Farmall H oil pressure

[CraigM]

The old H has come up with a new trick. The oil pressure drops off after it heats up. The oil level is full. At cold start up, the pressure gauge reads about half scale at full throttle and it drops off at idle. After it runs a while, the full throttle pressure shows a little less than cold idle, and dangerously close to the bottom of the normal range. At idle, it's just off the "0" peg on the gauge.

Pump going bad, or just a farmall quirk with a simple fix? How bad is pump rebuild?

 

[Soundguy]

farmall quirk? more like 'worn out' old engine quirk.

as the main bearing and rod bearings and cam to bore wear, the clearances open, thus more loss of oil pressure. add to that the pump itself wears.

the oil you use may be a factor as well, event he age of the oil, as the oil ages it gets fuel mixed and can thin.

if you are running a 30w or 10w30, my advice would be to go to a 15w40 or 20w50 oil. I'd try 15w40 first as it is a c rated oil, and is a really good product.

ideally you need a minimum of about 6psi of oil pressure per 1000 rpm. those 'zone' gauges don't really tell you much. I would swap in a 9$ sunpro gauge and see what your oil pressures are at hot and cold idle and throttle, then remember those numbers and compair them to your zone style gauge.

at idle you are running what? 500 rpm or maybee a bit less.. thus you can see why just a bit of positive pressure keeps her from knocking...

I know many ford n that at 500 rpm have 4-5 psi hot idle oil pressure and otherwise run fine.. .

while it is worn and would likely benefit from some work, if you can keep the oil pressure normal using a 15w40 or 20w50 oil.. it won't hurt it to do so.

if you feel up to it, many times you can make a few psi oil pressure gain by simply dropping the oil pan, and pulling the main and rod bearing shells, seeing what size thay are and rolling that exact same size back in. the new shells will be less worn than the old, and you won't need to plastigauge them to see if they fit, as you know that whatever came out was fitting when new.

just the new bearing shells alone should pick up some oil pressure.

you could always rebuild the pump if you were inclined, and then even ream the ridge and hone the cyl and install new rings and then hand lap the valves too watch out.. that poor mans rebuild I just talked about can lead you into a days work.. though is very cheap.. just bearing shells and rings and some tool usage. usually adds another 10ys or so of usefull service to a machine in the way of an oil pressure increase and some compression increase. I like to call the bearing shell replacement a poor mans 'lower' and the new rings and reaming the ridge and honing the cyls, and the the hand lapped valves a poor man's upper. also remember that if you repalce rings that you must ream the ridge on the cyl or it will break the new rings. I'd also lightly hone the cyls to make some crosshatching. remember to clean out any grinding compound from the valve areas too.

soundguy

 

[CraigM]

Thanks Soundguy. I figured it was just worn out, but hoping for an easier answer. I will try a calibrated pressure gauge and see how bad things are. Using your 6psi/1000revs rule will make that useful. I had never heard any rules of thumb on that, so a calibrated gauge would have been as useless as the current range gauge.

We did top off the oil with 15W40. As we replace the leakage, The concentration of 15W40 will go up and we'll see if that helps.

 

[Soundguy]

walmart 15w40 oil is 9$ for a gallon or 5 qts.

treat it to some new oil and that gauge. less than 20$ and you will know for sure where you are at.

soundguy

 

[WKTEDDYBEAR]

how long since the last oil change? I have seen posted on Redpower from a trusted collector/owner to never use multi weight in these old Farmall tractors.
I had 15-40 Delo in my SuperA but discovered it mostly never gets worked hard enough for oil to warm up most all the time I can put my hand on the oil pan and hold it there.multi weight oil when cold is the lower weight. modifiers in it react to heat and make it flow like a thicker oil.
another I have been taught is do not mix different grades/types or brands of oil different additives are not always compatible with each other.
take care and have a great safe one!
Paul

 

[farmall 55a case]

The only oil that should be ran in those old farmalls a non detergent oils straight 30w if you use modern eng oil it will wash out ur bearings

 

[Soundguy]

I know plenty of people using moden oils in them.

I have 2 farmalls myself.

no washed out bearings..

 

[BobG_in_VA]

Farmall engines, ie. for all the old letter and number series, used single weight, non-detergent oil when they came out of the factory...simply because that's what was available in the 40s and early 50s...the first thing I do with a "new" Farmall ('53/'52/'57'/'74) is change it over to 15-40 Delo (its what I use in the diesels so I have it already). All probably have over 5000 hours each on them and they run perfectly. Farmall engines are fine when they put out as little as 6-8psi oil pressure at hot idle. I'm sure its OK to still use non detergent single grade oil, but I ain't takin' chances..I'd use the best that can be had, except I won't use synthetic as the seals may reject that idea...BobG in VA

 

[Soundguy]

changed out a bunch already(seals ) on this C I have..

 

[flusher]

farmall quirk? more like 'worn out' old engine quirk.

as the main bearing and rod bearings and cam to bore wear, the clearances open, thus more loss of oil pressure. add to that the pump itself wears.

the oil you use may be a factor as well, event he age of the oil, as the oil ages it gets fuel mixed and can thin.

if you are running a 30w or 10w30, my advice would be to go to a 15w40 or 20w50 oil. I'd try 15w40 first as it is a c rated oil, and is a really good product.

ideally you need a minimum of about 6psi of oil pressure per 1000 rpm. those 'zone' gauges don't really tell you much. I would swap in a 9$ sunpro gauge and see what your oil pressures are at hot and cold idle and throttle, then remember those numbers and compair them to your zone style gauge.

at idle you are running what? 500 rpm or maybee a bit less.. thus you can see why just a bit of positive pressure keeps her from knocking...

I know many ford n that at 500 rpm have 4-5 psi hot idle oil pressure and otherwise run fine.. .

while it is worn and would likely benefit from some work, if you can keep the oil pressure normal using a 15w40 or 20w50 oil.. it won't hurt it to do so.

if you feel up to it, many times you can make a few psi oil pressure gain by simply dropping the oil pan, and pulling the main and rod bearing shells, seeing what size thay are and rolling that exact same size back in. the new shells will be less worn than the old, and you won't need to plastigauge them to see if they fit, as you know that whatever came out was fitting when new.

just the new bearing shells alone should pick up some oil pressure.

you could always rebuild the pump if you were inclined, and then even ream the ridge and hone the cyl and install new rings and then hand lap the valves too watch out.. that poor mans rebuild I just talked about can lead you into a days work.. though is very cheap.. just bearing shells and rings and some tool usage. usually adds another 10ys or so of usefull service to a machine in the way of an oil pressure increase and some compression increase. I like to call the bearing shell replacement a poor mans 'lower' and the new rings and reaming the ridge and honing the cyls, and the the hand lapped valves a poor man's upper. also remember that if you repalce rings that you must ream the ridge on the cyl or it will break the new rings. I'd also lightly hone the cyls to make some crosshatching. remember to clean out any grinding compound from the valve areas too.

soundguy

SG: thanks for the input--valuable stuff as usual.

I'm facing a ring job on my 1948 Farmall Cub. Lapped the valves but the compression is only about 60 psi (wet) now. Should be about 100 psi on a 6.5:1 compression engine.

Question: when you do a ring job on your Fords, etc. do you put in oversize rings (0.020" etc) assuming that there's significant wear on the cylinder walls? Or do you just use standard size rings?

I want to do the ring job on that Cub in my shop without having to send the block to the machine shop if I can avoid that.