Fresh and Clean

Mini Bike & Go-Kart Parts

#1
I have an old MTD Trail Flite, with a Tecumseh H-35. Hasn’t been run since 1981. Has been stored in my basement, out of the weather. Engine turns freely still. It was running great when I parked it, A litttle cleaning, oiling, and maybe a tune up will do. I have a question though. I plan on draining and refilling the oil. After all these years, I expect some sludge or deposits to not drain out completely. What could I use to flush out the crankcase of all old oil and dirt, that will wash away clean without leaving any residue that could contaminate the new oil ? Is Kerosene okay ? I was thinking maybe refill, run for a short time, and then re-change the oil. Thoughts ?
 
#2
The auto parts stores sell that Motor Flush stuff that I always heard was just kerosene. I'm not a fan, heard some bench talk of spun bearings from not getting that stuff all out.

If you really want to clean it out get a side cover gasket and a crank seal and do it by hand and eye. Otherwise unless you know it has sludge or gunk inside a good oil change and get it hot/do another sooner than later will be fine. On some of my vehicles with unknown history I have poured a quart of oil straight through to push out all the old oil...I don't know if it did anything but it felt good to see clean oil draining...probably just wasted a quart for peace of mind though.
 
#3
I’ve had success by adding “Sea Foam” additive to the first oil servicing, run it to heat/circulate, then drain. Next oil servicing straight oil. I’ve seen kerosene used on an old tractor once, thing always smoked afterwards. Scared me from using it myself. Good luck.
 
#5
I have an old MTD Trail Flite, with a Tecumseh H-35. Hasn’t been run since 1981. Has been stored in my basement, out of the weather. Engine turns freely still. It was running great when I parked it, A litttle cleaning, oiling, and maybe a tune up will do. I have a question though. I plan on draining and refilling the oil. After all these years, I expect some sludge or deposits to not drain out completely. What could I use to flush out the crankcase of all old oil and dirt, that will wash away clean without leaving any residue that could contaminate the new oil ? Is Kerosene okay ? I was thinking maybe refill, run for a short time, and then re-change the oil. Thoughts ?
 
#6
Re: Fresh and clean...
Thanks to all for your input. I probably will just fill with fresh oil, run until hot, then drain and refill again. I didn’t want to remove the side cover if I could avoid it. I’m sure it’s the original factory seal, so why take a chance on a possible future leak, even with a new gasket.
 
#7
Re: Fresh and clean...
Thanks to all for your input. I probably will just fill with fresh oil, run until hot, then drain and refill again. I didn’t want to remove the side cover if I could avoid it. I’m sure it’s the original factory seal, so why take a chance on a possible future leak, even with a new gasket.
I don't think I have one original un-touched Tecumseh that doesn't seep oil at the side cover or crank seal...if yours is dry I would definitely leave it be.
 

SAT

Well-Known Member
#8
I have an old MTD Trail Flite, with a Tecumseh H-35. Hasn’t been run since 1981. Has been stored in my basement, out of the weather. Engine turns freely still. It was running great when I parked it, A litttle cleaning, oiling, and maybe a tune up will do. I have a question though. I plan on draining and refilling the oil. After all these years, I expect some sludge or deposits to not drain out completely. What could I use to flush out the crankcase of all old oil and dirt, that will wash away clean without leaving any residue that could contaminate the new oil ? Is Kerosene okay ? I was thinking maybe refill, run for a short time, and then re-change the oil. Thoughts ?
I would add Sea Foam by the directions. Then run it.
 
#10
I guess I can’t leave this alone....why wouldn’t you open up the engine and see what’s going on...the years of sludge etc....only takes a day or two to rebuild one of these...gaskets and seals readily available....
 
#11
Then you’re not torquing to correct specs....None of mine leak and they’ve all been apart...
Huh? Me? Once I touch them they're dry, I'm a gasket AND RTV type of mechanic, I hate weepy engines...I said all of my untouched original engines always have a leak somewhere.
 
