siddus74

Hi guys myearly P80 stopped in flight with an over temp issue recently, on checking it when I got home the turbine intake wheel has picked up on the intake cone assembly and scrapes now when its turned ... If I push it forward all is good ... would some thing have moved forward during the or causing the over temp? I removed the front assy and although it sound bearing'y there is no play side to side in the shaft and the shaft and its components spin freely (if not quietly)

The turbine nut holding the preload cannot be tightened any further so I presume the preload is not the issue but and with front assy on the turbine wheel still rubs and sticks. With the front removed I can hold the small tapered washer behind the turbine wheel and push it in and out no problem.

Its an old engine so not really worth sending it for repair but im happy to chuck a set of bearing at it if I can got a cheap fix even if its down on power ... as it was a cheap one id like to use it as a bit of a learning curve as well.

Any thoughts or advice would be greatly received.

Best regards,

Scott.

frema

check the rear bearing , take the engine apart completely .
if the rear bearing have more play , you dont se it because the preload moved the shaft to the front.
its the compressor thats rubs right?

that can be the problem.

Hope this helps.

Regards,

Martin.

siddus74

Martin,

Thanks for the advice ... I have all the front - that was the easy part - how do I get it stripped further ?

What is inside that can allow the whole assy to shift forward?

Scott.

frema

oke , well , you need some pictures i think.
i dont have them ,but i stripped many p80 engines.
they all had preload failure .

i need some pictures from how far you are now.
then i can tell you what to do.

I can give you some advise:

Take out the glowplug , take of the thrust cone .
the purple cover is easy to damage , just be carefull with that too.

you will see an egt probe ,that is conect in the front board , be carefull with the probe , you can brake it easy.

the spinnernut on the compressor side is left thread ,so do it right when you untighten it.
then you can push the shaft to th back and take the shaft with turbine wheel out of the engine .
the combustor is connected with the diffusor.
you will see 6 needles for the feul , they are in the front of the chamber .
Its fun to strip turbines, you will learn a lot from it.

Regards,

Martin.

siddus74

Quite exciting this ...

A small tap of the shaft on it pushed through ... the bearings wobble a little but no real play foward / backward if that makes sense?

I can feel the preload assy, where do I go from here to test diagnose the issue? (the rear bearing is black)

I can feel the preload assy (I can push it in and out with my thumb ) Oh, I have assembled and dissasembled it a few times but am unable to get it back together without the compressor wheel fowling the aluminium intake) and 3 out of the 4 counter sunk allen key bolts are rounded off, they look like they have been out before - they will need drilling out, can I get replacements anywhere does anybody know)



Heres some pictures ...

jason

My Feedback: (1)

Martin is right, a worn bearing will make the rotor go forward.

Take the purple cover off
Remove the thermocouple off
Remove the PVC tube off marking the positions
Remove the PCB off
Remove the tale cone off
Remove remaining screws on diffuser cover
Using the 3 screws in the case carefully lever the diffuser cover off
*** With a fine tip permanent felt pen mark a line through the purple nut and compressor**
Using a bar and spanner undo the rotor (left-hand thread)
If the compressor don't pull off use a small amount of heat
Push the rotor rearward to remove

The bearings will most likely fall apart when removed and if you are lucky the outer race won't be stuck in the shaft tunnel.

When fitting a new bearing mark the turbine wheel and shaft in the same way as the compressor and nut so they too can be put back in the same radial position.

The chances of getting this back together and running right without balancing is slim. If you need to balance it then does a search on how to do that.

Jason

jason

My Feedback: (1)

No need to take the countersunk screws out or strip it any further. The one missing can be replaced with a M3 x 8mm allen screw.

lets see the rear bearing. When the outer race is pushed towards the wheel it should go no further back than the inner race (we are talking a very small amount) and rotate smoothly. I'm guessing it does go back and don't feel smooth

frema

Oh boy , the compressor wheel has rubbed a lot.

the rear bearing has to be worn out.

How is the combustor ?
if its an old p80 , it should have the light version ,the thin version .
i think you need a new compressor wheel as well.
i think the fitt of the compressor with the intake is not good anymore.
you can polish the intake .
hope you can still use the compressor ,but i dont know that for shore.

Regards,

Martin.

AFTERBURNER1

My Feedback: (80)

Or just send it in for service and have it repaired properly ..

siddus74

Yeah thanks for the support there fella, ive got money falling out of my **** . . . . .

frema

i think you are right about that one , then you can better buy a new engine scott.
I serviced a lot of engines , and they all are still running , even better then from the factory , so no worries Scott

jason

My Feedback: (1)

Hardly worth it, the repair would cost more than the value of the engine and Scott is having fun at the moment


Scott

buy a bearing, take the burs off the compressor, clean up the intake, balance it and bolt it back together. I will run if you get it right.

If it runs hot then it would be nice to experiment with shim a shim behind the front bearings to take up the material you have taken off the compressor/inlet.

Jason

siddus74

Now we have established that im not sending it back to be repaired by jet cat can we move on I want use this old boot to learn with, after all the wren home build kits ran perfectly ...

As far as the wheel goes, im going to tidy it up and try it!, why not its scrap anyway now right ...

