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Thread: Oil pump rebuild

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    Jedi Hopeful
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    Oil pump rebuild

    When rebuilding or checking a TR3 oil pump the maintenance manual states the end float between the rotors and the end plate should be 0.0005" to 0.0025". How do you make this measurement? I would think you'd remove the end plate, turn the pump upside down and check any clearance between the rotors and bottom of the upper portion of the pump. Is this correct? On my car, most of the time the oil pressure is 70 psi; however, after the engine becomes hot (not overheating) it may drop to between 50 and 70 at speed and as low as 20-25 psi at idle making me think the end float on the oil pump may be excessive.

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    Yoda CJD's Avatar
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    Re: Oil pump rebuild

    Several ways, depending on the tools you have at hand. I mic the rotor and mic the case to find the difference. You could also use a dial indicator on the drive shaft and pull the shaft up and down within the pump assembly with the cover on. Then, you could use a feeler gage on the edge of a flat plate with the cover off and pump upside down. You could use plastigage on the impellers and seal the case up to check.

    I am sure there are other ways!?!

    Your pressure sounds good to me, by the way...at least way better than I would be concerned with. Loss of pressure is normally a result of bearing wear. Bearing wear usually occurs much faster than end wear on the pump impellers.
    John

    1955 TR2

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    Re: Oil pump rebuild

    Thanks John. With all those ways to check the end float, I have the tools necessary to accomplish at least two of them, maybe three. Anyway, I'm rebuilding a spare oil pump and needed to determine how to accurate check the end float.

    The engine has only a little over 3000 miles on it. The PO rebuilt the bottom half before I got it so I presume he used new bearings and did something to the crank. I hope. And I don't know what was done with the pump. As long as the pressures stay good I'll stick with what I have.

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    Great Pumpkin TR3driver's Avatar
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    Re: Oil pump rebuild

    I lay a good straight edge across the end, and use feeler gauges to check the clearance between the straight edge and the rotor. Also feeler gauges to check clearance between inner and outer rotors.

    If you do replace the pump, be sure the new one has a pin to hold the rotor to the shaft. Some of the cheap aftermarket pumps used a soft rotor and a knurled shaft, which don't hold up in use.

    20-25 at hot idle isn't bad at all; but I would expect better than that from an engine with only 3k miles. Can't hurt to check while it's apart. Also check cam bearings, and the bushing that the oil pump drive shaft rides in.

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    Yoda
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    Re: Oil pump rebuild

    I gotta tell you I have about 5 or 6 oil gauges and they are all a little different and one of them when the engine is good and warm it reads zero oil pressure at idle!!!!, but 70 at start up and about 45 at idle until it just fell away. That was a very unsettling day because the motor had about 1K on it. I preplaced it with a different gauge and had 50 at idle and 70 going down the road. I would purchase a new mechanical gauge and run that for a while until I messed around rebuilding the oil pump. Oil pumps often have an easy life and if they did not it really shows with scars, IMHO.

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