1986 312 8

[mark in ny 27]

Ok first post here and I picked up a what I now know is a 1986 312 8 with a k301s. When I got it there was wires hacked and cobbed and no noise when trying to start. Ive been going through all the wires cleaning and greasing the grounds and contacts. I now get a click at the solenoid after some sorting out. If I hold the test button switch I can get it to crank over. The low pressure switch was cut and tied together if I seperate that and split it I get nothing anywhere. Any suggestions on where I should start looking first? Could the switch be faulty? Thanks

[pfrederi 17,147]

Wish I could be of more help  I avoid try to avoid the newer models with idiot lights... (I have  418 with them and that is enough)  any way the wiring diagram is here and some diagnotic charts

 

 

[gwest_ca-(File Mod) 10,499]

Welcome to the forum.

These diagrams may help

 

There has been some discussion about whether the diagrams for the low oil switches and relay are correct as some models/years are shown different.

The low oil switch is a magnetic float that monitors the oil level - not pressure. If the low oil switch needs to be removed there are special instructions so it does not get damaged. Replacements are no longer available.

There is a diagram of the switch in this bulletin Fig. 3. Standing on the left side of the tractor the NC (normally closed) should be visible on top on the portion of the switch sticking out. If not there look from the right side of the tractor and you should see NO (normally open) on top.

Left and right are always from the operators position in the seat.

The NO and NC are the status of the switch when it is not in oil. 

Let us know how the switch is mounted. The diagrams above show the low oil switch in the NC position which may not be correct.

If it is in the NO position we will find you different wiring diagrams.

Let us know what you find.

Sounds like the test switch is trying to supply power to the start circuit because something else is wrong.

 

Garry

[mark in ny 27]

 

kinda looks like the switch isn't original as it is. The hour meter says 2016 hours. is it even worth messing with the machine if that switch is bad or with that many hours and no previous maintenance records?

[midpack 804]

I have a Magnum 12 that had a bad low oil switch. I closed the circuit to disable it.

The engine is fine without it. Runs great!

Just check the oil level regularly 

[gwest_ca-(File Mod) 10,499]

I would not give up on it.

To eliminate the relay and low oil switch join the light blue and purple wires that go to the relay and it should start.

 

You should have power in the light blue wire with the key in START position.

If not go back to the clutch pedal switch (closed with pedal down) and then back to 1/2 of the pto switch (closed when pto is OFF) Pto switch gets it's power from the S terminal on the ignition switch.

 

Garry

[mark in ny 27]

I appreciate the help but i have kind of a dumb question where should i join them near the mother board? Only asking because a couple wires look like they were changed. Also got the hour and voltmeters back working. I noticed when i close the seat the voltage drops for 14 to 12 with the key on. Kinda seems funny

Edited September 3, 2019 by mark in ny

[gwest_ca-(File Mod) 10,499]

Two of the wires at the relay should be light blue and purple. If they are there pull them off and join them. Circled the low oil relay yellow. Starter solenoid red. There should be one end of the purple wire on a small terminal on the solenoid.

If they are not there look for the light blue going back to the clutch pedal switch. I think your's is on the right side next to the drive belt idler pulley. You should be able to see the back of the switch looking through the slots in the flat panel the shifter travels through. About the 2nd gear position.

More questions welcomed.

 

Garry

[mark in ny 27]

Ok so trying to eliminate the oil switch i now have nothing. When powered up the seat switch works as it should with voltage and the ignition works as the diagram for starting and running connectors. Now what ive found out is that the test switch was used as a start button with the key which confirms it turning over yesterday. There is a red power wire from that button to the starter solenoid and a wire that was connected to the low oil switch with a twin post connector. Im feeling im gonna have to completely rewire it but Im gonna need some help sorting out wires if you can haha. i have one wire cut at the ignition switch and wires cut at the main circuit to what im assuming was the test switch. I have some pictures showing what i mean if im not quite describing it right. 

