8N engine block crack?

McAllen

New User
Hi,
I have had my 8N for about 28 years. I had the motor rebuilt about 15 years ago.

I started it for the 1st time this season today - and after it ran about 10 minutes or less - It was hot - I check, and all the coolant had leaked out over the winter.

Anyway - When it got hot, It was missing - hitting on about 3 most of the time-- I shut it down filled it with coolant and noticed some coolant leaking out the side of the block - SO close to the head it was had to determine if it was the head gasket or a crack in the block..

I started it again - After the engine warmed up again - the leak STOPPED!

But it still ran bad - missing some..

Tore it down - here is what I found :

There is a hairline crack in the block along the top running length-wise with the motor - BUT is out in the area of the head bolts... Not over by the cylinders..

The engine block is still full of water - can see it in the port holes once the head was removed.

I see no indication of coolant in the oil. And no oil in the water ports of the block.

It appeared there was moisture on the the two center cylinders - likely from the head gasket leaking.
The cylinder walls all look great - virtually new. Now wear, scratches, etc. No carbon build-up on the valves. The tractor has had limited use - Only mowing about 1 1/2 hours a week through the spring and summer mowing season.

Question is -
What can I check to make sure the block is still functional - and only needs a head gasket?

Has anyone ever see a hairline crack like I described? And was the motor operational?

Thanks in advance for any advice, information, etc...
Fred
 
I think I would try a new head gasket on it. A composition head gasket. Not metal.

If the bolt holes have any grip on the bolts below the crack it may work OK.

Worth a try.

Zane
 
I would do as Zane said and also maybe try one of the better stop leaks like Car GoLiquid Glass Metallic. You do have to drain the system and flush it to use the stuff but it is said to work well for a problem like you have. Cost is around $10-15 for the stuff
 
After cleaning and further examination, the hairline crack I described is outside the head-bolt area, between the head-bolts on the block and the outside of the block.

However, there is also a small crack on the side of the block directly below the hairline crack on top.

Yet, this did not leak once the engine was warm, even after mowing for about 20 minutes. Still unable to determine if the initial leak was from the head gasket or the crack...

But the block is still full of water in the port-holes and no leaks..

Have ordered a head gasket.

Should I use a gasket sealer when installing?
 
You can put it on with out a sealer or in your case if it where me I would use copper coat which is a spray sealer made for head gasket and you can get that at any auto parts store
 
I have worked on a few cracked rite bad,,, the biggest issue is will the head bolts tighten up,,, I can tell, most can not when a head bolt is going to strip/pull out so I leave it B on a cracked block... The type of head gasket is not going to make the first bit of difference,,, I spec its going to leak externally no matter what the plan... Its up to you if you can deal/live with it...

So you have one are a few bolts that want pull down to spec,,, its a patch job,,, taking a chance to see if some more service can be got out of it... If they all pull down to spec then things look better... If it weeps coolant external and none gets into the cylinder check it regular... You mite clean up and take a good look at the head all of it especially the combustion chamber,,, they crack also...
 
Hobo, and others, Thanks so Much..

The head bolts are all fine. As I said, the crack is toward the outside away from the bolts.

The head looks good.

Maybe I caused it - when I realized the engine was hot - I put coolant in it - That is when it made some strange noises!!

So we will see...

Is there a sealer I could add to the coolant to seal any cracks if necessary?

Thanks,
 

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