Compression Test

[7080316]

So I am pretty much done pulling my engine on my 2n. Low Oil Pressure and fouled plugs were my main reason for deciding to 0 time the engine. I get the idea that I would like to do a compression test. I can't warm the engine and each spark plug was oily when removed.

1. 100 psi
2. 90 psi.
3. 90-95 psi
4. 105-110psi

Should I consider these numbers wet and???

What is the max psi of a fresh rebuilt engine? My FO-4 only says 90 psi min and no more then a 75% difference.

Side notes, My water pump had a stud twist off at the flange when removed so I have about 1/2-3/4 inch of rusted stud still remaining. My Main Axle Pin does not look like the ones I see for sale on this site. Not sure what I am seeing as it is all covered in grease, but it is a large triangle plate with two pins on the bottom pointing forward (I didn't measure it, but I am assuming it was around 6inchs tall and 6 inches wide at the bottom) and it had one 5/8 fine threaded bolt in the middle of it. I think it is a loader mount plate. The front axle pin is warn significantly and should be replaced. The two arms that stabilize the front axle. The bolts that go through the front axxle were worn out. I had to remove the head of the LH bolt to drive it down and out.

Does anyone have any advice for me??????

Thanks, Jeff Eck

 

[Dell (WA)]

Jeff.......while the FO-4 specs 90psi min, a NEW/rebuilt flathead will test out about 125psi. Remember, its 5-rumpa-rumpas fer each sparkie hole with ALL sparkies removed and ignition switch OFF and throttle about 1/3. The oil test fer ring wear is about 1-oz (tablespoon) in each hole after the dry compression test. I use 1-pump from a squirter oilcan. Good engine will up the wet compression about 10psi. Iff'n the wet compression don't raize yer comps, ya probably gotta burned exhaust valve. Never burned an intake valve altho they've been known to stick OPEN. .........HTH, Dell

 

[Bruce (VA)]

" Should I consider these numbers wet and???"

What difference does it make if you're going to rebuild the engine anyway?

But, to answer your question......unless you put a few tblsps of oil in each cylinder, you have the partial results of a dry test.

" What is the max psi of a fresh rebuilt engine? "

110-120 lbs

" I have about 1/2-3/4 inch of rusted stud still remaining"

And if you don't remove it & replace it, the water pump will leak.

" I think it is a loader mount plate."

It is. From a Wagner loader. The front axle pin you need to replace is attached to it. Depending on the year of your tractor, you need p/n 3126B or 3126D.

" The two arms that stabilize the front axle. "

They're called radius rods & are held in by pins on the 8N; not sure about the 2N, but I don't think they ever had bolts.

" Does anyone have any advice for me??????"

Check out tip # 39 at the link.

Post back if you have any more questions.
75 Tips

 

[7080316]

Thanks Bruce and Dell. It's really just curiosity. I am a mechanical person and I have never touched a flat head engine before. I love the way machine can operate and I really just love to learn about these kinds of things. I am going to try a wet test this afternoon before I pull the head and see what is going on underneath it... The water pump had shown signs of leakage and I plan to get that rusted stud removed..

Jeff

 

[souNdguy]

take a hammer and give a good flat whack on the stub of the stud.

slip a nut over it and weld it on, then turn it out with an impact wrench set kinda low. the hammering helps pull it vs twist it off.

don't forget generous spray oil before and after welding... especially after. the quench of spray oil on the weld hot metal will help break rust bonds and wick oil into the joint via capilar action. while it's still hot, get the impact on her and back her out.

 

[Den N Ms]

Bruce,9N and 2Ns had the radius rods bolted on the front axle.
https://nnalert/catalog/images/21191-S.jpg
Bolt

 

[Bruce (VA)]

Tnx Den. Didn't know that.