Power Steering Issue

JT4SC · February 09, 2015, 03:54:04 PM

Hi everyone, I started my MCI 102C3 with a 6v92 DDEC engine just to run her a bit. Everything was fine, and after about 15 minutes or so I shut it down. My 5 year old son wanted to see the engine compartment, so I showed it to him. As we were back there I heard a dripping noise and what sounded like water gurgling in a tank. I looked under the bus and saw a heavy fluid drip that I was able to confirm was coming from the power steering reservoir. For some reason the power steering overflowed, which is crazy because I know the power steering fluid was a little low (I was planning on making sure the fluid was topped off next week when we plan to take the bus out for the weekend). I have never seen this happen before.

I started the bus back up again, then checked the the reservoir to see if power steering fluid was coming out. Now I could see the little teeth in the glass peephole, so I knew the fluid was back somewhere doing its job. After I shut the engine off I went back to check the reservoir. The glass peephole was again full of fluid, and I could hear that gurgling noise again.

I have always had minor issues with the power steering system making some whining noises, and we have looked everywhere for a leak to no avail, but now it seems something else may be happening. Any ideas?

Lee Bradley · February 09, 2015, 03:56:14 PM

Plugged filter?

eagle19952 · February 09, 2015, 04:10:28 PM

Any air in the overflow... sounds like the pump has been cavitating, suction side air leak ?

JT4SC · February 09, 2015, 04:32:27 PM

I'm not sure how I should check if there is air in the overflow? Also do power steering pumps have a filter? Sorry for being so naive, I don't have much experience with engine components.

To expand on the past issues - the power steering fluid has always leaked, the issue is we have no idea where it's leaking because the fluid isn't making it to the ground. I've tried the power steering fluid with leak stop, which seems to help for a short time, but the fluid level inevitably drops again within a couple weeks or so. How much it drops I'm not sure, but the teeth in the glass peephole get exposed.

The weird part is this time there is some reverse flow happening since the reservoir is filling up (and at one point overflowing) when the engine gets turned off.

OneLapper · February 09, 2015, 04:49:41 PM

The reservoir has a filter or screen in it. With the fluid being thick from cold weather, and with a dirty filter, it may have sucked air in from somewhere and pushed the oil out the overflow.

eagle19952 · February 09, 2015, 05:20:28 PM

the overflowed oil would look "foamy"..

JT4SC · February 09, 2015, 06:11:54 PM

I didn't notice it foamy, but I will try again tomorrow. Also I'm running regular power steering fluid, which is what I was told to do by the previous owner. Should I be running something else?

luvrbus · February 09, 2015, 06:27:08 PM

MCI uses Dexron ATF if the leak is not showing up on ground it's going into the engine I would bet it, maybe time for a new power steering pump

Boomer · February 09, 2015, 06:29:40 PM

ATF is the normal oil used in the power steering on an MCI. Your comment about the PS oil going down but no visible leak should concern you. I would be watching the engine oil level very carefully to make sure it isn't increasing. If the seal goes out of the PS pump in can dump PS oil into the engine and possibly wash down your rod/main bearings.

Lee Bradley · February 09, 2015, 06:30:49 PM

ATF should be fine. There should be a filter inside the reservoir if it can't pass enough fluid to the pump the pump will cavitate and fill the line with foamy fluid. That foamy fluid will displace more volume and push fluid out the reservoir. You will not necessary see foam in the reservoir as the pump is pushing it to the power steering unit so it would have to make the trip to the front and back. Plenty of time for it to revert to solid fluid. When the pump cavitates, it doesn't add air to the fluid it creates bubbles of vacuum.

Boomer · February 09, 2015, 06:31:25 PM

We both said the same thing at the same time luvrbus.

Lee Bradley · February 09, 2015, 06:40:13 PM

If the fluid was going into the engine as happened to the Oddessy a few years back, the reservoir shouldn't be overflowing.

JT4SC · February 09, 2015, 06:43:23 PM

I hope your right Lee. I'll confirm the oil level is normal in the morning.
If I take the lid off the reservoir where should I find the filter? Is it easy to pull out and put back in? Should I not even attempt this as a novice?

Lee Bradley · February 09, 2015, 06:52:29 PM

There should be a wing nut holding a large washer on top of the filter. If there is a filter. My bus shows a filter in the reservoir but it is a US built Neoplan with a v8-92.

eagle19952 · February 09, 2015, 06:53:02 PM

Quote from: JT4SC on February 09, 2015, 06:43:23 PM
I hope your right Lee. I'll confirm the oil level is normal in the morning.
If I take the lid off the reservoir where should I find the filter? Is it easy to pull out and put back in? Should I not even attempt this as a novice?

easy peasy way to get you wrench on ...