The oil pressure guage on my '92 Firebird (305 TBI) is kinda jumpy and inaccurate. I suspect I need a sending unit. I have the Firebird Haynes Manual, but I can't find any info on removal/replacement. You don't have to drop the oil pan or take the guage cluster out do you? Any info on how to go about this would be appreciated.

Should be at the back of the block on the driver's side on the top, right behind the intake manifold. Has 1 wire going to it and is a snap to remove.

Especially with the block removed. However if your 40 miles from home at an O'Reily's and all they have is a vice grip and your pressure just dropped to zero so you have to know if that's the problem it's a PITA.

It can be a knuckle buster being that it's right next to your firewall and there seams to be a lot of little sharp edges around there.

Oh and it kind of looks like a bell about 2 to 3 inches tall.

So is it a "snap", or a "knuckle buster"? At any rate, I can remove it with basic tools from under the hood correct? I've never actually seen one, but I ordered one at the parts store for tomorrow. When I see the new one, the old one will be much easier to identify. On a sidenote, I ordered it at Advance Auto, and they had GP Sorensen in stock for $25.99, or they could order a Delco for tomorrow by noon for $17.99. LOL In all the parts I've bought I've never seen a genuine GM replacement for less than the generic.

If you have headers (edelbrocks here), I found it to be impossible with the headers in place using an plyers, vise grips, or a cresent wrench(only thing close to working). I only got it to turn maybe 1/16th of a turn at best and couldn't get the wrench on any other way ~ 1+ hr of trying. Just a heads up if you have headers.

How are your headers in the way? The senor is ontop of the engine, right behind the intake, by the distributor.

I believe on the newer V8s it is located right above the oil filter.

the sending unit is not that hard to replace but be careful, don't break the angle adapter that the sending unit screws into. I did and it took me about 2 1/2 hours to fix and it was a son of a. .. Just take your time and you'll be fine

I have both of those things. But the one on the rear under the distributor is the sending unit. I have to admit I am not entirely sure what the one above the oil filter is. But I leave it plugged in.

Mine was only 11 bucks at O'reily. Hmm.

I just went out and checked under the dist. on my '91 firebird 305 TBI 5 speed, all I found was pipe plug probably ~3/8" dia. You guys got me excited thinking I could finally fix my wacky oil gauge , oh well.

Newer cars have a combination switch/sender above the oil filter. Older cars, that was a switch only and the sender was behind the distributor.

The switch is the "fuel pump safety switch" I believe. Not present on carbed cars.

haha, stupid thing... i had to remove my distributor to get to the bottom nut on the bastard sender... oh well it got replaced with a mechanical gauge.. more accurate and failsafe... word of advice: dont use the crappy nylon cappilary line because if it breaks your ****ed!

On TPI cars, that unit can be a real PITA to replace. Getting it to catch threads is a pain too, with the old threadsealer on those fine threads in the block. Also, with those sending units, you want to remove and install them by grabbing onto the bottom half with a wrench. These units are pressed together, and the halves will just slip sometimes if you try to tighten or remove it by placing the wrench or socket on the top.

Ok now I'm confused...is it gonna be by the oil filter, or near the intake and distributor? It is a 92 TBI 5.0. I don't even know if I got the right part because it says "switch" on the box, and some of you are saying the sending unit and switch are seperate on some cars. If it helps any, the part I have is Delco #D1808A. It's about 3 inches long, mostly plastic and cylindrical, it's threaded on one end, and has 3 tiny prongs on the other end that wires plug into.
EDIT: Found a pic of it....

Don't quote me but I think the one with the 3 prongs is the combo unit (switch/sender in 1) If thats what you got from GM then it should be by the filter housing.

Go look under your distributor on the driver's side of the car. If you see a bell shaped thing about 2 to 3 incheds long sticking up and a wire plugged into it then that's the sending unit. If you don't then the one over the oil filter is probably the combo model with shutoff and sending.

i just replaced mine on sat on my 92 rs , ihave a factory manual and it show me that its right above the oil filter took it out with a small vise-grip

i sat there for like 10 mins wondering why it wasn't coming out the first time

Does the oil need to be drained when installing the newer style sending unit?

