McDonald Imperial Super Diesel Crude Oil Engine

[cobbadog]

Sounds like a good deal on the MIG. Like you say it gives him pleasure that he knows he has it there when he needs it and I too am like that. I have been looking at a plasma cutter but not in a hurry but one day. Are you running gas or gasless on the MIG? I started gasless but I was not doing so well then using the Bunnings gas I bought a gauge and tried it and away I went. I still have the gasless wire and now I have a better understanding on how to use it I may try gasless again. I also know about swapping the polarity around between gas and gasless and I think it was operator error not machine or gas or not that was the issue.
As for catching up we should have settled a bit by end of August early September now that the rallies are done. We still have a few more van trips to do after this one in July as we need to go back to Canberra and this has to be timed with the running of the large steam beam engine at Golburn and we have to cross the border into enemy territory once Anna opens the border to see the little wog great grand son. SO, yes we will catch up just not sure when but soon I hope.

[cobbadog]

Cam gear is home and I started to linish it to shape.
I can't believe the trouble I had posting this here but is good it made it on.

[cobbadog]

The next bit of dribble for today after work gave me just enough time to linish the cam profile but I found a couple of spots that need to be built up higher. The guy who welded this must have known as he mentioned that if I needed any part built up just bring it back, so it will go back to him next week.
Then I fitted both Speedi-Sleeves to the crankshaft. This took all of 5 minutes. I picked up a piece of exhaust pipe that was the correct ID to fit over the sleeve and a couple of light taps to get both sleeves into the correct position.
Not much play time today but at least something got done.

[cobbadog]

Well I went back to the job of removing the fuel cup from the injector body. Had no luck with electrolysis only that it is super clean on the outside. So there was no way that the small grub screw would undo even using an impact socket with the screw driver bit in it so I drilled it out of the way. After reading about so many different ways to achieve what I am trying to do today I went down the road of heating and quenching. Using what Dad used to cal a size C lpg burner I started to gently heat the cup and then quench it in water. I did this a couple of times and the last time I gave it full throttle and got the cup to the dullest of cherry red and then quenched it again. Then I left it sitting in water until next time where I will once again look closer at how much I have drilled out and if any more needs to be removed then will go back to the serious heating again. All the time I have been very gently tapping the cup to see if it shows any signs of moving. This tapping is dangerous as this is how the other cup was broken off the injector body, not because of tapping it directly but by using a lever to lift the body out of the head and the slightest movement sideways breaks the cup off. In the instruction book this is made very clear and that when you remove a stubborn injector it is a case of removing the head and prising the cup up.
So this is my SpacEx clean burn launch today.

[cobbadog]

Well I stripped the oil primer and had to remove the plunger from the brass tube, clean it all up and as suggested I simply reversed the plunger so that it was back to original specifications and not with all the wear on it. I tinned the end of the brass tube and sweated it back in place without having to remove the outter casing by heating it up through the bottom where the check valve should have been. I welded the plunger back into the cap then made a new gasket to fit between the body and hopper. My brass tube was still there so I made it to the new length as it was a bit too long, tinned it and again heated the brass tube and soldered it back into the body. Some silicone and then bolted it back into place.
I did a test on the bench by putting some oil in the case with the plunger installed and sitting down. No oil came out. I started lifting the cap up and down and it started pumping oil out so it is a win. It is amazing how much oil it displaces each pump.

[cobbadog]

With weeks of part time work done on the Hyvid/Brons fuel injector I have finally got it all the way apart and cleaned up. I have used some valve grinding paste both coarse and fine to re-seat the bottom needle to help stop compression blow back and all I need now is 2 new copper gaskets and a new spring for the needle then it can be assembled ready for action. I am making new valve guides for the head, am looking at 2 new valves also and the new set of piston rings are somewhere between N.Z. and here.

[cobbadog]

Finally got the injector back together today so will post pics of it assembled later but here are the last of the parts made up to do the job. There is a new spring on the needle, a roughly made grub screw to hold the cup in place and a new copper crush washer that I annealed even more to ensure a good seal when installed.
The grey length of cast iron is for making new valve guides for the head and I have some new valves apparently available but cannot confirm until next week.

[cobbadog]

Things are on the move again with the Mac. Injector is now been apart and sorted out all its issues but the good news is I now have an oil primer. It too was stuck solid but now it is freed up and working as new. For such a very simple design it really pumps the oil through to the piston and gudgeon pin via a brass tube through the water hopper.

[cobbadog]

Next was a fuel tank. I was going to use a simple old paint thinners can and strengthen it for the fuel tap and mount that. Then I was reminded about these engines and blow back. They can have a habit of blowing compression back up through the injector and into the fuel tank. So with plan B now in action I built a very solid fuel tank using 6" exhaust pipe as the body of the tank then some slightly heavier base and top sections and then tack welded a piece of flat bar iron around the lid so that it fitted snugly over the body. I now only have to drill and tap the hole for the fuel tap to fit into and that will be done when the head is back on the engine and the extended hopper fitted. Tank is fitted as per original and is a short gravity feed into the injector. To shut one of these engines down you shut the fuel and just as it is about to die then decompress the engine.

Lastly is a picture of the cam gear where the lobe was built up and linished back to size. Nearly all the way around had to be built up and hopefully I have the correct profile. Something I have done is to start making a list of possible "stuff ups" that could be a cause for it not to run.

[mike90045]

Next was a fuel tank. I was going to use a simple old paint thinners can and strengthen it for the fuel tap and mount that. Then I was reminded about these engines and blow back. They can have a habit of blowing compression back up through the injector and into the fuel tank. ..............

I would think compression/ignition blowing back thru the injector and fuel pump, would be a failure of the injector, and if it happened, would destroy the fuel pump.   At the least, a flimsy fuel tank would rupture, a sturdy tank will cause a line to blow. 

[oldgoat]

You will only get blowback if the needle and seat are leaky or the injector adjustment is incorrect.

[cobbadog]

YEs that is right but it can happen so I built this bomb proof model

[cobbadog]

Hi Mike,
As oldgoat mentioned the cause of the blow back is a poorly seating needle. Fuel is gravity fed to the Hyvid Brons injector and pressure is a very simple plunger inside that has a spring inside to help seal the needle. If blow back happens it all ends up back at the tank which for my tank the worse that can happen is the lid will lift off.

[cobbadog]

Today I got some play time and found an issue. Again I wiped out the bore and sprayed some Lanox inside and fitted the piston with no rings. I have a cylinder that is narrow in the middle of the stroke. Fromt between 45mm down from the top to 125mm down the piston sticks. But, if I rotate the piston 90' it does not. This may indicate an oval piston so I now have the piston in the chuck of the lathe and checking it with the dial indicator to see what is at fault.
I think that all that rust around the cylinder has swollen up and distorted the bore.

[cobbadog]

Not this one, fairly certain it is the bore that is distorted.