Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

(Snapped Connecting Rod) Twin Cylinder (Merged Thread)


dvargo's Avatar
Member

Join Date: Jul 2005
Posts: 15

09-21-05, 07:29 PM   #1  
(Snapped Connecting Rod) Twin Cylinder Engine

Hello,

I have inherited this tractor from my brother, however he was willing to depart with it because it won't start. The history goes like this:

It's approx. 4 years old with a B&S 19.5 HP Twin Cylinder engine, probably the oil was never changed (just added) and was cutting 4 acres. The last time he mowed the lawn he said he heard a clanking sound in the engine and it just sputted out. He was never able to get it started again. That's were I take over.

I have limited knowledge of engines, however I have start the diagnosis from recommendation from this site and the B&S.

First, the battery is about dead and so it requries a charge to get it the fly wheel turning however the engine obviously does not catch.

Second, I seem to be getting a good spark.

Third, When I try to start the engine and then look at the spark plug they are not wet nor have the gas smell. I opened the carburator and sprayed starter fluid and still the engine did not turn over. Additionally I sprayed some in the spark plug it still it did not turn over.

Fourth, Checking the oil revealed old oil and lots of it. The oil level was above full (no gas smell however). The oil was leaking out of the top of the oil case. I have drained all of the oil.

With some excitement and little reservation I jumped in and removed one cylinder head. (Prior to performing a compression check, probably a bad move). Things looked OK to me with the cyclinder and valves. No obvious damage, just carboned up. I manually turned the fly wheel and things seemed to function properly.

I believe my next step is to take the engine off the tractor and open up the crankcase, to see if the gears are busted.

Am I moving to quick and is there any ideas of how I should proceed?

Thank you,
Doug


Last edited by Sharp Advice; 09-24-06 at 05:16 AM. Reason: Posts Merged Into One Thread. Title Also Edited
 
Sponsored Links
v8driver's Avatar
Member

Join Date: Sep 2005
Posts: 767

09-21-05, 09:09 PM   #2  
general rule of thumb, if the oil wasn't changed, just topped off and it went clank, clank, clank inside, you know you'll have to pull it apart, and i'd actually either replace the engine or see if its actually rebuildable, and go from there..... did you check the other cylinder? may have thrown a connecting rod.

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

09-22-05, 01:38 AM   #3  
Yep, I agree. Doesn't sound good. Usually the highest cylinder of the two is the one that blows first. Also, the camshaft on these engines breaks from time to time.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
puey61's Avatar
Member

Join Date: Apr 2004
Posts: 3,224
NY

09-22-05, 02:44 AM   #4  
Mind you, the clank sound may not have been inside the engine. So, lets be sure. Remove the other cylinder head, with both removed turn the engine over by hand and watch for proper movement of both pistons and all four valves. If both pistons are moving the crank is OK, if all four valves move the cam is OK. Next, with both pistons halfway in their stroke take the flywheel and rock it back and forth feeling for any lag in movement between the action of movement and the moment both pistons move. There should be no lag. If it seems excessive you may have a worn connecting rod(s). Check these out and report back.

 
dave237's Avatar
Member

Join Date: Oct 2004
Posts: 255
NC

09-22-05, 03:52 AM   #5  
dvargo,

All good advice above however, before going to this extreme you may want to try this suggestion: Observation / Correction:

If your engine turns over freely with no knocking and if the spark plugs are not wet with gas after cranking a number of rounds you should look to your fuel supply first. It's the most likely cause. If your carb has fuel in the bowel then look to giving your carb a good reconditioning. Total disassembly and thorough cleaning should do the trick. If this doesnít give results then move on to Chesse and Pueys advice.

God Bless,
Dave237

God Bless,
Dave237

 
dvargo's Avatar
Member

Join Date: Jul 2005
Posts: 15

09-22-05, 06:01 AM   #6  
Thank you for the first round of advice. I will start with the carburator and move on from there.

