Rajay M20F Exhaust & Turbo Overhaul Questions

[ZentRose]

I am beginning the process of overhauling my Turbo Normalized IO-360-A1A engine (invoice attached) since it is making metal and near TBO. The turbo has roughly 500 hours since last overhaul and the exhaust was last overhauled by Dawley aviation about 1300 hours ago. 

I emailed acorn about inspecting and repairing the exhaust and they requested part numbers from me (not in my logbooks and not certain where to get those). As far as I can tell from the log books, the past owners have sent the exhaust in when needed and it tends to last much longer than 1300 hours between OH. 

I am wondering what your experience has been with the life of the exhaust and turbo with the Rajay set-up? From the logs, it seems appropriate to leave the turbo, exhaust and wastegate alone since they are easily removed from the plane and currently in good shape with many more hours of serviceable life.  

Thank you

-Tom

 

 

 

[Ragsf15e]

51 minutes ago, ZentRose said:

I am beginning the process of overhauling my Turbo Normalized IO-360-A1A engine (invoice attached) since it is making metal and near TBO. The turbo has roughly 500 hours since last overhaul and the exhaust was last overhauled by Dawley aviation about 1300 hours ago. 

I emailed acorn about inspecting and repairing the exhaust and they requested part numbers from me (not in my logbooks and not certain where to get those). As far as I can tell from the log books, the past owners have sent the exhaust in when needed and it tends to last much longer than 1300 hours between OH. 

I am wondering what your experience has been with the life of the exhaust and turbo with the Rajay set-up? From the logs, it seems appropriate to leave the turbo, exhaust and wastegate alone since they are easily removed from the plane and currently in good shape with many more hours of serviceable life.  

Thank you

-Tom

 

 

 

Seems like a good price from a quality shop.  I’m no help on your exhaust, but I think id ask the engine shop for a recommendation and then send in the exhaust in.  Id want to start with as much a fresh engine as financially possible.

[M20F-1968]

Which system do you have, the Original Rajay or the M20Turbo system?

[N201MKTurbo]

I would clean and inspect the exhaust, if there is no metal erosion, I would put it back in service.

I would pull the turbine and compressor housings from the turbo and clean and inspect them. I wouldn’t mess with the wheels, other than inspecting them. If everything looks ok, I would put it back together and put it back in service. 
 

I would take the scavenger pump apart, clean and inspect it and replace the oil seal.

[ZentRose]

44 minutes ago, Ragsf15e said:

Seems like a good price from a quality shop.  I’m no help on your exhaust, but I think id ask the engine shop for a recommendation and then send in the exhaust in.  Id want to start with as much a fresh engine as financially possible.

I agree with this approach for peace of mind but also want to be diligent. I had set aside $50k for overhaul when I purchased the plane so there is room left in the budget but I don't want to spend if I don't have to .

[ZentRose]

53 minutes ago, M20F-1968 said:

Which system do you have, the Original Rajay or the M20Turbo system?

Original Rajay with manual wastegate. The exhaust tubes & wastegate have been rebuilt/replaced over the years according to logs so those parts are not original.

[ZentRose]

55 minutes ago, N201MKTurbo said:

I would clean and inspect the exhaust, if there is no metal erosion, I would put it back in service.

I would pull the turbine and compressor housings from the turbo and clean and inspect them. I wouldn’t mess with the wheels, other than inspecting them. If everything looks ok, I would put it back together and put it back in service. 
 

I would take the scavenger pump apart, clean and inspect it and replace the oil seal.

This is good advice, thank you 

[N201MKTurbo]

I have hound the best way to clean the exhaust tubes is to get a long 1/4 inch drill extender and chuck up a 2” or so round wire wheel and run it as far as you can down the tubes and get as much of the deposits as you can. Wear a mask or respirator while doing this. The deposits are lead oxide and lead bromide. Try to avoid breathing the dust and wash well before eating. After that you can bead blast them. The stuff deep around the bends is very difficult to get out.

I was thinking a drain snake might work, but I’ve never tried it.

[1967 427]

Also, in an attempt to keep your oil system as sterile as possible. I would replace all the hoses have the oil cooler overhauled, IRAN on the prop governor and prop inspected and cleaned.

[M20F-1968]

16 hours ago, ZentRose said:

Original Rajay with manual wastegate. The exhaust tubes & wastegate have been rebuilt/replaced over the years according to logs so those parts are not original.

The reason I asked is that the original Rajay exhaust and wastegate parts are essentially junk.  When you make new parts, have them made of the next available thickness stainless.  The wastgate can be, and should be considerably thicker.  At 500 hours the turbo should be OK.  The scavenger pump likely should be rebuild by someone who does them routinely.  They are very simple but if they fail you have lost your oil.  

