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Sears DYT 4000 Engine issue

#1

S

stevestk

Issue with my Briggs 18.5 Intek on a Sears DYT 4000 lawn tractor. Replaced blade belt and fired up to test. Stopped to check the belt. Belt fine but I noticed oil dripping. Turns out it's from what looks like a small breather on the fuel pump. Over the next 10 minutes I figure out there's significant blow by to the crankcase. With the filler lid off it almost looks like the exhaust. Over the life of the tractor I replaced the head gasket twice. I can think of nasty things but the crazy thing is the engines starts and runs smooth. Scary thing is I checked the oil during this and is was very low. Didn't change after last season but believe I checked it in spring. In the past with the gaskets it was somewhat obvious with the way it ran. Though it may be a little off under load. Didn't want to push it. What's the most likely culprit?


#2

M

mechanic mark

Check crankshaft seals for leaking.


#3

V

VegetiveSteam

stevestk said:
Issue with my Briggs 18.5 Intek on a Sears DYT 4000 lawn tractor. Replaced blade belt and fired up to test. Stopped to check the belt. Belt fine but I noticed oil dripping. Turns out it's from what looks like a small breather on the fuel pump. Over the next 10 minutes I figure out there's significant blow by to the crankcase. With the filler lid off it almost looks like the exhaust. Over the life of the tractor I replaced the head gasket twice. I can think of nasty things but the crazy thing is the engines starts and runs smooth. Scary thing is I checked the oil during this and is was very low. Didn't change after last season but believe I checked it in spring. In the past with the gaskets it was somewhat obvious with the way it ran. Though it may be a little off under load. Didn't want to push it. What's the most likely culprit?
Click to expand...
Did you have the unit tipped for any reason when replacing the belt?


#4

I

ILENGINE

Is this the single or v-twin engine. If single then most likely you have another blown head gasket.


#5

B

bertsmobile1

And if you have not don e this before lap the head & barrel so they are flat
Note, not smooth just flat
They will have swirl marks in them from the flycutter they use at the factory which actually locks the gasket in place & makes it stronger .
But the actions of the hot gasses passing across the blown section of the gaskets cuts valleys in both the head & barrel so the weak spot is wider when bolted together so the gasket is not held as tight in the very region that it needs to be the tightest.
When I get some that blow repeatidly then I fit a solid copper gasket from Lanni at coppergasketsUS.com and those never ever blow again.


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