OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Tecumseh TVM 140 Rebuild & odd mods

See Pics... After umpteen litres of solvent and hours of cleaning I finally got the Tecumseh stripped down. Top ring gap is way too big at 0.026" so I guess a set of rings are on the menu, the bore needs a hone and really think it could do with a re-bore but if a blind man could see it he would be very happy with it (no funds for that)

I can't help myself with the die grinder and the lathe got fired up to give the valves some attention (it was a fun night in the man cave ) Were mods required? no.... was it fun yes... will they help? yes a little better breathing... (The sharp edges were just radiused a little). I left plenty on the valves really for a future rebuild, but I think by the time that happens it will be well and truly an historical oddity..








The bore marks are barely discernable to feel, however the long wide one (photo 3) is the one that bothers me, we will see how it looks after a hone as per grumpys method in the drill press....

That bore does look worn, with the classic vertical stripes. It looks as if there may also be a ridge at the top of the bore, above the highest point reached by the top ring. If the ridge is small you may be able to remove its bottom edge with a scraper, rather than doing the job properly with a ridge remover. The problem with leaving a ridge in place is that it has worn to match worn rings and ring grooves. If you then turn it over with new rings, unless the ring grooves in the piston are worn to excessive width, the top ring will hit the bottom of the ridge and mangle the bottom of its groove slightly. Before doing anything, though, you should measure the side clearance between a new ring and the top ring groove. If it is more than the specified amount, you will need a new piston (as well as the loan of a ridge remover). If you turn out to need a new piston, it is much better to rebore the cylinder at the same time.

The usual method for evaluating bore wear is to measure the diameter, at right angles to the axis of the crankshaft, 1 cm below the top of the cylinder. There is usually a wear limit specified by the engine manufacturer. It is probably around 0.010". In practice the wear is concentrated at the top of the cylinder, on the major thrust side, so there is a taper in bore size of about the amount of the wear. The rings have to expand and contract each stroke by the amount of the taper, which causes wear in the ring lands (the sides of the ring grooves in the piston), as well as preventing good oil control. Also, if you are using steel rail rings like those used in cars, the oil ring expander is likely to suffer metal fatigue and break in a fairly short time. I once made the mistake of choosing the wrong design of ring expander when I put new rings in a V8 with 0.010" of cylinder wear. After 3,000 miles, five of the eight oil ring expanders were broken, and oil consumption (which had been considerable right from the overhaul) became so severe that it smoked and oiled some of the spark plugs.

Yeah Grumpy it does look worn, fortunately not as bad as it looks . The last photo most of the lines there are gas blow-by marks I ran the hone over it and they went by the way side after 5-10 seconds of honing . The wide groove (mark) was "I think" caused by a burr/sharp edge above the gudeon pin bore, which may have been wiping the oil away???

I had to finish off the honing with a hand drill as the pedastall drill was too quick for me today at 210 RPM to get the hatching just right, although I have perhaps over compensated and ended up a bit steeper < than ideal. The wide mark which did worry me greatly goes from not there at the top to faint towards the bottom of the "usefull" stroke. I will try the camera again now have cleaned up, for your parusal and comment. I will mic up the bore too. I dont think (hope) it would be anywhere the 0.010" I guess maybe 0.003 - 0.005"? Give me an hour or so and we will see how good the estimation is..

I share your Pain RE: V8, I did a 253 on the cheap years ago... lasted about 30,000Km all mic'd up to OK upper limit at the time, but flogged out the new piston grooves and ring lands, and over heated the rings too I think, as they came out with little to no tension on them....no oil burning but too much blow by...

I'll be interested in your bore measurement - if it is only 0.003-0.005 oversize, taper should not be an issue, and ring gap will probably be reasonable as well. I'll also be interested in what the bore looks like, of course, but it is sounding positive at the moment.

In case it matters, those unsuccessful V8 rings had the SS55 expander that Repco used to sell. To be fair to Repco, they sold good expanders as well, the SS55 was a cheaper line they pushed hard. I should have known better.

