Overhauled F-20

ok, we try'd to pull start it. it fired up for about 5- 6 seconds then we messed with the choke and it died. I didn't look ate the oil pressure gauge. Now the next round we try starting it it, it runs for about 10 -15 seconds, I look at the oil pressure gauge and it says no pressure. So we turn it off. The gauge is brand new and I bought it from rice equipment. I took it off and blew in the hole with my mouth, nothing. I grab the parts tractor gauge and blow into it, it goes up. So I blow into the new gauge with air compressor, and at about 5 PSI it raises the needle to the middle position. How many PSI should this engine push out. I know that all the oil lines are clear. I put 15-40 oil in it, would that make a difference? What would you do?

The oil pump is very low pressure, not more than 10 lbs.

5 psi is good for this engine.
Inside the oil filter on the base is a brass plug with a strait screw head. Remove this plug and there is a spring and checkball under it. Make sure the spring is good and the ball and its seat are clean and not pitted or stuck. If this check valve is not functional your gauge won't show any pressure.

Is this that big brass bolt that the oil filter sits on?

ok, slow down a minute. I agree with the posts so far, but 15-20 seconds is NOT enough time for the oil filter canister to fill up. These are splash lubricated on the crank. If your oil is at the correct level, run it for 2-3 mins, then look at your oil pressure. Gordon is one of the best for parts, so I would think he sent you the correct guage, IF you gave him the correct information.

Before you go tearing into things, start it up and let it run for a few mins before checking the oil pressure. Did you oil the valves before starting it?

take an inspection cover off and look and see if the oil troughs are full of oil. If so the pump is working. As others said these are low pressure engines, nothing is pressure lubed, all splash and sprayed.Give it a little longer, or try swapping guages.

Everything was lubed up with cam lube during assemble. I'm just worried that if something isnt workin, and I run my engine on just cam lube, I don't know how long the cam lube will last. I'm going to try swapping gauges and let it run a little longer.

(quoted from post at 02:11:19 07/16/11) ok, slow down a minute. I agree with the posts so far, but 15-20 seconds is NOT enough time for the oil filter canister to fill up. These are splash lubricated on the crank. If your oil is at the correct level, run it for 2-3 mins, then look at your oil pressure. Gordon is one of the best for parts, so I would think he sent you the correct guage, IF you gave him the correct information.

Before you go tearing into things, start it up and let it run for a few mins before checking the oil pressure. Did you oil the valves before starting it?

Click to expand...

I disagree... if you don't have oil pressure in 20 seconds you have a serious problem and you better shut it down, if you have to wait 2-3 min for oil pressure you are going to be visited by engine parts exiting through new holes. The pump is submerged in oil and should pump instantly and build pressure in a few seconds.

Evan, here's some pics.

Brass plug and whats under it.




Now after checking and cleaning this one there is one other in the system and its on the oil pump itself. If the one in the filter was good and you still can't get pressure in a few seconds you may have to pull the pan and check/ clean/ or replace the one on the pump.

i would at least disconnect guage and hook up a hose to run in a pail and start engine and see if pump is pumping oil out. then you know engine is getting lubed and guage is at fault. low press. system so you may have wrong guage.

Did you prime that oil pump in a clean container of engine oil prior to installing it on your engine? Hal

I'm not gonna disagree with any of the posts. Yes, inspect the check ball in the filter housing base, good idea. Make sure the regulator on the oil pump is in good working order. Make sure the seal to the block/spray bar is good. If all of that is good I'll bet that the oil pump gears is worn out. You need to check the lash in the gears. If you get more than slight movement between the gears,it's too much. Also along side that, make sure the shaft is in good shape. If the shaft is worn and the idler gear pin is worn, that will also cause excessive lash in the gears. Also, I wet sand the bottom plate that the gears ride against until you don't see any wear marks in it, it all helps in the long run. This engine should take no time to build oil pressure. I put my pumps up dry, crank them over about 10-20 times and get oil out the gauge hole. Normally build oil pressure in a matter of seconds. Any engines that I build I want to see at least 15 psi at high idle, most of them run around 20 psi high idle hot w/ 15/40 oil. About 8-10psi low idle hot. Also, the repop gauge from Rice do not react the same as the old originals. I personally don't like them. I am use to the old gauges that run pegged all the time and when they read anything else you know you have a problem. Good luck to ya and have fun.

36F30, let's agree to disagree. Your approach is fail-safe regarless of who is right. I just can't figure how a splash lubricated crank is going to starve for oil if the oil level is correct in the pan.

On an F-12? Yup, presurized journals for both connecting rods and mains. Splash lube on the roller mains and connecting rods doesn't get all excited about no pressure.......not at least for 2 -3 mins. The oil troughs inside a Regular, F-20, and F30 engine provided additional oil, but not the only source of lubrication. My F-20 takes at least a minute for the guage to pressure up, and when it does, it shows good pressure, and it has the correct guage. Not sure I would go plow 20 acres without no pressure, but a short run to get the system pressured up for a minute or two is not a crisis in my humble opinion.

nuff said from my end.

I will explain it to you from my perspective. These are not true splash lubed like a briggs and stratton lawnmower engine, they are a combination type that splashes PUMPED oil. The only part of the crank in these engines that splashes oil is the dipper on the rod cap, the only place they touch oil is in the dipper trays, if the trays are not being replenished no oil is getting splashed. The crank and its bearings are above the oil, if you don't believe that take your hand hole cover off and look. Oil is pumped to the dipper trays and then to the front of the engine where a small tube oils the gear on the front of the crank, this oil flows back to the pan through the front bearing. the rest of the oil travels up to the filter and then one tube goes to lube the governor bushing, Starving the gov. bushing for minutes is bad, they are a notorious weak/ wear point the other tube returns to the block at the lower rear. The cam and rear main are lubed by splash caught in cast in trays in the block.

I have an F20 block here that was not cleaned well during its overhaul, a piece of debris plugged the number two oil orifice for its dipper tray. The motor had good oil pressure but even with all that oil being flung around the rod seized and broke with the piston exiting out the left side of the block. The guy paid $1500 dollars for his overhaul and I gave him $50 for what was left of his investment.

I do all my own engine work and it is my opinion that if you don't have pressure on that gage in 10 seconds or less you are doing damage to your motor. That is unacceptable to me and I could not tell others anything different.

We are both trying to save these old girls so I will respectfully agree to disagree with you

36F30, um, guess what. You just taught me something I didn't know about these old girls.......and I keep on learning.

I am now in complete agreement with your position, and retract mine.

ps. I am NOT just saying this either, I mean it! :wink: