hey i got an engine with a broken rod. it had oil in it why did the connecting rod break??? The piston and cylinder look good. the rod is broken about 1.5" below piston the rest of rod is in pieces. the camshaft is broken in half but i dont see any damage to heads or tappets... crank journal has material on it but im hoping it just aluminum that will come off???
are the aluminum rod the weak link??? should i replace the connecting rods when rebuilding this engine??? seems with these small engines its always the connecting rod that goes.
Rod breakage close to the piston is normally a sign of overspeed. So governor may of been the initial failure. Rods break 99.9% of the time due to two reasons. overspeed which breaks close to the piston and rod seized to the crankshaft due to lack of oil. Is the aluminum stuck to the crank shaft look like just impact transfer, or is do it appeared smeared around the bearing journal.
can i use the sump pan?? take a look at the crank thrust surface. I bought engine for $60. Dude said it still ran on one cylinder but no way because camshaft is broken in half So far im looking at rod and camshaft. Hopefully crank will clean up. There was oil in it but it definitely looks like it was run low or hot.
If you are going to take macrographs, please use a camera, not a phone and even then sit it on some sort of a platform.
You can not a phone or camera still enough when you are looking at the screen on the back at arms length.
From what I can see , which was not much was a lot of wear on the end of the semp plate.
Can not tell if your "crack" is a crack or just a casting flash.
The crank looks bad, degrease it then dump it in a bucket of Muratic acid for a few hours, not overnight then check the journals for roughness & / or ovality.
Muriatic acid will over time attack the steel
Lye will not
With acid it is basically dip or brush on the wash off
Lye will passivate so you will need to take it out wash it off, runb the surface then back into the lye again.
Acid will work fine cold
Lye needs to be hot
With the condition of the sump bearing, and the crank journal for the broken rod, I am curious what the other rod journal and magneto bearing looks like. Also the condition of the camshaft bearing surfaces in the engine. I suspect that they are also damaged.
no camshaft journals are good surprisingly perfect..
crankshaft has hot spots but no scratches i can catch fingernail.
same for bearing cap discoloration but no scratches/
I ordered a puller from amazon so i can remove flywheel and crankshaft.
Can i use the sump pan or is it no good???? i know ill have to use the muriatic and measure the crankshaft rod journals. hopefully the upper crank journal isnt scored. Maybe it has a bushing in there???
they used to make a .020" under size but it is obsolete. If the cranks is cut wouldn't the connecting rods have to be oversizex not undersized ?? Or do they just call it undersized because crank journal is undersized? These engine don't use rod bearings.
First thing to do is check those camshaft bearing bosses. Don't see how a camshaft can be broken in two without damaging them. Considering the cost, I think your engine is junk. IF I understand you and undersize con rods are no longer available then your choices are a new crank or have the old one built up and turned back to std., both very expensive choices.
the kohlar on the dixy windowed the block and it broke just above the crank
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motor was ill fated when we got the machine had been sitting was very tight and generally unhappy likely old starvation
from the pictures that looks like oil starvation and that crank is toast its heavily scored and galled
by the time you re polish and clean it up the clearances will be to loose
vanguards are cheap enough they put them in everything find a used tractor and pull the motor like we did
Well pull the crank and the flywheel side of case and it does have replaceable bearing insets but its in excellent condition no streaking or nothing..
I used acid on crank and the aluminum came off! The journal is smooth can catch my fingernail on anything it but has discoloration.(going in for tonsillectomy tomorrow so wont have time to try to polish) Briggs chart says the crank pin measurement is 1.455" . Does it have to be exactly 1.455"??? what is tolerance range. Before looking at specs i measured it with a cheap digital caliper and got 1.455-1.457. cant tell the bad journal from the "good one"
I don't know why you are hell bent on saving this vanguard
cost isn't the issue its gonna cost you more in the end to try and save this motor then simply surfing craigslist for a parts tractor or used motor
but since you are hell bent
take the crank to a machine shop and have them polish it seriously its worth the couple hours of labor cost to have it done right
you can do it on the bench but it takes a ton of time and you can ruin the crank if you don't know what you are doing
start with 400 emery cloth and work up to 1000 or 1500 make sure not to rock the cloth work in long wide slow strokes make sure you get a full 360 on every pass (make sure the cloth is wide enough todo the journal in a single pass
if its really just discoloring then all you need is some 1000 emery cloth and a eagle eye
Discolourising is not the metal changing colour, it is the oxide coating changing colour & getting thicker.
Once it is removed you will be amazed just how thick it is.
You really need to measure the rod clearences with plasti gauge strips.
Operator variations in micrometers means the just don't cut it for fractions of a thou.
I dont know about your neck of the woods but here Vanguards are rare. Now Kohler Commands are a dime a dozen. I never rebuilt one before .ill be into no more than $200 maybe even with new rings.
AS for plastigauge. Where would i find or calculate clearance spec? I can only find crank pin specs.
I dont know about your neck of the woods but here Vanguards are rare. Now Kohler Commands are a dime a dozen. I never rebuilt one before .ill be into no more than $200 maybe even with new rings.
AS for plastigauge. Where would i find or calculate clearance spec? I can only find crank pin specs.
The accepted norm for standard engines is 1.0 thou for every inch of journal diameter.
So a 1.5" journal needs 0.0015" running clearence.
Note this is 15 thenth thou so you are measuring in 0.0001" which is why you use plasti gauge to measure it.
Plasti gauge is good down to 0.00001 incriments.
It does not get printed because it is not a range, like the acceptiable limit of wear in a journal it s a function of the actual journal size.
There is zero limits on this unless you are a very experienced engineer with access to oil flow tables.