OK just learned you dont hit the backspace key just as you finish typing....30 min all gone lifes to short to do it all over......again.....

I did have a heap of numbers typed out in a nice format for your parusal and comment but at the end of the day it worked out to 1/2 thou oval @ 1cm with 3/10 of a thou taper @ 6cm with 1/2 oval there too. Piston clearance works out to 0.0056" with 8/10ths piston ovality. The wide groove was barely there and I wasn't able to measure a difference.

Whats the verdict Grumpy? might be a bit slappy? just re-ring using the old piston?



Thanks,
John

So far as piston clearance is concerned, for a solid skirt piston such as you have, you need a fair amount because of the thermal expansion of aluminium. The rule of thumb for newly-built engines of that type was at least 0.001", more usually 0.0015", per inch of bore diameter, which would be about 0.002" to 0.003" for your engine. If you have less than that you are at risk of seizure when the piston warms up. I would not expect audible piston slap below 0.004-0.005" cold clearance, after the engine has warmed up. Hence I think your engine would be a bit noisy if you put it back together like that. My view is that I don't expect much from a Tecumseh engine, least of all quiet or smooth operation. With regard to the look of your bore, you may have used a coarser abrasive than I would have used. In your situation, with some marks to polish out, I'd have been looking at 220 grit cloth or wet and dry paper. It looks more as if you've used a cheap hone, and honed it dry, rather than using 220 grade cloth and lots of kerosene. Your helix pattern looks fine - I like 30 degrees to the horizontal and you've probably got 45 degrees, but that is still a good angle to use.

If all it will take to finish the engine is a set of piston rings, which should cost about $15, I personally would put it together, fire it up, mow some grass, and see if I was satisfied. Chances are that as far as mowing pleasure is concerned it will be a glorious engine to use compared with a Victa 2 stroke, and at least as good as a Kirby Lauson. If you haven't been spoiled by a Briggs in decent condition or an OHV Honda, you might find it fully satisfying. Let's face it, if you'd been looking for Honda-like pleasibility, you would never have considered repairing a Tecumseh in the first place. The pleasure is in bringing a tired engine back from the dead at negligible cost, and there is a good chance you'll achieve that.

Yeah thanks Grumpy, yes it was a cheapish hone, although @ $125 15 yrs ago...I thought it wasn't! somewhat finer than 220 grit stones though, (seemed like 320-400 grit comparatively speaking) drowned in kero constantly, it was my first go at an alloy bore.....live and learn (I didnt like the look of them before and now I can say I really dont like them).

Yep I have no great expectations for the motor its off the Rover ride on I picked up and will head back to the farm for occasional use, although the kids will probably wear it out, as they tend to do. The only reason the motor came off really was the base/sump gasket was leaking badly, looked like it was miss fitted.

"The pleasure is in bringing a tired engine back from the dead at negligible cost, and there is a good chance you'll achieve that." Hopefully I will achieve that core project aim.. if not it's 30 cal. holes for fun up the farm and then I'll get a real motor eh?

As for the piston slap noise class 5 ear muffs! but sounds like they are a STD Tecumseh requirement Grumpy..... I gotta say I do like the ol boys Honda though and the big briggs on his WHITE ride on... sweet motor there all the fruit..18 HP I think?

Thanks for your time and input Grumpy. $15 for rings....I wanna shop where you shop...

I'll post some finished pic's and comments up here when the time comes.

Thanks for those clarifications, FAST GRASS. It sounds as if the marks in the bore were due to the aluminium grabbing the hone despite the kerosene, not to anything you did that I might not have done. My guess would be that your hone applied too much surface pressure to the aluminium, which seems quite likely if it is designed for use on a cast iron bore. This may help to explain why Briggs advise against breaking the glaze in an aluminium bore.

