Fresh engine questions

[lithium366]

Okay so I did a supervised overhaul with my A&P due to cam being worn on #4. Engine now has 8 hours but there are some persistent issues I am seeing, curious if I can use your brains. 1966 Mooney M20E, IO-360-A1A

1. Brand new PCU-5000 governor was installed during overhaul (old governor was contaminated and unrepairable). Before overhaul prop did not overspeed, after overhaul it is kinda lagging going into 2750-2780 and then coming back at 2700 limit. I also see RPM fluctuations in bumps, and while transition to a climb and descent. Propeller is a 3 blades hartzell installed new in 2000 and never overhauled (960 hours on prop). Some suggest to overhaul prop in case there is friction there but curious what other think 

2. Oil cooler is cold to touch. Oil cooler was overhauled and flushed. Not like cold but more like ambient temperature. It should be hot on temps above 185 when vernatherm opens? Wondering if it is working. Brand new vernatherm was also installed during overhaul. Oil temps are in 230-235 in cruse but I don’t pay much attention to oil temp yet since I only 8 hours on overhauled cylinders

3. #1 induction leak. Small RPM - 150 degrees higher EGT than other cylinders, cruise RPM - same EGT as others. I replaced rubber seal and used gasket maker on the paper gasket. Re-did this twice, #1 still has the same induction leak. Where else it can leak from? New injector nozzles with nearly equal flow. fuel flow divider was overhauled as well (I thought maybe below 8gph fuel flow divider can fake induction leak by spraying less fuel than at higher fuel flows when it no longer controls fuel) 

Edited April 14 by lithium366

[MB65E]

1 & 2 could both be the same issue. Check the pressure screen gasket to make sure you installed the correct gasket on the pressure screen. There are 3 types of gaskets. Depends on what screen, and filter set up you have.

3. What makes you think you have an intake leak? Fuel Stains? many times the tabs for the intake tube are overtorqued and bowed. Take the tube off and file the edges down on a flat surface. Also, intake tube can hang up on the lip of the riser and not fully seat. The tube should seal on its own with no spooge . Also, the oring on the sump has two different part numbers as well. The sump can ware a grove where it won’t seal on the sump. 

That’s all I can think of,

-Matt

[Dialed In]

1) I put a new PCU on last year and had the same symptoms.  Prop was new in 2006 and has 1500hrs on it.  I got ahold of the manufacturer APS and they told me to send it back to them. They polished a spool and sent it back to me. It now works as expected. If you need contact info let me know. 
 

2) Check and make sure your oil cooler lines are routed to the correct ports on your filter head. I also rebuilt my engine this year with oversight. OAT 60 degrees @ 6500ft yesterday 68%power 100 degrees ROP and 206 degree oil temp. 35 hours on engine so far. Oil cooler should be warm if your oil temp is over 190 at shut down. 

[Pinecone]

If you send your prop for work, ask for an IRAN, NOT an overhaul.

If you say overhaul, they will grind your blades. A few times doing that and you are buying new blades. 

[lithium366]

9 hours ago, MB65E said:

1 & 2 could both be the same issue. Check the pressure screen gasket to make sure you installed the correct gasket on the pressure screen. There are 3 types of gaskets. Depends on what screen, and filter set up you have.

3. What makes you think you have an intake leak? Fuel Stains? many times the tabs for the intake tube are overtorqued and bowed. Take the tube off and file the edges down on a flat surface. Also, intake tube can hang up on the lip of the riser and not fully seat. The tube should seal on its own with no spooge . Also, the oring on the sump has two different part numbers as well. The sump can ware a grove where it won’t seal on the sump. 

That’s all I can think of,

-Matt

Matt, I think I might be lacking some terminology, where this gasket is installed? Is it the one between governor and governor adaptor with a mesh screen in it?

