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Cracked O-320 Case - Best way to proceed?

qsmx440 said:
This brings up something I have pondered over the last two years:
After an overhaul or cylinder change is there any reason to re torque the case/cylinders at 10, 100, or 1000 hours? Should the prop resistance be checked before and after a re torque? It appears that this would show up fretting and would be a good time to check exhaust and induction for cracks inside the pipes. Any resistance change would dictate a tear down of course.
Click to expand...
It was interesting to me that the break-loose torque to remove the cylinder base nuts varied some (considerably?) when I took this engine apart. That was especially true with the large nuts, and they stayed tight for several resets of the base wrench. That struck me as strange, and I think would be consistent with the case mating surfaces being non-flat at the time it was assembled (stud tension remains high until case distortion is fully relieved). That's a subjective finding of mine, and I didn't keep track of which nuts were real tight, but I'm suspicious.
 
Installing a MP gauge will allow using the Lycoming performance chart Fig. 3-3/p. 3-11 (https://www.lycoming.com/sites/default/files/O-320 Operator Manual 60297-30.pdf). The point being getting to 65-75% power or more for run in depending on prop load (rpm/MP) and pressure altitude. No need for actual BMEP providing you can achieve the % power desired. The MP gauge is the best indicator of carb ice in constant throttle/level altitude I've found. A bonus if needed.

Add: The MP will offer more if observed. It'll drop more near idle speed as the rings seat and if valves are tight (lower is better/10-12" Hg for example at sea level), and at full throttle detect intake system loss over ambient air pressure due to excess filtration, or a loose carb heat box leak of heat into the carb (higher is better/1-2" Hg most below ambient). Any needle flutter can indicate valve issues or uneven compression.

Keeping track of this stuff with recorded data should get you familiar with the stages of break-in plus have some fun doing it besides riding around looking at trees and hills.

Gary
 
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How do you pros go about installing the non-split crankshaft nose seal? My case is the grooved style if that matters. I have the Service Instruction 1324, but it sorta just says "do it" using special tool such and so. I'm sure it can be readily done without that tool, so looking for advice. Thanks.

FWIW, I don't have my crankshaft back yet but am trying to be prepared for reassembly.

Thanks - - -
 
It's been a while, as I recall soak it in hot oil until it becomes very soft. Then with the flange protected against sharp edges slide it on.
 
Thanks, I thought I'd heard to warm it up first, but there's no mention of that in the service instruction.
 
A second question - -

I removed a couple different part number pushrods on disassembly, different lengths of course. I have Service Instruction 1060 which identifies them.

However, I have not found in the overhaul manual or elsewhere how to check for the correct pushrod length (O-320-B2B) upon assembly. Help please?

Thanks again - - -
 
This engine has hydraulic lifters. Not sure how that relates to "dry tappets"?? Maybe it means that the lifters (inside the tappet bodies) are fully collapsed (dry)?

I also found a similar instruction in the Lycoming Engine Maintenance Manual for O-360, pg 153. Same dimensions.

Thanks!
 
Gordon Misch said:
This engine has hydraulic lifters. Not sure how that relates to "dry tappets"?? Maybe it means that the lifters (inside the tappet bodies) are fully collapsed (dry)?

I also found a similar instruction in the Lycoming Engine Maintenance Manual for O-360, pg 153. Same dimensions.

Thanks!
Click to expand...

put a big flat head screw driver between valve and rocker arm for a few minutes, that will push the oil out of lifter, hence dry. Then measure clearance
 
Thanks Mike. I also see instructions in the overhaul manual for how to collapse the lifters. Probably good to do that procedure pre-assembly?
 
the few that i have done, i forgot to mention i use duct tape so the seal didnt catch on the prop bushings, sortve tape up the whole flange. worked good.
 
Gordon Misch said:
Thanks Mike. I also see instructions in the overhaul manual for how to collapse the lifters. Probably good to do that procedure pre-assembly?
Click to expand...

Absolutely pre-assembly. Make sure they are completely bleed or you may get an incorrect clearance check later; which leads some to start putting shorter push rods in. If everything is new (cylinders and rockers etc) then you should expect to have all equal length push rods.