#12
Huh? Me? Once I touch them they're dry, I'm a gasket AND RTV type of mechanic, I hate weepy engines...I said all of my untouched original engines always have a leak somewhere.
I hear ya. Skipp was referring to ChainDrive who didn't want to pop his side cover, after suspecting he's got bad juju inside. The side covers on these seal up readily, and stay that way if properly cleaned, torqued, etc. As far as original engines having a leak somewhere, we'd all be hard pressed to find a cheap, industrial gas or diesel engine that doesn't have a leak after 50 years.

I am just like you about leaks. I recently finished a Hodaka engine, and it ran great, tuned nice, didn't leak for two weeks, until much to my horror, I saw the tell tale drop of oil on the floor.

Not believing this engine would dare leak on me, I chalked it up to Carburetor over fill, or drain issues. After all, a 20:1 ratio of gas to oil in a hot, desert environment will look like an oil leak once the fuel evaporates in six hours. Nope, that wasn't it.

Pulled the side cover, re-faired, even applied some sealant over a new gasket. Nope. Two weeks later, there was just no denying it. The countershaft (chain sprocket side) oil seal was leaking about a drop every two days. Oil would collect in that side cover, then roll towards the front, then out to the frame to the next low point, and manifest a small puddle several inches from the offending seal.

Yesterday, I went back in, and found that the steel bushing that goes between the sprocket and the seal was worn after nearly 60 years of use, minus however long it sat out in the rain somewhere in Idaho. There was a groove worn right where the inner lip of that seal goes. When replacing the seals (and all of the bearings on that engine) I failed to replace a $4 bushing. Lesson learned. "Another" lesson learned I should say.

Skipp is right though, and I was thinking the same thing- there are indeed times when getting to something, or dealing with something requires less invasive action like adding sea foam, muffler grease, or in the case of my Hodaka, copious amounts of good grease garage soap sprayed on oily spots. But a Tecumseh side cover is a pretty simple fix, as long as the clutch isn't stuck. And as long as it doesn't have a bearing type of PTO where it has a seal that has to be destroyed to get to the snap ring to get the cover off in the first place. :) In that case, it's still a pain in the butt, but not nearly as much of a pain in the butt as trashing the non-bearing journals of crank and rod. (Sounds like a smut magazine)
 
#13
I guess I can’t leave this alone....why wouldn’t you open up the engine and see what’s going on...the years of sludge etc....only takes a day or two to rebuild one of these...gaskets and seals readily available....
Gaskets and seals cost money. I.’most not a,mini bike collector bent on doing a perfect factory new rebuild. I have one old mine bike, I bought it at a flea market for my son long time ago for $25. Changed the plug, the oil, and air filter, and he used it for about two years. It’s been parked ever since. I got the engine parts I do because they actuallly make it run better. If I wanted to spend more, I would replace the side gasket and seal. I cam eupon this site when I was looking for parts, and figured some of you old timers might have a few tricks to share. I’ve never had an engine sit that long before. Besides, replacing the gasket and seal would mean pulling off the torque converter drive, which might also be difficult after forty years or so. So, that’s why I wouldn’t pull that apart, unless I knew it leaked or intended to make it a showpiece.
 
#14
I hear ya. Skipp was referring to ChainDrive who didn't want to pop his side cover, after suspecting he's got bad juju inside. The side covers on these seal up readily, and stay that way if properly cleaned, torqued, etc. As far as original engines having a leak somewhere, we'd all be hard pressed to find a cheap, industrial gas or diesel engine that doesn't have a leak after 50 years.

I am just like you about leaks. I recently finished a Hodaka engine, and it ran great, tuned nice, didn't leak for two weeks, until much to my horror, I saw the tell tale drop of oil on the floor.