Unless the rings fail to seal against the bore, it should last fairly well, and be quite OK except for some slight additional piston slap, which hardly matters on a ride-on. You'll probably achieve quite reasonable ring gaps, based on the bore size measurements.

So far as affordable Tecumseh parts are concerned, you might try the US vendor Mr. Bonnar used in this thread:

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=38144&page=1

My recollection is that the prices he paid for his Lauson parts were reasonable. Incidentally the Honda rings I use are $15 including shipping for "basic" Thailand ones (to Honda's original design except no chrome on the top ring), and they would be $19.50 including shipping if I wanted chromed rings with steel rail oil rings, from Honda's Japanese original equipment vendor.

I'll leave this thread open, for you to post progress reports - which I for one look forward to reading.

Gday Fellers
Names Red Im new to posting but been pokin about here for some time now
Fab site Im very glad for its being yeah
Ive an old HK30 H4-4A It's on a SCOTT BONNAR greens mower.
The poor old thing was parked under a tree for Christ knows how long.
Filthy air cleaner, no muffler, carby full of crud, had to dig the bowl out.
So the fins were jammed packed with grass dust dirt and oil
spent three hours alone cleaning the carby up.

Surprisingly the bore was nice; the valves neat as and the thing turns over lovely
I stripped every thing off it n scrubbed it up nice,
lapped the valves, put her all back together with out paint as I wanted to see how she ran before I went to the trouble.

Well it fired first pull.... youuu lil bewdy
but wouldn't rev out
Ive re-cleaned the carby and checked the governor and everything is good o.

I think the bottom of the shaft that the main jet screws into to retain the bowl has corroded some were the square notch is normally to about twice its size.... I put a plastic sleeve around it and it helped.
The thing will run and free rev as long as I hold my finger over the intake of the air filter mount closing the hole by 3/4's
It will idle nice and free rev nicely although I feel that just a little muted as the timing wasn't absolutely spot on as I did it bushy style

I'm also wishing to see how the internal governor gears are aligned. I've searched this site through many, many threads and haven't found a great deal about them or pictorials on the innards on governors for H30s.
Maybe someone could point me in the right direction.

I did take the carby off another motor going well and it worked a treat on the motor I'm currently working on...
the only thing I didn't do to the carby was remove the welch plug and do the tip cleaner thing there...

In lieu of the fact that mostly all seems reasonably well, could anyone suggest other things for me to try with my carby?

Also would some one in the know mind if I was to ring them n talk in person? My number 0408 348 232 text or ring and I will ring you back to save you the money as I've a business number.
I'm chuffed with these little motors to cop sooo much neglect and still get up and have a go with little more that a clean up is pretty bloody good ay!
Thank you in advance for any help
Great site yeah
Cheers, The Redfella

Belated welcome RED AMOR , I hope someone helped you out

Life got a bit busy...anyway final photo's of the Tecumseh are on the way... got all enthused after seeing the Red Hot Little 125cc Victa in Rocket Red... (nice work)

Ok, The 140 is together! Just to re-cap I followed up on Grumpy's advice and found some rings etc on-line from the States easy as, and the rings were dirt cheap @$10 a set! It was not all beer and skittles though, TMV140 head and sump gaskets have to be ordered on top of the usual Tecumseh gasket kit....

I checked the ring gaps as per the work shop manual specs.

Top ring Gap: 0.015" (should be 0.010"?)@ 10 mm down the bore
: 0.0145" @ 48mm down the bore

FYI: I measured the gaps at TDC & BDC where the rings would be for worst case gaps. Also the manual states gaps as 0.010" and 0.020" which I have taken as top and bottom ring respectively; It could be read as anything between these is OK too. (clarification welcome Grumpy)

Second ring Gap: 0.016" (should be 0.020"?) @ 15mm down the bore
0.015" @ 48mm down the bore

Oil ring gap: 0.014" (gap not specified in book) @ 18mm down the bore
0.0135" @ BDC

As the rings were only $10 a set I bought another set to see if by chance I could get some with smaller end gaps, to see if manafacturing tolerences were swinging my way

They were out of stock and I had to wait.... but it didn't swing my way 0.018" on the top ring... seems I got the better ones first up

The valve clearence/lash settings after lapping were as follows:
Inlet 0.007" (should be 0.008") I left as is...
Exhaust 0.008" (should be 0.012") Machined to 0.0125"

Ignition timing set at 0.084" BTDC (should be 0.080")

She's all painted up nice, complete with a short straight through Polished stainless steel ex-pipe.. a heap of compression too; prior to the decomp action on the valve!

