OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Tecumseh / Kirby Engines Tecumseh TSV90

Picked up another Victa with a Tecumseh Engine Tvs90
The mower had a heap of problems but I have nearly sorted them all.
I pulled the carby off and it was gunked up with dirt and more cr*p than I had seen before. The engine was flooding because fuel just ran out of the primer bulb when you filled up the tank.
I thoroughly cleaned the carby which and replaced the following components:
- Top and bottom o rings on the emulsifier
- Needle
- Seat
- Bowl seal
- Primer - old one was cracked
The previous tenant screwed around with the throttle cable but I have the adjusted properly now like all previous Tecumseh engines I have worked on.
The difference with this carby is that it has the mixture screw at the bottom and one additional small tube that comes out beside the emulisifer where the air intake comes in. (Not sure what that is). Would love advice on that.
I have the mower running really well at full speed. It doesn�t smoke and sings sweetly. It doesn�t miss a beat however I am not real happy with the idle.
Can anyone help me with getting the idle on this machine a little smoother. It was surging badly at the start but now the surge (hunting) is only so slight. I know is not right as other tecumseh�s have shown this issue.
Hoping for some advice on getting the right idle. I have tried adjusting the idle and full speed screws however I obviously haven�t got it quite right yet.
Thanks
Peter

Hi Peter, the tube you're refering to is just an extension of the breather vent hole in the carby, they tend to fall off, break off or melt away with time with little or no effect to the rest of the carb.
The mixture screw should be set at one and a half turns out initially and adjusted in quarter turn increments at full throttle once the engine has warmed up. This process will definitely have it running sweet at full revs and hopefully the idle will follow suit.
If it doesn't i could only speculate that the carby needs another thorough clean, paying particular attention to the small hole at the top of the jet, there is a leak from one of the gaskets or the wrong primer bulb has been fitted. Test the primer first by starting the mower and setting the trottle to idle, then block the hole in the primer with your finger and see if that improves how it runs at idle.

Thanks Theo.
I ended up taking the carby off and having another look and I noticed some residual o ring left when I removed the emulsifier. About about 20 minutes of stuffing around I got it all cleaned up and reinserted the emulsifier with the 2 new o rings.
I also made a small adjustment to the float to get the level accurate after watching a couple of video�s grumpy referred me to from u tube again.
I put it all back together this afternoon after a couple of choice words�.. and it seems to be running pretty well. Thanks for the tip on the mixture screw.
Its now starting on the first pull, and running nice and smooth. I will reserve my judgement completely until I take it for a spin in the long grass tomorrow down the back of my suburb.
This one should be right to go unless something else happens!
If you can think of anything else beyond standard for this mower I�m always open to suggestions.


Cheers
Peter

Sounds good Peter, nothing else springs to mind atm. As usual with tecumsehs it's generally a carby problem more often than not and people have no patience for them as they are a litle tedious to get off and parts are a little harder to come by.
I believe you will be impressed with the way it performs in the thick growth and personally i kinda like them as an engine, but like most, i cringe at the thought of having to do "another" tecumseh carb.
Keep us posted on how it performs.

Ok, The mower starts and runs just about as it should. The mower does not smoke at all apart from a little on start up.

I am now pretty certain the mower has knock which is evident at low and high speed. I have made sure the base bolts were tight along with the head bolts. I have double checked the cowling and nothing is rattling at all.

I mowed for about 20 minutes on the weekend putting the engine under heavy load and it didn�t miss a beat. It just kept working away. I stopped and started the engine and it performed just about spot on apart from what appears to be a knock from the big end bearing.

I am pretty sure it�s a knock however its only light and the engines I have found that knock usually don�t start easily or have any power. This mower starts easily and had plenty of power so Im a little confused.

Would appreciate the more experienced mechanics thoughts!

Peter, a big end knock is what it is, generally due to no oil or not changing oil for years, but does not necessarily mean that it will be troublesome stating or lack power. If it performs well ignore it, but if you move it on, let the buyer know that its there.
Having said that, decarbonising the head and the top of the piston helps in reducing the knocking, which may not be coming from the big end.
Here is a list of testing procedures for knocking, straight out of the Tecumseh repair manual.
Any of the conditions listed in No.5 would require a teardown of the engine and rebuilding which would be a costly, non profit making excercise.

TESTING
ENGINE KNOCKS
1. Check the blade hub, blade adapter, or crankshaft coupler for loose fit, loose bolts, or crankshaft key damage.
Remove, inspect, replace if necessary. Reinstall and re-torque the bolts to the proper torque.
2. Check the flywheel key and the flywheel and crankshaft keyway for wear or partial shearing. Replace if any
damage is evident. Tighten the flywheel nut to the proper torque.
3. Check for the correct ignition module air gap or the correct timing (point ignition). Replace the points and condenser
if the points show any wear, oil, or pitting.
4. Remove the cylinder head and check for excessive carbon in the combustion chamber. Also check for the correct
head gasket used, and check the spark plug for proper reach and heat range (correct spark plug for the engine).
5. Check for the proper valve lash using a feeler gauge, and check the internal components (piston, cylinder, connecting
rod, crankshaft journal) for excessive clearance.

