Oil pressure

kewlgye · February 7, 2005

I've got a 98 k1500 with a 350. When I first start my truck, I'm running a constant 40 psi oil pressure, but when it warms up and is at idle (about 700 RPMs) it drops down to about 10 psi until I give it some gas, then it will increase depending on how much RPMs I'm running. I know this isn't normal becuase my work truck is a 99, and it runs a constant 45 or above. So should I be worried about this oil pressure problem? If so, what should I do. I was thinking new oil pump, but I've never done one before.

Jacqson · February 7, 2005

I've got a 98 k1500 with a 350. When I first start my truck, I'm running a constant 40 psi oil pressure, but when it warms up and is at idle (about 700 RPMs) it drops down to about 10 psi until I give it some gas, then it will increase depending on how much RPMs I'm running. I know this isn't normal becuase my work truck is a 99, and it runs a constant 45 or above. So should I be worried about this oil pressure problem? If so, what should I do. I was thinking new oil pump, but I've never done one before.

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How many miles are on the engine? Do you notice any unusual sounds coming from the engine? How long have you had this problem? Do you notice any change in performance? It could very well be the oil pump but I am thinking maybe it could be a loose or worn bearing. It's usually not that hard to replace the oil pump unless you run into problems getting the oil pan off.

kewlgye · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

Jacqson · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

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Down

Jacqson · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

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Down again

Jacqson · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

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Sorry about all these posts

Jacqson · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

<{POST_SNAPBACK}>

If it is the pump, there are two bolts holding the pump to the block, remove the bolts and the pump will come off, be careful as there is a pump drive shaft that goes up to the cam or distributor to power the oil pump. Make sure you replace that shaft when installing the new pump and also prime the new pump before installation.You may have to use the old pickup tube if your new pump doesn't come with one. Before you replace the pump I would go and get the pump pressure checked as you may just be dealing with a defective gauge, also with that amount of mileage the engine just may be getting very loose. It seems we have a lot of questions ,but not many sure answers.I hope this helps.

kewlgye · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

<{POST_SNAPBACK}>

If it is the pump, there are two bolts holding the pump to the block, remove the bolts and the pump will come off, be careful as there is a pump drive shaft that goes up to the cam or distributor to power the oil pump. Make sure you replace that shaft when installing the new pump and also prime the new pump before installation.You may have to use the old pickup tube if your new pump doesn't come with one. Before you replace the pump I would go and get the pump pressure checked as you may just be dealing with a defective gauge, also with that amount of mileage the engine just may be getting very loose. It seems we have a lot of questions ,but not many sure answers.I hope this helps.

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How is the oil pump pressure checked? And where would I get that done? Thanks.

Jacqson · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

<{POST_SNAPBACK}>

If it is the pump, there are two bolts holding the pump to the block, remove the bolts and the pump will come off, be careful as there is a pump drive shaft that goes up to the cam or distributor to power the oil pump. Make sure you replace that shaft when installing the new pump and also prime the new pump before installation.You may have to use the old pickup tube if your new pump doesn't come with one. Before you replace the pump I would go and get the pump pressure checked as you may just be dealing with a defective gauge, also with that amount of mileage the engine just may be getting very loose. It seems we have a lot of questions ,but not many sure answers.I hope this helps.

<{POST_SNAPBACK}>

How is the oil pump pressure checked? And where would I get that done? Thanks.

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I hate to say the Dealer but they can or a good mechanical shop. What they will do is either remove the oil filter and place a pressure testing unit in place of the filter or they can place a gauge setup in place of the oil pressure sending unit. If you get a low reading then you know it's not the gauge or the sending unit. I tend to think your engine is getting tired but you can ask the mechanic when they test the oil pressure and find out what they think it might be. Usually if an oil pump is not working you will get low or no pressure at all. The reason I think your engine is tired is because when the engine is cold you get good pressure , but once the oil warms up the pressure drops and that is because the engine bearings seem tight with cold oil but once the oil heats up it thins out and with less resistance in the engine bearings the pressure drops. Also ,with your vibration problem, maybe your torque converter or driveshaft is out of balance. I hope this helps.

