ezgo 350 oil pressure prime

[CP241]

No pressure. I'm currently using a mechanical gauge set I picked up locally. It's the tool type, not a gauge you would mount in the dash but has about 3 feet of hose so I can hold onto it while I drive. It is screwed into the port where the sending unit came from.

[Gearhead1956]

I looked at the path of this oil system.

suction side, pulls oil thru filter, passage in crank case, up passage in end cover to pump.

pressure side

leaves pump, splits. one passage go's directly to crank. other passage go's up thru sending unit. in that passage is the check valve.
oil continues up and out the end plate into the block and up to the head.

so the check valve is very close to the beginning of the pressure side of the pump, So could the 1/16 relief hole, if its the spring? make it act like this???

If so the pump may be building pressure and oiling the crank but losing pressure just before pressure gauge at the relief hole and beyond to the head.

Have you checked the passage going from the end cover up the block and head just to make sure there is not an issue there?

[CP241]

Unfortunately yes. Last time it was apart I blew compressed air through everywhere just to make sure there were no obstructions and a the paths were clear.

However, I don't think an obstruction in one of the passages would be intermittent either. I wouldnt think that little tiny hole would blow off sometimes all pressure either, or be capable of that. But I truly dont know. Anything is possible I guess, and sort of running out of possibilities!

As far as what would cause it to have perfect oil pressure one minute, zero a few minutes later, then perfect again, then low ~10psi a minute or two after that... that's what really has me puzzled

[trig123]

Do you know any history on this cart ? Who had it before you ? How much have you drove it before you rebuilt the engine ? Did you put an aftermarket oil filter on it ? Also I think oil passes through the inside of valve cover. Dang, I have one at my shop I could look at to see but just thinking back years ago it seemed like there was a hole in cover that oil passes through. I might be crazy. You would not see a leak if something was wrong with cover on the inside. Maybe I am just guessing. You got another valve cover you could put on it ?

[CP241]

Sorry, no known history. It doesnt appear to have been wonderfully maintained... it had a lot of sludge inside when j tore it down. But, it ran great. I drove it around a ton, for a couple months before tear down. I put a few hundred miles on it pretty easily. Only reason I rebuilt it was because it needed valve seals. It smoked like a train when I first got it, but was overfilled with oil. I drained it and put in 1.5qt and 95% of the smoking stopped. But it still acted like it wanted valve seals, which is no big deal. I just figured if I needed to pull the motor and pull the head and do valve seals, may as well re-ring it and deglaze the cylinders while it was out. Generally not a major undertaking by any means. I did put a new aftermarket oil filter on it, but I replaced it during this whole oil pressure investigation, but it didnt seem to change anything for better or worse.

It ran great, as it does now. Makes good power, fast, smooth, and strong. It just doesnt seem to want to maintain consistent oil pressure.

When I get back to working on it, I'll check the valve cover.

[Rooster59]

Just a thought. Can we absolutely trust the pressure guage?

[CP241]

Originally Posted by Rooster59

Just a thought. Can we absolutely trust the pressure guage?

I'm going to say yes. The sending unit and light behave the exact same way. And through the intake tone under the front seat you can clearly and audibly hear the difference when it goes from 0 to pressure (even 20psi is a big difference)

[Gearhead1956]

the intake tone under the front seat you can clearly and audibly hear the difference when it goes from 0 to pressure (even 20psi is a big difference)

That's different, is it because the rpm's changing? something binding?

[CP241]

No, it goes from a higher "crisper" type noise to a smoother, deeper type sound. It's kind of hard to describe, but definitely there, and very easy to hear. I will try and see if I can capture it on a video tomorrow if i get a chance to take it for a spin again.

[trig123]

Originally Posted by CP241

Yes, broke the belt and sheared the cam gear. But, when I took it apart the cam came out pretty easily. There was a little marring in the head, but it cleaned up easily and quickly with a bit of emory cloth and spun fine with no resistance afterwards.

I know you probably already mentioned this but will ask again.
Did the belt break after you rebuilt it ?

What caused it to break ?