Doug

 
dvargo's Avatar
Member

Join Date: Jul 2005
Posts: 15

09-22-05, 05:44 PM   #7  
Update

So I took off the the right side cycliner head (looking from sitting on the tractor) immediately saw a difference from the left side. First as I took the bolt from the bottom of the head I notice it had oil on it. As I took the head off I notice oil in the bottom of the cyclinder with oil all over the head casket. As I manually turned the fly wheel the piston did not budge. Addtionally the valves move but do seem to miss a stroke. The bottom valve does not seem to go all the way in on the return stroke. Valves and cylinder both seem in good condition.

I did push the piston back into the engine (really just to see if it would budge) It did go back and as a turned the fly wheel it move back out just a little bit then the flywheel locked up.

I am guessing I now need to remove the engine and get into the guts. Any suggestions / instructions as I dig deeper?

Thanks,
Doug

 
v8driver's Avatar
Member

Join Date: Sep 2005
Posts: 767

09-22-05, 06:27 PM   #8  
the connecting rod snapped. yeah you'll have to take it off and apart, first take the pulley stack after you take it off, it'll have a bolt way down in there, then remove all the bolts on the pan and tap it aloose. then inspect it, crank, cam, connecting rod on the other side, and the crank case itself for damage. probablly will look good, hardly no damage, just a couple things to replace, but then again it may be more money to fix then your in for.

 
dave237's Avatar
Member

Join Date: Oct 2004
Posts: 255
NC

09-23-05, 01:42 PM   #9  
dvargo,

I agree. Your piston rod or rod cap has broken. When you pushed the piston back into the cylinder you jammed the rod behind the crank so donít try to start it. Iím sure you will find some cylinder scoring and piston damage at the bottom of the cylinder. This is most likely repairable however, it will be time consuming and dollar intensive and in the end your dollars may be better spent on a new engine. Also, it sounds that you may need some valve work. You will know more about it once you open it up.

God Bless,
Dave237

 
dvargo's Avatar
Member

Join Date: Jul 2005
Posts: 15

09-18-06, 10:51 AM   #10  
Over the weekend I split the enigine and your initial diagnosis was correct. The connecting rod has snapped. I was a bit surprised to only see tiny pieces and some bent up bolts but no big pieces of the connecting rod. Seems the engine really pulverized the connecting rod. The internals look to be in pretty good condition however a few knicks where taken out due to the debris getting kicked around.

Next steps:
I would like to inspect the valves however I am not sure on how to proceed. They are on the other side of the engine and not easily accessible.

Is this engine worth moving forward on to rebuild?

Thank you,
Doug

 
dvargo's Avatar
Member

Join Date: Jul 2005
Posts: 15

09-18-06, 12:22 PM   #11  
Snapped Connecting Rod

This is a continuation from a previous thread (http://forum.doityourself.com/showthread.php?t=232850) Over the weekend I split the enigine and your initial diagnosis was correct. The connecting rod has snapped. I was a bit surprised to only see tiny pieces and some bent up bolts but no big pieces of the connecting rod. Seems the engine really pulverized the connecting rod. The internals seem to be in pretty good condition however a few knicks where taken out due to the debris getting kicked around.

Next steps:
I would like to inspect the valves however I am not sure on how to proceed. They are on the other side of the engine and not easily accessible.

Is this engine worth moving forward on to rebuild?

Thank you,
Doug

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

09-18-06, 07:13 PM   #12  
The valves are probably fine, and the least of your worries right now. I would take a close look at the crankshaft. Sounds like it is probably scarred up and possibly took some hard blows. Also check the piston skirts for damage. Check the camshaft bosses in the block for cracks, the cam for impact marks, and the lower side of the cylinders for cracks. Check the block all over for cracks/impact marks. You'll probably also want to check the top main bearing for the crankshaft to be sure it hasn't been damaged from lack of oiling.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
Search this Thread