Trans_AM_88

hey guys. i have an L98 converted to carb. im trying to put in a new oil pressure sender (the one on the top of the block by the distributor) but it doesnt fit because of the Edelbrock intake manifold is in the way. i went to NAPA and they gave me one that looked like the one pictured below but it's too fat and wont screw into the hole.

at my schools auto shop theres a 1978 chevy impala engine that that has a nice and slim oil pressure sender (that goes to a oil pressure gauge)...so i went to napa and asked for that same oil pressure sender, but they said that one is only for a light...

in any case, i need a slimmer oil pressure sender than the one below, and it has to be for a gauge. can anyone help out?

ede

wrong sender, that one looks like the one that goes above the oil filter. you could always use a couple of 1/8npt fittings and move it till it clears the intake if there is still a clearanve problem

Trans_AM_88

are you sure because both auto zone and NAPA give me ones that look like that one pictured above.

wm_sorg

I agree with ede. That is the sender that goes where the oil filter sits.

Guest

I disagree.

There are 2 sender setups on a TPI thirdgen that I know of. One is a single unit that mounts down near the oil filter, with 2 wires. Thats what should be on an 88 from my experience with a couple of them. The earlier setup has a single wire sender like the one in the picture, thats mounted by the distributor. I'm not positive on the later setup, but I think only the early one has a second sender mounted up near the distributor as well.
I think you have 2 choices. One is to grind the manifold a little. The other is to try rearranging the location of the 2 senders by the manifold, but be careful not to break any of the brass fittings there, they are really weak.

I dont know of any senders for a gauge that are smaller than the stock one, besides the later setup.

SpeedJunkie

I had this same problem with my truck(look at sig) i made them look for different part numbers for the senders and they found the right one for another chevy that fit. I too have the one wire sender and it needed the smaller size threads than the big ones they kept telling me fit.
Hope this helps!

Trans_AM_88

well i think i might have found a solution...i have the extension and a 90* elbow from my TPI setup...im going to try and see if i can get the big one to fit at a 90* angle. hope that will work

Trans_AM_88

which one is for the gauge? i was figuring the switch by the oil filter was to disable the fuel pump if there was no oil pressure and the top one was for the gauge. is that right?

RB83L69

78 Impalas didn't have a guage. The small sender is the switch for an idiot light, not a gauge.

The sender in the pic is the correct one (or at least it's the correct type and style).

Go to Home Depot or Lowe's or a hardware store or plumbing supply, and get a 1/8" x 2" nipple, and a 1/8" 90 degree elbow. That's basically what the factory used.

Guest

On the later setup with the long skinny sender with 2 wires (weatherpack connector, small pins) it serves both functions. There is no other sender. Its mounted above the oil filter.

On the early setup, the single wire sender is for the gauge, the other 2 wire sender is for the fuel pump. Both are mounted near the distributor off of the same fitting from the block. There's a fitting with a 1/8" NPT going to a hex shaped top that has one angled edge. Theres a 1/8" NPT tube thats 1" in length, then a dual 90 degree fitting that has a hole in the side of it that threads onto the tube. Both senders mount to that 90 degree fitting.

Not sure I snap a pic right now, its dark.

fb305svs

that IS the solution- my LG4 had that type of a setup, and if my sender was mounted by the distrubtor on my new car, it would have that little extension/90* fitting as well... intresting enough, on the 91-92, the harness's were different, and the OP guage is right above the oil filter mounting pad

EvilCartman

iTrader: (1)

That's how mine is, the extension of about 2 1/2 inches into a 90* then the sender threads into the 90*.

scottland

the factory setup looks like so

Trans_AM_88

thanks guys . yup thats what i did...i found my old stuff from my TPI setup and i found the angle and the extension. not sure if it works though...the gauge seems to go right up to 60 (a little past actually) and just stays there

when i unplug the wire, the gauge goes a little farther past 60 and stays there too

Guest

Check to see if the wire is shorted out on anything. They like to break up at the connector end too, they get bent pretty sharp there usually and it does it in.

EvilCartman

iTrader: (1)

Same with my gauge, goes past a little on first start up. Once the engine warms up though, it'll drop to around 45 psi at idle.

Trans_AM_88

would putting 12v on it make it pin past 60? that should test the wire and the gauge right?

RB83L69

Actually, if you short the oil pressure sending unit wire to ground, it will read 0. If you disconnect it altogether, it will read full-scale. Think of using an idiot light switch instead of a sending unit: that's exactly what this will do.

Shorting the OPSU wire to 12V won't hurt anything. It also won't test the gauge.

Your gauge should read zero with the key on and engine off. Start the engine, it should go up somewhere; turn the engine off and then turn the key back on, you should be able to watch the pressure decay. If it does that, then it's working. With the engine fully warmed up and idling, it should read somewhere well below full scale; 25 psi would be typical for a stock oil pump and new engine. Cruising, you should see 50 psi or so.

It's possible you have the wrong sending unit, as there are sifferent ones for different full-scale gauge readings (40, 60, 80 psi); these cars should use the one for 60 psi. 6-cyl motors with gauges IIRC use the 80 psi one.

okfoz

Of theTPI cars I have worked on (all 87 one from a 350, a 305 M5 and a 305 A4) they all used the 2 wire for the oil pressure sender. I belive one lead goes to the gage, the other is the Fuel pump shutoff in case of low oil I assume... The 2 wire kind will go into the hole just above the oil filter.

The other type will come up on their computers, with the single wire. THats what I had on my 87 LG4, it required the elbow, as it was a different size thread. I thought it actually went in the same hole tho as the 2 wre on the side of the block... Although I kind of remember the tall standoff like is picured there.

The Parts & Illustration catalog (Part 1) shows a sender unit in the side of the block for the 83-86 L69 & 82-86 LG4... I did not look at part 2 which shows the upper half with the intake.

John

rgarcia63

My 88'IROCZ 305/5.7L TPI has the following oil pressure gauge & oil pressure switch. The one on the left was next to the distributor, the other just above the oil filter.
With low oil pressure the switch will shut the fuel pump off if the fuel pump relay is not energized. This may not be true for earlier models. Others have posted that 89' models have a combo unit up top, or dowm low. I can't verify that because my bother's 89' is like mine, but it may have been rewired.