Not believing this engine would dare leak on me, I chalked it up to Carburetor over fill, or drain issues. After all, a 20:1 ratio of gas to oil in a hot, desert environment will look like an oil leak once the fuel evaporates in six hours. Nope, that wasn't it.

Pulled the side cover, re-faired, even applied some sealant over a new gasket. Nope. Two weeks later, there was just no denying it. The countershaft (chain sprocket side) oil seal was leaking about a drop every two days. Oil would collect in that side cover, then roll towards the front, then out to the frame to the next low point, and manifest a small puddle several inches from the offending seal.

Yesterday, I went back in, and found that the steel bushing that goes between the sprocket and the seal was worn after nearly 60 years of use, minus however long it sat out in the rain somewhere in Idaho. There was a groove worn right where the inner lip of that seal goes. When replacing the seals (and all of the bearings on that engine) I failed to replace a $4 bushing. Lesson learned. "Another" lesson learned I should say.

Skipp is right though, and I was thinking the same thing- there are indeed times when getting to something, or dealing with something requires less invasive action like adding sea foam, muffler grease, or in the case of my Hodaka, copious amounts of good grease garage soap sprayed on oily spots. But a Tecumseh side cover is a pretty simple fix, as long as the clutch isn't stuck. And as long as it doesn't have a bearing type of PTO where it has a seal that has to be destroyed to get to the snap ring to get the cover off in the first place. :) In that case, it's still a pain in the butt, but not nearly as much of a pain in the butt as trashing the non-bearing journals of crank and rod. (Sounds like a smut magazine)
My nemesis is Ford small block one-piece rear main seals, 1 out of 3 or 4 will be a dime size oil dropper no matter what I do...Ford Performance or Motorcraft seal , new cranks, pre-wiped with grease, oil or assembly lube, Rotunda install tool or block of wood, doesn't matter...at least my trans tunnels will never rust!
 
#15
My nemesis is Ford small block one-piece rear main seals, 1 out of 3 or 4 will be a dime size oil dropper no matter what I do...Ford Performance or Motorcraft seal , new cranks, pre-wiped with grease, oil or assembly lube, Rotunda install tool or block of wood, doesn't matter...at least my trans tunnels will never rust!
Now you’re talking more my language. I used to build racing engines in a shop here in Baltimore. Had a 68 442 with the original Rocket 400 engine with the Ram-Air Induction scoops in the front grill. I’m far from being a novice when it comes to engines. Just posted my original question because I wanted to hear some other gear head’s thoughts on the subject. I know, like Skipp said, it’d be best to open the engine, but I don’t plan on making it my life’s work. Just got an old mini bike, found your site, and was amazed to see how many people are really into it. There’s guys on here that have entire collections, so,e in mint condition, enough to make me jealous. But if I want to spend hours blueprinting an engine, it ain’t gonna be a one lumber that’s 40 years old. I hear ya on those Ford small blocks. Had a 67 Mustang with a 289, all stock. Had the big Ford 2 barrel carb. Same deal with the seal, and my friend had a van with a 302,same thing.
 
#16
Had a 67 Mustang with a 289, all stock. Had the big Ford 2 barrel carb. Same deal with the seal, and my friend had a van with a 302,same thing.
I have never had a 2 piece small block Ford rear seal leak. The trick is far to simple. Rotate the seal 1/4 of an inch so the parting lines on the cap and the seal dont line up. Just the tiniest spot of RTV on the ends of the seal and your done.

Havent had to deal with a one piece seal yet so we will see.
 
#17
I have never had a 2 piece small block Ford rear seal leak. The trick is far to simple. Rotate the seal 1/4 of an inch so the parting lines on the cap and the seal dont line up. Just the tiniest spot of RTV on the ends of the seal and your done.

Havent had to deal with a one piece seal yet so we will see.
Either way, if it’s a Ford you’ve already won. I believe your choice of oil makes a big difference too. Guys out here runnin around with feul-injected, turbocharged, MSD and all, using WalMart Mystery oil.
 

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