TWM140 is beating me!

[jp1961]

Hello,

Remove the spark plug and rotate the engine by hand to verify the valves are opening and closing,,,could be a sticking valve.

I'm thinking the valves might be working, but the slightest amount of heat is causing them to bind. If the valves open and close cold, try heating the cylinder hole with a propane torch to see if it fails hot.

Does the kill wire and it's connection to the throttle plate look ok? These Tecumseh's I think short out with the throttle lever.

Regards

Jeff

 

[Paxman]

Hi Jeff!

Since there is compression I guess the valves are OK at least. I haven't taken any tins of this engine, so I don't know how to access the valves. Is there a cover?

The kill function is under the plate. There is a thingie that looks like a bent paperclip that a lever operated by the throttle cable contacts when the throttle lever is pushed to the stop position. It looks to be OK. I don't know about the ground wire though, since it goes in under one of the tins.

Guess I should remove the tins and check that everything looks OK under there.

 

[cpurvis]

I tried to prime with some fuel directly into the cylinder and it fired but wouldn't run.

Compression, fuel and spark are the three things needed for an engine to run. That is evidence that fuel is the missing ingredient.

 

[Paxman]

This is what I suspect also...but why? The carb is brand new and I know the float bowl fills up.

it's not firing well when I prime, but it fires. Other engines revs up and dies, but this one sputters and sometimes it doesn't fire at all.

 

[jp1961]

Hello,

If this is a valves in block engine (not 100% sure as I can't find a TWM140 Tecumseh engine in checking the partstree.com website), you should be able to see the valves through the spark plug hole. Look off to the side with a powerful flashlight.

You'd have to remove the recoil starter to check the ground wire, not a big job, only 4 or so bolts hold it on. Sometimes mice chew through it, or the plastic abrades against a cooling fin, causing an intermittent short.

This statement is leaning me towards an ignition issue - I have checked the spark and it is there, but I have a feeling that it's not that strong. The ignition is solid state so there are no points to check.

It could be fuel related, but I'm not entirely convinced.

Regards

Jeff

 

[cpurvis]

This is what I suspect also...but why? The carb is brand new and I know the float bowl fills up.

it's not firing well when I prime, but it fires. Other engines revs up and dies, but this one sputters and sometimes it doesn't fire at all.

A brand-new Chinese carburetor means nothing. How much did it cost? About the same as a rebuilt kit for a Tecumseh carburetor? Because fuel is sitting in the bowl doesn't mean it's flowing through the passages and jets it has to flow through to mix with air in the correct proportions for the engine to run.

 

[Paxman]

To be able to remove the big tin I had to remove a couple of head bolts. One of them were really oily, so I decided to remove the head. Several bolt were the same, so now I suspect the head gasket. Obviously the gasket is crap now that I removed the head, but do you think my problems could have been a blown head gasket? Even if a new gasket is not that expensive, at some point I have to stop throwing money at this thing...

I could now inspect the valves and they looks pretty good. There is a lot of carbon deposits but they move nicely and it looks like they are seated well.

The flywheel is rather rusty (surface rust) but the key and the slot for it shows no damage.

Jack,

Here is a link to a parts diagram.

 

[cpurvis]

Obviously the gasket is crap now that I removed the head, but do you think my problems could have been a blown head gasket?

I don't think so. You had 90 psi compression; that is more than enough to run.

 

[Paxman]

A brand-new Chinese carburetor means nothing. How much did it cost? About the same as a rebuilt kit for a Tecumseh carburetor? Because fuel is sitting in the bowl doesn't mean it's flowing through the passages and jets it has to flow through to mix with air in the correct proportions for the engine to run.

Since the problem is pretty much identical with the new carburetor as with the old one I actually don't think it is the carb now that I think about it. There is no fuel pump, it's gravity feed with the tank above the float bowl. I know fuel in the float is not a guarantee that the fuel system is working. I only wrote that to inform that fuel is getting to the carb.

 

[Paxman]

I don't think so. You had 90 psi compression; that is more than enough to run.

So where did the oil on the head bolts come from?