25THRSS,
The oil does not need to be drained.

Yellow Camaro,
The unit in the picture is both a sender and a switch. The unit that is only a switch looks the same but the plastic cylinder part is only about half an inch to an inch long. You need to look near your distributor right behind the driver's side of the intake manifold and see if your car has a bell-shaped sender (it's about 1.5 in. long and 1.5 in. in diameter, hard to miss). If it does, replace that part and take the one in the picture back. If not, you have the right part and you just need to install it above the oil filter. Be sure to put some teflon tape on the threads to help keep your oil in the engine.

BTW, if you're replacing the one above the filter and you can't seem to thread the unit back into the hole, make sure you're trying to put it in the right hole. On some engines there's a bolt hole just above it that has coarse threads but seems to be the same diameter.

Im going to replace mine too this weekend... I guess I have a combo sender/cutoff since I have a '91 305 TBI, and that would be located just above the oil filter?

yes its right above the oil filter, I changed mine in january and its a 91 305 tbi so theres no reason yours should be any diffrent.

The one you got is the wrong one. Like mentioned above that is a oil pressure safety switch. The one you need is a large brass cyclinder right beside the distributor you cannot miss it. Its huge.

on the later model third gens that is the right part.

Yes, the combination switch is the right part for at least 91 and 92 cars...

Maybe this will help...

Carbed cars with only mechanical fuel pumps usually only have #1 (near distributor). Cars with an electric pump and pre-'91 usually have both #1 and #2(above oil filter). Cars around '91 and '92 usually have only #3(gauge sender & switch above oil filter). The only difference between #2 and #3 is the length of the plastic cylinder, and their weight. Both can have 3 prongs, 2 for the switch, and one for an indicator light(#2) or a gauge(#3). I believe some of the #2's only have 2 prongs though. There are switches that look different, but these are the most common.

My 89' L98 has the combo switch above the oil filter and does not have the sending unit next to the distributor. It took me longer to jack the car up than it did to change it. My 86' IROC with the LG4 had both the sending unit next to the distributor, and the switch above the oil filter. On that car, the switch was tied into the electric choke.

#1 in the picture above is the one that controls the gauge on later model 3rd gens. My car had TBI and thats the one. You disconnect that and the guage will go straight up.

He needs #1 if hes trying to fix his gauge.

Noooo he doesn't. He has a 92RS and he has number #3. On newer thirdgens, 89-92 they used #3 in the picture. Anything below that will have #1 or a combination of #1 and #2.

I only have #1, at the back of the block. behind the intake. My engine block is a 1980. There is no plug on the harness for another, so im sure LG4's are this way.

ding ding ding. when i first bought my car the gauge went dead. we knew it had pressure so i got me a new sending unit. its easy as hell to get to, had it replaced in a few minutes and that was that.

Yep, I know that POS all too well. I had to replace it at least 5-6 times since I bought the car. I went about bought a special socket that Pep Boys sells to fit on these things. A LOT easier then trying to get at it with a set of pliers. hehe

Funny I had the same problem with my wife

Hello,

I have a 1983 Firebrid with a 305 engine in it. The kicker is the engine is not the original. The original was a cross fire fuel injected one.

The engine in it now has a Holly 4 barrell carb on it. I was told the engine was either a 1984 or 85 out of some kind of pontiac. The tranny is supposed to be a 700R4. I just got the car about 2 weeks ago and it has finally stopped raining in cloudy central ohio long enough for me to do little work on it.

When I got the car both the water temperature gauge and the oil pressure guage were not working. They are still not working.

I looked for the oil pressure sender unit and found the little dinky one next to the distributor. It has one big male spade connector coming off of it. I just changed my oil and filter but I did not look for the other sender unit above the oil filter yet. That is the next step.

The other problem I have is that there does not seem to be any wires coming out of the harness for the dinky switch sender unit. The Haynes manual indicates that the wire to both the oil switch and the oil guage are tan colored. I did find one tan colored wire that was loose but it has a male spade connector on it. It also did not seem to do anything as I tried grounding it while the engine was running and neither the idiot light nor the oil pressure guage indicated anything. The oil pressure guage is buried all the way counterclockwise and it does not move when the car is running. I did notice the water temperature guage does swing from buried counterclockwise to the lowest reading when you start the car.

