Thread: Sump gasket.

I have the thick sump gasket - PN for it and the thin paper one are in the sticky thread.

Note that if you have the thick one, I don't think you will be able to use the thinner one without new sump bolts - mine didn't screw in far enough for it.

Not sure re rebuild.. where abouts are you?

The thick gasket was used up until the 4BD1 was upgraded in about October 1988.

The thick gasket was to help quiten the acoustic emissions. The later engines are smoother (as well as other improvements) and the thick gasket was deemed as not required.

Originally Posted by flagg

Note that if you have the thick one, I don't think you will be able to use the thinner one without new sump bolts - mine didn't screw in far enough for it.

Correct - I replaced the bolts.

John

l'm actually over in England, and l've got a really weird problem with my engine. Trouble is, they are quite a rare unit over here, so l was hoping to chat with someone who knows the engines inside and out.

There is a good amount of knowledge among members here.

I wouldn't have thought the sump gasket is a weird problem.

These engines were used in many applications, trucks, excavators, fork lift vehicles, stationary industrial engines driving pumps and generators, etc. and marine propulsion. Parts are swapped to suit the application.

There are several sumps, the following pages from the parts book:

Hello there, l've tried before asking about the engine problem, which is no oil pressure on start up for several seconds. You can hear the internals banging and crashing about. Then the pressure rises as normal, but once its up to operating temp the pressure drops to nearly zero on tickover. But the threads went off on a bit of a tangent so no fresh ideas were suggested. l've stripped and rebuilt it about half a dozen times. New oil pump, pressure relief valve. (the one in the block is OE. The spring has plenty of resistance and does'nt stick). New main bearings, big ends, cam bearings, oiling jets. Different oil filters, grades of oil, oil filter housing. The rocker shaft is ok. The last rebuild l fitted 6BD lower half main bearings without the oil groove. l turned it over by hand when fitting bits on. All seemed fine. l had oil at the oil sender unit running out ok. Come startup time it made no difference at all. The only plus was running it up before putting it in. But all the above does'nt mean that l have'nt made some school boy error that someone who rebuilds them for a living could point and say, "You knobhead! Theres your problem, what did you do it like that for?).

Ive searched and found 2 of your threads where this was discussed
low oil pressure high blood pressure! and Grasping at straws!!! and going by some posts, must have been mentioned in others.

It doesn't help that you keep starting new threads for the same thing, and only provide snippets of information here, there .... I don't think I'm alone in not remembering details, such as what was done/checked, from other threads.

Blknight.aus is probably the most knowledgeable member on here. He is a mechanic in the Australian Defense Forces and does know them inside out. It's strange he hasn't posted in this forum for a good while. You could try sending him a pm.

I see from one of the pics that it is a 1985 engine. FYI Isuzu changed to a larger flow oil pump in Oct 1988, but this was for improved oil cooling of the pistons, and unlikely to have anything to do with you issues. Related to this, they changed to a smaller piston cooling jet diameter.

Some relevant spec's from the manual concerning the oil lubrication system are:

1. Pressure relief setting at lube pump is 7.0 kg/cm2 (99.6 psi)
2. Pressure relief setting at relief valve in oil gallery is 4.5 kg/cm2 (64.0 psi)
3. Pressure setting for valve in bolts for piston cooling jets is 3.0 kg/cm2 (42.7 psi).

From this 3'rd value the normal operating oil pressure should be somewhat above 43 psi.

I've gone through my memory, and the manuals, and couldn't come up with anything that might be assembled wrong and result in low oil pressure.

In the oil lubrication system, pressure results from the resistance to flow, so IMHO the culprits for low oil pressure can only be one or more of:
4. A faulty pressure relief valve, either lubrication pump or oil gallery. It is normal practice to replace the relief valve in the oil gallery when the engine is overhauled.
5. A faulty valve in one of the bolts for the piston cooling jets.
6. A faulty lubrication pump, or pump drive.
7. Excessive clearance in one or more bearings.
8. Excessive oil flow to any of the external items; turbo, vacuum pump, fuel injection pump, IP timing gear, bypass filter.
9. Internal leakage between the high pressure delivery and return side where the oil filter housing attaches to the block.
10. leakage from the oil cooler into the coolant system. But you would have seen oil in the coolant, and the oil level go down.

You've made many snide remarks about the Isuzu 4BD1 engine, and quite frankly none of them are remotely warranted, and reflects on yourself. Comparing a 300Tdi to a 4BD1T is chalk and cheese.

What oil are you using? What are you using to measure the pressure?



Also, I imagine the oil pressure is different at different places, where is the best place to measure it?