Briggs 17.5 opposed twin will not restart when hot 42A707

[troy-built]

We know why engine will not restart when hot
the problem is almost no one comes back with a
" the problem ended up being xyz, thank you"
so when others like you search, you see lots of suggestions but no solutions.

Without the engine right in front of us, all we can do is give you some tests to do .
You come back with the results of the tests then we can make a diagnosis

Only 3 reasons why a hot engine does not restart
1) bad spark
2) wrong fuel : air ratio
3) sticky valves

Having read through all of the posts and in particular the last one I would be looking at overheating .
So after 3 minutes with no airflow the carb has gotten so hot the fuel is vapourising in the float bowl or fuel lines
A lot of engines require a heat shield to prevent the fuel boiling in the fuel lines

Hi, Thank you that's what I was looking for a little input. It always helps when there is more than one person is thinking.
{Without the engine right in front of us, all we can do is give you some tests to do .} That's all I was asking for. And I do understand about not having it in front of you I'm on a couple other forums and it's tough sometimes. But I always try to give Ideas what to look for.

Many thanks that has been very helpful.

 

[slomo]

Absolutely, when was the last time you removed blower housing, cover over engine, & cleaned cooling fins on each cylinder top & bottom? Do not use water, I use small dental like tools, small wire brushes & a Shop Vac to remove crud from engine. Using water will create electrical & mechanical problems.

Please repeat saying this for those in the back.

 

[troynstan]

If you lose spark when the engine is hot, it may be the coil overheating. It happens alot on push mowers. Although, if this is a twin cylinder, you would think it would at least run on 1 cyl. I would check for spark on both cylinders when cold, then again when hot and see if it is spark related. If you sprayed starting fluid in the carb when hot and it didn't fire, then it is either flooding, losing spark, or losing compression.

 

[woodysand]

I think that motor has a wire coming from the coil that when you turn the key off it grounds that wire which kills the engine. Try tracing that from the coil and disconnecting it from the switch. If it will then start up when it’s hot you have something wrong either in the wire or the switch.

 

[Ariens A19A42]

Could be valve adjustment . Mine has a hard time cranking if it stopped on the compression stroke and think it's the vavles making it hard to turn over. But it will always run if I by had spin it past the compression stroke. Hope its not the compression release. Doesn't have a whole lot of hours on the Briggs 19 hp motor. It would backfire bad when I would shut it down until I figured out how to shut it down so it didn't Hope when it did backfire it didn't break the Compression Release.

 

[Scrubcadet10]

If you lose spark when the engine is hot, it may be the coil overheating. It happens alot on push mowers. Although, if this is a twin cylinder, you would think it would at least run on 1 cyl. I would check for spark on both cylinders when cold, then again when hot and see if it is spark related. If you sprayed starting fluid in the carb when hot and it didn't fire, then it is either flooding, losing spark, or losing compression.

These opposed twins use 1 coil for 2 cylinders.

 

[Scrubcadet10]

Could be valve adjustment . Mine has a hard time cranking if it stopped on the compression stroke and think it's the vavles making it hard to turn over. But it will always run if I by had spin it past the compression stroke. Hope its not the compression release. Doesn't have a whole lot of hours on the Briggs 19 hp motor. It would backfire bad when I would shut it down until I figured out how to shut it down so it didn't Hope when it did backfire it didn't break the Compression Release.

Opposed twins don't have a compression relief mechanism on the camshaft.

 

[peteco]

Coil problem, when hot, low spark. Try change the coil. Common problem in VW air cooled engines.

 

[troy-built]

Please repeat saying this for those in the back.

Are you saying to wash a mower or to not wash a mower? That wasn't clear. I did answer his question by the way.

I myself will continue washing my mowers and everything else I own. It's NO different than washing a motorcycle to me. I have a 2013 zero turn that looks as good today as it did the day I bought it.

Water isn't the problem with my mower I'm sure it's just age.
Thanks

 

[beg]

my guess is your coil is bad had the same problem on two of my Toro ccr1000 snowblowers wound not start after being warmed up