Starting Difficulty

no a leak down test is when you bring each individual cylinder to TDC ,,,inject air into the cylinder then see where it is escaping from...

who rebuilt your motor?
 
It was a local shop to my town. They have done motors here since I can remember. I wills top and see them tomorrow. Was hoping for a head gasket but zero pressure seems alarming, especially since it seems to "fix" itself once the engine heats up.
 
It was a local shop to my town. They have done motors here since I can remember. I wills top and see them tomorrow. Was hoping for a head gasket but zero pressure seems alarming, especially since it seems to "fix" itself once the engine heats up.

i think your best bet is to have them diagnose the problem... could even be a misadjusted valve or sticking valve but since they are local go for it they built it
 
Thank you for the continued advice. Will advise what they say/find. The issue for them may be they can only handle a motor and not a car, unless they come to me to diagnose. Will post results.
 
good idea to go back to engine builder. If you followed their breaking recommendations and still have problems, maybe it is something they can cover by warranty? I also agree that it could very well be a sticky valve!!
 
Any chance you had corn crap gas in the tank and it sat around for months while the engine was rebuilt?

I know guys that have had valves stick when they use crap gas and the car sets over the winter. I had that problem on my antique motorbike about 5 years ago. It took Kroil and a hammer to get my valve freed up again.
 
i have seen stale gas goop stick valves many times.. usually it effects more than 1 cylinder hangs up multiple valves...
 
It almost sounds like your rings on cylinder 3 are not sealing the chamber. As your engine warms, the piston should expand and maybe takes up the clearance?
 
I'm bettin on sticking valves

That's what I think also, but air needs to be blown into the cylinder with the piston at TDC to see where it goes. Also the side cover could be removed to see if any valves are stuck. or slow to close. I've seen this happen on newly rebuilt engines a few times. Intake valves should have .001" to .002" stem clearance and exhaust valves should have .002" to .003" stem clearance. That's what I've always used for the heads I did in the 80's, and never had a problem.
 
Well, this has taken a turn for the worse. Shop came up today and magically I have compression on that cylinder. We pulled the valve cover and manifolds to find a mess. A black shiny, smooth tar substance has completely coated the intake ports, the intake and is inside my brand new carb. Looking at the old carb, the same substance is there too and most likely caused its demise. Brittle when dry and comes off in chips. Acetone seems to cut it (one of photos show a litle scrubbing in intake port). It is gumming up the carb and has completely coated the intake system. We assume this caused the valve to stick. Piston/valve top is fine. Valve stem visible in intake ports shows coating. I drained the gas and it is nice and clear as is the tank. It must harden with heat. I can't figure out what it is or where it is coming from but it appears to be passing through carb, so I have to assume it is in the gas. Anyone have any ideas?
 

Attachments

  • IMG_2683.JPG
    IMG_2683.JPG
    77.9 KB · Views: 29
  • IMG_2685.JPG
    IMG_2685.JPG
    94.7 KB · Views: 29
  • IMG_2687.JPG
    IMG_2687.JPG
    82.2 KB · Views: 27
  • IMG_2689.JPG
    IMG_2689.JPG
    100.4 KB · Views: 31
  • IMG_2688.JPG
    IMG_2688.JPG
    95.7 KB · Views: 30
  • IMG_2690.JPG
    IMG_2690.JPG
    118.1 KB · Views: 32
Try cleaning substance with clean fresh has...non-ethanol. If it cleans up with gas, set up a "temporary tank" that is known to be clean. Run your engine on that tank for awhile in the driveway and vary the speed occasionally. Recheck for black goo. Remove the spark arrest or screen from your tank (if it is in place) and shine a light or run a camera in it to see if the goo is in there. If it is, you will have to run some solvent through the tank to remove goo and check it again. I agree that it seems to be a failed tank sealant. You may be able to re-seal the tank after it is CLEAN. Let us know what you find...GOOD LUCK!
 
I am soaking a few gallons of Acetone in the tank for the night. Plan to add 5 gallons of new gas and another gallon of Acetone. Just need to watch good for leaks that may develop. I put the drained gas next to virgin gas and the drained gas is orange tint, compared to new so gas must be breaking it down (hence getting to the carb). Sprayed block intake ports and carb with carb cleaner and the solvent with pressure breaks it down immediately. I just hope it is not on top of tank too and that it will break down enough to drain out. Do the make any sealant kits that can be sprayed without removing tank?
 
You can't spray the Model A tank on the inside because it has baffles. If someone lined it they most likely did it with the tank off and rolled it in all directions for full coverage. I have the tank out of my 1950 Studebaker so I can remove the old tank liner that is coming off and plugging the fuel line.
 
I was afraid of that. I took a careful look inside and don't see any coating but do see some drops of brownish cud. I am soaking it with a mixture of acetone and premium gas for 24 hrs and will drain and see how it looks. Gas must have cut the material before to get it into the carb so this hopefully will work.
 
Since the 10% crap gas is what started the tank liner removal and problems, I bought a gallon of 85% crap gas to finish the removal process.
 
Well, after a soak with gas and acetone, things got messy. Shut off immediately clogged so I could no longer drain the tank. Used a suction pump and pulled out tons of crap/solids/matter. Out of 5 gallons, the photo is what I pulled out. The gas is so contaminated that I could only pour out about 1/2-3/4 gallon before the orange/brown gas clogged a T-Shirt filter. Going to repeat this a few times. Also found that methaleyne chloride seems to attack the material the best. Much better than Acetone or MEK. Tank will get a 4 hr soak with that in the bottom couple of inches to try to dissolve more solids. This is going to be a long process (if it works at all).
 

Attachments

  • image1.JPG
    image1.JPG
    195 KB · Views: 22
Back
Top