MC8 8V71 skinner valve and fuel leak

[jok]

I am working on a new to us 1977 MCI 8 with an 8V71. I have an air leak that I believe is in the fuel shut off skinner valve. It still works okay but I would like to replace or rebuild it. The local Detroit Diesel place is no help. Are there skinner valves or rebuild kits available? Also, I have a fuel leak that is coming from the fuel tank area. I have not looked too far into it yet but it seems to be running out the bottom of the front bay doors. Not sure if there is a loose drain or connection. Any ideas on where I should look first. I lose about an inch of fuel per day.

Thanks,
John

[LutherC]

John,

I also have a 1977 MCI 8 and purchased a rebuild kit for the engine shut down Skinner Valve from this source. The kit contained a plunger, spring and O ring.

http://busfixx.tripod.com/busservice/

Luther

[Tony LEE]

If you have the auxiliary fuel tank fitted, I guess that would be the first place to look - although the bottom interconnector pipe runs under the floor. Otherwise at least remove the whole fuel tank compartment door and have a look. There is a fuel level switch that could be leaking, of maybe you just have a rusted out fuel tank like others have had.
1" a day is an expensive leak and also a very messy one.

There is also a fast idle valve next to the engine shut off valve - both look similar and if you have the optional electric tag axle unload system, there is another valve on the next step forward. Easily accessible through the rear floor hatches.

[buswarrior]

Hello jok

Default answer is you have a hole in your fuel tank.

You need to act now, as your are having an environmental spill, not taken kindly by any jurisdiction in the US or Canada. Fines and clean up costs will ruin your day.

Park bus so that you can get the 6 feet of tank to slide out the side where the fuel filler is. Pull the front panel off in front of the tank. There is a bolt in each of the upper corners, on the inside, and then it lifts up and out. Bottom is on pins.

The drain plug is at the very bottom, on the side face you are looking at. You need something big enough to transfer whatever fuel you have to drain out.

Then you may relax and get the tank out. Take careful note of how snug it is. This dictates the repair strategy. If someone just welds a big patch on the bottom and adds depth to the exterior dimensions....well, it won't go back in. Same for replacing the thin wood base that it should be resting on. Do not put anything else in there but the 1/4 inch hardboard that came out.

You may have to really haul on that tank to get it out. A 3/8 thick piece of plywood, oh, a foot wide a couple long driven in under the tank will get the low part to pop out of the rut it is sitting in. That's why the tank isn't pulling out after you get the fastening strap removed. A chain and the pick-up truck also works, keep your fingers clear!

Unfortunately, this all makes sence after the tank is out, and doesn't before!

Go and catch the drips.

happy coaching!
buswarrior

[jok]

Luther, TonyLee and buswarrior, thanks for all the great information. I have catch pans under the bus to catch the fuel. Hope to work on the tank this week. Your details about the tank and removal are very helpful. I contacted the people at Bus Service, Inc. in Kansas (http://busfixx.tripod.com/busservice/). I think I spoke to John. He was very helpful and took the time to explain possible problems and fixes, not only for the skinner valve but a few other things I had questions about. I was impressed that he spent so much time during his busy day to help with all my questions. He told me he had 20,000 parts in stock, including the skinner valve rebuild kit. But he recommended that I try cleaning it with BrakeKleen before spending money on the kit. Can't beat that. As always, this is a great place to come for answers.

John

[Fredward]

John,
I removed and repaired the tank in my -5A last winter. It was no problem. Like Buswarrior said, it will all make sense after you have it out. But in my case the bracket straps were accessible and not rusty. The tank itself slid out after draining without issue. But it is a tight tight fit. Its all aluminum so it shouldn't really rust out but I guess they do. Mine leaked at the fuel sending unit because there was no gasket on it. And it also leaked on the drivers side end because I un knowingly ran a self drilling screw into it while working on neatening up the wiring in the former AC bay. I was an EPA hazard anytime she was over 1/2 full.

While I was in there I replaced the sending unit and now as an added bonus I have a tank that doesn't leak and a fuel gauge that works! Good luck. I think I attached a picture of my tank after removing it. 

This is also a good time to install an electric pump for priming the fuel system. It will take you awhile to get prime after this ordeal.

Fred

[LutherC]

John,

I am glad John at Bus Service was able to help you out.
I first met John 5-6 years ago when my Bus broke down while traveling the Blue Ridge Parkway. At that time he operated a Bus garage near Nashville TN. He was recommended to me by a friend who was a mechanic at a Charter Bus Company in San Antonio TX. They worked together at Greyhound for many years. John decided it was too much of a hassle finding/keeping good mechanics, so he relocated to Kansas, set up a parts distribution center and now uses his extensive knowledge to guide people in getting the correct parts. 

Luther

[Tony LEE]

Thanks for that busfix contact John.  I've been trying to get an email reply from US Coach for a couple of weeks and another forum member even chased them up for me but still no reply so I'll have to try busfix.

Not too many MCI parts suppliers in this part of the world and maybe not many in the US that can be bothered to ship overseas.

Tony

[jok]

The skinner valve is no longer leaking. Taking it apart and spraying with brake cleaner did the trick.

Fred, It is amazing how big the fuel tank looks in the back of your truck. I am also planning on adding a fuel gauge when I pull the tank.

Luther, Bus Service is a good resource whether on the road or at home. I am adding their phone number to my emergency numbers list for when I am on the road. Thanks for sharing.

Tony, I saw that you are in Australia. Are you visiting or are you from there. In the early 60's my dad was a Seargent in the Air Force and was stationed in Perth/Welborne. We lived there for 3 years. I started school there. We had a pet baby kangaroo, which was very rare in our Australian neighborhood (no base housing). I even picked up an accent, which didn't last too long after coming back to the US, but long enough to get a lot of teasing. It was a little strange celebrating Christmas in the summer after living in the Michigan UP.

John

[Tony LEE]

John,

I'm Dinky Di Aussie currently on the road full time.

I guess by the time the 60's came the old "Bloody Yanks - Overpaid, Over-sexed and Over-here" bit from WWII would have been long forgotten  . 

Anyway, a wife and a kid or two would have kept him under control.