My lad is happy that his "tractor" motor is together and he even helped with the painting (he is 6) He informs me that I now need to make a trailer so he can take grain feed to Granpa's ewe's and lambs...

I have ordered some bits through Bruce "The Outdoor King" ( mate) & I thought ~$20 for a muffler was pretty good, as the straight out pipe was just a bit of fun, from scrap in the shed...

I promised photo's but seems they wont load for the momment , and my posting tool bar doesnt look like the Popular topics "How to post Photo's in your post" so stay tuned, I suppose!

Merry Christmas all,
FAST GRASS

Thank you for the update, FAST GRASS. While ring gaps for first and second rings are sometimes slightly different, I would not expect one to be double the other. Here are Honda's specifications for the GXV120:
Top and second ring gap: 0.008-0.016" new, service limit 0.039".
Oil ring gap: 0.006-0.014" new, service limit 0.039".
Hence I think the 0.010-0.020" Tecumseh specified would be the lower and upper fit-limits for new rings in a new bore. Do not go below the lower limit, or the engine might seize.

All in all, it sounds as if you should have a good solid engine there, at negligible repair cost, and you've had fun doing it. In my rather limited experience, Tecumseh engines do not usually lack mechanical reliability, though they may be rather prone to problems with the peripheral items, in particular the carburetor.

Please post the pictures when the photo-loading facility is back in action, FAST GRASS. It has been an interesting project and will be very useful in our archives when the record is completed by pictures - and perhaps some commentary on any tricky issues that came up in doing the work.

Thanks grumpy, a prompt about tips and tricks gave me something to think about!...mmmm

This won't be an exhaustive list and has omissions etc. and assumptions are made of the readers general mechanical knowledge etc. hopefully proves to be helpful in giving a few prompts to someone in a rebuild of a motor. A couple of "tricks" specific to a Tecumseh TVM 140 as well..

Method/Tips:

1. Have an area cleaned out to house cleaned and need to be cleaned parts, with a dust free area for short term storage of critical engine internals (I used an old cupboard)

2. Clean everything! before and during strip down, I like to to have everything spotless before opening up an engine, or anything mechanical.

3. More cleaning! and dont forget to clean gunk out of sockets and spanners etc. degrease and blow off with compressed air, throw out dirty rags

4. Have a Milo tin or big tuna tins to keep nuts bolts, screws, keys etc. in (nothing should get lost)

5. Last before opening up engine spray with degreaser scrape off any hard cruddy bits with a wire brush & scraper before hosing off and blow off with compressed air

6. Be carefull when opening up the crankase breather unit, as dirt etc. hangs around the gaskets and the screw holes and lock washers

7. With clean tools, hands and clothes (relatively speaking) strip out the internals of the motor, cam, piston/conrod assembly and the crank shaft. TIP: Slip out valve lifters wipe off with a clean rag one at a time inspect and write "E" on the exhaust one and "I" on the inlet one! and place in your clean area, and strip out the valves and springs etc. keeping them matched up

8. Degrease and wash off internal engine parts drying off with compressed air, inspect and place in your clean area

9. Degrease and wash off cylinder and crank case etc. same with small parts, buff threads and bolts heads with power wire brush on a bench grinder if you have one etc.

