40# compression on one cyl????

[Lou Earle]

Tested the compression on the taxi ( stock engine) This is my oil leaker or burner. I believe most oil loss is from front timing chain seal in wrong etc.

Anyway compression check revealed all except #2 had between 8o and 90 pounds.

ALL plugs even #2 ere cream color and not sooty or wet - just right.

So what gives? Opinions?

can I just replace the rings in #2 and let her rip?

What do I do from here of moderate repair.?

Lou

[JIPJOBXX]

Lou on that leaky seal, I had the same problem and I did sort of a micky mouse fix! I completly cleaned the outside of the timming cover case and where is bolts on to the engine I filled in that area with some JB Weld and no more leak. That cover is one hell of a thing to get oft and then to reseal and I found that just by doing what I just stated it did the trick! Jon

[1just4don]

are you REAL sure it was held tight for that hole?? Does it run rough?? maybe a leaky valve?? If everything is good enough inside I cant see why you couldnt just rering or replace that cylinder,if the piston is cracked. I have taken old motors and just put a 'set' of rings and bearings in it and ran them a LONG time. Honed the walls a bit. Opened one once a four banger and EVERY piston was broke,,that one was a bit MORE expensive but as you can imagine,,,it was NEEDED. Biggest problem is we dont run them hard enough,long enough any more. To the store and back and forth the driveway doesnt get them enough excercise,,,specially if they sat for 20 years or so in barn storage!! But back to your project,while the 'head' is off you make want to peek at whether the valves need ground. Another BIG way to be a skeeter smoker is the valve guides so easy to drop those in too IF you grind the valves,if not leavem be!! Once the head is off obvious will be what you want and need to do.

[Normspeed]

Lou, if you're up for pulling off the head, that should tell you a lot. Look for valves that look something like this.

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[Lou Earle]

I will be pulling the head- I tested again this AM a-cold- all other cyls are around 50 cold but #2 is 15. When you hold thumb on the hole it will not push it off. The other cyls will push the thumb off with ease. I am beginning to wonder if maybe it is something like a bad valve like norm is showing. Keep in mind the plug is clean and the engine runs great. So I conclude it is burning the gas entering the chamber and maybe when running at speed there is some type leak but not down into the crankcase( no big blow by coming out of either tube). Is it possible that I have a stuck valve or it is not closing completely? I just do not know.

[bob westphal]

Lou,

Apply compressed air to that cylinder and listen for where the air leaks out. ie: exhaust pipe, carb, oil filler tube. You'll know exactly what's causing the low compression. A stuck valve will make the engine run rough and possibly pop out the carb. If you suspect a stuck valve, try pouring some water or ATF down the carb while running the engine.

[Plymouthy Adams]

While that is true...it can be one serious pain in the butt to lock the engine from rotation when airing up the cylinder...it must be checked TDC compression stoke, both valves closed...90-120 lbs of air pressure will rotate the slud to BDC as soon as you shoot the air to it...in gear, emergency brake on, may not yet be enough to prevent the engine from rotating..but...once locked in TDC and air applied..the test Bob mentions are very helpful in looking for compression loss..during this test I recommend that the radiator be filled real close to capacity so to view any bubbles into the cooling system via a blown headgasket...last one I did took putting the tranny in gear and someone standing on the brakes, (disc) real hard to prevent engine from moving..

Lou has run enough water down that carb when he got it to clean the carbon that the thing is dang near weaned off gasoline....

[Lou Earle]

Next test - talked ot an older engine builder. he suggested to shoot a couple squirts of 30 w oil into the #2 cyl turn over twice then test.

1- if compression still low it is probably being casued by valve problem

2- iof increased it is ring ,cracked piston . Narrows the search for the escaping air!!

Lou