John Breda

[N201MKTurbo]

4 hours ago, M20F-1968 said:

The reason I asked is that the original Rajay exhaust and wastegate parts are essentially junk.  When you make new parts, have them made of the next available thickness stainless.  The wastgate can be, and should be considerably thicker.  At 500 hours the turbo should be OK.  The scavenger pump likely should be rebuild by someone who does them routinely.  They are very simple but if they fail you have lost your oil.  

John Breda

It’s hard to imagine what could fail in the scavenger pump. At worst, they would slowly loose effectiveness. I have three EBay scavenger pumps of different vintages. They all look new inside. The only thing that seems to fail is the oil seal. New ones are $5.

[Gee Bee Aeroproducts]

I have made some silicone molded ducts for this installation per sample.

Baffle seals are the same as oem pattern.

 

i will add pictures later

i can only recommend Lycon in Visalia 

[M20F]

Main turbo for RayJay overhaul.  
 
I wouldn’t mess with the exhaust unless it is actually giving you a problem.  Mine as at least 2000hrs on the exhaust. 

[M20F-1968]

On 12/26/2024 at 12:15 PM, N201MKTurbo said:

It’s hard to imagine what could fail in the scavenger pump. At worst, they would slowly loose effectiveness. I have three EBay scavenger pumps of different vintages. They all look new inside. The only thing that seems to fail is the oil seal. New ones are $5.

I agree, but it is such an important part, I would just be sure that your work is done properly, with the correct seals and installed without damage to the seal.

John Breda

[N201MKTurbo]

1 hour ago, M20F-1968 said:

I agree, but it is such an important part, I would just be sure that your work is done properly, with the correct seals and installed without damage to the seal.

John Breda

Mine was leaking oil and it was getting on the vacuum pump. I replaced the seal twice and it wouldn’t stop leaking. I chucked the shaft in a lathe and polished the surface the seal rides on. It hasn’t leaked since.

[ZentRose]

Thanks everyone, I want to add more background on my engine problems:

Before the oil change I had a rough engine on my way back from Colorado and lost all EGT reading in the #3 cylinder due to a clogged injector. I made a landing at Bryce Canyon, found a piece of metal blocking the injector and multiple flakes in the fuel servo finger screen. Some of the flakes were ferrous but most were not. (I don't think this is related but I am not certain)

I am currently waiting on the last oil sample from Blackstone to confirm the iron trend, flying 10 more hours and checking the filter again this weekend. I assume I am witnessing cam/lifter wear and it will just get worse. 

 

[ProtoFly]

I don't think there's anything ENGINE internal that has anything to do with the fuel system and a clogged injector.  That sounds more like a fuel pump failing to me, or contaminated fuel, or something else bad in the fuel injection system that's throwing metal.  (Disclaimer:  I'm not an A&P, but am an ASE Certified Auto Tech, and I do assist in a shop with the hopes of one day getting my A&P).  That's not to say that you might not have things going Tango Uniform in the engine, but I don't think they are related to the injector clogging.

Side note:  I also have the Rajay turbo.  How's the heat in your plane?  Mine sucks.  And it's cold outside!  My plane is in annual right now, and I'm getting the door seals replaced, and sealing any air holes I can find, but the heat just seems....weak.  My Piper Cherokee would cook my feet if you put them on the tunnel vents!

[ZentRose]

44 minutes ago, ProtoFly said:

I don't think there's anything ENGINE internal that has anything to do with the fuel system and a clogged injector.  That sounds more like a fuel pump failing to me, or contaminated fuel, or something else bad in the fuel injection system that's throwing metal.  (Disclaimer:  I'm not an A&P, but am an ASE Certified Auto Tech, and I do assist in a shop with the hopes of one day getting my A&P).  That's not to say that you might not have things going Tango Uniform in the engine, but I don't think they are related to the injector clogging.

Side note:  I also have the Rajay turbo.  How's the heat in your plane?  Mine sucks.  And it's cold outside!  My plane is in annual right now, and I'm getting the door seals replaced, and sealing any air holes I can find, but the heat just seems....weak.  My Piper Cherokee would cook my feet if you put them on the tunnel vents!

Yes the heater is pretty weak in my plane too. I bring a coat when I take it up to the higher altitudes because it can get very cold lol 

[EricJ]

14 hours ago, ZentRose said:

Thanks everyone, I want to add more background on my engine problems:

Before the oil change I had a rough engine on my way back from Colorado and lost all EGT reading in the #3 cylinder due to a clogged injector. I made a landing at Bryce Canyon, found a piece of metal blocking the injector and multiple flakes in the fuel servo finger screen. Some of the flakes were ferrous but most were not. (I don't think this is related but I am not certain)

I am currently waiting on the last oil sample from Blackstone to confirm the iron trend, flying 10 more hours and checking the filter again this weekend. I assume I am witnessing cam/lifter wear and it will just get worse. 

