same amount of fluid as the larger bore mc, you will get a stiffer pedal with the larger mc, but I kinda prefer that.

1-5/16 bore ^

Simplest way to get the right one is to order a mc for an Fsuperduty, if your still running the drum brakes in the rear make sure to swap over the residual pressure valve(big hex shaped piece) to keep the rear brakes functioning properly.

As for the excessive heating of the fluid goes, you have a restriction somewhere in the system, it should be way hotter than the fluid is or it may even be making a hissing type noise.

 

[Thewespaul]

1-5/16 bore ^

Simplest way to get the right one is to order a mc for an Fsuperduty, if your still running the drum brakes in the rear make sure to swap over the residual pressure valve(big hex shaped piece) to keep the rear brakes functioning properly.

As for the excessive heating of the fluid goes, you have a restriction somewhere in the system, it should be way hotter than the fluid is or it may even be making a hissing type noise.

I was under the impression the 1 5/16” weren’t bolt on?

 

[gandalf]

When I did the hydroboost conversion I got my "new" master cylinder at the local Pick-n-Pull. It came with the necessary hoses attached, and a steering pump reservoir with the additional port. The MC is 1 5/16 inch, replacing the 1 1/8 stock. I pulled the parts from a proper year SuperDuty. I did not need to change or alter my brake pedal.

Once everything was installed I was a bit disappointed. I did not have "throw you through the windshield" brakes. They were barely better than stock. I had already replaced and adjusted the rear shoes. I mentioned this to Russ (Typ4), and he told me to replace the front brake lines. I did that (working under the truck and taking a brake fluid shower) and it made a world of difference. The old lines must have been soft and bulging with the pressure. I'm very pleased with the improvement.

 

[ifrythings]

I was under the impression the 1 5/16” weren’t bolt on?

That’s what came stock with the Fsuperduty, I’m not sure if they ever made a 1-1/4”mc, I’ve only seen 1-1/8, 1-5/16 and the newer trucks run a 1.5” mc which is what I’m running with an 08 booster as it won’t fit the older boosters.

 

[Thewespaul]

That’s what came stock with the Fsuperduty, I’m not sure if they ever made a 1-1/4”mc, I’ve only seen 1-1/8, 1-5/16 and the newer trucks run a 1.5” mc which is what I’m running with an 08 booster as it won’t fit the older boosters.

I’m probably just wrong on the bore size then, I think I remember seeing someone running the newer mc but slotted the holes for the narrower stud spacing. Does the 08+ booster bolt in the same?

 

[mblaney]

@I fry things I agree with you. This would explain why it heats on the highway when it should be cooling off. I will take the power steering hose off and check the bore size on the fittings and work from there.
I am using my original master cylinder with the smaller bore. If my pedal gets any stiffer I don't think I will be able to drive it. It should take less pedal pressure with the smaller master cylinder.

 

[ifrythings]

Does the 08+ booster bolt in the same?

No, but all I did was remove the nut and backing plate and push rod(input rod) and swap them from a dead obs unit to the 08. I’m also running the 08 gear box so I used a stock line from hb to gear. I reused the obs pump to hb but cut the hb end off and put an AN-6 end on and used a jic-6 to orb m18 fitting.

Note: 08 hb uses orb m18 in and orb m16 out.

You must be registered for see images attach

If someone wanted to run the 08 hb all you need to do is redrill the backing plate to match the obs firewall and cut a few inches out of the push rod and it will work.

 

[ifrythings]

@I fry things I agree with you. This would explain why it heats on the highway when it should be cooling off. I will take the power steering hose off and check the bore size on the fittings and work from there.
I am using my original master cylinder with the smaller bore. If my pedal gets any stiffer I don't think I will be able to drive it. It should take less pedal pressure with the smaller master cylinder.

You could have a collapsing hose, plugged hb or gear box. Do you have the useless factory cooler on the front crossmember?
I have seen these get hit and crushed and could be your issue.

You must be registered for see images attach

 

[gandalf]

I was under the impression the 1 5/16” weren’t bolt on?

The 1 5/16 inch MC was a direct bolt on exchange for my '92 truck. Iirc, it came from a late '80s superduty. I did not have to enlarge the bolt holes to make it fit. It just slipped in like it was made for it. I did not have to alter the mounting hole on the brake pedal. Everything fit as though it was a direct replacement.

I did make one serious mistake that day, and hopefully have learned something. It was a very hot day, and I became badly dehydrated. I was working hard, intent on getting all the necessary items for the hydroboost, and failed to notice the symptoms. By the time I was finished I had quit sweating, I was shaky standing and walking, and my hands were trembling. A gentleman appeared out of nowhere and walked me through the cash line and helped load things into my car. He pushed the wheelbarrow with all my stuff. He actually looked out of place in a Pick-n-Pull. He saw me safely into my car, where I had a single bottle of water. When I told Calvin that evening he berated me unmercifully, but kindly, about what I had done. If I was to EVER be in that situation again I was to call him, day or night, and he would come get me. He was that good a friend.

 

[mblaney]

@ifrythings Thanks for the info. I will look at the factory cooler for damage. I will be ordering a proper cooler to replace the factory loop anyway.

I really don't want to replace the HB as a shotgun fix... plus it is very difficult and $$ to get. If I have to replace I would much rather look for a newer HB like yours.

20km ride to work and at idle I have no power steering unless I give it some throttle... sucks.

@Thewespaul I am running ATF.

 

[snicklas]

Ok, this may sound stupid, but are the lines connect the right way? I was watching a YouTube video of someone that did a Cummins swap into a dead 6.4 Ford. In the initial few fire it up and check stuff out, the brakes and power steering weren’t working quite right. They thought it might be air in the lines, or issues with the power steering pump. They used a Cummins out of an F-700, and used the pump that was on it from that application. In the meantime, someone had stopped by his shop that was more familiar with the Ford setup asked if the lines had been installed correctly on the hydro booster, because it’s a fairly common mistake to hook them up backwards. He reversed the lines at the booster and the brakes and steering started working much better. He still has a couple of issues, but they are leaks from grafting stuff together.

I might be way off, but it doesn’t hurt to ask. Sometimes in troubleshooting, you have to start over. In a different job, my partner and I had an agreement, if we got stuck on a problem and asked for help, we would step in and help, but you had to answer any question asked. Occasionally the questions would start with is it plugged in and turned on...... and yes there was a instance or two that was the issue (grabbed wrong connector on the bench)......