I noticed, even before the rebuild and again after the rebuild, that it takes a more time for my Trooper's C223T engine to build oil pressure than I like(4-6 seconds for the idiot light to turn off). This only occurs when the engine was hot and then shut down, and left long enough to really drain the engine of its oil. But not long enough to completely cool down. When it is cold/cool, or you had only left the engine off for a few mninutes, this is not an issue. Does anyone else experience this?

For instance, today, a mild winter's day, I shut it off, and I was in a customer's office for a quick meeting. I was in there maybe 30 minutes and came back out, started the engine, and the pressure delay occurred. When I was in the bank for a quick minute this afternoon, it did NOT have this delay. Tomorrow morning when it is dead cold, I will likewise NOT see this delay.

One other thing, and I assumed this was normal, but maybe not: Both before and after the rebuild, when the engine is dead cold, the pressure pegs the guage at max until it warms up. Then pressure is normal.

Just looking for some corroborating testimony (-;

NCDiesel

Was your oil pump overhauled or checked when you did the rest of the engine?

It sounds like to me the oil is draining out of the oil pump when you shut down and it has to re-prime itself on each startup. If only shutdown for a while the oil hasn't had a chance to fully drain. I'm not that familar with the C223's oil pump and oil gallerys to suggest anything specific.... Now if it was a TD-18 I could help, I've just done one, big and clunky, the oil pump stands about 2 feet high!

Thanks for the quick reply. I did replace the oil pump during the rebuild with a brand new Isuzu oil pump. It does indeed act like the pump is re-priming, but it did this before the rebuild too.

As for the TD-6, I haven't opened up mine yet (-; I hope it isn't 2' tall!

NCDiesel

There might be a sticky valve somewhere, like the pressure releif valve in the bottom of the oil filter housing? I'm not sure, need a C223 book.

I'll be a TD-9 expert soon to, our TD-9 has just developed the water in the oil syndrome along with spewing it all out the rear main seal. The engine has gotta come out.

Best of luck with your problems tho'

NC--

It does sound like a leak somewhere is letting the hot, thin oil drain back down into the pan so that any empty galleries must be pumped full before pressure is registered.

But, seems like your cold morning starts should have this problem too, if you shut it down hot.

To answer your question, my truck does not do this but it is a n/a version with a turbo added.

I just happened to have an oil filter base and regulator valve on my bench so took a photo.




If the regulator valve is leaking, then air from the drain to the crankcase can enter the pump discharge gallery and this would let the oil drain back to the pan.

Since the oil filter base is sealed only around the outside with an o-ring, I think a leak could occur between compartments inside the base. This could do the same as a leaking regulator valve. I can't figure why there is no gasket here. For the base to be reasonably leakproof it must be very flat and without any divets.

Also, you should make certain that you are using the correct oil filter with a check valve in the inlet. Almost all do but the lack of a check valve will let the oil drain back too.

My oil pressure when cold also pretty much pegs the guage and then declines to about 55 psi when hot and running at road speeds. Idle is about 30 psi when hot. The manual says that the regulating valve (in photo) is supposed to limit the pressure to 85 psi. My guage reads up to 110 psi max.

Paul

Thanks for the great post and pictures Paul! It sounds like our engines generate the same pressure, so I am not worried about running pressures.

As to cold, you could still be right. The lack of cold symptoms, may simply be a case of viscousity masking the problem. The thicker oil could prime the pump/gallies quickly enough to minimize the problem.

The check valve is interesting idea, as I didn't know they had one. I am using a parts store filter right now and used parts store filters before the rebuild(mainly WIX). Immediately after the rebuild I used an Isuzu filter, but I changed oil so quickly after the rebuild, I never noticed if I had this problem or not. Currently I am using a parts store filter because I had one left over. In the future I will be using only Isuzu/OEM and the two I have in stock are from Jerry Lemond and are Isuzu/OEM. So the filter idea is conceivable since I only used one filter briefly that would be absolutely correct and wasn't a cheap immitation.

As for the regulator you mention, My valve had a small scratch on it. The scratch was clearly older though and it was not what I would consider a "significant" scratch and prior to the rebuild it performed its' function just fine. It moved within the bore without a problem. The scratch could indeed leak hot oil past it though, as I was too ignorant about these engines to consider this as a something that could be an issue. This might actually be my culprit.

Thanks again Paul, I really do appreciate it!

NCDiesel

Guys,
This might sound silly...but did you check to see if the PSI sensor/sending unit is either clogged, loose or has a poor electrical connection?
Remember that there is a ground connection being made someplace in this circuit and the ground often corrodes first. (There is some electro-chemical reason for that but I forget what it is)
:-)
Eric

Yep, the sender and guages all do work properly. And in the case of mine, the engine was actually also hooked up to a mechanical guage as well when I first rebuilt the engine just to be safe and the two guages agreed.

Spencer

Howdy all.
I have a scanned image of the oil passage from a Isuzu manual, but I can't post it here. I can e-mail it to anyone who wants it.
My best guess is a leaking regulator valve. The valve is slow to close, and doesn't seat all the way, so when shut down long enough, the oil drains back to the sump. Good chance there is some crap in the valve.
Just my 2ó.
<img src="/forums/images/graemlins/smile.gif" alt="" />

NC, OK on th eelectricals.. I kinda guessed that you would have already checked that one.
If you find the oil passaage in the regulator is scored and need an oversize piston get in touch with me. I can bore it out (slightly) and turn a new piston for you.
Eric