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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8426
Experience:  I am ASE Master Truck Certified.
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Have an 06 c13 with low oil pressure drops to 12psi at idle

Customer Question

Have an 06 c13 with low oil pressure drops to 12psi at idle after 15min of running. Did a complete out of frame rebuild, had crank ground and installed the undersized bearings they said it needed. Plasti gauged them and all are at 3 thousandths. Has a new oil pump and filter base within 3k miles before the rebuild. Put mechanical gauges on the filter base before the filter which starts at 70 psi when cold and drops to 42 psi after 15min. Had a second gauge after the filter housing and that starts at 25 psi and drops to 12 psi after 15min. Any thoughts?
Submitted: 11 months ago.
Category: Medium and Heavy Trucks
Expert:  Wayne replied 11 months ago.

Hi I'm Wayne

I will help you with this

did you replace the Cam Bearings

let me know

Customer: replied 11 months ago.
sir, put a cat gold kit in. All bearing are new
Expert:  Wayne replied 11 months ago.

That is the biggest over looked item

I will send this to another Cat expert

hang tight

Wayne

Expert:  Cat Man replied 11 months ago.

Thanks for asking your question. I will try and help you out.

I would like to ask you a few questions first about your problem. I hope that is ok.

May I ask why the engine was overhauled? Did it have low oil pressure before the overhaul?

Can you tell me how much was cut off the crank? Do you know the part numbers of the rod bearings?

Was the oil cooler housing and relief valve replaced during the overhaul?

Customer: replied 11 months ago.
I dont remember what the amount ground off the crank was, but it now requires the .51 bearings part number(###) ###-#### ***** this truck had low oil pressure so a different shop replaced the oil pump and filter base. Truck made it 150 miles and oil pressure dropped again then the #1 liner broke right below the coolant seal and locked it up. It bent the rod and piston. Had crank checked and was still straight but had grooves in it so they ground it
Expert:  Cat Man replied 11 months ago.

Thanks for the information.

.51mm or 0.020 thousands rod bearings are the correct ones if only 0.020 was taken off the crank. That's the correct part number (128-0395) for 0.020 Undersized.

These engine have a known problem of low oil pressure caused by the relief valve in the oil filter base. It gets worn and sticks open. When this happens. Both the oil cooler or filter housing base along with a new relief valve must be replaced in order to correct this low oil pressure problem. It sounds like your problem judging by the psi readings you gave earlier. I would definitely suspect this first.

The next thing I would want to check is the piston cooling jets. I have seen one of them get knocked off after an overhaul because it is bent. When they get knocked off, the oil pressure will drop.

Please reply back if you need more help. I am happy to assist.

Customer: replied 11 months ago.
All the piston cooler nozzles are new, we also took the pan back off to triple check them and plasti gauged the bearings again. The oil cooler and filter base are both new. The relief valve is in the filer base correct?
Expert:  Cat Man replied 11 months ago.

Thanks for the information.

Yes you are correct. Its in the filter base. The reason they have a problem sticking open is the C13 KCB produces a lot of soot in the oil form the IVA's. This soot gets in the valve area and causes wear. Once it wears, it begins to stick open.

Since all the cooler nozzles are in tact and the plasti gauge readings looks good. I must suspect the relief valve in the filter base. You may also want to inspect the pick up tubes in the oil pan as well. I have seen them crack and suck air.

On another note. I know that 12 psi sounds low. But the minimum allowable psi at idle hot is 10 psi.

Let me know if you need more help.

Customer: replied 11 months ago.
I checked the pick up tube also and couldnt see any cracks in it. Cat did have us replace the spring in the filter base with a supposed updated spring which made no difference
Expert:  Cat Man replied 11 months ago.

Thanks for the information. Yeah I have not had much luck with a spring either. I would look into the relief valve. If it was not replaced. I would definetely replace it. I have put many of them in for low oil pressure.

Customer: replied 11 months ago.
That is the one behind the big allen plug towards the from of the engine correct
Expert:  Cat Man replied 11 months ago.

Yes that is correct.

One more thing. You may also want to check for leaks around the Iva housings. I would get the engine warm to when the pressure drops. Then remove the valve covers and unplug the injector harness. Then crank the engine and look for leaks. I have seen the Iva housings have large leaks and cause low oil pressure.

Customer: replied 11 months ago.
Ok ill try both of those and let you know
Expert:  Cat Man replied 11 months ago.

Ok sounds good. Let me know how you make out.

Expert:  Cat Man replied 11 months ago.

Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.

Customer: replied 11 months ago.
Sorry i was out of town. The filter base did not solve the problem and dont see any leaks up by the iva housings
Expert:  Cat Man replied 11 months ago.

No problem. Sorry you did not see anything. The good news is the oil pressure readings you currently have are within specs. As long as the oil pressure does not drop below 10 psi at idle. You should not have any problems.

Let me know if you need more help.

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