 

intake leak - #1 EGT is higher than other cylinders on low RPMs but equalizes on high RPMs. I would think this is a classic symptom of an induction leak since the difference in EGT is likely due to the difference in manifold and ambient pressure 

Edited April 14 by lithium366

[lithium366]

2 hours ago, Dialed In said:

1) I put a new PCU on last year and had the same symptoms.  Prop was new in 2006 and has 1500hrs on it.  I got ahold of the manufacturer APS and they told me to send it back to them. They polished a spool and sent it back to me. It now works as expected. If you need contact info let me know. 
 

2) Check and make sure your oil cooler lines are routed to the correct ports on your filter head. I also rebuilt my engine this year with oversight. OAT 60 degrees @ 6500ft yesterday 68%power 100 degrees ROP and 206 degree oil temp. 35 hours on engine so far. Oil cooler should be warm if your oil temp is over 190 at shut down. 

When I reached out to PCU they didn’t suggest me an option to send it back, they just said something like your engine after an overhaul has more power now and your prop might not be able to catch up quickly with governor. Curious how you convinced them to take a look at yours 

[Kelpro999]

Induction leaks happen at the updraft tube to cylinder connection. The tube lip is held onto the gasket with the aluminum tube clamp. This clamp becomes bowed closer to the cylinder at the studs and further away across the midsection. The fix is new never installed clamps with new gaskets then careful tightening method. 
 Updraft tube connector hose leaks are more obvious if there’s a problem and usually only needs a slight hose clamp tightening.

[Ragsf15e]

4 hours ago, lithium366 said:

Matt, I think I might be lacking some terminology, where this gasket is installed? Is it the one between governor and governor adaptor with a mesh screen in it?

 

intake leak - #1 EGT is higher than other cylinders on low RPMs but equalizes on high RPMs. I would think this is a classic symptom of an induction leak since the difference in EGT is likely due to the difference in manifold and ambient pressure 

Saavy has an airborne induction leak test.  It’s not perfect but maybe worth a try…

Page 6 of this:

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2012-01_flight-test-profiles.pdf

[PT20J]

Seems like you could take a clean shop vac with a fresh filter and pressurize the intake and spray all the connections with soapy water same as testing for exhaust leaks. 

[lithium366]

2 hours ago, PT20J said:

Seems like you could take a clean shop vac with a fresh filter and pressurize the intake and spray all the connections with soapy water same as testing for exhaust leaks. 

Where would I connect vacuum to and how y’all sealing it to the intake? I wiuld imaging I will have to drop lower cowling first to somehow ductape into the fuel flow servo?

[lithium366]

4 hours ago, Ragsf15e said:

Saavy has an airborne induction leak test.  It’s not perfect but maybe worth a try…

Page 6 of this:

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2012-01_flight-test-profiles.pdf

Yeah, I submitted my files for them to analyze they confirmed looks like an induction leak

[lithium366]

4 hours ago, Kelpro999 said:

Induction leaks happen at the updraft tube to cylinder connection. The tube lip is held onto the gasket with the aluminum tube clamp. This clamp becomes bowed closer to the cylinder at the studs and further away across the midsection. The fix is new never installed clamps with new gaskets then careful tightening method. 
 Updraft tube connector hose leaks are more obvious if there’s a problem and usually only needs a slight hose clamp tightening.

Interesting. I had to replace intake pipes (bought used ones) due to sandblasting shop messed up with mine trying to remove chrome, maybe it is bowed as you said

[EricJ]

3 hours ago, PT20J said:

Seems like you could take a clean shop vac with a fresh filter and pressurize the intake and spray all the connections with soapy water same as testing for exhaust leaks. 

You can also do it from the exhaust side, too.   If one cylinder has both valves open it'll pressurize the intake, too, if the inlet is blocked, which isn't that hard to do.    I've done it both ways, from the intake and from the exhaust.    Imho, from the exhaust side is a little less likely to blow something into the fuel servo ram air tubes, but maybe a little lossier to try to control more leaks.

[lithium366]

53 minutes ago, EricJ said:

You can also do it from the exhaust side, too.   If one cylinder has both valves open it'll pressurize the intake, too, if the inlet is blocked, which isn't that hard to do.    I've done it both ways, from the intake and from the exhaust.    Imho, from the exhaust side is a little less likely to blow something into the fuel servo ram air tubes, but maybe a little lossier to try to control more leaks.

