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Posted

2017 sierra 5.3 with 230k kms/ 140k miles. Oil pressure when hot drops to 10 psi at idle. Spikes back up as soon as you hit the gas. It's always dropped low to like 20psi since new but seems to be getting worse very gradually. At highway speeds it's up around 35-40psi. If I step on it it will jump up to 60 or so. Local shop is recommending oil pump replacement which is a pretty pricey job. Anything else this could be before we go ahead? They checked with a mechanical gauge and otherwise the pressure seems correct so don't think it's a sensor issue....

Posted

It's normal. You just noticed it and panicked.  Many do the first time they catch it low. 

 

The oil pump is driven by the engine. The engine runs at various rpms, so naturally the oil pressure will drop at idle. 

 

Long ago a mechanic told me 10psi per 1000 rpm.... no worries unless the engine is making abnormal sounds.

 

 

Posted
8 minutes ago, Snowcamo said:

It's normal. You just noticed it and panicked.  Many do the first time they catch it low. 

 

The oil pump is driven by the engine. The engine runs at various rpms, so naturally the oil pressure will drop at idle. 

 

Long ago a mechanic told me 10psi per 1000 rpm.... no worries unless the engine is making abnormal sounds.

 

 

It's getting worse though which is what concerns me, it never used to drop below 20psi (1/4) on gauge, down at the 1/8th mark now (10psi). When would you start to be worried if it continues to get worse? 5psi?

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Posted (edited)

I'd be worried when the engine starts making noise. 

 

There is more to oil pressure then the oil pump. The oil goes through passages in the engine and can loose pressure there. Making the pump replacement a waiste. 

 

Been there.

Edited by Snowcamo
Posted
5 minutes ago, Snowcamo said:

I'd be worried when the engine starts making noise. 

 

There is more to oil pressure then the oil pump. The oil goes through passages in the engine and can loose pressure there. Making the pump replacement a waiste. 

 

Been there.

I get what your saying but if it starts making noises it's already too late to save it... Seems unlikely normal wear would be enough to make a 10psi difference. It's only got a 140k on it. If it was 250k miles I'd be less concerned about it. I ended up telling them to go ahead with it. Will see if it improves.

Posted (edited)
21 minutes ago, Mackenzie Stephenson said:

It's getting worse though which is what concerns me, it never used to drop below 20psi (1/4) on gauge, down at the 1/8th mark now (10psi). When would you start to be worried if it continues to get worse? 5psi?

 

 

 

Yea, shouldn't be that low on the gauge at idle even with 140k on it. 

 

Minimum hot oil PSI is 22 psi (151.69 kPa) at 1,000 engine RPM for the gen 5 V8s in these trucks.  At idle every one of these I've gotten in and on my 2019 old body that I owned never dropped below the 2nd notch on the gauge at hot idle.   

 

I'd have the shop inspect and or replace the timing chain tensioner as they have a TSB out to watch for the tensioner spring putting holes in the back of the oil pump.  

 

32 minutes ago, Snowcamo said:

Long ago a mechanic told me 10psi per 1000 rpm.... no worries unless the engine is making abnormal sounds.

 

 

 

Edited by newdude
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Posted
1 minute ago, newdude said:

 

 

Yea, shouldn't be that low on the gauge at idle even with 140k on it. 

 

Minimum hot oil PSI is 22 psi (151.69 kPa) at 1,000 engine RPM for the gen 5 V8s in these trucks.  At idle every one of these I've gotten in and on my 2019 old body that I owned never dropped below the 2nd notch on the gauge at hot idle.   

 

I'd have the shop inspect and or replace the timing chain tensioner as they have a TSB out to watch for the tensioner spring putting holes in the back of the oil pump.  

 

 

Yep, they are doing chain and tensioner at same time.

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