Unable to Fully Install VA-128 Restrictor Fitting Into Oil Port on Engine Accessory Case

[avatty]

Yesterday I tried to install the VA-128 45 degree restrictor fitting into the oil port above the e-mag on my -EXP119 engine per KAI 43-05. About 1/2 turn before reaching the 45 degree clocking position, the fitting solidly bottomed out, as if the port was not threaded all of the way through the accessory case (but I don't know if it should be). Two A&P friends looked at this, and agreed with this observation. It's hard to see in the attached photo, but with a flashlight we were able to see the upper area of the threaded port appeared to be obstructed, again, as if not threaded completely through.

The FWF kit contains two VA-128 fittings so I tried both with the same result. So what's the solution? I could slightly file back the VA-128 at the restrictor end to allow proper tightening and clocking (filing back anything over 1/2 thread should be enough), but it's surprising I should have to. Or I could "assume" Lycoming made a mistake on the accessory case, and tap the port the rest of the way through (which might require removing the accessory case) but do not want to make a $$$$ mistake. Has anyone else run into this? Thanks!

 

[Jpm757]

Here is a good reference.

 

[RViator60]

I don't recall having this problem, but had it occurred, my first instinct would be to call Lycoming.

 

[avatty]

Thank you, the RV-14 KAI shows this quite clearly, as well. I was out at the hangar and confirmed I'm doing this correctly, so there does seem to be an issue.

 

[avatty]

I don't recall having this problem, but had it occurred, my first instinct would be to call Lycoming.

I agree, but these issues always seem to crop up on Friday afternoons! Can anyone share specific contact information? Otherwise I will call their general number on Monday.

 

[bjdecker]

...or back out the plug in the adjacent hole. Seal the threads up with a good thread sealant (Loktite 565, 592, etc.)

 

[avatty]

...or back out the plug in the adjacent hole. Seal the threads up with a good thread sealant (Loktite 565, 592, etc.)

Thanks, we've been talking about that, too. I can spend the weekend starting work on the wheel pants, and try to get Lycoming's input on Monday. Much appreciation to everyone!

 

[jrs14855]

I doubt that Lycoming is going to help you with a Vans part. I still have seen no confirmation that the Vans fitting is 1/8 NPT thread. This is the starting point for solving this and Lycoming will not be any help.
Get and auto parts place to help you find any fitting with 1/8 pipe thread and see how it fits. Compare it to the Vans part.
Also the history of the engine might be helpful. New, quality rebuild, used engine with some hours or shade tree overhaul??

 

[PaulvS]

I doubt that Lycoming is going to help you with a Vans part. I still have seen no confirmation that the Vans fitting is 1/8 NPT thread. This is the starting point for solving this and Lycoming will not be any help.
Get and auto parts place to help you find any fitting with 1/8 pipe thread and see how it fits. Compare it to the Vans part.
Also the history of the engine might be helpful. New, quality rebuild, used engine with some hours or shade tree overhaul??

VA-128 description from Van's web store states:

An oil/fuel flow restrictor fitting designed to fit the Lycoming engine oil pressure port as well as the fuel pressure port on the KB-090-T. This fitting is a modified AN823-4 and the restriction is a .040" hole. Threaded end is 1/8" NPT.

 

[PaulvS]

Yesterday I tried to install the VA-128 45 degree restrictor fitting into the oil port above the e-mag on my -EXP119 engine per KAI 43-05. About 1/2 turn before reaching the 45 degree clocking position, the fitting solidly bottomed out, as if the port was not threaded all of the way through the accessory case (but I don't know if it should be). Two A&P friends looked at this, and agreed with this observation. It's hard to see in the attached photo, but with a flashlight we were able to see the upper area of the threaded port appeared to be obstructed, again, as if not threaded completely through.

The FWF kit contains two VA-128 fittings so I tried both with the same result. So what's the solution? I could slightly file back the VA-128 at the restrictor end to allow proper tightening and clocking (filing back anything over 1/2 thread should be enough), but it's surprising I should have to. Or I could "assume" Lycoming made a mistake on the accessory case, and tap the port the rest of the way through (which might require removing the accessory case) but do not want to make a $$$$ mistake. Has anyone else run into this? Thanks!