How can I effectively block intake that way? I would think, duct tape on the cowling side will not still have some leks from alternate air? Still need to remove lower cowling? Also a bit confused about both valves open, when would that happen? 

Edited April 15 by lithium366

[PT20J]

1 hour ago, lithium366 said:

Also a bit confused about both valves open, when would that happen? 

There is a period of “valve overlap” at the end of the exhaust stroke/beginning of the intake stroke when the exhaust valve is closing and the intake valve is beginning to open. 

[Dialed In]

Curious how you are coming on these issues. From what I know these guys manufacture the PCU 5000 https://www.aircraftpropeller.com/partsales-airframesupport. I contacted them and told them that before the change my old governor, that had 2300 hours on it I believe, would hold rpm very well +- 10 in level cruise. Since the pcu was installed it was more like 30 or so and I was unhappy with the performance. He told me they had seen that a few times and they would bench test it, if it did not meet spec they would fix it, if it did meet spec I would own them $300 for the testing. I sent it in, they tested it and polished a spool, and sent it back free of charge. It now holds +- 10-20 rpm in cruise. Although the old governor held rpm better in cruise this governor reacts way faster when the power is changed ie go around or practicing stalls. 
-Chase

[lithium366]

27 minutes ago, Dialed In said:

Curious how you are coming on these issues. From what I know these guys manufacture the PCU 5000 https://www.aircraftpropeller.com/partsales-airframesupport. I contacted them and told them that before the change my old governor, that had 2300 hours on it I believe, would hold rpm very well +- 10 in level cruise. Since the pcu was installed it was more like 30 or so and I was unhappy with the performance. He told me they had seen that a few times and they would bench test it, if it did not meet spec they would fix it, if it did meet spec I would own them $300 for the testing. I sent it in, they tested it and polished a spool, and sent it back free of charge. It now holds +- 10-20 rpm in cruise. Although the old governor held rpm better in cruise this governor reacts way faster when the power is changed ie go around or practicing stalls. 
-Chase

Thank you for the report. How long ago dis you send it to them and how long was a turnaround?

[Dialed In]

I sent it in July of 2023 and had it back in two weeks. 

[TheAv8r]

Also following along... I'm wrapping up an engine overhaul and bought a new PCU-5000 for my M20E. We haven't installed anything yet (still waiting on the engine to get back) but you've got me concerned now!

[A64Pilot]

Ref oil cooler.

Even on cold days it should be pretty warm / hot. Oil flow is always through the cooler, but when cold and the Vernatherm retracted the oil flows both through the cooler and bypasses it, majority bypasses it as that’s the least resistence. As there is still oil flow through the cooler that’s why in cold weather covering the cooler helps raise temps. If there wasn’t constant oil flow through the cooler in real cold temps the oil in the cooler would turn to almost grease so there has to be some flow to prevent that.

You may have a blockage, 235 in cruise sounds hot to me.

When the oil is hot, the Vernatherm extends and blocks off the bypass around the cooler and All oil flows through the cooler meaning maximum cooling of course.

[lithium366]

3 hours ago, A64Pilot said:

Ref oil cooler.

Even on cold days it should be pretty warm / hot. Oil flow is always through the cooler, but when cold and the Vernatherm retracted the oil flows both through the cooler and bypasses it, majority bypasses it as that’s the least resistence. As there is still oil flow through the cooler that’s why in cold weather covering the cooler helps raise temps. If there wasn’t constant oil flow through the cooler in real cold temps the oil in the cooler would turn to almost grease so there has to be some flow to prevent that.

You may have a blockage, 235 in cruise sounds hot to me.

When the oil is hot, the Vernatherm extends and blocks off the bypass around the cooler and All oil flows through the cooler meaning maximum cooling of course.

This is on my list to do. Something I noticed that vernatherm gasket seem to be thicker than the one I previously had, I am thinking of taking an entire oil filter adapter with vernatherm and throwing it into a hot water monitoring temps and how it seated and how it closes. Open to any better ideas tho