Oil Drop on Accel

[foxtrotzulu]

Changed the BHG last year and everything runs pretty good, the oil pressure seems real low compared to what it was before the head gasket blew.

Symptom - On acceleration the oil pressure drops, then goes back up off pedal but still idles low (near 1 or 2 psi). When I first start it, it goes up to 30psi then drops to 2psi when warm. Has not stalled and every other gauge looks within spec. Feels a little less BALLSY though on the take off.

7mgte manual
Could this be dirty oil from the rebuild? or clogged filter?

 

[CyFi6]

try hooking up a mechanical gauge to the sender port to make sure your gauge is reading right. Clogged filter would generally cause high oil pressure i would think. from what i hear when you get a bhg and the car runs a lot with the watery oil (if it blew into the oil passage) it loses its lubricity and can wear out parts like bearings and things fairly quickly, and when those oil clearances get larger oil pressure drops. Could be a possibility. Its also very common for cars to get rodknock soon after the head gasket is repaired because of this same idea.

 

[Fletch124]

First off replace oil and filter. 6 quarts and a new filter.

 

[foxtrotzulu]

Thanks CYF and Fletch,

The oil and filter I'm definitely doing first, I thought maybe the pick up was pulling more oil than was coming into the pan causing the pressure to drop down wind the filter. No noticeable knock that I hear.

Whats this mechanical gauge? Can I buy it at Partsource? Can't I just give the sender some voltage or check resistance across to test the gauge?

PS There's a Ft of snow outside here in Toronto and I don't think I'll be taking the targa off this week!

 

[Fletch124]

I wouldnt really drive the car til you put 6 quarts in it and put a new filter on. Just to make sure you dont spin a rod bearing. Better safe than sorry. Try not to drive the car til.

 

[flubyux2]

a clogged filter will read low oil pressure. the oil pressure sending unit is After the filter.

 

[jdub]

A clogged filter will go into bypass...it will not cause this. Unless you're running a crappy filter like a Fram...and even then, your pressure would be high due to the restriction. I'd change the oil and filter as suggested and fill to the top line on the dipstick...then add a quart.

You could either have a piece of crud blocking the sending unit or a relief valve is sticking open.

 

[CyFi6]

Sorry to change the topic slightly, but what needs to be removed to acess the relief valve to "shim" it?

 

[Fletch124]

Sorry to change the topic slightly, but what needs to be removed to acess the relief valve to "shim" it?

The motor, then the oil pan, then the pump.

 

[CyFi6]

i cant remove the pan and pump on the car?

 

[7MGTEsup]

i cant remove the pan and pump on the car?

Yes if you have a means of supporting the engine from above, but it involves dropping the subframe. This is how id did a repair on my sump a few months back. Is less work than an engine removal but isn't a small job by any means.

 

[Fletch124]

i cant remove the pan and pump on the car?

Supposedly someone has pulled the oil pan with the motor in the car. But I dont really see how without having to lift the motor. Its much much easier to just pull the motor and turn it upside down then to try and work on your bottom end laying on your back.

Ohh and if you do end up shimming your oil pump. Just buy a new toyota one and shim that.