Tecumseh VLV126 too hot

[Lubener]

I know know how you service Tecumseh valves and they are NOT ADJUSTABLE!!! I don't consider. removing a valve and grinding away the stem an adjustment

If it is out of specs(too little clearance) and additional clearance is needed, why not? It really is not an adjustment. However, as the seat wears, the valve sets lower and the clearance decreases. If it gets out of specs, you either replace the valve (which you might have to remove stock anyway or you take off some stock from the old valve. I don't use a grinder because it is too easy to remove too much. Done it carefully on wet sand or an oil stone. Done it before with great results.

 

[Propflux01]

So update?

 

[Cosmopolit]

So update?

Yes, I will update for sure, I know how important this is for the others. Sorry, I did not have the time until now to do anything about it, hope next week.

 

[Kamele0N]

Not that it is important for us (ok speaking for myself)....but we would be happy if you will succeed

 

[Cosmopolit]

Not that it is important for us (ok speaking for myself)....but we would be happy if you will succeed

Well, what I mean is, me too speaking for myself, that I learn from other topics and threads, this is what makes such sites valuable.

 

[andyd]

Please post your results.

 

[Cosmopolit]

Please post your results.

Well, here I am. No news = bad, and bad news = good.

No change. The same low power and getting hot. Revs sounds uneven, and warm starting is difficult. When idle, the governor moves close-open at a pace of about 2 per second. Sometimes I hear something like a stalling, or like a spark is missing (am not sure about how to interprete this).

I have checked and cleaned the valves. The exhaust one had the right 0.2 mm clearance, I have filed a very small amount the intake one, now is 0.1 mm. There was carbon on the stem of both, but I think this does not really matter. As I wrote, in one position they close both OK, the next turn of the crank they are a bit open (whether an anomality or not, I still don’t know), the „open“ position of both are wide open.

I have changed the coil, the spark plug again, the head gasket. Tightened all screws to specifications. Put an additional insulation on all wires that are near the engine.

I am close to giving it up.

 

[Lubener]

Well, here I am. No news = bad, and bad news = good.

No change. The same low power and getting hot. Revs sounds uneven, and warm starting is difficult. When idle, the governor moves close-open at a pace of about 2 per second. Sometimes I hear something like a stalling, or like a spark is missing (am not sure about how to interprete this).

I have checked and cleaned the valves. The exhaust one had the right 0.2 mm clearance, I have filed a very small amount the intake one, now is 0.1 mm. There was carbon on the stem of both, but I think this does not really matter. As I wrote, in one position they close both OK, the next turn of the crank they are a bit open (whether an anomality or not, I still don’t know), the „open“ position of both are wide open.

I have changed the coil, the spark plug again, the head gasket. Tightened all screws to specifications. Put an additional insulation on all wires that are near the engine.

I am close to giving it up.

Don't overlook the flywheel key being partly sheared and shifted, throwing off the ignition timing.

 

[Cosmopolit]

Don't overlook the flywheel key being partly sheared and shifted, throwing off the ignition timing.

Yes, I forgot to write: I checked this, too. The key is intact, and as someone here wrote, with this kind of mower the blade is driven by a belt, not directly by the crank, so there is probably no damage to the key if the blade hits some object.

 

[Kamele0N]

@Cosmopolit what if.... Everything is in order....except for your muffler which has collapsed and now obstructs flow of exhaust gases? Unscrew its muffler and shake it if you hear anything moving inside...

 

[mk378]

Yes consider restricted intake or exhaust, or running rich (choke stuck on). Rich would usually make some black smoke. Remove muffler and test drive.

It would not be hard to repower the machine with a new engine of a brand that is easier to get parts and service for.

 

[Cosmopolit]

@Cosmopolit what if.... Everything is in order....except for your muffler which has collapsed and now obstructs flow of exhaust gases? Unscrew its muffler and shake it if you hear anything moving inside...

Yes, this is something I did not check yet: to power the engine without the muffler. I will do it in the next few days.

 

[Cosmopolit]

Yes consider restricted intake or exhaust, or running rich (choke stuck on). Rich would usually make some black smoke. Remove muffler and test drive.

It would not be hard to repower the machine with a new engine of a brand that is easier to get parts and service for.

There is no choke, but the governor moves open-close. The exhaust is not black, only hot (but this is normal, I think). Yes, I will try to remove the muffler.

To install another engine is indeed not easy and not cheap, in this case I think I would rather give it up...

 

[Cosmopolit]

@Cosmopolit what if.... Everything is in order....except for your muffler which has collapsed and now obstructs flow of exhaust gases? Unscrew its muffler and shake it if you hear anything moving inside...

Thank you again. No, the muffler is OK, no moving parts inside. I also tried to run the engine without it. Except for being loud, no change, same uneven running and hot. The muffler does not get cherry red as some write. It is more the engine that is too hot.

 

[Kamele0N]

Then the only thing that can cause engine overheating is its carburetor...something is not set right and its running to rich..


Found an interesting site while googling for vlv126...

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[Cujet]

What if you disable the governor and manually operate the engine? Is the oil viscosity and level correct? I think the governor uses oil.

Also, it's good to know that air cooled engines can run very hot. Aircraft engines cylinder heads may reach 250 deg C (nearly 500 degrees F)

 

[Cosmopolit]

What if you disable the governor and manually operate the engine? Is the oil viscosity and level correct? I think the governor uses oil.

Also, it's good to know that air cooled engines can run very hot. Aircraft engines cylinder heads may reach 250 deg C (nearly 500 degrees F)

I think I cannot disable the governor, it is an automatic one. It reacts very quick to surges in the speed (when I engage the blades, for example), I surely cannot do this job manually. Oil is the designated one, W30, and level is correct, too.
About the air cooled engines: I have had an identical mower some years ago, with a slightly different engine (VLV60, the previous model of the present on VLV126), it had other problems, but was by far not running that hot. It became hot during use, but this is normal. I don't know how to measure the temperature, but as I first wrote, it is for sure abnormally hot, for example one of the plastic coverings near the engine has deformed. Maybe the engine is already damaged by the heat somewhere inside.

Thank you all for the time and thoughts. I will give it up, try to sell it to someone who has more experience and time for it.

 

[andyd]

To me, running hot, suggests a lean condition. Either an intake leak or the mixture is too lean. A quick and dirty check is run with the choke partially closed. If carb lacks a choke, use tape, etc to block intake 1/2 way . If power increases and heat lessens...

 

[Wrenchturner44]

Another thing it could be. Some Tecumseh engines used a small nylon gear spinner for slinging oil. Could it be possible that the slinger is no longer doing it's job.....nylon gears could be worn and only turning half speed or something similar.