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6V92 fast idle

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6V92 fast idle
Mon Jul 20, 2009 3:01 pm


My friend has a 1982 Eagle with a 6V92. He mentioned to me the other day that his fast idle does not work and I was wondering if I could help him fix it. Can some of you that are diesel mechanics explain to the rest of us how the fast idle works and if I can help him fix it?
Manny & Darlene's
1972 Silver Eagle 05
VIN # 8851
8V71 / HT740 4 Speed Automatic
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buscrazyinFL
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Re: 6V92 fast idle
Mon Jul 20, 2009 3:38 pm


I'm assuming this is an MUI engine? If so, I would start at On/Off switch and check for loose connections. If all is good there, I would go to the buffer switch on the governor housing and check for loose connections. If all looks good I would check to make sure I was getting power all around. Hopefully it is just something simple. Worst case scenario would be if the buffer switch is bad because they are pretty expensive.
Dale Houston
1993 Eagle 15-45
Nashville, TN
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Songman
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Re: 6V92 fast idle
Mon Jul 20, 2009 3:52 pm


Manny,

First, have your friend check the high idle cylinder on the top of the engine. It is next to the engine stop/run cylinder and looks the same. Make sure this valve is not stuck. The cylinder is exposed to the elements and gets gummed up inside. It can easliy be removed and taken apart and cleaned up, maybe even install an o-ring kit. You can also just spray some penetrant on it and see if you can free it up. Also make sure it is not loose and missing the mark.

If this is not it, check to be sure he has power across the 89 circuit breaker located in the front electrical panel near the upper right hand corner. The circuit breaker will have bus bar 80 on one side of it, which powers the circuit breaker from the master switch and 89 wire on the other side of it.

If he has power across the circuit breaker, then go to the front air control panel in the compartment below the front electrical panel and check to see if there is power at the 89 wire going into and out of the high idle air switch. The high idle air switch closes at 70psi, so make sure the bus has sufficient air pressure and the high idle switch on the dash is on and the park brake is set. When the high idle air switch is closed it sends power through 89 up to the park stop air switch located just above the high idle air switch. At the park stop air switch 89 wire and 109 wire are on a common terminal.

Power from 109 wire at the park stop air switch is then sent to the gear shift switch. The gear shift must be in the neutral position. From the gear shift switch, 109 goes up to the high idle switch on the dash.

Then check to see if there is power at the 109 wire going into the high idle switch on the dash. If he has power at 109, then check to see if there is power at the 110 white wire coming out of the high idle switch when the switch is in the on position.

If there is power at 110 wire, it then exits and goes back to the high idle skinner valve in the engine compartment which was located just to the right of the rear electrical panel. This skinner valve activates the air pressure to the high idle cylinder on top of the engine.

Keep in mind that I am assuming everything is original in the bus. If he has lost power between any of the switches or components, then we will have to start checking connectors in the wiring harness. If this is the case let me know and I will tell you which connectors to check.
Daniel Lenz
Brownsville, Texas


The work of an unknown good man is like a vein of water flowing hidden underground, secretly making the ground greener.
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Re: 6V92 fast idle
Mon Jul 20, 2009 4:44 pm


I appreciate the info guys... I think this is way over my head. I can check the electrical part but when it gets to the engine part you guys lost me. I would love to learn all about these diesel engines. If I could see some pics or diagrams that would help me tremendously.

Here are a couple of pics from the bus in question. It was one of the Eagles that Greyhound inherited from Trailways. You would all go crazy over this bus. The owners decked it out inside with a Harley theme. He is actually a member on this board (Eagle1), but hasn't done a whole lot of postings (so far). I keep encouraging him. He and his wife are some of the nicest people you'd ever want to meet.

Image

Image
Manny & Darlene's
1972 Silver Eagle 05
VIN # 8851
8V71 / HT740 4 Speed Automatic
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buscrazyinFL
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Re: 6V92 fast idle
Mon Jul 20, 2009 4:53 pm


Beautiful Eagle! Please have him start posting, I would like to learn more about it. Gorgeous interior! This coach deserves a place in the project thread, even though it looks finished, I'm sure it would be eye candy to see all the goodies!

I think Dan has the problem pretty well covered, so I won't muddle it up! ;)

Paul
Becky & Paul Lawry
Dreamscape
1968 Eagle 01 #7443
Silver 8V92 HT 740

Dreamscape Eagle Travel Blog: https://dreamscapetravels.wordpress.com/

Dreamscape Build Blog: https://dreamscapesilvereagle.wordpress.com/
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Re: 6V92 fast idle
Mon Jul 20, 2009 5:13 pm


Manny, does your friend have Jake Brakes he may not have a fast idle if he dosen't have the right switch.
Dan the fast idle is mounted on the side of the govenor housing under the 2 on top where the Jake buffer switch is installed when equipped.
The ones on top are for shut down and the other to hold the govenor when you activate the fast idle.
If he has a fast idle with no Jakes it will be a cylinder about 1 1/2 around and 4 inches long with no wires only a 1/4 inch air line that works from a skinner valve on the back wall I have 3 skinner side by side.
Can you get a photo for us Manny and we can tell if he has a fast idle or not.
I have got to figure out this photo posting thing LOL

good luck
Clifford
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