EXHAUST SYSTEMS!

With every Snowcat I have purchased each one has had some type of exhaust system leak. This is potentially very deadly to us and the ones we have in our snowcats plus it makes the system less effective. I will be going over an exhaust system overhaul here in the next few days on one of my Thiokol 1202B. This will kinda give you an idea of whats involved in making the exhaust system more efficient than it currently is and most importantly safe for us. So bare with me as I go through the system a little bit at time and I will be posting step by step pictures as well. This system will be pretty close to what stock was. My next Exhaust system rebuild will be designed for more flow. So stay tuned.

Ok the FIRST thing you should do is disconnect the battery. Then disconnect the throttle linkage and spring. Then remove all but two of the exhaust manifold bolts. Slowly loosen the last two. The manifold I kept bolted to the exhaust system. This ended up supprting the weight pretty well so it wasnt a dramtic drop as the manifold can do when unsupported. The exhaust manifold can be very heavy in such tight spaces. I was pretty luck because once the exhaust manifold came down the old gasket fell off. I didnt have to scrap any stuck pieces off. I then checked the old part against the new and everything lined up. The OLD gasket (originally) I feel was not as good as the new NAPA one I purchased. Its of a much better quality material. The cost was $7.19 plus tax.

Where did you get your shifter boot? Do you have a part number. I'm also interested in the routing of your exhaust pipe. Mine is uphill and exits over the top of the OC-12. It is routed very poorly and I need to improve on that.

Here is a picture of the part number for the Exhaust manifold gasket. This is for any 170 200 or 250 Ford inline six in the U.S.. If you put an Aussy head on your 170 200 or 250 then you will need to get an aussy gasket. Anyway I then cleaned each bolt with a wire brush. I then in stalled two bolts on the bottom that corrilates to the new gasket. This lets you line all the bolts up before tightening and assures the gasket stays in the correct spot. I know the pics arent that great but you can see how the manifold is about 3/8 from the head. The gasket just slips right down onto the two outer bolts. See the picture of the gasket to see what i'm talking about. I also used High Temp Lock tight. In a regular car I wouldnt worry about it but this thing will be a vibrating monster as all Snowcats are and every nut and bolt should have some type of thread lock. We can get more into that later. after all the other bolts were tightened I removed the two last bolt that aligned the gasket and lock tighted tham and installed. Simply reconnect the throttle linkage and spring. Re-connect the battery. I then started her up and man WHAT A DIFFRENCE! No more sucking exhaust fumes and the in cab noise is all but gone compared to before! Hope this helps someone. Next will be installing a new muffle and rear pipe section. The front pipe section is in excellent shape and looks to have been replace a year back or so. They kept the original muffler but should have changed that to a stainless steel muffler. I will keep you posted.

Please feel free to add anything you want here as well. If you see something that would have been eaiser or a better way then please feel free to show us. After about 5 to 6 heat cycles I will recheck the exhaust manifold bolts and re tighten if needed.

scooterd said:

Where did you get your shifter boot? Do you have a part number. I'm also interested in the routing of your exhaust pipe. Mine is uphill and exits over the top of the OC-12. It is routed very poorly and I need to improve on that.

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Believe it or not when I was comming home from my last thiokol pick up. I stopped at a Napa dealer to pick up a tire wrench for my trailers lug nuts. (I realized I didnt have the proper size). I saw in the parts bin at the counter this CV boot that was priced at $1.09. HHHmmmm that should be a real close replacement for my manual trans boot. Sure enough it fit perfectly in the factory hole! They didnt know what it belong too so I was able to pick it up cheap! But I can tell you this. Its the MOTHER of all shift boots. It should out last everything else on this cat in the application its now being used for! Talk about Heavy Duty but pliable. I will now always check those bargain bens for sure!

For $7.19 plus tax, gas to and from the auto store and my 35 minutes or so of work has proved to be the best thing I have done so far to this Old Thiokol! Can not wait to install the new muffler.

Previously I replaced the exhaust donut which cost me $2.99 from NAPA. It took me a good hour to finally figure out the fastest way to do it in the future. Heres the quick steps

1. Disconnect battery
2. disconnect starter power cable
3. disconnect throttle linkage and spring
4. unbolt and remove starter (you will need to go undernieth for the bottom starter bolt, why you are there loosen the muffler clamps and spray with a penetrating lube lightly)
5. remove two nuts that connect exhaust pipe to manifold. Pre-lube these several times a day for a few days to make your life alot easier (Use KROIL penetrating lube)
6. Once the nuts are removed seperate the pipe from the exhaust manifold
7. remove tho old donut. Its wedged on pretty good so use a standard (flat) tip screw driver and gently cut through the ring and pry off. Once the ring is cut it will come off easily.
8. gently place the new donut on and slide down as best you can.
9. If you can find them use new exhaust nuts that are 3/4 long and made from brass. (Brass will not adhear to the exhaust studs as steel does over time) Throw the old nuts away.
10. I couldnt find brass or anything 3/4 long so I used two grade 8 nuts each side with a lock washer in between. (I hope the diffrence in heat treating will have them contract and expand at diffrint rates. This should keep them from bonding like all exhaust nuts do to studs) The two nuts that were on there had loosened up and created the exhaust leak.
11. after several heat cycles check to make sure everything is still nice and snug!

scooterd said:

Where did you get your shifter boot? Do you have a part number. I'm also interested in the routing of your exhaust pipe. Mine is uphill and exits over the top of the OC-12. It is routed very poorly and I need to improve on that.

