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Lycoming High Volume Oil Pump Part Numbers???

Vans101

Well Known Member
I thought I would start a new thread for this inspection.

As you know I have lower than normal oil pressure on a TIO-540 and I after painstakingly eliminating all of the items on the troubleshooting list I finally removed the accessory cover and opened up the oil pump. I discovered a damaged impeller drive shaft and the 61297 impeller. The aluminim impeller PN 61298 is undamaged.

First Question: What could have caused this shaft and impeller to get so worn out in only 170 hours since these parts were new when the engine was overhauled???

Second Question: Could this this worn-out shaft have been the culprit for low oil pressure or is it just an impending failure that has not been revealed and I still have some other problem?

Third Question: Since I have the accessory case removed what other "usual suspects" should I be inspecting?

Forth Question: I know that since the airplane has an oil operated turbocharger that I should get a high-volume oil pump. Does anybody know what part numbers I should get and an economical source (I am OK with "experimental" parts)?

As always Thanks for your help!
 
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Also...the oil pump assembly that I removed from the engine has cast in the cover "75277" and then someone etched in a new part number "75287-ASSY".

The logbook during the rebuild states a number of parts that were installed during the overhaul and the only oil pump related parts are "61297" and "61298" and those are indeed the parts that came off of this engine.
 
without looking at the damage or a better description of the damage, it is hard to say. I can certainly presume that a damaged part has a good likelihood of producing sub-optimal performance of the assembly.

A worn shaft will allow a greater clearance between the impellers and the housing, reducing pressure and volume.

I suggest getting a complete, new pump assembly, assuming that the worn shaft also allowed abnormal wear on the housing, which will reduce pressure and volume.

Nothing else to look at back there that would point to low oil pressure.

I suspect you will find your problem gone after re-assembly with the new pump.

Larry
 
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I thought I would start a new thread for this inspection.

As you know I have lower than normal oil pressure on a TIO-540 and I after painstakingly eliminating all of the items on the troubleshooting list I finally removed the accessory cover and opened up the oil pump. I discovered a damaged impeller drive shaft and the 61297 impeller. The aluminim impeller PN 61298 is undamaged.

--- snip ---

As always Thanks for your help!

Who ever did your overhaul needs to be contacted. Aluminum oil pump gears were suppose to be removed from service by SB524 over 20-years ago.

The oil pump impeller gear replacement with two steel gears is an AD that is over 20-years old. AD 96-09-10.
 
It is not common for an oil pump impeller to be damaged after 170 hours. Either the oil pump gears were not new when installed, they were installed damaged, or there was a lot of metal that went through the pump.

How is the housing? Is there scoring or small specks of aluminium in the housing?
 
Who ever did your overhaul needs to be contacted. Aluminum oil pump gears were suppose to be removed from service by SB524 over 20-years ago.

The oil pump impeller gear replacement with two steel gears is an AD that is over 20-years old. AD 96-09-10.

I thought they then went from steel to sintered iron.

Larry
 
Direct from AD 96-09-10.

I thought they then went from steel to sintered iron.

Larry

"This amendment supersedes an existing airworthiness directive (AD), applicable to certain Textron Lycoming reciprocating engines, that currentlyrequires replacement of sintered iron impellers in oil pumps. This amendment continues to require replacement of sintered iron impellers, but also requires replacement of aluminum impellers. This amendment is prompted by reports of additional oil pump failures caused by aluminum impellers, which do not have the reliability of the hardened steel impellers."
 
"This amendment supersedes an existing airworthiness directive (AD), applicable to certain Textron Lycoming reciprocating engines, that currentlyrequires replacement of sintered iron impellers in oil pumps. This amendment continues to require replacement of sintered iron impellers, but also requires replacement of aluminum impellers. This amendment is prompted by reports of additional oil pump failures caused by aluminum impellers, which do not have the reliability of the hardened steel impellers."

My memory fails me again. Thanks for clarifying.

Larry
 
>How is the housing? Is there scoring or small specks of aluminium in the housing?

The housing looks clean...just some expected wear marks but not deep or like there was metal spinning around.


>Who ever did your overhaul needs to be contacted. Aluminum oil pump gears were suppose to be removed from service by SB524 over 20-years ago.

The engine was in another experimental prior to this and it was rebuilt in July 2003 so before the SB. I am actually OK with having to do this unexpected project because I was not sure that the SB was complied with...now I know...Grrrr

>Nothing else to look at back there that would point to low oil pressure. I suspect you will find your problem gone after re-assembly with the new pump.

I opened up the strainer to accessory case port and looked in and it was completely clean...zero debris. I looked in the oil pan and likewise zero debris...All of the Allan plugs are installed... No cracks or other indication of leakage. The oil pump was fastened to the accessory case snugly... the gears are all clean and look like new. No corrosion, sludge, or any other negative effect from storage these last number of years...the compression test was all 72 (or over)/80 so...IF...I can only figure out why this abnormally low oil pressure is.

Does anyone know of a high volume oil pump kit for the IO-540...because of the turbo I REALLY want to find a high volume unit.

THANKS!!!
 
>
Does anyone know of a high volume oil pump kit for the IO-540...because of the turbo I REALLY want to find a high volume unit.

If memory serves me correctly the high volume pump housing is taller has a different arrangement to interface with the crank gear. So I don't think it will fit. Its not just a pump gear swap.

I have some old oil pump gears from a high volume pump on a 540 I overhauled several years ago and both are steel.
 
gears

The high volume gears do not have an AD or SB to replace them. They do have a kit now with the same style gears as the low volume but no mandatory replacement! 05k23463 and the housing and drive shaft are sold separately! You can buy the old 61297 and 61298 gears still but they are priced over the new kit!

Jesse
970-874-7575
 
>


The engine was in another experimental prior to this and it was rebuilt in July 2003 so before the SB. I am actually OK with having to do this unexpected project because I was not sure that the SB was complied with...now I know...Grrrr

The Service Bulletin and AD were in 1995 and 1996 so it was a known problem at time of rebuild.
 
Service Limits/measurement tells you what is wrong.

Mr. Smith,

Did you check end gap, backlash, housing clearance against the service limits?

It is a gear pump and although Lycoming calls them impellers they are gears and it is a positive displacement pump. If the key dimensions are way off then internal losses are high and the fundamental reason for the lack of volume and resulting pressure. Understanding the root cause lays a solid foundation for action and confidence of success before spending time and money from this point.
 
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