Low hot idle oil pressure?
- Thread starter AcIdBuRn02ZTS
- Start date
With two different gauge sets yes... first mechanical gauge was reading 0 at hot idle... after reading and getting ready to pull the engine, swapped to a different mech. gauge and it registered 7psi hot... first mech. gauge was junk.
Only reason I am still going on this topic is to get information out there for others who may search for the same topic as I came up empty for causes of low/no idle oil pressure besides bearing failure... but it sounds to me like there could be other causes to look at before doing a full rebuild.
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Only reason I am still going on this topic is to get information out there for others who may search for the same topic as I came up empty for causes of low/no idle oil pressure besides bearing failure... but it sounds to me like there could be other causes to look at before doing a full rebuild.
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AcIdBuRn02ZTS;2024393 said:
That is not a problem.
AcIdBuRn02ZTS;2023799 said:
That is the problem. I wouldn't be too concerned with your numbers, and it seems you are not.
At this point... not concerned at all as that's well within spec. My problem was the no oil pressure... POS mechanical gauge. Lol
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To round out this thread here are some things that could cause low hot idle oil pressure on the stock 7MGTE:
1. Stuck open Oil Squirter - Never heard of it myself, but if one were to fail and remain open you would lose some pressure. They can wear with age and open a little earlier (lower pressure) than they should and that may be somewhat common. They cost around $70 to replace when I did my last 7M rebuild. I'd replace them anytime you open the bottom end if they haven't already been replaced in the last 100k miles. It's cheap insurance on an engine build.
2. Worn engine bearings - Common, especially after a BHG. Bearings can wear from normal usage, oil starvation, improper oil type (too thick or too thin), or contamination. A BHG makes contamination likely. Coolant will eat away at the bearings when mixed with the oil which can happen with a BHG.
3. Stuck open oil cooler circuit - Never heard of it myself. The cooler circuit drains to the pan so if this valve stuck open you could have a loss in pressure. I've never heard of anyone finding an even slightly faulty oil cooler circuit valve, but I'm sure it's happened.
Realistically, by far the most common cause is worn bearings. Also note that the accuracy of your pressure gauge may not be good enough to trust it for a rebuild diagnosis. Like you found, low pressure can register inaccurately on a variety of gauges. The 7M has a relatively low idle oil pressure. Don't freak out if you're not seeing good pressure on an oil pressure gauge.
Also, IMO, to use the factory pressure specs you need to be using factory weight oil. If you're using a higher viscosity oil you're giving yourself false readings. A very poor engine might register ok pressure on 20W-60 oil, but the engine is still in poor shape. Use OEM viscosity oil and compare to OEM specs with a known good gauge. Don't fret if your idle readings are off. If you have a problem at idle it would probably show problematic at 2k rpms as well.
Conversely, if you have a custom built engine with different clearances in the bearings do whatever you think is right. Once the clearances are changed the Toyota specs go out the window, IMO.
1. Stuck open Oil Squirter - Never heard of it myself, but if one were to fail and remain open you would lose some pressure. They can wear with age and open a little earlier (lower pressure) than they should and that may be somewhat common. They cost around $70 to replace when I did my last 7M rebuild. I'd replace them anytime you open the bottom end if they haven't already been replaced in the last 100k miles. It's cheap insurance on an engine build.
2. Worn engine bearings - Common, especially after a BHG. Bearings can wear from normal usage, oil starvation, improper oil type (too thick or too thin), or contamination. A BHG makes contamination likely. Coolant will eat away at the bearings when mixed with the oil which can happen with a BHG.
3. Stuck open oil cooler circuit - Never heard of it myself. The cooler circuit drains to the pan so if this valve stuck open you could have a loss in pressure. I've never heard of anyone finding an even slightly faulty oil cooler circuit valve, but I'm sure it's happened.
Realistically, by far the most common cause is worn bearings. Also note that the accuracy of your pressure gauge may not be good enough to trust it for a rebuild diagnosis. Like you found, low pressure can register inaccurately on a variety of gauges. The 7M has a relatively low idle oil pressure. Don't freak out if you're not seeing good pressure on an oil pressure gauge.
Also, IMO, to use the factory pressure specs you need to be using factory weight oil. If you're using a higher viscosity oil you're giving yourself false readings. A very poor engine might register ok pressure on 20W-60 oil, but the engine is still in poor shape. Use OEM viscosity oil and compare to OEM specs with a known good gauge. Don't fret if your idle readings are off. If you have a problem at idle it would probably show problematic at 2k rpms as well.
Conversely, if you have a custom built engine with different clearances in the bearings do whatever you think is right. Once the clearances are changed the Toyota specs go out the window, IMO.
^^ Good info.
I had read a member here had built an engine and didn't replace the piston coolers... overlooked them. After assembly, he was only seeing 4psi at hot idle with tight clearences... pulled it back apart and changed the piston coolers and it came up to 10psi.. this is where I got the stuck/worn cooler nozzles causing a pressure issue.
I've also heard from some engine builders that its wise to increase oil wt as the engine ages/wears to prolong bearing life and to maintain proper pressure as the clearences increase.
Thanks for the input guys.
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I had read a member here had built an engine and didn't replace the piston coolers... overlooked them. After assembly, he was only seeing 4psi at hot idle with tight clearences... pulled it back apart and changed the piston coolers and it came up to 10psi.. this is where I got the stuck/worn cooler nozzles causing a pressure issue.
I've also heard from some engine builders that its wise to increase oil wt as the engine ages/wears to prolong bearing life and to maintain proper pressure as the clearences increase.
Thanks for the input guys.
Sent from a pay phone... using Tapatalk v2.0