I think I am probably going to have to trace the wires from the instrument cluster and just ohm them out until I get everything sorted out.

One question I have is, can I just take out the dinky switch type sending unit by the distributor and replace it with a guage type sending unit? I am not sure about clearence as the disributor is very large and nearby but I think there would be room enough.

The other issue is the water temperature sending unit. The part that you hook the upper radiator hose to that goes over where the thermastat sits has two things that look like sending units for water temperature. Both have one connector coming out of them though one has two wires connected to that one connector. With all that the water temperature guage never moves off of cold except to swing over to cold from the far counterclockwise limit when you have the engine running.

The Haynes manual says there is supposed to be dark green wires going to both the water temperature idiot light and the water temperature gauge. None of the three wires are dark green. two are black and one is yellow. I am guessing someone tried to piece something together but it does not seem to be doing anything.

That is my story. Luckly the car runs great and the transmission works ok for having its kickdown cable all cobbled together. I really would like to get both the oil pressure and the water temperature working as I like to keep an eye on those things in any car I own.

Any suggestions would be welcome. I wish all those fake allen head screws on the dash were real so I could take the guage out and look at its wires by removing 4 screws, haha. I do know how to use and I do have a nice digital multimeter. It looks like it will get some use in the next week or so.

dzimmerm

dzimmerm
You should start a new thread for this new topic, you'll have more people looking into it.

:sillylol:

i ahve a L69 HO 305 motor out of a 86 monte carlo mine it right above where the oil filter goes.

I have the same deal as dzimmerm. Mine is a 1985 Z-28, 305 L4, not sure if the motor is original. My sender is about 2 inches tall and 1-1/4 inches wide with one wire (tan). I was thinking that maybe it is the switch for a dummy light. I have a gauge that stays pegged. I went to Discount Auto Parts today to get a new sender and they sold me the bell shaped one. It physically will not fit in the space. The intake manifold is in the way. Maybe there is supposed to be some kind of adapter that goes between it and the block to raise it up a little. Any help would be appreciated...I'm really confused.

Changed out the sender on my 1992 RS with a 305 last week and it was located above the oil filter with a three wire connector. I changed it because the oil pressure guage quit working. Man in the parts store said the diaphrams in these break. Mine was odd in that it took a 30 mm socket to take out the old one. The sender cost me $21.99 and the socket to put in the new one $5.99. Both from Autozone. Gauge works great now.

The sending unit in question is located ABOVE THE OIL FILTER!

I just did mine the other day, it IS above the oil filter, on the driver's side of the block, sticking out. Mine was pissing 2 qts every other day lol... now that's an oil leak. It was an unscrew it and put a new one in repair, but be aware you need the #'s off of it to get a new one, as there are about 4 different ones... mine was the most expensive (figures)

If you had a bell-shaped one (#1 in the picture above), replace it with a bell-shaped one and if it won't fit, make it fit with 1/8" NPT threaded pipe and angle fittings.

If you had a cylindrical one, then replace it with the same kind.

I've also seen a light sender that looks like #2 but it has a spade connector and goes next to the distributor. Sometimes people with gauges put this in because they can't get the bell-shaped one to fit and need to plug the hole.

If you can't find the oil pressure gauge sender, it's either located next to the distributor or above the oil filter so check both places if you're not sure. Don't assume that it has to be in one place or the other just because someone on here says so, there are many different combinations of senders and switches that all do the exact same thing and your car could be different.

ok i have an 88 305 tbi trans am and what i'm getting is the oil pressure sending unit is by the oil filter...... is that correct???

I left a message on this thread a while ago. I think I took the advice of a moderator and started a new thread with the same message. I see there are still folks asking questions about the oil sender units on their cars so I wanted to put some closure to my question in this thread.

For starters, I have had my oil pressure and water temperature working now for some time.

The water temperature was the easy one. The only thing hard about it was locating the broken sensor down on the block on the drivers side. Once I found it I just unscrewed it, and screwed the new one in and hooked up the connector that was hanging nearby. That connector had the correctly colored wires the Haynes manual identified.

