C2 SB Oil pump change

[Dwight P.]

My 65 SB has either a high press oil pump or high volume pump installed. Oil pressure remains "pegged", even at idle until the temperature is normal and then it remains at 45-50psi at idle and "peggs" with any rise in RPM.

I want to install a normal "original" pump. (Melling 10553?)
1. What parts have to be removed before the oil pan can be removed?
2. What special precautions must be observed during the installation of the new pump?

Thanks,

DP

[Mike M.]

Re: C2 SB Oil pump change

If you have a melling HP init now you can just change the spring if its a high pressure pump. Thats what I did with mine. I don't have the part number handy for the spring. I got it from GM. Joe Lucia found the correct part number for me. If nobody comes through with the number for you I'll dig it up tomorrow. I had to drop the steering damper and starter. I think that was it and then the pan. Its a easy job.

[Mike M.]

Re: C2 SB Oil pump change

If you have a melling HP init now you can just change the spring if its a high pressure pump. Thats what I did with mine. I don't have the part number handy for the spring. I got it from GM. Joe Lucia found the correct part number for me. If nobody comes through with the number for you I'll dig it up tomorrow. I had to drop the steering damper and starter. I think that was it and then the pan. Its a easy job.

[Verle R.]

Re: C2 SB Oil pump change

Dwight,

Disconnect the battery cable at the battery end; battery cable shorts are not a good thing.

Drain the oil, drop the tierod on one end, remove the oil filter and starter to make thing easier and remove the pan.

Clean the pan rail and inspect to make sure it is straight. They are often distorted by "someone" over torquing the pan bolts. You can straighten the pan rail with a small hammer and tapping lightly.

Turn the pump by hand to make sure it turns smoothly. Pour some oil into the pump to lubricate it and to help prime the pump. Make sure the pickup is positioned about 1/4 inch above the bottom of the pan and is well attached to the pump. Some people tack weld the pickup tube to the pump. Torque the oil pump to 65 lb (if I remember correctly); someone correct that number.

Clean the pan rail on the bottom of the block. Scrape off the old gasket and make sure the rail is clean and dry.

When you install the pan gasket, use orange sealer on to eliminate leaks. The orange will blend with engine paint. Make sure you use the correct seal at front and back of the pan; there are different sizes. If you are not concerned with originality use a one piece gasket. They work well but may require longer bolts than your original pan bolts.

Don't over torque the pan bolts. You will bend the pan rail and cause leaks.

This is not a hard job, but can be an oily one.

Verle

[Verle R.]

Re: C2 SB Oil pump change

Dwight,

Disconnect the battery cable at the battery end; battery cable shorts are not a good thing.

Drain the oil, drop the tierod on one end, remove the oil filter and starter to make thing easier and remove the pan.

Clean the pan rail and inspect to make sure it is straight. They are often distorted by "someone" over torquing the pan bolts. You can straighten the pan rail with a small hammer and tapping lightly.

Turn the pump by hand to make sure it turns smoothly. Pour some oil into the pump to lubricate it and to help prime the pump. Make sure the pickup is positioned about 1/4 inch above the bottom of the pan and is well attached to the pump. Some people tack weld the pickup tube to the pump. Torque the oil pump to 65 lb (if I remember correctly); someone correct that number.

Clean the pan rail on the bottom of the block. Scrape off the old gasket and make sure the rail is clean and dry.

When you install the pan gasket, use orange sealer on to eliminate leaks. The orange will blend with engine paint. Make sure you use the correct seal at front and back of the pan; there are different sizes. If you are not concerned with originality use a one piece gasket. They work well but may require longer bolts than your original pan bolts.

Don't over torque the pan bolts. You will bend the pan rail and cause leaks.

This is not a hard job, but can be an oily one.

Verle

[Dwight P.]

Re: C2 SB Oil pump change

Verle and Mike:

Thanks for the info. It will help a lot. I will wait to see if anyone posts the part number for the lower pressure spring. I am not sure what brand pump is in the car now.

DP

[Dwight P.]

Re: C2 SB Oil pump change

Verle and Mike:

Thanks for the info. It will help a lot. I will wait to see if anyone posts the part number for the lower pressure spring. I am not sure what brand pump is in the car now.

DP

[Mike M.]

found the part number

The spring number is GM#3814903. Its easy to change the spring. This will work if you have the high pressure GM or melling pump.

[Mike M.]

found the part number

The spring number is GM#3814903. Its easy to change the spring. This will work if you have the high pressure GM or melling pump.

[Dwight P.]

Re: found the part number

Mike:
Thanks again....I will be on the hunt on Monday.

DP

[Dwight P.]

Re: found the part number

Mike:
Thanks again....I will be on the hunt on Monday.

DP

[Joe L.]

Re: found the part number

Dwight-----

You didn't say what engine you have. If it's an L-76 or L-84, then it was originally built with a high pressure pump, standard volume pump. If that's what you currently have, I would not recommend changing it.

However, if you have a 250 hp, L-75, or L-79, you don't want to use a high pressure OR a high volume pump. First, you need to determine if a high volume pump has been installed. If so, I recommend changing it to a standard volume. In that case, change the whole pump to a Melling M-55 or a GM #12555284. You will also need pick-up screen GM #3830080.

So, how do you tell if it's a high volume pump? Simple. Take off the pump cover and remove the gears. If the pump is a standard volume, the gears will be 1.3" long; if it's a high volume, the gears will be 1.5" long. You can also tell by just looking at the pump housing. With an "untrained eye", though, you'll need a standard volume pump side-by-side to compare it to.

If you have a standard volume pump and it's in good shape, all you need to do is to change the relief spring to the one previously mentioned. This takes about 2 minutes (assuming you're slow) once you have the pump out of the engine. You can even do it with the pump still installed, but I don't usually do it that way. One bolt drops the oil pump.

[Joe L.]

Re: found the part number

Dwight-----

You didn't say what engine you have. If it's an L-76 or L-84, then it was originally built with a high pressure pump, standard volume pump. If that's what you currently have, I would not recommend changing it.

However, if you have a 250 hp, L-75, or L-79, you don't want to use a high pressure OR a high volume pump. First, you need to determine if a high volume pump has been installed. If so, I recommend changing it to a standard volume. In that case, change the whole pump to a Melling M-55 or a GM #12555284. You will also need pick-up screen GM #3830080.

So, how do you tell if it's a high volume pump? Simple. Take off the pump cover and remove the gears. If the pump is a standard volume, the gears will be 1.3" long; if it's a high volume, the gears will be 1.5" long. You can also tell by just looking at the pump housing. With an "untrained eye", though, you'll need a standard volume pump side-by-side to compare it to.

If you have a standard volume pump and it's in good shape, all you need to do is to change the relief spring to the one previously mentioned. This takes about 2 minutes (assuming you're slow) once you have the pump out of the engine. You can even do it with the pump still installed, but I don't usually do it that way. One bolt drops the oil pump.

[Terry R.]

Re: C2 SB Oil pump change

Just to add to Verle's post, the one piece pan gasket comes with longer bolts. Snug it down and replace bolts with originals one at a time. The one piece gasket won't leak a drop.

[Terry R.]

Re: C2 SB Oil pump change

Just to add to Verle's post, the one piece pan gasket comes with longer bolts. Snug it down and replace bolts with originals one at a time. The one piece gasket won't leak a drop.