No compression

L

lesbliss

Member
I've had a srange thing happen to my stock 51 Mercury with merc-o-matic. It has been driven very litle for the last 8 months. Took it out of storage and drove about 30 miles on the freeway. Ran ok but stalled in traffic when starting from a stop. Worked on reposistioning the the electric fuel pump to tuck it up further in frame. Noticed a slight tick from the valves so put 8oz of marvel mystery oil and drove around
or a while.
Six hours later went to start her up and no start. Turned out I had zero compression in all cylinders. Pulled the heads and found three stuck valves. I haved pulled the valves and they are not pitted or burnt.

My questions is has any one ever had compresion all all cylinders fail so suddenly like that and what is likely cause?

Les Bliss
 
No, mine have stuck valves from years of inactivity. Maybe something in the gas? Old gas in the tank?
 
timing gear was my first thot... especially if you have a stock fiber gear. I had one blow up going down the road.
 
I would not consider loss of compression on all 8 cylinders a common thing. Sticking valves will only cause the cylinders affected to have no compression. Did you put the MMO in the fuel or in the oil? You can use it in either but it would act better as a top end lube if it were in the fuel. This is a normal treatment for sticky valve problems. Your rings may be gummed up or the fuel has gone bad. E10 fuel is causing all sorts of headaches now days. Putting ethanol in the fuel causes all sorts of problems if the vehicle is stored in an area that is susceptible to condensation. If too much H2O gets in the tank, it mixes with the alcohol until it's fully absorbed then it all goes to the bottom of the tank in a sticky mass. Too much of this collects in the tank and it will eventually be drawn into the fuel system. If you still have a fuel pump with a sediment bowl, you may see signs of the crap in there.

You might verify that the distributor rotor bug is still lined up with the #1 tower with # 1 cylinder on TDC of the firing stroke.
 
Richard may very well right, remove dist cap and turn engine over, if rotor dosnt turn good indicator the cam gear is stripped
 
I put five gallon of stale gas in my 8N tractor a few years ago and it stuck all the valves and I had to remove each one and clean in solvent. They were covered with a gooey gunk.
 
Thanks for the replies. I thought it was vavle related but I didn't want to overhaul the valves and still have the problem. The post about bad gas makes sense. I plan on grinding valves and deglazing cylinders and new rings and bearings. Car only has 68,000 miles. Living in Las Vegas I hope I can get it going before the hot weather hits. No air conditioning.

Les
 
lesbliss said:
I've had a srange thing happen to my stock 51 Mercury with merc-o-matic. It has been driven very litle for the last 8 months. Took it out of storage and drove about 30 miles on the freeway. Ran ok but stalled in traffic when starting from a stop. Worked on reposistioning the the electric fuel pump to tuck it up further in frame. Noticed a slight tick from the valves so put 8oz of marvel mystery oil and drove around
or a while.
Six hours later went to start her up and no start. Turned out I had zero compression in all cylinders. Pulled the heads and found three stuck valves. I haved pulled the valves and they are not pitted or burnt.

My questions is has any one ever had compresion all all cylinders fail so suddenly like that and what is likely cause?

Les Bliss
Click to expand...

I heard of the possibility of bending all the exhaust valves by using a compression tester that threaded too far into the cylinder... Right over exhaust valves...

Karl
 
If 8 months ago it was a good running car I wouldn't be doing rings and bearings .look for the cause see if there's a sticky goo on the valve .Even if you had a fibre gear stripped it will have compression on the ones that are closed .change the oil ,could be diluted .Ted
lesbliss said:
Thanks for the replies. I thought it was vavle related but I didn't want to overhaul the valves and still have the problem. The post about bad gas makes sense. I plan on grinding valves and deglazing cylinders and new rings and bearings. Car only has 68,000 miles. Living in Las Vegas I hope I can get it going before the hot weather hits. No air conditioning.

Les
Click to expand...
 
Last edited:
Karl Wolf said:
I heard of the possibility of bending all the exhaust valves by using a compression tester that threaded too far into the cylinder... Right over exhaust valves...

Karl
Click to expand...


Good call Karl. An "Occam's razor" for sure. As I remember the story, the person did it again after replacing the valves.

Lonnie
 
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