oil pressure

[valyidol]

95 Chevy Silverado 6.5
Oil pressure indicator idling pressure began to show 1. On start oil pressure is 4 or higher. Together with the oil pressure indicator pointers fuel temperature indicators. Today, I will measure the real pressure gauge.

 

[Will L.]

Testing with secondary mechanical gauge is correct- double check oil level on dipstick.

Psi or bar? If bar then those numbers are well within specification. 0.5 bar at idle is ok, below that GM says find and fix the problem. If psi, then we have a problem.

Reardless, when low pressure is occurring:
Check oil level.
What oil grade are you using?
Drain and replace oil,ensuring you drain oil cooler. Replace filter.

 

[valyidol]

Sorry! It's not my truck. Oil pressure is 10 psi

 

[valyidol]

Start the engine. Oil pressure at the start of 40 psi. I warm up the engine. Temperature of about 175, an oil pressure of about 12 psi. Light bulb lit Check Gages

 

[Will L.]

12 psi at idle is well withon spec. If it is high mileage engine, chanes are it is just notmal bearing wear. I have seen several 6.5s at 9 or 10 psi idle and around 35 psi full load go an additional 200,000 miles.

You can always try draining 1 quart of oil, replace with atf. Drive for a day then replace oil pump with a new one and new oil & filter. The atf will lower the oil pressure some, but will wash out any contamination and break free any loose carbon. It is not a needed step, but may help.

If it currently has the low volume pump, replacing it with a high volume one will raise the pressure.

Years ago I was researching who makes the best 6.5 oil pump. I found out that Melling makes the oil pump for every brand out there, there are all relabels. This was verified to me by speaking to one of the engineers at melling. He said there was one company that was offering different relief pressure springs as a kit with theirs, but his recommendation was not to bother. So
You basically have two options, low volume or high volume pumps. The high volume is identified by the spacer block making the body longer- the one on the right in the picture. Notice the pickup tube may need to be reused if the one you get is for a different pan- an easy swap.

 

[valyidol]

Well...

 

[Will L.]

Looks like 6 psi to me.
Not a good day for somebody.
You could try a new oil pump, then if you dont get lucky- reuse that new oil pump when you put in all new cam, crank, and main bearings...rings while your there.

 

[WarWagon]

Send the oil out for a sample. Diesel fuel in the oil can lower oil pressure. Gasoline contaminated diesel fuel can result in the same thinning of the oil as the fire can go out in a few cylinders at idle. Gasoline can put the fire out in a diesel engine! When the fire goes out oil contamination from diesel wash down is quick.

It's difficult to blow both IP seals to get fuel in the crankcase, but, not impossible if the weep hole is plugged. Very remote possibility.

How does the engine run overall? Missing at all? Start without drama?

This could happen if the owner starts it up and lets it smoke white and idle to warm up. These engines need a load to get the precups hot and I load mine the second oil pressure comes up. This load combined with just enough throttle stops the smoke. IP Timing problems is the sole reason I have the white smoke and high drama starting.

 

[valyidol]

Looks like 6 psi to me.
Not a good day for somebody.
You could try a new oil pump, then if you dont get lucky- reuse that new oil pump when you put in all new cam, crank, and main bearings...rings while your there.

I compiled this engine 6 months ago. The new crankshaft, new bearings. old ring camshaft, old oil pump.

 

[NVW]

12 psi at idle is well withon spec. If it is high mileage engine, chanes are it is just notmal bearing wear. I have seen several 6.5s at 9 or 10 psi idle and around 35 psi full load go an additional 200,000 miles.

You can always try draining 1 quart of oil, replace with atf. Drive for a day then replace oil pump with a new one and new oil & filter. The atf will lower the oil pressure some, but will wash out any contamination and break free any loose carbon. It is not a needed step, but may help.

If it currently has the low volume pump, replacing it with a high volume one will raise the pressure.

Years ago I was researching who makes the best 6.5 oil pump. I found out that Melling makes the oil pump for every brand out there, there are all relabels. This was verified to me by speaking to one of the engineers at melling. He said there was one company that was offering different relief pressure springs as a kit with theirs, but his recommendation was not to bother. So
You basically have two options, low volume or high volume pumps. The high volume is identified by the spacer block making the body longer- the one on the right in the picture. Notice the pickup tube may need to be reused if the one you get is for a different pan- an easy swap.
View attachment 48891

All the non squirter engines I've had apart use the pic up on the left and the squirter blocks had the one on the right.

 

[valyidol]

Engine starts badly. Air. I found this problem. After starting 1 minute engine shakes. After a short heating run good. White smoke is not. The oil level does not increase.

 

[WarWagon]

Oil level increase is not always true with fuel dilution if the engine is using oil. Work this engine hard and it can use 1 quart of oil every 500 miles (~1L to 804km): It simply evaporates oil off the hot heads and sucks it through the CDR system regardless of new or old rings, seals, etc. Sample the oil to help you decide if you need to pull the engine. At the minimum pull the oil filter and cut it open to see what's in it. If you don't sample the oil: try an oil change.

Parts may be hard to find, but, reusing an oil pump during an engine rebuild will come back and haunt you way too often. Depending on the kind of engine failure reusing the GM oil cooler is also high risk as debris is impossible to flush out of them.

@Will L. I am surprised you didn't mention the most likely bad news of early cam bearing failure causing low oil pressure due to priority oiling of the camshaft vs. the mains.

Regardless good luck with this one and let us know how it turns out.

 

[Will L.]

When you said new bearings- did that include new cam bearings?

Did you measure the camshaft where it rides on the bearings?

@WarWagon as for how bad I hate the cam bearings from GM- this is a pic of my gearshift and the ammo can is my "center glove box" and drink holder. Notice the cam bearing? Yeah... hate them.

 

[valyidol]

Yes, I, too, begin to think about the camshaft and bearings. One month ago, broke one of the hydraulic lifters. May the pressure to fall because of bad lifts?

 

[Will L.]

Yes

 

[valyidol]

Well... I took the time to see this diesel. 8 lifters were broken. Why is this? Is it the scratches on the body lifts itself? Or is it the worn rocker arms?

 

[valyidol]

Here too there is a worn surface

 

[valyidol]

There is another surprise. In oil emulsion. It's all just do not need to buy gaskets unknown manufacturers.

 

[Will L.]

Buy felpro or Victor Reinze head gaskets, no others.

That is a ton of wear on the lifters from not enough oil. Chances are the cam is shit too. Time to replace entire upper train. Dont try to save $, the $40 you "saved" before is probably what cost all this. Cheap is cheap, not less expensive.

 

[valyidol]

I also said the truck owner that the entire upper train needs to be replace.