Why does Honda have their own formula?

I have been a grease monkey for many years and this has always had me wondering....

The book says the seals will swell and leak if the proper fluid is maintained, there has to be other collateral damage as well. What would I be looking at for damages of non-Honda fluid was used?

The reason I ask: I suspect the wife's Accord has been topped off with regular PS fluid.

 

I never knew the real details. Must be something about the formula that makes the seals swell differently than "normal" PS fluid.

It's more common than you think, for rubber parts to swell or shrink depending on what they're wetted with. I had a fuel pump go bad (on an 89 Saab) and while I waited for the new pump to arrive I cleaned up all the mounting stuff around the pump. The pump was held inside a can in the gas tank, inside a bunch of rubber bushings. A week later when the pump arrived, those rubber bushing had shrunk about 20% so I couldn't get them to fit around the pump. When I realized what's happenning, I put the bushings into a jar of gasoline for about 4 hours, then they fit just fine.

The reason I tell that story... Someone in Honda must have chosen their favorite combination of rubber compounds & a certain concentration of additives in the PS fluid. They make the rubber seals & bushings so they swell just enough to fit properly with that fluid.

I bet if the fluid was "topped off" with regular fluid you're probably OK. It's still MOSTLY the proper fluid. If it was drained & filled then you should worry about it.

 

Cool works for me!

I had to refill it the other day as it was growling. The fluid in it is dark brown, so it's time for a flush.

When they run low, they sure don't sound like a traditional PS pump. They sound like they are going to die, right then and there! It took a few minutes, but it finally burped and has quiet ever since. Don't know why it was so low, and can't find any leaks, so I will have to keep my eye on the level....

 

When you flush it, check out the fluid reservoir. There's a fine mesh screen down low in there - it should be submerged. If that's plugged with crud, it might be starving the pump. If any seals were sketchy, it might cause the pump to suck in some air & make foam.

 

It's not making foam now, but I am keeping an eye on it. How difficult is it to pull the reservior and clean it?

Flushing is the easy part, except for which hose to pull to do the flush.....

 

Removing the reservoir is the easy part. Just have to handle the mess of spilled fluid.

The low-pressure hose (pump inlet) just has a simple hose clamp. High-pressure hose (pump outlet) is a bolted connection with an O-ring. Some people disconnect at the reservoir & connect long hoses to a bucket.

Some years have a PS fluid cooler in front of the radiator - looks like a big hairpin of steel tubing just one pass back & forth visible through the lower grille opening. That's another place to disconnect & add hoses to add/drain fluid.

 

Yep, hers has the the cooler! I will be ordering a case of fluid and flushing the system here soon. Chocolate brown isn't a good color for PS fluid.....

 

Just an update:

It's been a month, and the level (overfilled, oops) has now dropped from completely full to the brim, to just above normal. No more noise, no weird feelings when steering and the level hasn't changed in two weeks.

Still don't know where the fluid went.....