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-   -   Engine hydrolocked with fogging oil - did I do damage? (http://www.mastercraft.com/teamtalk/showthread.php?t=82961)

hardycm 10-19-2017 12:51 PM

Engine hydrolocked with fogging oil - did I do damage?
 
1 Attachment(s)
They say hindsight is 20:20, and this story is a good example of this.

Background: For last 20 years I have followed the same winterization / fogging procedure on my ’88 PS 190 that was taught to me by the previous owner. This includes 1) fogging with oil through the carb while running, then 2) removing spark plugs, putting ~ 1 tsp of oil in each cylinder, 3) reinstalling plugs, then 4) cycling engine with coil plug removed to ensure good coating of all cylinder walls.

I’ve always wondered about putting the plugs in before turning it over. The PO told me if you do it the other way, oil spurts out everywhere. I figured the process was working, so why change it. Until this year…. This year I think a bit too much fogging oil got into a few cylinders (I believe it ran down the intake manifold b/c there was certainly more in the pistons than what I put in through the spark plugs). Regardless of the cause, the effect was that I essentially hydrolocked the engine while turning it over with the starter (step 4 above). Something went bang and an expensive noise ensued. I determined that the hood on the starter actually broke (see pic). I believe that the torque of the starter motor against the “seized” engine forced something to give, and the starter was the weakest link. The expensive noise was the starter gear skipping on the ring gear because (I think) without the hood to hold the shaft on the starter straight, it was able flex a bit and not engage with the teeth.

At this point, I removed the spark plugs and was able to turn over the engine via a wrench on the main pulley. I was surprised how much torque it took to turn it over (maybe 25 ft lbs) but it seems to turn freely and I don’t feel any binding or hear any noises indicating internal damage. I THINK my damage is limited to the starter and maybe a worn tooth on the flywheel. So, I’ve learned the hard way that this method of fogging and putting the plugs in before cycling the engine is a bad idea (no need for you guys to remind me :) ) . My questions for the group:

What is normal torque required to turn over a 351 with plugs removed? Is the ~ 25 ft/lb normal? Note: I was NOT able to turn the engine by hand or by turning the water pump – the belt would slip before turning the engine.

Beyond the damage mentioned above, what other damage might I look for / test for?

What tests would you do before the “acid test” of firing up the engine (to risk any further damage)?


Thanks as always,

Chuck

little_franny 10-19-2017 12:58 PM

I would put a new starter in it, remove plugs and coil wire, put lots of rags near plug holes and crank till oil stops coming out, then install plugs and see what happens. It is possible you bent a connecting rod, but the only real way to check would be to remove the heads and measure from deck height to piston top at TDC. USUALLY the starter doesn't produce enough torque and there is not enough inertia present during cranking to bend a rod, but IT IS possible.

ValveCoverGasket 10-19-2017 01:51 PM

Quote:

Originally Posted by little_franny (Post 1381319)
I would put a new starter in it, remove plugs and coil wire, put lots of rags near plug holes and crank till oil stops coming out, then install plugs and see what happens.
It is possible you bent a connecting rod, but the only real way to check would be to remove the heads and measure from deck height to piston top at TDC.

USUALLY the starter doesn't produce enough torque and there is not enough inertia present during cranking to bend a rod, but IT IS possible.

definitely replace the starter and pull all the plugs. keep cranking as mentioned with something covering the plug holes and let the thing empty out

if you bent a rod - and its a definite possibility - youd still be able to turn it over by hand with the plugs out.

the best way to tell at this point would be to check the compression, without pulling the heads or tearing into the motor.
youll need a working starter for that, but keep all the plugs out, insert the compression tester into one hole at a time and check to see the readings you get after a few seconds of cranking.
if youve got a bent rod, youll see that cylinder as significantly lower than the others.

1redTA 10-19-2017 02:13 PM

there would need to be considerable oil to hydrolock the engine. You would need to account for the average cylinder head volume of 64cc, head gasket volume age of 9.0 cc, pistons depth in block volume?, piston cc -10cc. my point is 83 cc equals 0.325 cups of oil in one cylinder

tommurtha 10-19-2017 02:22 PM

btw NAPA will sell you just the starter top, at least they did years ago

CantRepeat 10-19-2017 02:23 PM

Quote:

Originally Posted by 1redTA (Post 1381327)
there would need to be considerable oil to hydrolock the engine. You would need to account for the average cylinder head volume of 64cc, head gasket volume age of 9.0 cc, pistons depth in block volume?, piston cc -10cc. my point is 83 cc equals 0.325 cups of oil in one cylinder

Agreed!

Like enough to fill the entire cylinder and then have an exhaust valve be closed.

This is not a hydrolock a motor. Something else must have cause the started to grenades like that.

Even if the motor was completely seized it wouldn't blow apart a starter. Something else must be wrong.

BrianS 10-19-2017 02:27 PM

Quote:

Originally Posted by 1redTA (Post 1381327)
there would need to be considerable oil to hydrolock the engine. You would need to account for the average cylinder head volume of 64cc, head gasket volume age of 9.0 cc, pistons depth in block volume?, piston cc -10cc. my point is 83 cc equals 0.325 cups of oil in one cylinder

I was thinking the same thing... times 8 cylinders you would need almost 2.5 cups of oil!

03 35th Anniversary 10-19-2017 02:31 PM

If you bent a connecting rod it will sound like a Diesel engine idling.

Also "Tuliping" a valve is a great possibility as well. If that happened it will have a dead miss on that/those cylinder(s) with zero compression.

Or it could be both of the above.

paintpollz 10-19-2017 02:47 PM

you did not bend any connecting rods or bend any valves. as others have mentioned, remove oil and replace starter and put her to bed.

toddvdh 10-19-2017 03:06 PM

Quote:

Originally Posted by hardycm (Post 1381318)
What is normal torque required to turn over a 351 with plugs removed? Is the ~ 25 ft/lb normal? Note: I was NOT able to turn the engine by hand or by turning the water pump – the belt would slip before turning the engine.

That sounds pretty normal to me. Starters get old and break. Cast aluminum isn't overly strong to begin with. I agree with the guys who said:

Replace starter
pull plugs to get excess oil out
put plugs back in and good to go.


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