no compression

reomack

Member
Finally go things back together and tried to start the tractor (mutt 49 with 52 side distributor, 12v 1 wire conversion) but spins really fast and no start so I assume no compression. It has been sitting for 4 years but it did run well before that. I assume the valves are stuck. Is there an easy or simple procedure to unstick them? I would dearly love to not have to take the head off again. I had good fuel flow and spark.
 
Before you assume anything, do a compression check. 12 volts spins these machine over pretty fast.
 
Reomack,You should always check your valves for operation and sealing when you have the head off.
Now, you need to remove the plugs and add a teaspoon of engine oil to each cylinder and check compression with a gauge with throttle wide open,or a quick check with your finger in each plug hole.If the valves are stuck you won't have any compression in that cylinder.If you have any valves sticking open you may be able to free them up by removing the covers clean,lube and finesse them.
 
The first thing I would do is pour about
half a cup of MMO in each cylinder. Then
with the spark plugs out slowly turn the
engine over by hand. That will flood the
valve stems and guides from the top.
Next I would pull the valve covers off and
use a good penetrating oil and spray the
valve stems and guides from the bottom.
That will work on the valves from both
ends. Remember: WD40 is not a good
penetrating lubricant. Liquid Wrench or PB
Blaster is far superior.
It might take a week or more of repeated
"treatments" to free the valves but short
of pulling the head back off that is the
best way IMO.
 
(quoted from post at 12:36:18 11/07/18) The first thing I would do is pour about
half a cup of MMO in each cylinder. Then
with the spark plugs out slowly turn the
engine over by hand. That will flood the
valve stems and guides from the top.
Next I would pull the valve covers off and
use a good penetrating oil and spray the
valve stems and guides from the bottom.
That will work on the valves from both
ends. Remember: WD40 is not a good
penetrating lubricant. Liquid Wrench or PB
Blaster is far superior.
It might take a week or more of repeated
"treatments" to free the valves but short
of pulling the head back off that is the
best way IMO.
IRST thing I would do is about the easiest thing one can do to determine whether valve(s) are stuck or not. Take the plugs out and use mirror/light to look down the plug hole, where you will see both intake & exhaust valves and easily see whether they are moving or not as you rotate the engine. So easy, even a cave man could do it. :) Or you could just spend a week soaking and pouring oil only to find that the problem is elsewhere?
 
You are assuming he doesnt have the hood
and tank back on it yet?
Your idea might work with some sort of a
mini cam though.
Short of having a mini cam a guy could
accomplish a visual on the valves just by
pulling the valve covers too.
 
(quoted from post at 13:30:16 11/07/18) You are assuming he doesnt have the hood
and tank back on it yet?
Your idea might work with some sort of a
mini cam though.
Short of having a mini cam a guy could
accomplish a visual on the valves just by
pulling the valve covers too.
'm not assuming anything. I don't post speculatively here. I have done exactly as I said hood & gas tank on. I have even measured valve lift using probes with hood & gas tank installed. BTDT!
 
Reomack,With out tearing any thing else apart ,do what I suggested in the post below and let us know the results.
 
(quoted from post at 13:01:08 11/07/18) Reomack,With out tearing any thing else apart ,do what I suggested in the post below and let us know the results.

Reomack Listen to Den, first things first, before you start tearing things apart. You need to confirm that you have compression problems first, like has been said, 12 volts will spin your engine over quickly, don't assume you have no compression without confirming it.
 
After putting the head back on I was able to turn the engine over by turning the fan without any resistance at all and I heard none of the normal huffing and chuffing of air being compressed and released. I have spun the engine over many times now with the starter and I think I am starting to feel a bit of compression when I try to turn the engine with the fan. I have pulled the plugs and valve covers and lubed things up with PB Blaster and will let it set overnight and try it again in the AM. I appreciate all the helpful comments from everyone. I didn't pull the covers until after I had turned the engine over with the starter but looking at the valves at that point they appear to be operating normally. Maybe I just had left some of the old gasket gunk under some of the valves. I tried to blow everything clean with compressed air but probably didn't get it all. Wish me luck and thanks again everone.
 
Reomack,While you have the valve covers off set the valve lash Intakes .010-.012 Exhausts .014-,016 cold.
 
Would love to do that but can't since The engine does not have adjustable lifters, old school all the way.
 
Checked compression, cold and dry, all four at 90-95, which I know in on the low side but it should run. Will post when i get it running.
 
The valves have to have clearance or at least close to the specs or your valves will be held open and not seat.
 
(quoted from post at 15:04:49 11/08/18) The valves have to have clearance or at least close to the specs or your valves will be held open and not seat.
You are exactly right but if the valves were being help open by too little clearance there would be no compression. Additionally, It did run pretty well before I (semi) abandoned it.
 
(quoted from post at 01:50:31 11/09/18) Checked compression, cold and dry, all four at 90-95, which I know in on the low side but it should run. Will post when i get it running.

Yes it should run decent @ 90-95...
 

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