In the photo of the port it looks like the obstruction at 11 o'clock is due to the port hole being drilled slightly out of alignment with the galley that it intersects.
+1 that a call to Lycoming is the best next step.

 

[sportflyer]

Yesterday I tried to install the VA-128 45 degree restrictor fitting into the oil port above the e-mag on my -EXP119 engine per KAI 43-05. About 1/2 turn before reaching the 45 degree clocking position, the fitting solidly bottomed out, as if the port was not threaded all of the way through the accessory case (but I don't know if it should be). Two A&P friends looked at this, and agreed with this observation. It's hard to see in the attached photo, but with a flashlight we were able to see the upper area of the threaded port appeared to be obstructed, again, as if not threaded completely through.

The FWF kit contains two VA-128 fittings so I tried both with the same result. So what's the solution? I could slightly file back the VA-128 at the restrictor end to allow proper tightening and clocking (filing back anything over 1/2 thread should be enough), but it's surprising I should have to. Or I could "assume" Lycoming made a mistake on the accessory case, and tap the port the rest of the way through (which might require removing the accessory case) but do not want to make a $$$$ mistake. Has anyone else run into this? Thanks!

From the look of the photo, the port you are showing is not the oil sensor port. This is, perhaps that is the problem?

 

[RV6_flyer]

I doubt that Lycoming is going to help you with a Vans part. I still have seen no confirmation that the Vans fitting is 1/8 NPT thread. This is the starting point for solving this and Lycoming will not be any help.
Get and auto parts place to help you find any fitting with 1/8 pipe thread and see how it fits. Compare it to the Vans part.
Also the history of the engine might be helpful. New, quality rebuild, used engine with some hours or shade tree overhaul??

May be easier / lower cost to get one at the local big box lumber store.

I would be looking at the cheaper of the two parts. It is possible that the cheap fitting is bad and not the hole in the expensive engine.

I saw a comment about using a bottom tap. The thread is NPT so that makes it tapered. I am not aware of a NPT (pipe thread) bottom tap. IF it were a screw hole with straight threads, then yes a bottom tap may help.

I would have expected Lycoming to have had a PLUG in that hole when the engine was shipped. IF the plug went in, then most likely the hole is the correct thread. Can the plug go back in to test the hole if you cannot find a pipe fitting to try?

 

[blaplante]

I'd really want to avoid using a tap. Any chip that drops into the hole is a chip right in the oil gallery. Next stop... crank bearing?
Yes, I know all the tricks to keep chips from falling in. I still wouldn't be very comfortable risking it.

 

[jakej]

Avatty - the ‘hole’ you’ve shown is the incorrect one ( post #11 SportFlyer) shows the correct location. I’m very surprised others have not noticed that, maybe too focused on the thread etc issue

 

[avatty]

Wow, thanks for the responses. Here is a reply on at least some of them:

VA-128 is described in Van's store as "An oil/fuel flow restrictor fitting designed to fit the Lycoming engine oil pressure port as well as the fuel pressure port on the KB-090-T. This fitting is a modified AN823-4 and the restriction is a .040" hole. Threaded end is 1/8" NPT."

I agree that attempted fixes ordinarily should be made to the cheaper, more replaceable part (the accessory case is not one of these!). Also about the risk of metal chips if you don't remove the accessory case to complete the tapping if Lycoming were to say that is the problem.

There is not any doubt I am installing into the correct port, which is clearly specified in the KAI, and by several experienced friends who have been looking at this with me.

There was a plug that I removed to install the VA-128. The hole is threaded correctly in size, the issue is depth. We have measured the available depth and it corresponds to the thickness of the accessory case, not any part of the plug installed into the port on the right-hand side of the accessory case adjacent to the rear-facing port into which the VA-128 installs.

Everyone, I appreciate your responses so please don't take this reply as defensive, I'm just recounting where things seem to stand. Today I submitted a report to Lycoming's technical assistance portal hoping that would get a more considered response than a phone call. I will follow up upon hearing back.

