Tecumseh 5hp lock up.... - Snowblower Forum : Snow Blower Forums
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post #1 of 35 Old 04-29-2015, 03:40 PM Thread Starter
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Tecumseh 5hp lock up....

I have a 1984 Ariens snowblower with a Tecumseh 5hp motor.

In 2014 the motor finally broke.

I replaced the piston, ring, crank and rod and had the block bored.

The local CTC shop put everything back together and it fired up but since it was in June, I didn't have the need to use it.

Just this year, I used it for the first time and the motor locked up.

I took it back to the shop and they told me nothing broke, but the rod locked up on the crank.

What could have caused this?

My concern is, what damaged was done on the journal or rod, and is it safe to have them put it back together and run it as is or should parts be replaced?

If it matters, all parts were Tecumseh brand.

Thank you.
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post #2 of 35 Old 04-29-2015, 06:45 PM
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The most important thing is to be able to determine the cause, otherwise it may very well happen again.

The only two possibilities I can think of (although are related) are:
1. Lack of lubrication.
2. Tolerances too tight.
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post #3 of 35 Old 04-29-2015, 07:45 PM
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Asuming your 5 HP only has 1 shaft coming out the front of it I would just stick one of the 212cc Predator engines on there.

As to why your rebuild failed, no idea. Was there any assembly lube used? Maybe it was put back together dry and the rod started to weld itself to the new crank right away? I think the rods and cranks come with different journal sizes, so maybe you got the wrong parts?

Please direct all snow blower questions to the forums and not to me with PMs.
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post #4 of 35 Old 04-30-2015, 07:00 AM Thread Starter
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I didn't know what to think when this first happened. I cleaned the driveway off and then later that night went back out and after it started, it puffed and shut down. I went to restart it and it was locked up.
I thought the rod bolts let loose.
I ordered all new parts from Tecumseh, but now thinking about it, the only part I had to order with a tolerance was the piston.
I don't know if the crank and rod journal were checked?
But now knowing what happened, I'm worried if there is some rod or crank damaged possibly due to lack of oil?
I'm going up to see it today and see what my options are.
This motor has the two shafts.
Thanks
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post #5 of 35 Old 04-30-2015, 06:38 PM
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Either someone put it together dry (you don't need assembly lube, but you do need at least some motor oil on the crank journal before putting the rod and cap on) or someone over-torqued the cap bolts on the rod.

At this point it will need a new rod, and the crank will have to be cleaned up.
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post #6 of 35 Old 04-30-2015, 07:13 PM
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I will toss my .02 cents in.
Possibly the con rod was installed backwards, then the cap/oil slinger installed correctly from the side view. This would result in the rod/cap not matching to the machined ID.
Or a stack up of tolerances. Outer limits for crank OD and smaller ID for con rod.
At this point see whats damaged. Hopefully all you will need is a new con rod. Simple enough to check the NEW bearing clearance with plastigage.
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post #7 of 35 Old 04-30-2015, 10:05 PM
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Quote:
Originally Posted by scrappy View Post
I will toss my .02 cents in.
Possibly the con rod was installed backwards, then the cap/oil slinger installed correctly from the side view. This would result in the rod/cap not matching to the machined ID.
It's been a while since I had one apart but I'm almost positive you can't get the rod on backwards, you can get the cap on backwards though and that can potentially cause some clearance issues.

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At this point see whats damaged. Hopefully all you will need is a new con rod. Simple enough to check the NEW bearing clearance with plastigage.
It's not normally something you check, there's no bearing, and no different sized rods or cranks, yes you can check it, but you can't really change it if it's wrong so no one ever does.
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post #8 of 35 Old 04-30-2015, 10:17 PM
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Quote:
Originally Posted by 94EG8 View Post
It's been a while since I had one apart but I'm almost positive you can't get the rod on backwards, you can get the cap on backwards though and that can potentially cause some clearance issues.



It's not normally something you check, there's no bearing, and no different sized rods or cranks, yes you can check it, but you can't really change it if it's wrong so no one ever does.
Yes agree. If the clearance is wrong, something is wrong, or run it until the problem shows. For the 5 mins it takes check it.

Not starting an argument. Something was wrong with the assembly of parts.
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post #9 of 35 Old 05-01-2015, 07:04 AM Thread Starter
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Here is an update. There is rod and crank damage. I'm hoping both can be cleaned up. The slinger and rod cap were installed in the correct location, BUT he told me he did not have a torque spec, so he just tightened it up. In fact he told me he didn't check any tolerances, since all the parts were new.
So I got a crank with a small gouge and the rod has score marks on it, which I'm hoping will clean up but my question is, the gouge on the journal will grab your fingernail, if this has to be turned, do they make a spacer or can one be made to fit between the rod and crank? I'm used to working on big block chevy's, and don't know much about these small engines.
Also, when you put the rod on the crank, it does not spin freely, without help. It feels egg shaped and gets tight on the one side.
To me, since the cap was not torqued correctly, and from the marks on both the rod and crank, I think it was oil starved and locked up.
I'm surprised it lasted an hour!
What options do I have at this point?
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post #10 of 35 Old 05-01-2015, 02:28 PM
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Quote:
Originally Posted by bruce69camaro View Post
Here is an update. There is rod and crank damage. I'm hoping both can be cleaned up. The slinger and rod cap were installed in the correct location, BUT he told me he did not have a torque spec, so he just tightened it up. In fact he told me he didn't check any tolerances, since all the parts were new.
So I got a crank with a small gouge and the rod has score marks on it, which I'm hoping will clean up but my question is, the gouge on the journal will grab your fingernail, if this has to be turned, do they make a spacer or can one be made to fit between the rod and crank? I'm used to working on big block chevy's, and don't know much about these small engines.
Also, when you put the rod on the crank, it does not spin freely, without help. It feels egg shaped and gets tight on the one side.
To me, since the cap was not torqued correctly, and from the marks on both the rod and crank, I think it was oil starved and locked up.
I'm surprised it lasted an hour!
What options do I have at this point?
Have any pics?
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