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Mine is also routed about the same way. I will improve it when I install the new Stainless steel Muffler and Stainless steel pipe from the back of the muffler out. I will still go over the OC12 but it should be a straighter run. Stay tuned.

I have my motor out so I can only guess where the exhaust will run. I was thinking that a flat run or downhill slightly would help on the moisture problem and the muffler and pipes would last longer. Stainless is probably the answer! I'm looking forward to see what you come up with.

A downhill run really isnt possible in my opinion. They need to run straight out the back over the OC-12 or make a 90 degree turn at the back of the cab and go up with a downward turn at the tip like on a big rig. Stainless steel is really the way to go on a snowcat. The systems get so much abuse with all the moisture and road salt ect ect.

I havent located the exact muffler I want yet. If anyone has a suggestion please feel free to post. I want the system quiet and made from stainless steel. On this set up I will have a 2" in and 2" out.

Do you think you would dare go under the diff. right along side the drop box? I don't have any rock guards in place either. Do you have any pics of those and the mounting points? I'm green, and have alot of ideas that may, or may not work. Thats why I ask alot of questions and read what others do!

No I would not go under the dif for sure. Way to low and would get mangled sooner than later. Then you risk the chance of damaging the entire exhaust system or a good section of it. That could also lead to leaks which can be deadly. Stock location is pretty damn good.

I spent today purchasing and installing the muffler for my Thiokol 1202B. Since I may be changing this motor out to a 250 cid I decided to stay on the a budget for this exhaust system. So far I have used all NAPA parts and have found them to be as good and better in some cases than the original Ford parts used by Thiokol.

As you can see in the pictures the muffler is completely rotted out. I went to NAPA and gave them the dimensions of the old muffler. 21 L x 6 D x2"x2" inlet outlet. They had in stock a 25x6x2x2. Perfect! Price was $43 and will work just fine. Took me about two hours to get the old one out and the new one installed. She fired up and purred like a pleased woman! Next will be the rear pipe section which I will have fabbed at my local muffler shop. My next exhaust system will be all stainless steel with a stainless steel muffler. Heres the pictures.

I am still under a hundred dollars and about 3 man hours. The diffrence is amazing and the cab pretty much safe from carbon monoxide. It will completely safe once I get the rear pipe section added and routed to the outside.

PICS

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As you can see the space is cramped to work in. Next time I will pull the Cat up onto some beams to give me a bit more room. Even though it was a cramped and I had to make 5 or so trips underneith ect it still didnt take all that long. The front pipe section had to be cut free from the muffler.

Also all new pipe hardware was installed as well. They were a bit more heavy duty (1/2" VS 3/8") and all three cost me under $5 bucks! Its so much easier to work with new hardware than trying to re-use the old stuff.

I will post the the rest of the pictures once she is done.

Ive been going over the records that came with this unit. That was the stock exhaust system. No one has ever changed it out according to my records and by I believe this to be true by inspecting what came out. That is the original FORD muffler from the Thiokol factory. Everything Ive replaced should give many years of trouble free service. Maybe even decades.

I will link these to my other thread on this Thiokol.

Now that my rear deck frame has been welded onto the main frame I could finally finish up my Exhaust system. I first prefit each piece and mokced it all up. I then cut everything to length and double checked. I then figured out where the exhaust pipe brackets needed to go. I then cleaned the surfaces and welded the brackets in place. all the pipes and clamps have been installed. I will pull everythig apart and paint everything with engine paint. Heres the pictures.

All the pipe clamps are turned up where possible to give it a cleaner look.

I know exactly what you mean by exhaust leaks. My new project has flex pipe welded from the exhaust manifolds, and with several leaks till the exit! If you look closely at my avatar, you will notice the flex pipe finding its way up the side of the cap upwards. I am also in the process of replacing all of that old crap, with new. It will be nice not to have it sounding like Harley!!! Can you imagine a Ford 391 with no muffler?

I just re did my exhaust on my snow trac when I did the engine the thing sounds great

I'm going up to 2 1/4" since the old exhaust is smaller. It should run a lot better than straight pipe, as it was beforehand! Incidentally, what did you use for a muffler? I have a 391 Ford V-8. Just wondering. Let me know. Thanks.