310 oil pressure drops below 10

dnd

Member
Hi, I have a 310 in an 1800B, last winter I put new rod bearings in it and this summer when I was using it after the engine warmed up the oil pressure dropped quite low, if I remember correctly it was below 10 psi, I put an over/under in it as I wanted to use on tractor rides. Low oil pressure concerns me and I am wondering if the cam bearings are worn? Thoughts on fixing this, as I assume there is a process to get the old ones out and put new ones in. Any chance a new crank would help? Just looking for some ideas as I’ll be working on it again after Christmas.
 
A lot of the older engines never really had much more than 20-25 psi. There is usually a relief valve in the oil system that can be adjusted. Have you changed oil grade or brand? My JD A always had good pressure with Valvoline SAE 30 but was low when I switched the Rotella T4 15W-40. The relief valve took care of that.
 
FIRST I AM NOT A GURU OF 310'S. I like RR Lunds first thought, second determine where it gets it oil pressure. Cam or crankshaft as all the bearings including mains can effect oil pressure. Also what Scooter said and rule out wrong filter. Does it have a pressure relieve or pressure adjustment valve? Could it be wrong or inferior oil?
 
Thanks to everyone, here’s is what I tried over the summer to help.
A,, I verified this an accurate gauge that the oil pressure was in fact dropping way down after tractor warmed up to operating temperature.
B,, Drained oil and put in new White oil filter plus new Cenex 15/40 oil
C,, I removed the spring by oil filter and stretched it out a bit. Maybe I should see if I can get a replacement? Drained 15/40 out and then put in 20/50
D,, As a last resort when I was bush hogging in early October I added 3 quarts of the Lucas product that’s thick like STP.
Planning on getting it in my garage after the new year and pulling the engine.See what I have for main and rod bearings. Check oil clearance and replace. I’m hoping I just find main bearings with too much oil clearance. Same with the rob bearings.
Biggest question Im wrestling with is the Cam and if I can tell the condition of bearings and the process of removal and install new ones.
Sorry to ramble but kind on thinking out load here.
 
Hi, I have a 310 in an 1800B, last winter I put new rod bearings in it and this summer when I was using it after the engine warmed up the oil pressure dropped quite low, if I remember correctly it was below 10 psi, I put an over/under in it as I wanted to use on tractor rides. Low oil pressure concerns me and I am wondering if the cam bearings are worn? Thoughts on fixing this, as I assume there is a process to get the old ones out and put new ones in. Any chance a new crank would help? Just looking for some ideas as I’ll be working on it again after Christmas.
You didn’t mention what the oil pressure was before you changed the rod bearings. Did you mic the crank before hand or just throw a set of standard size bearings in and call it good? Need more information here.
 
Good question! I did the engine rod bearings 3-4 years ago. I don’t think I mic’d the rod bearings though, I most likely just put back in new ones of the same size as what was in there. I can’t recall if I even looked at main bearings. I was kind of rushed to get the engine and over/under installed along with a swap out of power steering. Haste makes waste so now I need to do that portion right.
 
Thanks to everyone, here’s is what I tried over the summer to help.
A,, I verified this an accurate gauge that the oil pressure was in fact dropping way down after tractor warmed up to operating temperature.
B,, Drained oil and put in new White oil filter plus new Cenex 15/40 oil
C,, I removed the spring by oil filter and stretched it out a bit. Maybe I should see if I can get a replacement? Drained 15/40 out and then put in 20/50
D,, As a last resort when I was bush hogging in early October I added 3 quarts of the Lucas product that’s thick like STP.
Planning on getting it in my garage after the new year and pulling the engine.See what I have for main and rod bearings. Check oil clearance and replace. I’m hoping I just find main bearings with too much oil clearance. Same with the rob bearings.
Biggest question Im wrestling with is the Cam and if I can tell the condition of bearings and the process of removal and install new ones.
Sorry to ramble but kind on thinking out load here.


You can quickly tell if your bearings are disintegrating by examining the oil filter media and look for sparkly fine metal glitter, like I said above. Super easy with the sock filter too. If you see glitter at least you'll know you have metal everywhere and the engine needs to be gone through.

What are the specs of the motor? Is this an original engine or a transplant?
 
Good question! I did the engine rod bearings 3-4 years ago. I don’t think I mic’d the rod bearings though, I most likely just put back in new ones of the same size as what was in there. I can’t recall if I even looked at main bearings. I was kind of rushed to get the engine and over/under installed along with a swap out of power steering. Haste makes waste so now I need to do that portion right.
Well then if the main relief spring under the plug in the front of the block isn’t broke. There’s no signs of glitter in the oil and you confirm pressure with a known working gauge. Everything else is a moot point until you pull the engine down and start micing crank journals and tear the oil pump apart to measure the shaft and gear clearances. I’ve done three 310s so far and haven’t had a cam wore out of stock spec yet. You can put washers under the spring retaining plug to tighten up the spring and increase pressure. But that’s only a bandaid. Call the Floyd county museum and get a service manual if you don’t have one already. You’re going to need it.
 
I am leaning toward bearings, get a manual mic the crank, rods and mains Cam will be a little harder, but manual should show how to install cam bearings. Also check the oil pump and pick up manual should explain that too.
 
I can't lean any direction, but when I say "bearings," know I'm also including the wrist pin bushings, which, if you've never done anything with them, are a very likely source of low oil pressure and glitter in the filter.
 
I would check your crank tolerances after you check your filter for shavings like scooter says. If crank tolerances are greater than book specs, I would go ahead and look into cam bearing tolerances. Wrist pin bushings also need to be checked. Get with Maibach tractor in Ohio for parts

Bailey @ Antique Acres
 
Hi, I have a 310 in an 1800B, last winter I put new rod bearings in it and this summer when I was using it after the engine warmed up the oil pressure dropped quite low, if I remember correctly it was below 10 psi, I put an over/under in it as I wanted to use on tractor rides. Low oil pressure concerns me and I am wondering if the cam bearings are worn? Thoughts on fixing this, as I assume there is a process to get the old ones out and put new ones in. Any chance a new crank would help? Just looking for some ideas as I’ll be working on it again after Christmas.
When I rebuilt the 283 in my 1650 a couple of years back, with a different crankshaft within spec for original rod and crank journal sizes, plastigage on the rod bearings when torqued to spec indicated some areas of the rod bearing had too much clearance. I did some checking on the connecting rod bores and they were all ovaled several thousands beyond the allowable spec. One of the techs at our closest Napa machine shop ground the flats on the rod caps and rods, then rebored the rod/cap assembly to original diameter. Now a check with plastigage showed even clearance within specs. This engine previously had low oil pressure also due to a torn injector pump seal. I reduced the clearance between the bottom of the oil pump gears and end plate, replaced cam bearings, installed new oil pressure relief springs and replaced worn parts on the rocker arm assembly. I did a bench test of the pressure relief valve on the oil pump to make sure that it did not relieve at too low of a pressure. Now the engine runs 37 lbs when warmed up and working (using Rotella T4 15W/40).
 

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