(what it owes me does not warrant the repair bill for it)

Here are some pictures of the rear bearing, can anybody offer advice as to how to remove the rear wheel and bearing?

[youtube]http://www.youtube.com/watch?v=Sl4Xz44BfTs[/youtube]

(Thanks in advance)

Scott.

G4guy

My Feedback: (13)

Whats the average charge (from Jet-Cat) for a bearing replacement on a P-80?

jason

My Feedback: (1)

Scott

they can be easy or they can be right buggers to get off. I would not attempt it without a lathe. Put the shaft in the lathe chuck and undo the round nut (left hand again) then undo the chuck so the shaft can just slide in and out the chuck, put a centre the the tail stock, lock the stock and see if it will push the wheel , if not use heat. Be careful not to damage the thread.

Jason

siddus74

Im not sure, when I need to send it back Ill ask - if I sent it back they would want to change the bearing and the turbine wheel and the intake assy then with the labour it would come to more thatn £450 im sure ... thats what the engine cost me in the first place ...

I still have the two later gen small valves a V6 ecu and the kero start plug etc etc ... so im not down by alot ...

The serial number is 734 so is an old one any way ....

Scott.

siddus74

Is the rear bearing the only reason that the preload would cause the wheel to hit the intake?

Scott.

ash 26

Hi Scott
I can tell you for sure your bearing is shot I was in the same situation with my first turbine a simjet 2300 it was just not worth sending it back so I decided do have a look at it myself the comb- chamber was burned out so had to make up one and change the bearings and guess what it runs like a Swiss clock ever since
and after the simjet my wren SS started get noisy and tight after running in the cool down period and it had done only 8h from new at that stage [] the same thing back bearing was shot so I changed it and has done nearly 30h since
but I would say in your case you will need to get it balanced I did mine myself it takes a bit of time but it can be done

cheers

Andy

frema

well i am not shore about that.
i am curios to see the combusting chamber.
in the old p80 engines the inner one burns easy through .
check the lub to the bearings , maybe there is a leak somewhere.

but yes, when the rear bearing has more axial play ,the shaft comes to the front , and the clearance is very little with the p80 engines, so if the compressor rubs just a little , the wheel is becoming hotter and expant ,and thats why the rubbing gets worse.
the intake is not smooth anymore so it keeps rubbing.

i had the same problem with a simjet 1200 .
i raized the preload to 6kg , nothing wrong with that , but then i had a lub failure , and the compressor was gone.

Regards,

Martin.

siddus74

@ Martin can you give me any infor on checking the lube etc?

@ Ash, sounds like your my king of man ... I think Im going to throw a rear bearing in it, clean up the intake and test ... not chucking a heap of money at it though, just want to do it for learning experience etc ... be very interested to see what difference the turbine wheel scrape actually makes ...

After reassembling it I cant see what else there is to affect the forward position of the wheel? all the pressure is on the back bearing by the looks of it? What do I know if the first one I dissasembled ...

(just for the complete picture Ive had some over temp issues that could have been caused by installation . thrust tube issues but only 3 time has it stopped with over tempt ... if the rear bearing was on its way could this have tipped the ballance?)
Any idea the cheapest and most local place to get bearing or two?

Scott.

siddus74

Well ... I thought I would have a closer look at the bearings ... the rear one rocks from side to side quite a lot and put some sidewards pressure on the front one and it fell apart ball bearings everywhere lol ... is this normal?

Scott.

jason

My Feedback: (1)

Yes, use grease to put it back together. The outer race has a V on it and one side of the inner race is smaller than the other to allow them to go together. make sure the V points to the same side of the inner race as the rear one does. Also when putting back in the engine they must go in the correct way.

Jason

siddus74

well having destroyed the front, ill need a couple ... £100 plus the postage ... still got to be worth a try - worse case is I have a spare set for my other P80 I guess ...

Scott.

ash 26

Frema is right in what he is saying you could still have a problem with your com-chamber they do burn out over time its not like the new ones that are made of inconell so you better have a closer look at it changing the bearings will not cure that problem as you will still have excess heat around the tunnel and shaft that can cause bearing failure again get onto Wren they did have some J66 type com-chambers that I no will fit the P 80 as well as it did my Simjet wit a few mods .

cheers

Andy

vega406

My Feedback: (73)

a little info on my P-80 problem in the U.S....i have number 1064 and it ran great but a guy in Netherland i sold it to sent it in for inspection and sent back to me saying 1100 dollars to fix..turns out after showing John Redman and Bob Wilcox the turbine and repair order they tell me the History and reason...My number shows ordered form Jetcat Direct across sea,s in 1999 and called it the Hammer...U.S is not suppose to touch these they have outdated parts,,,Wilcox says the bearings fall apart in your hands the Thermo wire usually doesn,t work again after disconnecting and aluminum parts get replaced with upgrade over the 12 years..what was bad in my case was it had 1.5 hours on it and probably already had this done but they gave an estimate before closely looking at it atleast all the way anyway cause the ECU was not sent in with it...it still runs but made dry bearing sound for a second so i don,t trust who did what over there him or Jetcat SOOOO if you were to send it in it wouldn,t surprise me if you get the same answer...Heck after fixing yours you can do mine next