[dbeiter]

Hey Bob, This Odyssey that I just got is really challenging me.... When I got it running it was not firing on the RH bank, it would run, but very rough.. I bought 2 new coils, installed them, polished the rust off the flywheel, and air gapped them to spec (.008") ok, it now "sounds" a little better (not near a smooth as my 4016 though) but get this, If I pull the plug wire off the RH bank while running sound doesn't change, If I pull it off the LH bank, it roughens up... another thing, if I ground the plug with a screwdriver on the RH bank, engine continues to run, if I ground the LH bank it stalls................. I checked compression and it is at 150 psi on each side.. installed new plugs (I even swapped sides with the plugs, no difference) I have pulled this engine 3 times today and am about ready to shove this thing in the creek!! Do you have any ideas??? :headscratcher: :headscratcher: :headscratcher:
Thanks
Dave

 

[Hydriv]

Are you getting heat off the exhaust pipe on both sides and is the heat even? Did you try swapping coil wires? If both cylinders were actually firing properly, then the engine would continue to run on just one cylinder or the other. Have you adjusted the valves? I realize that 150 psi on both sides would indicate a near perfect engine but maybe heat is causing expansion and one valve is staying open after it's running for a while. In other words, you can't leave any stone unturned. This is always a process of elimination.

 

[Bob MacGregor]

Hi dbeiter,
A Vanguard will make spark just by cranking. So in order to shut it down, the coils must be grounded and this happens in the key switch and the seat switch. Disconnect each one to rule out and find the bad one. Is the seat switch still connected or bypassed? This grounding wire also goes to the PTO switch thru the three prong connector, check it out. Check the coil wiring for chaffing. Check the wiring diagram in the parts manual or operators manual. :facepalm:
Bob MacGregor in Taxonnecticut :mrgreen: :mowlawn:

 

[bhildret]

Don't rule out valve/tappet clearances as the root cause.

With the specific ACR on these, you can get strange compression readings ... good ones ... and still have not valve seating when it runs. There is a unique valve setting procedure and you should invest in a Vanguard service manual if you wish to keep the tractor. Might be able to download the procedure or manual on line.

I also recommend the LED spark testers which insert inline to the plug wire. Let's you very quickly move beyond spark as the base problem. No light ... ignition problem. Lighting up ... look elsewhere.

Brian

 

[walter kern]

I remember reading in the briggs repair manual about a controller that will only run one bank during light loads,used diodes, if one went bad the engine would run on one all the time

 

[walter kern]

had to find it in my book,the diodes are in the lines from the transformers ,shows line comes from trans thru each diode then tied together,then to a connector in equipment harness... DIODE FAILURE DIAGNOSIS ------- (switch on -engine runs on one cylinder-switch off engine shuts off -cause i diod closed )(switch on-engine runs both cylinders-switch off one cylinder shuts off -cause 1diode open) ( switch on -no spark- cause-2 diods closed ) (switch on-runs both cylinders -switch off-engine won't shut off-cause-2 diodes open )2

 

[Bob MacGregor]

Actually the diodes for each coil are in a harness of their own. Get your engine model and type numbers, got to the B&S website, plug in your numbers and select parts manual or IPL. It will be a pdf, save it to your documents so you can refer to it any time. The Vanguard service manual that I have is P/N 272144-6/04. The last part is the update date. Get youself a Vanguard service manual, but be carefull while using it as it covers many different Vanguard versions in both vertical and horizontal configuration.
Bob MacGregor in CT :mowlawn:

 

[dbeiter]

Ok, I adjusted the valves, they were a little loose... Would the diode issue cause the engine to run either bank when at idle??? Because I can pull either plug wire off when it is running and the motor still runs.. I am going to check the RH bank kill wire tomorrow and see what it looks like, then look for those illusive diodes I cannot see where these could be as the only wires on/ going to the coils were the kill wire and the high tension plug wire.. I will look at my manual again

Thanks
DJB

 

[Bob MacGregor]

The coil wires plug into a Y harness, in the Y harness are the diodes. The Y harness may be a separate unplugable harness by itself or it may be part of a larger harness.
Mad Mackie in CT

 

[dbeiter]

Bob, you mean the grounding (kill) wires right?? As it looks in my service manual they should be right there close to the coils themselves.... I hope to tear into this thing again tomorrow night.. I will then report back

 

[Bob MacGregor]

Yes, they are the "kill" wires. The diodes are there to prevent cross feeding between the two coils when the keyswitch is selected to off.
Bob MacGregor in CT :mowlawn:

 

[dbeiter]

Bob, pulled the sheetmetal panels tonight and got to the coils from the backside (Yeah didn't have to pull the engine again!!!) found the y cable and diodes... I am going to go get the wire tomorrow, I hope they are in stock!!! Will report back after this attempt!!

 

[Bob MacGregor]

Check the diodes with an ohmmeter to see if they are OK or if there is a bad diode.
Bob MacGregor in CT :mowlawn:

 

[ironheadxl]

I Know this sounds silly. But put a brand new set of plugs in. some times you will have good fire with the pulgs out. but under compression they can be "snuffed out". It doesnt take much to semi-foul a plug. I've seen this a few times.

 

[dbeiter]

I put 2 different sets of plugs in it... the new set of Champions and a set of Autolites out of my 4016.... I wish it was that easy!! :sidelaugh:

 

[dbeiter]

Bob and others, you guys are awesome!! I finally received the diodes the other day and finally got them installed today...The engine purrs like a kitten

thanks
Dave

 

[Hydriv]

Dave,
Now you will really be able to experience the Odyssey.

 

[tanandorange]

Dave,
Glad to hear it's running like it should. I think you'll like that tractor, especially considering the price.
John

 

[Bob MacGregor]

Vanguards Rock!!!! Well-----most of the time!!!! :sidelaugh:
Mad Mackie in CT :thumbsup: :mowlawn:

 

[dbeiter]

I agree that Vanguards Rock!!........... I took it out for a drive this afternoon and she seems pretty peppy, Now I just have to get a new rectifier and all will be good (mechanically)

Thanks again guys!