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Discussion Starter #1
on my 2002 chevy the oil pressure guage goes up to about 60-70 psi when i speed up and when i slow down it goes to about 20 psi. so it fluxuates alot. it is all stock except for the K&N. and ideas on why this is or if it is normal?
 

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Wow no that is not normal. The dmax is known for having low oil pressure. Mine goes no higher than 40psi and down to 15-20. Id check the oil sending unit. I doubt it costs alot. If its not that there is suppose to be a mechanism to slow the oil pressure. I think an internal check ball. If it is that then there is a possibility you could have a serious problem. Some gaskets and oil lines will start to blow with all the pressure.



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FWIW, mine does that. When driving at highway speeds I run about 60 psi and at idle it is about 25-30 psi depending on temp. Mine has always done this since new...and when cold I have seen as high as 80-90 psi. on accelleration.
 

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yeah its doing exactly what ob_1jr's truck is doing and a friend of mine has the GMC same truck and his does the same. should i be worried about it if others are doing it to? but i will definently check the sending unit to be sure. thanks
 

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I wouldn't be worried. You have to have RPMs to have higher oil pressure. Oil pressure is a resistance to flow anyway. I have read that the oil pump on the duramax is a high flow pump anyway. What brand/weight of oil you using?
 

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I have just bought a 05 crew lly 4x4 and am new to the deisel world. My pressure does the same when in the gas and at idle is about 30. The highest it ever gets is about 80 and cruises at 65. If anyone thinks this might be a concern, let me know. Also my dmax is all stock and the first thing I need to get is a new air filter. Any sugestions on waht is the best?
 

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alrightie well i talked to a diesel mechanic and he said this is normal for the pressure to go this high. its not dangerous... he said it is actually good it is doing this because as your RPMs go up the faster your crank is turning your oil pump which increases the pressure. as long as its not below 15 or even as low as 9 your good. as far as stock air filters go amsoil, banks, or K&N are good. but if you want to step it up a notch i'd go with a cold air intake. some good brands are volant, S&B, amsoil. hope that helps
 

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From personal experience, stay away from the k&n unless you like to let dirt into your engine. I had the stock replacement and you could see pinholes through it.
 

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Discussion Starter #10
i'd go with a volant but some of the less expencive ones like bully dog and banks are pretty good too. just depends on how much you wanna spend. but dont go with the cheap ones
 

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My mom has an "03 GMC with the LB7 in it and it runs at 90psi hot or cold at idle and when you get into the throttle it gets pegged at 120psi. I'm goin to school for Diesel Tech. and I was talking to another guy here thats works at GM on these trucks and he said its either the oil sender is wrong or the oil pressure regulator is broken, which is located in the oil pump and you have to replace the oil pump to fix it. I don't know if it's just for my mom's case at running that high but he told me if it really is running that high then there is a good possibility that the main bearings will get "welded" to the crank at that high of pressure. So I would be careful on just letting your pressure run high if its not your sender.
 

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My 2003 LLY is doing the same thing 60-70 idling then shooting to 110-120 with acceleration. I replaced the sending unit with an aftermarket unit but it is still doing the same thing. I'm not wanting to go into the engine but from what I understand the pressure sensing valve is in the pump.Any better ideas?
 

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Have to throw some metric in here....Cold start mine runs about 500 kpa and when warm at highway speeds sits at 400 kpa and idle 200......
 

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My 2003 LLY is doing the same thing 60-70 idling then shooting to 110-120 with acceleration. I replaced the sending unit with an aftermarket unit but it is still doing the same thing. I'm not wanting to go into the engine but from what I understand the pressure sensing valve is in the pump.Any better ideas?
Are u sure u have an lly should be a lb7 in 03
 

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Sorry all these L's are confusing me, it's an LB7. The pressures have always run around 20 to 30 idling and pulling our 32 ft fifth wheel they only ran around 50-60. I changed the oil using the same type of filter as always and the same oil as always and it started these high pressures. Do these oil filter adapters have a bypass valve in them? I've heard these can cause high pressures.
 

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Surpised nobody has mentioned this yet...


But when your truck is cold oil pressure will be a lot higher due to the oil being thicker. It will go down as your oil temp drops/
 

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When we drive the truck the pressure runs around 60 but when you accelerate it shoots straight to 120. It's never run this kind of pressures.
 

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When we drive the truck the pressure runs around 60 but when you accelerate it shoots straight to 120. It's never run this kind of pressures.
Has it colder than normal? Does it go back down once the truck warms up.
 
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