[mark in ny 27]

also this is the relay for the seat switch one has a double terminal on it on the top relay and nothing else. Thats the one that im assuming goes to the starter. So i tie the oil safety switch together and plug into that terminal then the open terminal i run to the starter? The safety switch and seat switch go on the double terminal or seperate? this is confusing why are people such hacks when it comes to this kinda stuff.

[gwest_ca-(File Mod) 10,499]

23 minutes ago, mark in ny said:

also this is the relay for the seat switch one has a double terminal on it on the top relay and nothing else. Thats the one that im assuming goes to the starter. So i tie the oil safety switch together and plug into that terminal then the open terminal i run to the starter? The safety switch and seat switch go on the double terminal or seperate? this is confusing why are people such hacks when it comes to this kinda stuff.

These are the pto switches - one for the starter circuit and one for the ignition. Click on the picture.

Here is a file on the ignition switch. Click on the picture and again on the next page to see the terminals identified.

Garry

[The Tuul Crib 7,332]

to

[mark in ny 27]

ok so now the update after 2 days of discouraging discoveries, we now have a smooth running and mowing tractor. Ended up having to rewire a bunch of the tractor and gotta still mess with the lights not the biggest of deals but if i have them why not make them function. I cant thank you enough for the time and help. To think one of my mothers neighbors put it at the curb for free and all i have invested is some wire connectors and about 7 hours. Now time to find a snowblower for winter.

[953 nut 51,703]

7 minutes ago, mark in ny said:

one of my mothers neighbors put it at the curb for free and all i have invested is some wire connectors and about 7 hours.

        Wish I had a neighbor putting a out for free!         You stuck with the job and your persistence paid off!      

[peter lena 8,067]

mark in ny , glad you stayed with it , dealing with a series of issues , that you are not familiar with only add to the problem. MIDPACK helped me with advise on a similar problem  , on a magnum engine swap , with the oil sensor issue. after trying a number of experiments , finally got it , so worth it. glad you found us and asked for help , pete

[peter lena 8,067]

mark, is your steering column  sloppy ?  that picture showing the wear and rust  indicates it is. now that you have it running , doing a thorough baseline service should be the next issue .   all oils, engine and trans , replace transmission shift boot , to stop moisture entry, changing oils after thoroughly  warming up  units works best. grease chassis and lubricate  any and all friction points. i am just adding this , because if you plan to get a snow thrower , you will be loading up the engine and drive train , give it the service BEFORE  the work. SEAFOAM  GAS TREATMENT , will help out your carburetor, along with , new fuel lines and gas filter. we have all been through similar problems, but a baseline service will let you know what you have , and make regular  checks , routine . good luck with it, let us know, pete   

[mark in ny 27]

On 9/6/2019 at 8:32 AM, peter lena said:

mark, is your steering column  sloppy ?  that picture showing the wear and rust  indicates it is. now that you have it running , doing a thorough baseline service should be the next issue .   all oils, engine and trans , replace transmission shift boot , to stop moisture entry, changing oils after thoroughly  warming up  units works best. grease chassis and lubricate  any and all friction points. i am just adding this , because if you plan to get a snow thrower , you will be loading up the engine and drive train , give it the service BEFORE  the work. SEAFOAM  GAS TREATMENT , will help out your carburetor, along with , new fuel lines and gas filter. we have all been through similar problems, but a baseline service will let you know what you have , and make regular  checks , routine . good luck with it, let us know, pete   

I'm starting to take a look at some of the minor issues. New battery fires right up and runs amazing.  Trying to make sure I have all the parts I need for the snowblower before I place a order for the shifter boot that was dry rotted. I also dont have brakes haha but the clutch works temporarily. Also I'm looking into the steering slop because the console is cracked, I'm not sure what I'm gonna do. Been searching alot for a replacement console with little luck.

[Rob R 951]

What I do when I get a tractor that has been hacked is run a wire jumper from the correct start terminal on the start switch to the solenoid relay this normally bypasses everything and you can crank and chk out the engine operation, always you decide on what you have and where to concentrate you $ and time.