'99 7.4L, what is this sensor?

Dropped88 said:

In my experience the small blocks are at back of block and the big blocks had it down low at front of engine

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Maybe gen5 or mk4, but the gen6 is on the back......unless there could be two?

454cid said:

Maybe gen5 or mk4, but the gen6 is on the back......unless there could be two?

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Your probably right. Most has been 5 gen and older.

But his pic is identical to how my 5 gen looks

1998_K1500_Sub said:

That's not the EVO connector and EVO assembly, mounted on the back of the PS pump, is it?

IIRC the EVO is two wires.

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No, this is definitely into the side of the block, right at the front edge. According to the FSM, there's a bolt there for an oil galley plug. I just can't find any documentation for an oil pressure sender being installed there, in either the engine parts diagrams or in the wiring diagrams.

jcwren said:

No, this is definitely into the side of the block, right at the front edge. According to the FSM, there's a bolt there for an oil galley plug. I just can't find any documentation for an oil pressure sender being installed there, in either the engine parts diagrams or in the wiring diagrams.

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Could possibly be a really late change for whatever reason. There are a few differences in the last of the GMT400's vs. the year just prior. I can't imagine a previous owner simply moved the OPS to the front of the engine themselves, it would take extending the harness quite a bit and you'd see evidence of that somewhere along the line. Crimp connectors, heat shrunk solder joints, twist and tape etc.

Richard

jcwren said:

No, this is definitely into the side of the block, right at the front edge. According to the FSM, there's a bolt there for an oil galley plug. I just can't find any documentation for an oil pressure sender being installed there, in either the engine parts diagrams or in the wiring diagrams.

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That is the exact spot that I moved a sensor to on my 97. Was on the back before. Might have been someone just relocated it. I made that change because my replacement block does not have a port on top rear, and I did not want to try and have it close to the exhaust above the oil filter

^^^ this

I have a 01/99 7.4 and there is nothing there on mine.

My '97 K2500 plow truck has that same sensor. I thought it was an oil pressure sensor, until someone on this forum convinced me it was for EVO.

To me, it screws into the block, not the PS, but I shut the hood and quit looking at it a long time ago.

Schurkey said:

My '97 K2500 plow truck has that same sensor. I thought it was an oil pressure sensor, until someone on this forum convinced me it was for EVO.

To me, it screws into the block, not the PS, but I shut the hood and quit looking at it a long time ago.

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I've never seen a power steering system that has any connection to the engine block (as far as fluid and such). Given the location shows as "oil galley plug" in the FSM, I now believe it's a late model change that moved the oil pressure sensor. The easy test will be to disconnect it and see if I no longer have any indicated oil pressure. AFTER I spray some Gunk engine cleaner down there and remove the 1/4" of grime and dirt.

jcwren said:

Unless I'm just totally wrong, this is the early model '99.

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What do you mean by early model 99? Do you mean assembled in late 98?

jcwren said:

I now believe it's a late model change that moved the oil pressure sensor.

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My truck was assembled in April of 99, and its on the back of the engine.

Looking at your past posts.... is this your 3500HD? I'm not sure what the reasoning might be, but it's possible this is a specific change for the HD.

454cid said:

What do you mean by early model 99? Do you mean assembled in late 98?



My truck was assembled in April of 99, and its on the back of the engine.

Looking at your past posts.... is this your 3500HD? I'm not sure what the reasoning might be, but it's possible this is a specific change for the HD.

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I'm not sure of the assembly date, I don't have a door sticker. Do you know of anywhere else it might be? I'm still learning about these things, but this was based on the old guy at the auto parts store who generally knows his stuff (a real auto parts store, not Autozone/Advance). He said the door handle style indicates if was after May of '99 or not. I know there was some renaming of models and other BS right around that time, and there doesn't seem to be a 7.4L after '99 (went to a 8.1L I think?). If I've got that wrong, please edumicate me

This is a C3500 HD, and it's got a dump chip box on it (the type tree removal blow chips into from the tree shredders). I haven't crawled on top of the engine to try to get a really good look back there. I'd like to find the block stamping, which I'd assume is on the back somewhere. There's no sticker on the valve cover, unfortunately.