Ok, so my mom has a MKIII supra that she's had for about 3 years now. The headgasket was recently blown but we replaced it and milled the head and block to ensure that all was even for a good seal, but recently she's had HUGE problems. When the oil is cold the car will keep oil pressure, but when the oil heats up it loses oil pressure, whys that?
could it be that the viscosity of the oil is just gone or that the ring-lands maybe collapsed?

any help is great. thanks guys/gals


if this doesn't belong here im sorry. mod move if needed.

 

Rings will not affect oil pressure. Main and rod bearings that are wasted can cause oil pressure problems. Failing oil pumps can also cause a problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b19coupe &raquo;</TD></TR><TR><TD CLASS="quote">Rings will not affect oil pressure. Main and rod bearings that are wasted can cause oil pressure problems. Failing oil pumps can also cause a problem.</TD></TR></TABLE>

but how would that explain when the oils cold theres pressure but when warm, there isn't?

 

What else was done to engine while it was apart other than milling head and block??

 

Describe the loss in pressure to us.

At idle, my dad's MKIV is at 65psi cold and 25psi warm.

My car at idle is at ~70psi cold, 20psi warm.

Is that what you are describing?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by doublej &raquo;</TD></TR><TR><TD CLASS="quote">What else was done to engine while it was apart other than milling head and block??</TD></TR></TABLE>

only thing that was done was the head was rebuilt with all oem parts tahst it. block wasn't touched but to mill it a bit to insure straightness.

no its like 45psi cold, thne boom 0psi when it starts to get warm.

 

My Mk2 supra at idle in the summer wouldnt move the needle on the stock oil pressure gauge. I switched to 20 50 and the motor picked up oil pressure and the lifters got quiet too. Did whoever fixed your headgasket fill your motor up with a light oil? Try 20-50

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BIGTUNA &raquo;</TD></TR><TR><TD CLASS="quote">My Mk2 supra at idle in the summer wouldnt move the needle on the stock oil pressure gauge. I switched to 20 50 and the motor picked up oil pressure and the lifters got quiet too. Did whoever fixed your headgasket fill your motor up with a light oil? Try 20-50 </TD></TR></TABLE>

we put mineral oil in just for break in, i put the oil in. i put 10w 40 in. but that wouldn't explain why there isn't oil pressure at all, 0psi, when warm.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b00sted-Hatch &raquo;</TD></TR><TR><TD CLASS="quote">

only thing that was done was the head was rebuilt with all oem parts tahst it. block wasn't touched but to mill it a bit to insure straightness.

no its like 45psi cold, thne boom 0psi when it starts to get warm. </TD></TR></TABLE>

New rod/main bearings or old parts reinstalled after milling block?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b00sted-Hatch &raquo;</TD></TR><TR><TD CLASS="quote">

we put mineral oil in just for break in, i put the oil in. i put 10w 40 in. but that wouldn't explain why there isn't oil pressure at all, 0psi, when warm.</TD></TR></TABLE>

20-50 and Supra motors make a happy family

 

If the bearings are pooched that bad you should hear it. 0 oil pressure would kill things off pretty quickly. Are you driving it or is this just from idling?

Don't overlook that the gauge could have some issues as well. My old Audi would read oil pressure when cold and then drop to zero after idling for a bit. It didn't creep down as the temperature went up though it just clicked right back to zero after a bit.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BIGTUNA &raquo;</TD></TR><TR><TD CLASS="quote">

20-50 and Supra motors make a happy family </TD></TR></TABLE>

that will be taken into consideration when i rebuild or just buy a new motor.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HBoy &raquo;</TD></TR><TR><TD CLASS="quote">If the bearings are pooched that bad you should hear it. 0 oil pressure would kill things off pretty quickly. Are you driving it or is this just from idling?

Don't overlook that the gauge could have some issues as well. My old Audi would read oil pressure when cold and then drop to zero after idling for a bit. It didn't creep down as the temperature went up though it just clicked right back to zero after a bit. </TD></TR></TABLE>

I did think maybe a bad gauge and getting like an autometer one. this is at idleing. im not gonna drive it if it says 0 lol.

 

Stock gauge oil pressure gauge or aftermarket?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BIGTUNA &raquo;</TD></TR><TR><TD CLASS="quote">Stock gauge oil pressure gauge or aftermarket?</TD></TR></TABLE>

stock.

 

FYI my supra would read 0 on the stock gauge yet 15 on a autometer, stock gauges are worthless.