10. Degrease and wash off tools ready for a clean re-assembly of engine.

11. On assembly set the ingition timing before the head goes on etc.


Tricks/Traps:

1. Have a copy of or hand written notes of piston ring placement and all the torque settings for the screws and bolts (a down loaded manual is a winner)

2. Use a #3 phillips head bit in a socket to torque up the inlet manifold and carby on your torque wrench

3. Make sure you have the Tecumseh oil pump the right way round, with the bevel facing the crankshaft (inwards) or you'll wonder what the #%^#$ is going on!! ie. why wont this go together (I got caught)

4. Check that you have the Governer arm in the right position when you put the cases together! (I got caught while fiddling around with the oil pump!)

5. Dont forget to pre lube everything with clean oil on assembly TIP: I had trouble with the oil pump plunger staying in place when trying to put the outer case on, as the plunger end is in this and on the crank shaft! I have some thick "Wynns no smoke" oil treatment, it stopped it flopping around, also put a dob of this on the cam lobes.

6. Give the keyways and shafts a light smear of "never sieze" on assembly, I also took out the grub screws on the pulley and did those as well, grease would suffice as well, if you dont have "never seize".

Generally this rebuild went pretty well, I got caught out ordering on line a little (to the States), but was my fault really by not asking before I ordered! So I have a few left over gaskets for the larger Tecumseh engines and a spare set of STD TVM 140 piston rings, I also ordered an extra TVM 140 head and sump gasket, if anyone is interested...

The Outdoor King online order is in the mail on its way too, no worries!

See before and after picks Engine # for the record is TVM140 70370K SER 12660







I'll put in one more final post later with what it cost me to do...

John

Thank you for that report FAST GRASS, it will make a welcome addition to our archives. Good workshop practice makes jobs easier. "Saving" time by cutting corners often results in time being lost through things going wrong, and/or not lasting as long as they should. Worst of all, you can not have confidence in the job done if you did not do it properly.

One additional point you did not mention: generally Tecumseh engines have crankcase ventilation valves that can be fitted either the right way up or the wrong way up. If you fit them the wrong way up, they gulp crankcase oil and pass it into the engine air intake, which is unfortunate when it happens, especially if you don't know why.

Yes good tip grumpy, I didn't mention that! I had to refer back to the manual (pg. 74) at the time to check that... I got it the right way around, as there is a small 1/32"? oil drain hole in the offending bit which gives a clue to which way is "up" i.e. the hole faces down to allow misted oil to return to sump I assumed. This model vents to Atmosphere as it happens, I was tempted to drill a return to the carby, (for better pollution control) but decided against it. I figured it might stuff up the carby calibration and may cause "phantom" issues.

So what did it cost?

MFG Supply (USA) Order #1
Parts:
Air filter: $4.99
Gasket Set: $25.99
Needle and Seat: $2.59
Rings: $9.39
Shipping: $14.74
Total: 57.70
International credit card charge: $1.50? (I think thats about right)

MFG Supply (USA) Order #2
Parts:
Head gasket x2 $3.98
Base Gasket x2 $2.18
Oil Seal: $2.29
Air filter: $4.99
Rings: $9.39
Shipping: $13.17
Total:$36.00
International credit card charge: $1.50? (I think thats about right)


Outdoor King Order #1 (and my first one of many I suspect!)
Parts:
Muffler: $21.53
Carby bowl gasket: $8.37
Shipping: ~$2 (there are other Victa items in this order, so full cost of $10.50 not shown here)
Total: $31.90

Other costs:
Solvent: ~$20.00
Paint: ~$20
Sundries, ie. Power, blasting grit, oil, never sieze, bearing blue, lapping paste, gasket sealer, thinners, rags: ~$10
Total:~$50

Grand total: ~$178.60 with a few "spares"

How long did it take at FTE (full time equiv.) hours?
Dunno really I guess about a week, and had a heap of fun in the man cave

Merry Christmas all, and thank you grumpy
Regards,
John aka FAST GRASS (if it grows fast, mow it fast!)

Thanks FAST GRASS. I will now close this thread. If anyone needs to post to it, just PM a moderator.