- Tom

 

[AZSteve053]

Figures 16 & 17 in the attached Lyc parts manual may help you out, would have been useful if you had mentioned angle valve engine previous. Hard to tell from picture but possible plug coming in from Cyl 3 side of acc case is not a std pipe plug... or maybe accessory case is not properly machined. Is this a FIELD built engine ? Could consider inserting VA-128 on Cyl 3 port instead.
Just interpreting images from parts manual.
Best of luck.

 

[avatty]

Figures 16 & 17 in the attached Lyc parts manual may help you out, would have been useful if you had mentioned angle valve engine previous. Hard to tell from picture but possible plug coming in from Cyl 3 side of acc case is not a std pipe plug... or maybe accessory case is not properly machined. Is this a FIELD built engine ? Could consider inserting VA-128 on Cyl 3 port instead.
Just interpreting images from parts manual.
Best of luck.

Thanks for the parts manual download! This is a factory-new EXP119 (not Thunderbolt). Hopefully I can reach Lycoming on Monday.

 

[jrs14855]

The OP previously stated the fitting was a 8D. -4 is one of two options and is for a 1/4" tube or hose. The OP photo is very hard to interpret. The OP is using the proper hole. Two options for simple fix. Install a brass 90 degree street elbow on the right facing hole along with the appropriate straight fitting for the hose AFTER the elbow is installed. Before installing the elbow press a restrictor in the end.
Option #2 is to install the Vans fitting at the front end of the right oil gallery. Easily identified by the 1/8 steel allen head plug at that location. Then a hose all the way to the firewall. The oil pressure at the front will be 8-10# less than at the aft end. All recent Cessna 172's use the front location.
If the OP insists on the aft location it is likely the accessory case will need to be sent back to Lycoming.
The key to all this is that the factory plug is likely shorter than the pipe thread portion of the Vans adapter
If a dozen fittings from different venders were tried on the engine it is likely that some of them would not bottom out due to manufacturing tolerance on the threads.

 

[avatty]

The OP previously stated the fitting was a 8D. -4 is one of two options and is for a 1/4" tube or hose. The OP photo is very hard to interpret. The OP is using the proper hole. Two options for simple fix. Install a brass 90 degree street elbow on the right facing hole along with the appropriate straight fitting for the hose AFTER the elbow is installed. Before installing the elbow press a restrictor in the end.
Option #2 is to install the Vans fitting at the front end of the right oil gallery. Easily identified by the 1/8 steel allen head plug at that location. Then a hose all the way to the firewall. The oil pressure at the front will be 8-10# less than at the aft end. All recent Cessna 172's use the front location.
If the OP insists on the aft location it is likely the accessory case will need to be sent back to Lycoming.
The key to all this is that the factory plug is likely shorter than the pipe thread portion of the Vans adapter
If a dozen fittings from different venders were tried on the engine it is likely that some of them would not bottom out due to manufacturing tolerance on the threads.

 

[avatty]

I heard back from Lycoming, but accidentally replied to the duplicate (moved here because I shouldn't have posted in the General Discussion forum as well):

"It appears that a small piece of the casting was not machined out during the drill/ tap operation/ deburring operations. If I were to repair this without removal of the accessory housing, I would wrap a rag around a screwdriver or dowel and push into the other hole on the right side to block any debris from dropping down the oil galley, then use a swivel deburring tool or other sharpened tool to remove the piece of casting that is obstructing installation. Afterward remove any debris with tweezers/ shop vacuum then remove the rag from the hole."

 

[avatty]

I heard back from Lycoming, but accidentally replied to the duplicate (moved here because I shouldn't have posted in the General Discussion forum as well):

"It appears that a small piece of the casting was not machined out during the drill/ tap operation/ deburring operations. If I were to repair this without removal of the accessory housing, I would wrap a rag around a screwdriver or dowel and push into the other hole on the right side to block any debris from dropping down the oil galley, then use a swivel deburring tool or other sharpened tool to remove the piece of casting that is obstructing installation. Afterward remove any debris with tweezers/ shop vacuum then remove the rag from the hole."

I replied to the tech rep asking if he could comment on the proposed fix of slightly filing back the end of the fitting (1/2 thread or slightly more) so it would install without bottoming out:

"Either approach would be considered acceptable provided the fitting can be installed to full torque without bottoming out."

Just adding that in case it may help anyone out.