B5100E Low Oil Pressure at Idle

Daren Todd

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Thanks.

Is there a step in the cam oil galley which stops the plug from going in too far, or, is the plug tapered, or is the galley tapered?
Tapered. I used a punch that was bigger then the fat side and tapped it in flush.
 

Lawnmowerman

New member

Equipment
B5100E
Mar 20, 2019
20
0
0
Tullahoma Tn.
I hate to drag up a old forum but i am looking for some advice. I am a small engine mechanic for well over 25 years. i have torn down my b5100e and found the plug is out of my cam. but i have a few questions
Do i need to remove the cam and check the rear plug?
What is suppose to hold the plug in after knocking it in?
Is the camshaft steel or cast iron? it looks like steel with a cast pulley to me
i have access to a mig welder and i know how to use it should i tack weld it in ? is the original plugs steel or aluminum? i want to repair this permanently and if that means removing the cam and replacing the rear plug as well that is no problem...

I ordered both the aluminum and steel plug didnt know at the time which would be better (This is my first rodeo with a Kubota) if i should weld it in i am thinking about removing the cam and ordering another steel plug...
 

GeoHorn

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If you go back through these 5 pages I'll bet you find your answers!:D
Or one of us who has recently read this thread could be courteous and simply answer the question. :rolleyes:

The plug can be either aluminum or steel. Loctite the alum one and tack weld the steel one. 15261-96860 aluminum and 15261-96880 the steel one.

I haven't heard (but also am not that familiar with this issue) but...the rear plug doesn't seem to be a similar issue. Your Kubota dealer can probably help answer this question (and Messicks has some of the most helpful technical-experts in the business besides our own NIW.) Give them a call.

As low oil pressure issues go generally (and other than specifically caused by a mechanical fault such as a missing gallery/cam plug),,,. an engine at low idle can be left alone at 5 psi without harm usually, as long as above idle the oil pressure comes up within normal operating pressures (20 psi or greater). This statement is actually made by most engine mfr's in factory documentation. My aircraft engine mfr'r states it, as does Ford/NH.
At low idle the engine is not doing any real "work" and spinning shafts only need a light oil-film to prevent damage to themselves and bearings. 5 psi is commonly acceptable specifications for hot engines at idle. Taking an engine apart that is old/infrequently-used may not make economical good sense if pressure comes up above idle. It is usually a sign of worn (or improperly-sized-when-assembled) main crankshaft bearings with excessive clearance. As an example, I have personally operated an engine with 5 psi at idle that recovered oil pressure to 20+ psi for as long as 15+ years and then sold that tractor to another owner who continued operating it without repairing that "defect". The only significant adjustment I made was to use SAE 50 aircraft oil rather than the recommended SAE 30 automotive. It would start up and indicate 35 psi...then heat up during work and drop to 20 psi (while pulling a much-too large shredder for the tractor for 6-8 hours a day) and indicate only 5 psi at hot idle as I put it away in the shed.
Not saying that's the ideal...only that for old equipment... it can be reduced to a simple question: "How much do I want to spend to correct a "defect" that makes little difference in actual practice?" I think that the 15 years of service I got out of that little 9N Ford without tearing apart the lower-end was the correct response. So does it's new owner.
 
Last edited:

North Idaho Wolfman

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I hate to drag up a old forum but i am looking for some advice. I am a small engine mechanic for well over 25 years. i have torn down my b5100e and found the plug is out of my cam. but i have a few questions
Do i need to remove the cam and check the rear plug?
What is suppose to hold the plug in after knocking it in?
Is the camshaft steel or cast iron? it looks like steel with a cast pulley to me
i have access to a mig welder and i know how to use it should i tack weld it in ? is the original plugs steel or aluminum? i want to repair this permanently and if that means removing the cam and replacing the rear plug as well that is no problem...

I ordered both the aluminum and steel plug didnt know at the time which would be better (This is my first rodeo with a Kubota) if i should weld it in i am thinking about removing the cam and ordering another steel plug...
That model does have a rear plug too, it's very rarely an issue, and when it does come out it can't go anywhere and all the oil is still trapped in the blocked space, but if it will give you piece of mind pull the cam and do the back one too, note the max protrusion of the original plug and make the new plug that protrusion or less.

Note that setting the timing on all the gears is 100% critical.

The original plugs were aluminum, new plugs should be steel and yes tack weld them in place.
The Cam is forged steel where the pulley is cast.
 

Lawnmowerman

New member

Equipment
B5100E
Mar 20, 2019
20
0
0
Tullahoma Tn.
That model does have a rear plug too, it's very rarely an issue, and when it does come out it can't go anywhere and all the oil is still trapped in the blocked space, but if it will give you piece of mind pull the cam and do the back one too, note the max protrusion of the original plug and make the new plug that protrusion or less.

Note that setting the timing on all the gears is 100% critical.

The original plugs were aluminum, new plugs should be steel and yes tack weld them in place.
The Cam is forged steel where the pulley is cast.
Thank you for the help... All my parts came in yesterday and I plan on staying late where I work today and start putting it back together.. I wanted to make sure tack the plugs in with a mig welder if it had been cast iron I was planning on using brass to tack it into place..... Thanks again
 

D2Cat

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When you weld the plug be sure you have a good ground and as close to the work as possible. If you get current to flow through the engine you could cause problems with the bearings.