For the one piece seal I have found that a heavy duty zip lock bag over the shaft that is well lubricated will cover sharp edges and the thing will slip over fairly easily even without the special tool. Just make certain to clean any of the grease or oil that you used off of the outer side of the seal with a good de-greaser if you want your sealant to hold.

Does this engine have the retaining plates on the front for the seal? If so they are great to keep the seal in place and prevent slippage and eventual rotation which can wear out the case.
 
I was going say it but cubpilot 2 did it for me.... freezer ziplock and oil over the flange.. I'll add this part...then 1/4 drive extension through one of the holes.. boil rubber seal in water in your microwave as long as you feel like.. (engine rubber is good for 250 degrees like all other engine rubber - water won't get it too hot) hook it over your extension and stretch it over quickly with your fingers.. then clean off the seal and stick it in your engine with whatever sealant you like. I like permatex 3 for that but to each his own. I like hylomar for case halves but blew out a front seal on first test using it on the seal because (I think) it is too stiff for that.. I went back to hylomar for case-halves and permatex 3 for front seal.
 
Gordon Misch said:
How do you pros go about installing the non-split crankshaft nose seal? My case is the grooved style if that matters. I have the Service Instruction 1324, but it sorta just says "do it" using special tool such and so. I'm sure it can be readily done without that tool, so looking for advice. Thanks.

FWIW, I don't have my crankshaft back yet but am trying to be prepared for reassembly.

Thanks - - -
Click to expand...

I put the spring from the seal together behind the crank flange. Then I put the seal into a small cup full of water and put it in the microwave I keep in the hangar. I run a few short cycles until the water is steaming, or ready to boil. Even boiling it isn't going to hurt anything. Pour the water off, then start working the seal over the prop flange. I usually end up using the rounded edges of a couple of screwdrivers to work it around the flange. (No screwdriver tips or sharp edges that might scratch or cut) Once it pops over the flange, start working the spring into the back of the seal. The seal will shrink back to size as it cools. Once the spring is in the seal, apply whatever gasket cement you plan to use and press the seal into the case. Usually the whole process takes about 5 to 10 minutes at most.

The zip lock baggy sounds like a good idea. I'll try that in the future, but have done it without numerous times with no issues.

-Cub Builder
 
46 Cub said:
. I like hylomar for case halves but blew out a front seal on first test using it on the seal because (I think) it is too stiff for that.. I went back to hylomar for case-halves and permatex 3 for front seal.
Click to expand...

Lycoming has approved using Locktite 515 for case halves which is great stuff, and what i use. I also work on lots of industrial equipment and use it on closely machined surfaces. It sets up under pressure. Do not use it for any rubber seal though; as it will probably not hold. It just isn’t designed for it. The good old permatex usually does the job.
 
You guys who use Locktite 515, do you also use the silk thread with it? I don't have the service instruction in front of me, but if I recall correctly, I think it's approved without the thread.
 
Gordon Misch said:
You guys who use Locktite 515, do you also use the silk thread with it? I don't have the service instruction in front of me, but if I recall correctly, I think it's approved without the thread.
Click to expand...

Correct. Bulletin 1125D. It says “do not use silk thread”.

Be sure to clean the mating surfaces of any oily film or it may not work as well. I use Berryman B-12 carburetor cleaner.
 
Ditto, have done it both ways over the years. Silk thread is a pain but works. Assembled an AEIO-540 several years ago for a crank change and had LyCon o'ring the crankcase. That was pretty nice.
 
I do wonder why not use thread with 515 as "belt and suspenders". Does it create a problem with that material, or is it just not necessary?
 
Gordon Misch said:
I do wonder why not use thread with 515 as "belt and suspenders". Does it create a problem with that material, or is it just not necessary?
Click to expand...

If i had to guess it most likely isn’t needed. This applies to the RTV-102 as well as the 515.
Yet they seem emphatic about not using it.....
 
Maybe reduces the pressure on the glue? Which maybe makes it not set as it should? No clue.. just guesses..and thinking if you're going to use their stuff then you should probably follow their directions. It's such a big commitment its hard to do something you're not familiar with.. once I used the NAPA form of Hylomar (completely different than the Aerograde) and worried for 1500 hrs. It turned out fine too... which I think all these solutions would with a flat case..
BTW..not trying to say what I think anyone should use. I would love to learn what the absolute best material for case-halves is.. Might do another one one of these days..
 
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