Friz · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

<{POST_SNAPBACK}>

If it is the pump, there are two bolts holding the pump to the block, remove the bolts and the pump will come off, be careful as there is a pump drive shaft that goes up to the cam or distributor to power the oil pump. Make sure you replace that shaft when installing the new pump and also prime the new pump before installation.You may have to use the old pickup tube if your new pump doesn't come with one. Before you replace the pump I would go and get the pump pressure checked as you may just be dealing with a defective gauge, also with that amount of mileage the engine just may be getting very loose. It seems we have a lot of questions ,but not many sure answers.I hope this helps.

<{POST_SNAPBACK}>

How is the oil pump pressure checked? And where would I get that done? Thanks.

<{POST_SNAPBACK}>

I hate to say the Dealer but they can or a good mechanical shop. What they will do is either remove the oil filter and place a pressure testing unit in place of the filter or they can place a gauge setup in place of the oil pressure sending unit. If you get a low reading then you know it's not the gauge or the sending unit. I tend to think your engine is getting tired but you can ask the mechanic when they test the oil pressure and find out what they think it might be. Usually if an oil pump is not working you will get low or no pressure at all. The reason I think your engine is tired is because when the engine is cold you get good pressure , but once the oil warms up the pressure drops and that is because the engine bearings seem tight with cold oil but once the oil heats up it thins out and with less resistance in the engine bearings the pressure drops. Also ,with your vibration problem, maybe your torque converter or driveshaft is out of balance. I hope this helps.

<{POST_SNAPBACK}>

Let's look at this from two different angles:

1) You need about 10psi of oil pressure for every 1000 rpm you turn. If you've got 104,000 miles on the truck, chalk it up to wear.

2) Most oil pressure problems are not from a worn pump. Think about it - the pump gets more cool oil than any other component in your motor and they are very simple devices. They usually don't wear out.

Most of the time low oil pressure is caused by worn main bearings. When the bearings get worn and a little loose, oil is slopped out the sides and the pressure going up to the sending unit, cam and heads is less than optimal.

kewlgye · February 8, 2005

I've got 104,000 on the truck. I do have a slight vibration comming from the engine, but it ony happens when I'm in drive, and when I'm around 1000 RPMs. It won't do it when I'm in park or neutral, so I'm thinking it's something with the trans or something. The vibration started when my transmission went out back in November. I had the trans rebuilt, yet this vibration still happens. The oil pressure has been like this for as long as I've owned the truck, (1 year). It's performing like a champ. So once I get the oil pan off, does replacing it just consist of a couple of bolts, or is it more complicated than that? Thanks.

<{POST_SNAPBACK}>

If it is the pump, there are two bolts holding the pump to the block, remove the bolts and the pump will come off, be careful as there is a pump drive shaft that goes up to the cam or distributor to power the oil pump. Make sure you replace that shaft when installing the new pump and also prime the new pump before installation.You may have to use the old pickup tube if your new pump doesn't come with one. Before you replace the pump I would go and get the pump pressure checked as you may just be dealing with a defective gauge, also with that amount of mileage the engine just may be getting very loose. It seems we have a lot of questions ,but not many sure answers.I hope this helps.

<{POST_SNAPBACK}>

How is the oil pump pressure checked? And where would I get that done? Thanks.

<{POST_SNAPBACK}>

I hate to say the Dealer but they can or a good mechanical shop. What they will do is either remove the oil filter and place a pressure testing unit in place of the filter or they can place a gauge setup in place of the oil pressure sending unit. If you get a low reading then you know it's not the gauge or the sending unit. I tend to think your engine is getting tired but you can ask the mechanic when they test the oil pressure and find out what they think it might be. Usually if an oil pump is not working you will get low or no pressure at all. The reason I think your engine is tired is because when the engine is cold you get good pressure , but once the oil warms up the pressure drops and that is because the engine bearings seem tight with cold oil but once the oil heats up it thins out and with less resistance in the engine bearings the pressure drops. Also ,with your vibration problem, maybe your torque converter or driveshaft is out of balance. I hope this helps.

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Thanks a lot. I wish I knew for sure what the problem was so I wouldn't have to take it to the dealer. All that money spent there could go towards a rebuild. But the truck is running great right now. The drive shaft or torque converter being out of balance makes sense.