MM Jet Star 3 Super

Walkinfuss · Sep 18, 2023

Can use some more help. The original MM volt meter does not work. I replaced it with a new meter, however the new meter will not allow the engine to crank or star when I jump the starter. Tried a second new meter the same. Put the original meter back in and it starts every time, just no meter operation.

When I ohm the old meter out, its a complete circuit. The new meters are open? The new meters read the voltage when I turn the key, just will not allow the motor to turn over of start???

Tried reversing polarity with no success? Both are new Bosch gauges. Any ideas? Thanks

ChrisQ · Sep 18, 2023

The original gauge is an amp meter. Volt meter gauge is different. A volt gauge just measures voltage. Amp gauge measures the current flowing through it.

Walkinfuss · Sep 19, 2023

Thanks

molinegb · Sep 19, 2023

As with all gauges a difference potential is required for meter movement. More positive than negative or vice versa. Can easily be checked with a battery charger
or power supply.

sms · Sep 20, 2023

Ammeter is connected in series, voltmeter
is connected parallel.

Walkinfuss · Sep 26, 2023

Thanks, I knew that at one time.... I seem to forget how bad my memory is.
On another note, concerning the oil pump spacing between the engine and oil pump surfaces. .002-.004 spacing is the target and can be achieved by shim/gasket thickness combinations.

My conundrum is this. When I lay a flat edge across the pump idler and drive gears to measure the gap using feeler gauge, the side with the idler is level (no gap) with the pump housing, while the drive gear is .015" from that side of the pump housing. I compiled gasket shims to a collective thickness of .018". I have ZERO oil pressure regardless of how the pump pressure is adjusted. Is it a standard practice to mill/surface grind both the drive and idler gears to the same length? Using plastic gauge to measure the clearance would seem useless with the gears not being the same elevation above the pump housing.

I am so close to wrapping up the project!!

MMDEL · Sep 27, 2023

have you checked the relief valve and spring???? Even with those clearances you should have some pressure. With cold oil. Dose the drive gear rotate when you crank it over with the starter?? Blow out the oil passage from the pump to the pickup screen.
MMDEL

Walkinfuss · Sep 27, 2023

(quoted from post at 08:43:36 09/27/23) have you checked the relief valve and spring???? Even with those clearances you should have some pressure. With cold oil. Dose the drive gear rotate when you crank it over with the starter?? Blow out the oil passage from the pump to the pickup screen.
MMDEL

Relief valve and spring are in great shape, Gets worse now... Took off shims to achieve less gap. Started up, still no oil pressure, then completely stops. Distributor rotor not turning took out the pump drive shaft.... a lot of elbow grease to drift the shaft up and out. ... got it out, the drive gear pin was sheared off an the gear was pushed away from the cam drive gear. The oil pump drive gear was shattered. Cam drive gear looks good. Looks like the distributor shaft is bent, wobbles when its in my end mill. Shaft is pretty scared up. I have another pump drive gear, gona have to either straighten the shaft or have one made... will keep posted my progress.. Thanks for the in-put.

molinegb · Sep 27, 2023

I would check endplay of crankshaft. Too much endplay may be damaging governor on end of crankshaft. Can inturn be causing cam to float forward hitting oil pump
shaft. No reason for gears to pile up in pump unless somehow chunk of steel got into it. Same oil pump gears used back in TC days of 12-20 etc. All MM had ammeter
and never voltmeter. To me sound like motor need rebuild especially bottom end.

Walkinfuss · Sep 27, 2023

Will do. Didn't think of end play. Someone was in the motor before, the pistons are .040 over and the crank rod journals miced .020 under size. Didn't want to split the tractor, guess I may have to anyway.

Thanks again

molinegb · Oct 6, 2023

No reason to split tractor unless rear seal is leaking.

ChrisQ · Oct 7, 2023

I more than likely have a used oil pump shaft on the shelf.

Walkinfuss · Oct 8, 2023

Thanks for the offer, all is working well..

Walkinfuss · Oct 16, 2023

Uggggg... another set back. Rear wheel hub cracked almost all the way from end to end. Glad I found it now, not when the wheel flies off and kills someone.

I could use some direction (again) where to find one. The cast part number is 10A 21924. It's on a 68' Jetstar 3 super.

As always, i appreciate the experts out there.

ChrisQ · Oct 21, 2023

I should have a hub on the shelf.

ChrisQ · Oct 21, 2023

I should have one on the shelf.

Walkinfuss · Oct 22, 2023

That would be great. Was looking at one off an Oliver, just need to open the I.D. from 2.25" to 2.5" What do you want for it? BTW, the oil pump was perfect, thanks

Walkinfuss · Oct 26, 2023

Thanks Chris. I found one local.

Now I'm looking for the hydraulic oil filter element. Book says OEM # is 10P1851. Crosses to a Wix 51828. The wix 51828 is about 1 taller than the OEM and the O-rings supplied with the filter are
way too small, can't stretch to fit the canister.

Tractor has a 3pt. Don't know if that matters.

About 80% complete on this project. Now the hydraulics wont function. Filter was plugged and oil looked like chocolate milk when I drained it. Got about 3 gallons out of the fill level plug hole
before it quit running out.... way over filled, hope that didn't destroy anything. Thought I'd start with new oil and filter and go from there. The 3-point jerks as it goes up very slowly. The bucket
lift cylinders won't move regardless of the lever position. Hoping new oil will be the fix..

Again, relying on the experts for direction.

Thanks

MMDEL · Oct 26, 2023

You said you was having issues with oil filter. Don' know how you resolved it but be sure you have a good seal at the top of the oil filter canister.( and bottom bolt ). The pump has to draw fluid up and out of the reservoir and it could be sucking air at the filter.
MMDEL

Walkinfuss · Oct 26, 2023

Good point, thanks. It does not leak, but if it's a vacuum, then it would not leak oil. I'll dig into that tonight after work. Thanks for the input.

MM Jet Star 3 Super

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