Intake valve won't close
#1
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Intake valve won't close
Hi,
I have a B&S md 204412 type 0142e1 code 050119e. Not sure what horse it is but it is on my 5500 watt portable generator. I bought the generator a while back I am not sure how many years but I only used it once or twice in the first year and it ran great and then as generators due it stayed in storage. I went out to start the motor the next season and I found that it would rotate and stop at one point. I could rotate the motor back and it would stop roughly at the same point . I took the valve cover off (OHV) and found that the intake stem was not rising as high as the exhaust. I loosened up the rocker and found that the valve would rise and apparently seat with the rocker tension off. I also found a bent push rod. Both valves will move fairly easily when pressed with a hammer handle. I heard the valve guides can come loose in these heads and bend the push rods but my problem seems to be more with the valve stem not rising enough rather than lowering enough. Is there a decompression mechanism that could interfere with the valve movement?
Thanks Dan.
I have a B&S md 204412 type 0142e1 code 050119e. Not sure what horse it is but it is on my 5500 watt portable generator. I bought the generator a while back I am not sure how many years but I only used it once or twice in the first year and it ran great and then as generators due it stayed in storage. I went out to start the motor the next season and I found that it would rotate and stop at one point. I could rotate the motor back and it would stop roughly at the same point . I took the valve cover off (OHV) and found that the intake stem was not rising as high as the exhaust. I loosened up the rocker and found that the valve would rise and apparently seat with the rocker tension off. I also found a bent push rod. Both valves will move fairly easily when pressed with a hammer handle. I heard the valve guides can come loose in these heads and bend the push rods but my problem seems to be more with the valve stem not rising enough rather than lowering enough. Is there a decompression mechanism that could interfere with the valve movement?
Thanks Dan.
#2
Does the push rod move up and down when rotating the engine? Sounds kinda like the lifter is stuck since the valve moves freely.
#3
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Yes the pushrod does move on both the intake and the exhaust
#4
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
What could cause the lifter to stick? Can the same varnish that seizes the valve stem in the guide cause the lifter to stick?
#5
No, I don't think so. Cooked on oil could cause a lifter to stick. So... the valve doesn't close all the way, and the lifter moves all the way down, and the valve does close all the way with the rocker arm off, right? If so, then that says either the valve clearance is too tight or the camshaft is holding it open somehow.
#6
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
No, I don't think so. Cooked on oil could cause a lifter to stick. So... the valve doesn't close all the way, and the lifter moves all the way down, and the valve does close all the way with the rocker arm off, right? If so, then that says either the valve clearance is too tight or the camshaft is holding it open somehow.
#7
The camshaft can't hold the valve open that far if the engine and cam is at TDC position.
Take a flashlight and look at the lifter. I'm thinking it is damaged and not falling back down to the cam lobe.
Take a flashlight and look at the lifter. I'm thinking it is damaged and not falling back down to the cam lobe.
#8
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Thanks, I am out of town but as soon as I get back I will check it out.
#9
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Well I took a look and it looks like the top surface of the lifter maybe damaged a bit which would keep it from sliding all the way back down the guide. I assume these lifters can be removed and replaced from the topside? Can I replace a lifter without replacing the cam? That may seem silly but in a car you are supposed to replace the cam and the lifters as a set.
#10
The lifters are replaced from the inside of the engine. It must be removed and opened up. The lifter has to slide through, and if the end is damaged badly enough, it may be hard to get it through. If the cam looks like both lobes are in good shape and come to a nice high point at the peak, I'd use it and look for a second-hand lifter. Make sure the lifters you use have a completely smooth flat surface with no marks or impressions of any sort. Completely smooth. Lube them well before installing. Most small engine shops should have a few laying around.
#11
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
The lifters are replaced from the inside of the engine. It must be removed and opened up. The lifter has to slide through, and if the end is damaged badly enough, it may be hard to get it through. If the cam looks like both lobes are in good shape and come to a nice high point at the peak, I'd use it and look for a second-hand lifter. Make sure the lifters you use have a completely smooth flat surface with no marks or impressions of any sort. Completely smooth. Lube them well before installing. Most small engine shops should have a few laying around.
#12
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Ok, I now have the lifter replaced and the engine would start and stall because the float was stuck. So I took the carb bowl off and cleaned things up and I know longer have fuel flooding the carb and running on the ground but I have no fuel getting into the engine at all. The bowl is full but the plug is dry. There is a round spring that I was unsure of its original location so I put it in the center of the bowl and pushed the bowl straight up and then tightened down. Is this the right placement of the spring or did I just pint the float down so the needle never leave the seat?
#13
Is it a Nikki carb? Plastic float connected to a plastic inner body that drops out of the carb? If so, the spring is in the right place. It could have a plugged main jet.
#14
Member
Thread Starter
Join Date: Oct 2009
Location: mi
Posts: 22
Upvotes: 0
Received 0 Upvotes
on
0 Posts
That describes the carb perfectly. I will check out the jet thanks