 

There's no expected path for cam/lifter metal to get into the finger screen, since that only carries fuel from the tanks.   The only two things that move and might make metal in that path are the boost pump and the mechanical fuel pump.   The mechanical fuel pump is a diaphragm pump, so it's unlikely to be the source of the metal.   You may have a bearing failing in your boost pump.

Glad you got it down okay.   I've had an injector clog on a four-cylinder before and it was not fun.   I thought the motor was going to come off the mounts.

[M20F]

On 1/6/2025 at 5:19 PM, ProtoFly said:

Side note:  I also have the Rajay turbo.  How's the heat in your plane?  Mine sucks.  And it's cold outside!  My plane is in annual right now, and I'm getting the door seals replaced, and sealing any air holes I can find, but the heat just seems....weak.  My Piper Cherokee would cook my feet if you put them on the tunnel vents!

It sucks but it is for usually 3 reasons.  
 
Difference in ambient.  I was based in Chicago a number of years and I am now in Atlanta.  Amazingly my heater works better.  You get at best 40F of heating.  If it’s 40F outside, it’s 80F in the plane.  You will see all kinds of people living in PHX talking about how great their heater is and they can’t understand why people based in North Dakota are bitching.

Altitude.  We bought a RayJay to fly in FL’s.  FL190 generally being the sweet spot.  It is again mostly an ambient issue.  People who fly around at 5000FT talk about how great the heater is and can’t understand why all the windows freeze at Fl210. 
 
Lastly the design just sucks.  I have tried a million things, Maxwell has tried, otherwise men have tried.   There just isn’t much heat coming off the design.  
 
You will freeze in general flying behind a RayJay especially in a cold place to begin with.  I just dress warm and fly in the day (sun will bake you).  I did make a run in January once from KJMS to KLZU at FL210 at night.  The 104kt tailwind + 165 knots TAS was great.  I still can’t feel my toes.  
 

[ZentRose]

On 1/7/2025 at 5:29 AM, EricJ said:

There's no expected path for cam/lifter metal to get into the finger screen, since that only carries fuel from the tanks.   The only two things that move and might make metal in that path are the boost pump and the mechanical fuel pump.   The mechanical fuel pump is a diaphragm pump, so it's unlikely to be the source of the metal.   You may have a bearing failing in your boost pump.

Glad you got it down okay.   I've had an injector clog on a four-cylinder before and it was not fun.   I thought the motor was going to come off the mounts.

The suggestion from Blackstone was that the clogged injector may have caused the cylinder to run lean and make metal. I didn't think that was likely but I'm probably wrong. 

Today I cut open the filter after 10 hours of operation and it had nothing in it. The engine was scheduled to come out this week for overhaul but my mechanic said no after cutting open the filter. I'm going to continue flying and will revisit this thread when I need to overhaul. 

The engine is at 1850 hrs since factory overhaul so I am sure I will be updating this thread soon.

[ProtoFly]

On 1/12/2025 at 9:14 PM, ZentRose said:

The suggestion from Blackstone was that the clogged injector may have caused the cylinder to run lean and make metal. I didn't think that was likely but I'm probably wrong. 

Today I cut open the filter after 10 hours of operation and it had nothing in it. The engine was scheduled to come out this week for overhaul but my mechanic said no after cutting open the filter. I'm going to continue flying and will revisit this thread when I need to overhaul. 

The engine is at 1850 hrs since factory overhaul so I am sure I will be updating this thread soon.

Resurrecting this thread:  what was the outcome of everything?  Did you get the engine overhaul done?

[ZentRose]

3 hours ago, ProtoFly said:

Resurrecting this thread:  what was the outcome of everything?  Did you get the engine overhaul done?

• still flying
• oil analysis is healthy
• Only engine problem I have had this past year was a leaky turbo oil return check valve (just needed to be cleaned)
• debating buying an acclaim or keeping this plane 
• Can't get my deposit back from the engine shop 

[MikeOH]

48 minutes ago, ZentRose said:

Can't get my deposit back from the engine shop 

UGH!  What reason are they giving you?  I was considering Corona Aircraft Engines but....

[ZentRose]

8 hours ago, MikeOH said:

UGH!  What reason are they giving you?  I was considering Corona Aircraft Engines but....

unpaid bills from other customers. I got $7500 (out of $15000) back but it's been over a year. 

Edited March 4 by ZentRose
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