Engine mystery?

[longshot2171]

Hey all...
Puked my shiny chrome coil after 7 years of service during the 4th of July parade. I replaced it with a good take out coil, and reassembled w/o a problem.
Here is my question...
Number 1 cylinder is not in line with number 6.
#6 lines up at tdc. #1 is significantly before the timing marks. Rotor lines up at correct 7 o'clock position for plug 1. #6 compression cycle has rotor correctly at 180 from #1.
If #6 is still Tdc, and rotor is correct then I suppose it is not a timing chain/oil pump/distributor issue. #1 piston is going up and down full stroke and has good compression. Plug is not fouled. No ignition miss. Compression good, oil pressure good, temp good. No noticeable knocks. Truck runs and drives strong with smooth idle.
Thinking back, It has always been like this for as long as I have had it (2007). When I got it I had zero flathead experience and thought it might me normal, but now I am stumped. Has anybody else ever experienced this?

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[just me]

1 can't be different than 6. They are both TDC, BDC or any other position at the same time. The cam determines compression or exhaust stroke. The 1-6 and 3-4 and 2-5 throws are on the same plane. All determined by the crankshaft.

 

[longshot2171]

That's what I though. Is the crank a 1 piece design or a pressed together multi piece unit?
My first thought when I saw it was a broken piston..but it goes up and down as you crank the engine. I have seen cracked Pistons in wave runner motors. The piston stops at the highest point or bangs around in the cylinder.
The truck runs too well to be a piston/rod failure. The oil is clean and at correct level.

 

[NDT]

On the Dodge military engine, you cannot stab the distributor 180 out, the drive tab into the oil pump gear is offset. Possibly the oil pump gear is not clocked correctly to the cam.

 

[longshot2171]

Pump and distributor are correct. Distributor is correct for #1 plug. My #1 piston seems to hit Tdc before #6. Just pulled cap to recheck rotor orientation. Got me baffled good....truck runs great and has for years. I guess I'll follow my grandpa's motto..."if it ain't broke then don't fix it.."

 

[Roller]

How are you checking TDC for number 1? You can't use the spark plug hole as it is not over the piston. Number six has a plug in the head that is over the piston that is used to find TDC. As stated above number 6 and number 1 are in the same plane as determined by the crankshaft.

Frank

 

[Bill W]

As already mentioned when #6 is at TDC of its "Exhaust" stroke than #1 will be at TDC of its compression stroke.

 

[longshot2171]

Make sense..thought I was going crazy. I will pull it out later and recheck. I Had looked into the spark plug socket while turning the fan by hand. Swore I could see part of the piston moving up and down but I could be wrong..After all it is summer and with 4 kids home and 3 puppies, by the time I get to work on the truck it's amazing that I can even see straight.

....could I be eyeballing a valve instead?
if so I humbly beg for mercy and forgiveness from the mv gods.......

 

[mdainsd]

You are seeing the top of the intake valves if you are looking down the spark plug hole(s). I just came in and read this after finishing putting the head back on my M37.

 

[longshot2171]

New update...
Guess I will be starting a new thread soon...
Left this morning for a show..Truck started and ran fine. Got about 2 miles from home when it started to miss and pop under load. Seems to be a little low on power. I limped it home..
There seem to be a slow bubbling leak coming out from under the head directly behind the oil pump. Looks and smells like oil/gas.
dipstick has clear oil on it.l
No foam in oil fill tube
Do not see oil in rad.
No steam from tail pipe.
Plug does not look fouled.
Fuel pump/carb/filter seem to be fine.
New coil/cap/rotor and ignition lead.

Truck runs fine at idle..starts quick. No miss in neutral. Lent my compression tester so I can't check that at moment. Does this sound like a blown head gasket w/ compression loss?

 

[just me]

Yep. Sounds like head gasket.