The oil pressure sender was a different story. The connector that was hanging near the distributor was a three connector style. Of those three connectors the center one was the one that went to the gauge. I verified this by grounding it out and observing that the guage pegged to the highest pressure reading. You can do this with the car not running but the ignition on. I then removed the small sensor that was located by the distributor and verified the threading on it. I purchased the large "Bell" type sensor from the local car parts store and after verifying its threads where the same as my old sensor I went to the local Lowes home improvement story and got brass 1/8 inch pipe fittings. I got two 3 inch pieses of straight pipe and one 45 degree elbow and 1 coupler. My thought was to thread one of the 3 inch pipes into the hole by the distributor and then put the elbow on that one and then the second pipe on the elbow with the coupler on the second pipe and my sensor on the coupler.

Well, after actually getting into the process I found that the 3inch section of pipe with the elbow on it moved the sendor unit to a position where it would fit without dealing with two extra pieces. Since as few connections as possible are a good thing I ended up just using one 3 inch section and one 45 degree elbow.

Once word of caution. I tried using teflon tape and I found that teflon tape is not oil and heat resistant. I am glad I went with brass fittings as they tend to have a bit of give to them and they seal quite well when you tighten them down. Be carefull as brass is not as strong as steel so don't over do it!

My car has been running with this setup since 2003.

Some other caveats.

I have an old 1983 with an old 1985 engine. I have a carb and a mechanical fuel pump. I did not need the oil pressure switch unit to tell an electric fuel pump it was ok to run.

I am a patient guy. Your mileage may vary if you are not the sort that takes his time with fine threaded pipe fittings while leaning over an engine at an odd angle, .

I think I got lucky that the folks who had modified the car before I got had not messed up the wiring harness too much.

Oh, and on my previous posts I asked about "extra" water temperature sender units located on the upper radiator hose block fitting, the one that has the thermastat under it. Those sender units don't do anything, on my car, as far as I can tell. I think they may have been from a car that had electric fans and a water temperature idiot light. I removed the wires and taped them off.

dzimmerm

Edited due to noobishness.

isnt that a picture of your power steering shaft?.... what are you talking about the part they are talking about is a small sending unit screws in to the block above the oil filter horizantally and perpindicular to the block

Yeah probably, I'm retarded.Ii just saw a bell shaped component of the right size and close to the location they were talking about.

That is a nice sharp clear picture. But it does not look like either of the two places an oil pressure sending unit would be.

It appears to be a picture of the drivers side engine compartment centered around where the steering column comes out of the firewall.

I do not see any oil pressure sending unit in that picture.

If you have a V8 the oil presure sending unit should be either on the top center of the engine, close to the firewall OR on the drivers side of the engine lower than that picture shows, just above where the oil filter is. I think you would have more luck taking a picture of the oil filter area from under the car, looking up at the side of the engine, from the drivers side. You would probably have to have the car up on jackstands to get a good angle.

I have never played with taking pictures of my engine and its components. It might be interesting once it warms up outside. It is going to be brrrrrrr 14 degrees out tonight here in central ohio.

dzimmerm

Yeah, i got the wrong picture of where it would be in my head. I actually changed my oil and filter yesterday, i woulda looked if i saw this thread. Thanks for the clarification, ill jack it up and take a peek.

I just found this thread by doing a search on Google for "Oil Sending Unit" for a 1983 Firebird Trans Am. My '83 T/A has the 305 V8 Cross-Fire Engine in it. I too have been trying to trace down some recent problems with my oil gauge. Now, I replaced the oil sending unit that is beside the distributor, near the firewall about four years ago. Yet, if I understand what I've read here, there is a second oil sending unit located just above where the oil filter is that could be causing me problems???

Oh, I am working with the Helm Service Manual, and it only identifies one tan wire going from the oil sending unit to the oil gauge, it says the wire should read either 0 or 90 Ohms (depending if the ignition switch is off or at run). However, the oil sending unit there beside the distributor has three wires - two are tan, and the other is black (or maybe dark brown).

Also, does anyone know where there might be a picture/diagram that identifies all the components in the engine bay? This Helm manual referrs to a lot of the electrical sensors, etc, but does not identify where everything is very clearly.

Any help/ideas/suggestions would be appreciated.