Not understanding why my Techy does what it does.

[formariz 11,865]

Absolutely correct Paul. I was only listing various mechanical components found on small engines that could cause this issue.

My boss has a newer pull-behind finish mower with a Briggs OHV single and (eventually) it pulled over so hard that he ended up breaking the starter cord.

The cause ended up being the exhaust rocker arm stud loosening & slightly backing out of the head. That created excessive valve clearance, which entirely cancelled the ACR function. It's amazing how much difference ACR made in that application.

Cas ~ I know your 653 is a well-kept, low-hour machine. It might not have been used much, but I'm wondering how many times someone has attempted to start it over the years. A couple of long cranking attempts could have overheated the starter enough to cause issues with the brushes & mounting plate.

Even though it still works, it could be weak.

 

I know you don't want to disturb the paint, etc., but it might be worth trying a different (new - or known to be good) starter for comparison.

 

The more I research and test the more I am convinced that you may be correct. I pretty much eliminated all electrical possibilities. Indeed when I first got it before I knew its little quircks sometimes it would take a while before successfully starting it. I am sure that the same happen to the previous owner who was only its second owner.

 

As the next step,the least disturbing test would be to indeed change the starter and see if there is a difference. I do have a couple of good ones here.

 

If the problem is the starter is there anyone you know or a way that I can repair the old one while keeping it rather intact on the outside? Perhaps canibalize the interior parts from an older one?

[Rob R 951]

A new starter will help (especially if the old starter was bad) similar to a new battery...... but I doubt if it will solve your compression problem...... see my previous reply..... 

[TT-(Moderator) 1,128]

A new starter will help (especially if the old starter was bad) similar to a new battery...... but I doubt if it will solve your compression problem...... see my previous reply..... 

Your previous reply doesn't apply to this engine. The H60 in question does not have a compression release of any sort.

A "tight" exhaust valve would reduce compression if it's not allowing the valve to seat.

Carbon build-up is a possibility, but I doubt Cas wants to pull the cylinder head to check.

This tractor is about as close to a 100% original unmolested 1963 machine as you will find without it still being in the shipping crate.

I understand why the owner does not want to remove and disassemble any part of it.

 

[Save Old Iron 1,563]

it might be interesting to see what the compression measures with throttle closed and throttle open - a non destructive test.

[formariz 11,865]

Your previous reply doesn't apply to this engine. The H60 in question does not have a compression release of any sort.

A "tight" exhaust valve would reduce compression if it's not allowing the valve to seat.

Carbon build-up is a possibility, but I doubt Cas wants to pull the cylinder head to check.

This tractor is about as close to a 100% original unmolested 1963 machine as you will find without it still being in the shipping crate.

I understand why the owner does not want to remove and disassemble any part of it.

 

 

That is the big "issue" here. I don't really want to change or disturb anything on it. It works well the way it is, since it starts, as long as you know what to do. It would be better of course if it would start "normally" since due to the fact that I don't start it very often, I sometimes sort of forget its little trick and try to start it with throttle open.

 

it might be interesting to see what the compression measures with throttle closed and throttle open - a non destructive test.

 

That is actually a great idea. It will go a long way to relieve my obsessive need to understand what is going on with it.

 

[Rob R 951]

Okay I was not aware that model Tecumseh  engine does not have a compression release..... it sure sounds like the problems I have seen many, many times on the HH120 all I was trying to do is let you know that on the Tecumseh, HH120 with the same problem it was a compression problem, related to bad compression release cam,  timing, or not enough exhaust valve clearance (worn valve stems).  Most of these folks changed the starters and the battery which help temporarily but did not solve the problem. You obviously can chk the starter and battery prior to replacement.

 

 

P.s. one individual help the situation by draining the old worn out oil and replacing it with Mobil 1 to aid in lubrication and spinning. Again just trying to help you with your problem and save you some $.

 

p.p.s. I would also bet you that if you take the plug out clean it put a smidgen of gas in the cylinder ... it will start right-up since the addition of quick compression on fresh spark will give it the added boast to help spin against the high compression.