Delay in oil pressure on start up

[Garbage_Mechan]

I drive an 86 F250 6.9 / C6/ GV/ 3.55's. Truck has 360,000 miles but engine was rebuilt 70,000 ago. It has been doing great, but just lately it has began taking several seconds for the oil pressure to come up on the first start after sitting a few hours. I have mechanical oil pressure gauge. I use Baldwin oil filters. There has been no change in engine performance, noise or running oil pressure. I'm wondering if there is some kind of check valve that can fall out and allow oil drainback after it has been sitting a while? Any ideas?

BTW, I'm new over here, been lurking for years but I've been on TDS for a long time. I'm a diesel mechanic and maintenace manager for a trash truck fleet.

 

[NCheek]

My truck does the same thing, but I say no cause for concern because I figured it just takes some time to get the oil up to the sender. The only real "fix" for this "problem" is to buy of fabricate some sort of "pre-luber" that will oil the engine components before startup. Others will chime in about the preluber

 

[Garbage_Mechan]

Yes, but the problem is for 65,000 miles or so it didn't do it and it takes long enough the rod bearings ar just starting to rattle the second it gets oil pressure so I'd say something has changed for the worse.

 

[Diesel JD]

Did you replace the oil pump when you did the rebuild? I also wonder if you might be seeing something happening with that pressure relief valve in the oil cooler header. I'd say if you hear bad noises then your gut is right something is not acting like it should on startup. If there was no problem with the components complaining I'd say maybe your mechanical oil pressure tube had an air bubble or some sludge but it sounds like you hear something that worries you, and since you are an experienced mechanic and know diesels I would trust your ear.

 

[subway]

didnt seem like a real problem until you mentioned the noises. could you have lost a piston oil jet?

 

[69dieselfreak]

mine does the same thing but no noises like that

 

[Agnem]

I think this is typical on a lot of motors. Viscosity will definitely affect the time for the oil presure to come up. With a mechanical oil presure gauge, you should check to see if you have any air in your lines, as this adds to the delay and makes the reading lower.

 

[EMD_DRIVER]

My locomotive at work, will take between 20 and 30 seconds for the oil pressure to even come off of zero on the gauge. It goes up to 55psi at idle. The oil pressure in my 87 6.9 comes up almost immediately.

Gary

 

[Mr_Roboto]

Any system had a drainback valve to prevent the oil from running back down through the oil pump gears into the crankcase. Most are in the oil filter itself, not sure on the IDI's.

If the oil drains back, then the oil pump has to refill the filter etc before you get any pressure.

I would try changing the oil filter with a quality unit (no fram!!).

 

[69dieselfreak]

Any system had a drainback valve to prevent the oil from running back down through the oil pump gears into the crankcase. Most are in the oil filter itself, not sure on the IDI's.

If the oil drains back, then the oil pump has to refill the filter etc before you get any pressure.

I would try changing the oil filter with a quality unit (no fram!!).

in mine im running a fleetgaurd LF3630 so i must have air bubble or something
but it did that even when my trk wasnt turbod

 

[Garbage_Mechan]

I agree on the quality oil filter, I have used nothing but Baldwin on the whole fleet for 26 years or so. I have B134 on all of the IDI's probably 10 million miles alll together. I never ran into this before, and of course it is on my personal co pickup. I've never lost the bottom end out of an IDI and I don't plan to start.