John Deere 400 questions

[Friesen400]

I just picked up a '73 400 (my first snowmobile actually) which had been sitting since the spring of '09. I've heard that the crankshaft seals can fail, which leads to disaster. My question is (and I probably should know this but I want to make sure): when the seals fail, how can you tell? Will fuel leak from behind the recoil and/or clutch side? I know it will make the engine pull in more air and it will run lean, what are the symptoms to listen/watch for?
Also, if I put in fresh fuel, do I still need to take apart the carb to do a thorough cleaning? Or would some Sea Foam with the fuel be good enough?
And lastly, is there anything in particular On this sled that I should watch for? As in known weaknesses or anything of that nature. Like I said, it hasn't been sitting for too long and it is in pretty good shape from what I can tell. I don't plan on riding it too hard, mostly just half a mile to work and back and the odd "vintage cruise" with some friends.
I have wanted a JD sled for a long time (always been a JD tractor guy) and when I found this one so close to home I couldn't pass it up. Thanks in advance for the help.

[400brian]

Welcome aboard, you've found the right place.

Go to the "Articles " section. There are several threads there that will help answer your questions.

Your sled is pushing 40 years old, and its not like they were trouble free when they were new. We have gotten to the point that we recommend seal replacement to everyone, just based on the age of the material. Your carb is the same deal, it most likely needs cleaning and diaphragm replacement (age ) The fan belt ( age ) and the 8 ball bearings in the sled ( excluding the bogies ).

Parts are getting harder to find all the time, so it makes sense to head off all the potential catastrophic problems that you can. Going through the sled will give you your best chance for a reliable rider as well.

[HoosierDeereMan]

Friesen400,

Congratulations on picking up your 400. I also have a 73 400 that was my grandfathers.

I would recommend picking up a SM-2100 service manual. It covers your 400 and will answer almost any question you have. In my experience with my 400 it seems the fuel system and the points ignition were what I had the most problems with. The service manual did me wonders as far as getting the points and timing set on mine. It's also very helpful on the fuel system. Some additional issues I had with the fuel system were my gas tank rusted inside. It rotted the old fuel line off the fuel check valve in the bottom of tank so the fuel system would not hold a prime. I also learned not to use regular automotive gas line for fuel lines. The line will separate inside and allow it to suck shut. The aftermarket fuel line is see through which helps aid in toubleshooting the fuel system as you can see the fuel moving in the line.

Good Luck

Troy

[Friesen400]

Thanks for the help so far guys.
So I went to newbreedparts.com and found the "Winderosa Gasket & Seal Set for 72-75 400, JDX4 Special." Here's the link:
http://www.newbreedparts.com/index.php? ... duct_id=73
It looks to me like this is the right one for my '73 400. It appears that the crank seals are included, is that right? I read that the crankshaft diameter went from 25mm to 30mm from 72-73, so does this kit include both? Or...?
Another question, what fuel grade and fuel/oil mixture is everyone running on these sleds? I have regular dyed (farm) gas at home, is that going to cause any harm?
Thanks again. And it looks like I've got a lot of reading to do...

[JD600]

First off, hello and WELCOME!

I myself have 8 sleds, 7 of which are mid engine models like yours. I believe Deere recommended premium fuel for these sleds. I always run the highest octane rating avalable at the pumps when i get it. It has been said that 87 octane can cause some issues with preignition in these high compression engines. I would also recommend that you stay away from ethanol blends as they draw moistrue, which can obviously cause some issues.

I run all of my sleds on a 50:1 ratio with Klotz Super TechniPlate synthetic oil. If you ask 10 people on here what kind of oil they run, you will most generally get 10 different answers, so take that for what its worth. I run it because it burns cleaner, which means it produces less smoke and fouls less plugs. It also is formulated for racing. And is smells so good coming out of the pipe. The down side of this is that it will set you back about $50 a gallon, which isn't bad when you start to price engine parts for these machines.

Ultimatly, enjoy your machine! Good to have you aboard.

DE

[400brian]

I'm thinking that the '72 400 was the only one with the 25mm pto, So you would need one 25 x 62 x 10, and one 30 x 62 x 10. You don't need the gaskets unless you plan on disassembling the engine, the seals can be replaced without opening up the case.

Run premium gas and a 50:1 mix. I run Pennzoil, but any modern sled rated oil is no doubt better than what we ran back in the day.

[Matt]

Thanks for the help so far guys.
So I went to newbreedparts.com and found the "Winderosa Gasket & Seal Set for 72-75 400, JDX4 Special." Here's the link:
http://www.newbreedparts.com/index.php? ... duct_id=73
It looks to me like this is the right one for my '73 400. It appears that the crank seals are included, is that right? I read that the crankshaft diameter went from 25mm to 30mm from 72-73, so does this kit include both? Or...?
Another question, what fuel grade and fuel/oil mixture is everyone running on these sleds? I have regular dyed (farm) gas at home, is that going to cause any harm?
Thanks again. And it looks like I've got a lot of reading to do...

That's a good question. I just checked the book, and that kit comes with two OS1301, which are the 25mm seals. If that's really the case I can switch one of the seals with the 30mm version for ya.

Agreed on the high-octane, that's what the early engines were designed for.

[WinnipegStPaul9]

Keep in mind that the "premium" gas of the 60's and 70's (we called it Ethyl) was a lot more potent than todays "premium". Oh, and it cost about .39 to .49 a gallon...............just sayin

DA

[80spitfire]

Don has a really good point there. I was looking into what to use in a Dator one time when I was bored and I knew that you had to use premium in it. However I knew that 1976 premium was not the same as 2011 premium, so I looked a little further and found out that premium back the was actually 98. Try finding that one at a regular gas station! It'd be easy to make though if you bought some octane booster or you could just buy some race fuel. Either way I still thought it was pretty interesting to learn.

[HoosierDeereMan]

Gosh DA, for .39 or .49 cents a gallon I bet they even washed your windshield, checked you tire pressure, and looked under the hood too!


When I first got my 400 in the mid 80's I was reading the manual and was paranoid about what gas and oil to run. The early 70's gas had lead in it. So I was using a lead additive. The manual also calls out for ashless oil. You could still get it through Deere and some of the small engine makers brands advertised ashless 2 stroke oil. Lawn-boy is one that comes to mind. So I'd buy premium gas, ashless oil, and lead additive. Now days I run Shell premium gas, Valvoline or Pennzoil 2 cycle oil, and a little Sea Foam to help keep things clean and disperse any moisture in the system. I've had really good luck with it.

Troy

[WinnipegStPaul9]

Gosh DA, for .39 or .49 cents a gallon I bet they even washed your windshield, checked you tire pressure, and looked under the hood too! Troy

Yep, that's why they were called "Service" stations.

I still mix my gas starting with today's premium, octane booster, lead additive, and Sta-bil. Cost about a zillion dollars per gallon

DA

[JDT]

When I was in High School I worked at Jim's Philips 66 Station on US hwy 10 in Detroit Lakes MN.
Our Ethyl pump was labeled 100 octane.

Keep in mind there was a different system for rating gas back than. (R+M)
If I rememeber corectly the switch happened in 76 and the old 98 rating became todays 93.

Most premium at the pumps in this parts of the snowbelt does not contain ethonal but I think it is mandatory in some states.
I do not no anything about lead additives as I have never used them in any engine but I have been buying 10% ethonal since 1979.

[Friesen400]

Thanks again everyone. This site is incredibly helpful.
I'll order the right seals (hopefully) and see what I can figure out.
We just got a nice layer of snow this morning, too bad I've got a few things to fix first.