Thanks for the explanation. I guess the engines I have found the knock hard must be a lot more warn out so things in this instance don�t look so negative.
Followed your advice:
1) Checked the flywheel key (all good)
2) Decarbonised the head � It had a fair amount of carbon in it but its all clean now. There was a little/ tiny scoring on the bore but I don�t think its too much to be concerned about.
3) Rechecked the magneto gap � all good
4) Blade hub, crankshaft key etc, all check tight with no problems.
The engine wasn�t low on oil when I picked it up and it was relatively clean so things might be ok.
I didn�t encounter another problem that gave me the sh*ts. The primer bulb was leaking fuel again. I took the carby apart and re-set the float just a little past level with the frame of the carby (happy to be corrected if you think differently). I checked the needle to make sure it was seating correctly by sucking on the fuel hose connector and all good, no problems identified.
The last couple of tecumsehs havent caused this much trouble with the carb so it�s a little surprising.. maybe I just got lucky on the last couple.
I haven�t had a chance to give it a test after these changes but would appreciate any thoughts.
Thanks
Peter

So a flooding problem is evident and can be caused by a couple of things:
1) a leaky needle and seat, which i know you've said you replaced. is the seat in the right way up. ie. with it in place can you see the concentric rings or have you placed the face down?
2) Tecumsehs are notorious for leaky floats, especially the brass type. Check the float to see if it has a hole in it by taking it out and shaking it. If you hear liquid inside the float its buggered.

Below is an extract straight out of the Tecumseh manual for how to adjust float level.

Hi Bigted and sorry for the slow reply. I got back to this one tonight after fixing a few others I had on a agenda.

I measured the float clearance with the correct drill bit and re-set it as close to the 4.36mm level that I possibly could. The float has no leaks.

The new seat has the rings face down as they should be. Well I am happy to be corrected if thats not the case.

Tonight I put it back together carefully and no fuel was leaking so fingers crossed its all good.

I also re-checked for anything to cover the light knocking/rattling and I nothing stands out.

Worst case this one is a learning experience as I am not comfortable moving a mower on that I'm not 100% comfortable with..... I havent crossed this one off the list yet.


Would appreciate your thoughts as always

Sounds ok to me, let's just wait and see if it leaks.
As for the knock, sometimes a knock is a knock and can't be remedied unless you're considering a full rebuild!

I had a Honda GXV120 a few months ago that had severe wear due to being run for years with a sump-full of metallic sludge, enormous ring gaps, and only enough oil in the sump to keep the sludge wet. After fitting new rings it ran perfectly except for an audible knock at idle only. At first I hoped it was the Woodruff key driving the blade-plate. (So far the bar-blade Hondas I get that are ex-contractor all have sheared keys in that location, and sometimes the shaft has been damaged by running them that way, with the broken key sometimes slipping.) Unfortunately the knock seemed to actually be slight slack in the big-end bearing. I replaced the cylinder block, crankcase cover, cylinder head, piston, and rod, and the noise went away but I wasn't comfortable with a crankpin that was worn 0.002", so I went back to the job and threw the crankshaft away as well. So now that engine is like grandfather's axe: it's still the same engine, because it has the original starter, flywheel, all of the covers and stamped tin bits, fuel tank, ignition module, carburetor, air cleaner, and all of the bolts, other fasteners, external linkages, and hoses. It's a really nice engine now, and it's survived 30 years of very harsh treatment before I got it.

See how Hondas sometimes get a reputation for extreme durability? It doesn't mean anything unless you know what has been replaced along the way.

Thanks for the tips guys. I followed your advice and the engine is now running so close to spot on its not funny. It still has what I think is a very very slight knock however I could be wrong. I mowed long grass with this machine for 20 off minutes today and short of one very small cough from the engine it didnt miss a beat. It stops and starts relatively easily and doesnt blow any smoke apart from a minor puff on startup. This engine actually has plenty of power. I know some dont like them but they are a pretty sweet machine when you get them running right.

When I come across a 4 stroke engine that is viable to completely rebuild I guess we will cross that bridge accordingly.

Unless anyone else has something to add I think the thread can be closed.

Thanks Peter, i'm glad it worked out. And yes, i too like the tecumseh's when they're running right. Deep down i think i like the way they run and perform better than a Briggs. My Dad has a 207cc tecumseh on an alloy bodied Victa and i can cofidently say it outperforms any Quantum i have ever used.
I will close this thread and if anyone has anything to add please PM a moderator.