 

[longshot2171]

Started right up with smooth idle. Let it warm up for compression test. As it got hotter, the black bubbling ooze began from the front of the head. All cylinders 90 -100 psi w/o oil. Tried pulling air it cylinders with valves closed to see if a valve was not seating. No noticeable results, but I did think I heard a little hiss from radiator.
Put plugs back in and now have bad misses in multiple cylinders. Plugs do not look bad or fouled.
Hopeful that it only needs gasket, but I guess I will see anything else once head removed. I did notice that the current gasket has the extra hole for the water hump that my head doesn't have.

 

[mdainsd]

In an earlier post you said the bubbling crud was "just behind the oil pump" Now I have read your latest and it seems you meant just behind the water pump. The head gasket I just put in also has that extra hump in front. you can actually see the hole. But the one I took out had it too, so Im not too concerned (yet). 90~100 pounds of compression is not red hot. 90 is the minimum and you should have no more than 10 pounds difference between highest and lowest.

But this still doesn't explain the bad performance. Since you aren't getting steam out the exhaust and you have decent compression if the head gasket has failed its likely just the water passage to outside thats leaking, making your bubbly mixture.

Now you have multiple misses after the compression test? Id go over the spark plug wires a couple of times, 3 and 4 are easy to get wrong...

 

[longshot2171]

I will double check wires, but I numbered the plugs and wires prior to removal.
Yeah I meant the water pump. What ever is bubbling out is oil or gas. It does not smell/ look or smell like antifreeze. I know my readings are low, but I need to get a new tester tomorrow. Mine got returned to me with a guage that now will not reset to zero. Releases to 30 psi, So I do not know if this morning test was accurate.
...that said, I fear the worse case untill I pop off the head. What ever happened was caused by excessive idle time in hot humid weather waiting for the 4th of July parade to start/finish. I hoped it was only the coil. At least it made it home w/o a tow and is in the garage for now.

 

[NAM VET]

I just finished a six month saga with my own M37's engine. It seemed to run fine, being new to me, but decided to a compression check, had about 85/80/80/80/70/40. So thought it best to do a full rebuild. I did it all in my driveway, being in UpState SC, I worked many hours each day, took the motor out, took it down to the block then took it over to a local trusted machine shop, whom I have known for two decades, tear down showed some broken rings, and carbon caked valves, so ended up new pistons, several sleeves, two replacement rods, new valve train, balanced crank and other moving parts, surfaced block and head, and all that sort of stuff. Took about three months, then it came back to me to put it all together, which I did carefully with the utmost attention to detail. In the meantime, I refurbished the front sheet metal, new brake/vent/fuel lines, that sort of thing. Put it back in and a week a ago it fired right up, runs smooth, set the timing, and spending the last few days, remounting the sheet metal, hooking up lights and such. Sent out the carb, starter, generator and fuel pump (but I put in a 24 volt Facet fuel pump).

I suggest you use ARP head studs instead of bolts, you can get a much more consistent torque over bolts. Best Gasket has the best head gasket, fits perfectly. There are tricks to ensure a replacement water pump won't leak. There are specialty gasket and thread sealants for specific applications. Lots of minor parts and hoses and tubing will be needed. Let us know how it goes and what you find.

NAM VET

 

[longshot2171]

Got a new gauge this morning, so I will retest tomorrow. Misfire turned out to be dying pertronix unit...maybe from blowing coil. It was sparking from center of coil to positive terminal. Put the old points plate back in temporarily and replaced coil again to be safe. Used an air hose on low psi to vent distributor since I had the vents off to work. Seemed to smooth out at idle and higher rpm, but have not driven under load. Know head gasket needs to be done anyway so I will probably do new pump, tube and thermostat & have radiator cleaned. Should hopefully know more tomorrow,

 

[M543A2]

With the water pump off pull the water distribution tube out of the block and be sure it is not rusted off. With it not working right you will get hot spots in the block/head. Mine has the larger displacement Canadian motor which has a brass tube so it was OK. Vintage Power Wagons has pullers to remove the tube.

 

[longshot2171]

New comp. Test...engine warm, throttle wide open, all plugs removed...1-6..90/95/90/95/100/100. Head gasket is still bubbling by cylinder 1. No oil in gas and no discoloration or moisture in exhaust. I know the valves are due for an adjustment because I can hear the clattering.