Lionclaw

Lionclaw

Well Known Member
I have an O-320-H2AD engine on my 9A. I just finished a rebuild on my engine to replace a bad cam/lifters and to try to seal some pesky oil leaks. After doing a 15-minute run today to test my new single mag (51360-46 FTW!), I found oil splattered on the firewall. Upon close inspection it seemed to be coming from the first junction in the exhaust. There was also oil dripping from the end of the exhaust.

My first thought was that I had perhaps busted the oil ring on one of the pistons. I did a compression test and got 79/80 on that cylinder. Afterwards I also found quite a bit of oil had pooled in the air box.

It would seem to me that the oil in the airbox would preclude the possibility of this being a broken ring. Another symptom I've noticed is a clicking sound coming from the valve covers. I removed the bottom plugs and spun the prop by hand for about 30 seconds, then was met by a deluge of oil when I removed a few of the valve cover screws.

Anyone have any thoughts? Right now I'm leaning towards some kind of blockage in the oil drain back line, causing the rocker area to become pressurized with oil, and it being pushed through the valve guides. As a side thought, does anyone have any part numbers for valve stem seals that will work? I see Graham has some on his engine, but I'm having trouble locating some that are the right size...
 
Lionclaw said:
then was met by a deluge of oil when I removed a few of the valve cover screws.
Click to expand...

The only reason I can imagine why oil would collect here is a blocked return line. These are easy to pull off to fix, assuming access is good. Be sure to also check the nipple/fitting on the crankcase. Pooling oil in the valve covers would account for burning oil (leaking through intake valve stems and sucked in for combustion). It would also account for oil in the airbox. Oil dripping through the intake valve stem while not running will lead straight to the carb courtesy of gravity. Same will happen in the exhaust.

Larry
 
I have an O-320 H2Ad as well and the creaking noise is normal. The creaking is the Ford style rockers. Could the oil be left over from the rebuild?

Russ
RV9-A N1909K Flying
 
Russ54 said:
I have an O-320 H2Ad as well and the creaking noise is normal. The creaking is the Ford style rockers. Could the oil be left over from the rebuild?

Russ
RV9-A N1909K Flying
Click to expand...

I thought about that, but this was the second time I've run the engine. I'll try clearing the drain tube this weekend. Another thing I noticed was lots of black carbon deposits on the back of the intake valves when I rebuilt the engine. I'm going to keep looking for stem seals. If anyone has a lead on which ones I'd need it'd be appreciated! My understanding is that I need ones that will work on 0.5" and 0.4" stems.
 
The creaking sound is normally from worn fulcrums under the rocker arms. It doesn't hurt much, when it is like that, but it is indicative that the top of the fulcrums is a bit worn out. Maybe just one or could be several. You can listen to each one with the covers off and see which ones you might want to replace.
The oil in the air box happens if the rings are not seated yet. Believe it or not the oil is actually splashing out of the combustion chamber when the intake valve is open. Sometimes you will also get raw oil in the exhaust when this is happening. Don't know what run schedule you are using for the newly overhauled engine but you need to run it more, keeping the cylinders as cool as possible, to get the rings seated and then the oil will clear up. Sounds like things may be not good already and maybe running it in more may not fix it and if so the only fix will be re-hone and re-ring. I would be happy to supply you with a ground run schedule that I know works well, if you want it.
Guide seal will not fix anything as the guides are well up in the rocker area and if the drains are open the oil never gets as high as the guides in the rocker box. Guide seal are more effective when the guides are in a vertical position and the oil in the rocker area can drain down them. But when in a horizontal position, with open drains, there isn't much oil available to drain down them and that is why there are no guide seals normally installed.
Hope this helps.
Good luck,
Mahlon
 
I love it when Mahlon chimes in! I learn something new every time he posts something.

Thanks, Mahlon!

What are you up to these days?
 
mahlon_r said:
I would be happy to supply you with a ground run schedule that I know works well, if you want it.
Click to expand...

I would be very interested in this. I am also rebuilding an O-320 and have wondered how I would manage all of the ground running prior to first flight. It will be going in the RV-6A that I am building. I know that I need to get it to full power quickly to seat the rings.

I would very much appreciate your guidance here. I have read recommended break in procedures, but given that it is going into a new experimental, I was curious how others have managed this process.

Thanks,

Larry
 
CYLINDER RUN-IN INSTRUCTIONS FOR CHANNEL CHROME,
CERMICROME, AND CERMINIL BARRELS

1] Install mineral oil in ALL normally aspirated engines and all Teledyne Continental turbocharged engines.
2] Start engine, run at 800 R.P.M.'s for three (3) minutes, shut down, check for leaks.

3] Start engine, run at 1,000 R.P.M.'s for three (3) minutes, shut down, check for leaks.

4] Cowl aircraft.

5] Start engine, run at 1,200 R.P.M.'s for three (3) minutes, shut down, park into wind.

6] Start engine, run at 1,400 R.P.M.'s for three (3) minutes, shut down, park into wind.

7] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, run up to full power, check all engine parameters, retard power to 1,000 R.P.M. for one (1) minute, shut down.

8] Check for leaks, return engine to service (see Engine Break-In Instructions).

All runs should be made into the wind.

At no time during these runs should CHT exceed 350F. If it does terminate run and continue it after a cool down.

Between all engine runs, allow adequate cool off time.

Before proceeding to next run, you should be able to hold your hand on a rear cylinder head for three to five seconds.



CYLINDER RUN-IN FOR STEEL,
NITRIDED OR REBARRELED CYLINDERS

1] Install mineral oil in the engine.

2] Start engine, run at 800 R.P.M.'s for three (3) minutes, shut down, check for leaks.

3] Start engine, run at 1,000 R.P.M.'s for three (3) minutes, shut down, check for leaks.

4] Cowl aircraft.

5] Start engine, run at 1,200 R.P.M.'s for three (3) minutes, shut down, park into the wind.

6] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, shut down, park into wind.

7] Start engine, run at 1,400 R.P.M.'s for ten minutes, shut down, park into wind.

8] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, run up to full power, check all engine parameters, retard power to 1,000 R.P.M. for one (1) minute, shut down.

9] Check for leaks, return engine to service.
All runs should be made into the wind.

At no time during these runs should CHT exceed 350F. If it does terminate run and continue it after a cool down.

Between all engine runs, allow adequate cool off time.

Before proceeding to next run, you should be able to hold your hand on a rear cylinder head for three to five seconds.

For any further ground running never let the cht exceed 350F or duration exceed 5 mins. Wwhichever occurs first.

Good Luck,
Mahlon
 
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