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Oil Pressure Sending Unit location

V

vmrod

Guest
A little background. About 7 years ago, I put a different 350 engine in my vette. (I think it came from a MonteCarlo.) I had tried to re-install my oil pressure sending unit in the side of the engine, but I could not get the plug out. I used a 1/4" socket wrench in an attempt to remove the plug, but I broke off the tip of the wrench inside the tiny square orifice. Since I could not get it out, I drove for awhile with no oil pressure indication at all.

Flash to present. Yesterday, with some creative work using metal drill bits, I removed the tiny piece. Next, I slowly and carefully drilled through the plug, until I made a hole through it. I used an 'easy-out' and the plug came out. I tried to install a new pressure sending unit, but it seems like it doesn't want to fit. I think that some of the threads from the plug are still in the hole.

I want to use a tap/threader, and clean out the hole for the oil pressure sending unit, but I have a problem/question. Although I was extremely careful drilling through the plug, using a tap will definetley drop some metal fillings in my engine. If I drain the oil and remove the oil filter, will I be able to see the hole right above the oil filter? What other options do I have?
 

AKRAY4PLAY

Well-known member
Joined
Oct 14, 2001
Messages
584
Location
Wasilla, Alaska, U.S.A.
Corvette
'77 L-82, black on black. Full mod 406 small block
YOU WILL HAVE TO REMOVE THE OIL FILTER ADAPTER HOUSING (THE THING THE OIL FILTER SCREWS ON TO). IT HAS TWO BOLTS SECURING IT TO THE BLOCK. THERE IS NO NEED TO DRAIN THE OIL UNLESS IT IS OLD AND YOU WERE GOING THE DO IT ANYWAY. THAT WOULD BE THE SAFEST WAY OF NOT GETTING CONTAMINATION (METAL) PUMPED THROUGH YOUR ENGINE. ANOTHER WAY OF DOING IT WOULD BE A LITTLE MESSY, BUT A LOT LESS WRENCHING. PULL YOUR SPARK PLUGS SO THE MOTOR CAN TURN FREELY. USE THE RIGHT TAP. IT SHOULD BE A 1/8TH INCH PIPE THREAD TAP. WORK THE TAP A BIT, REMOVE IT AND TURN THE MOTOR OVER. THE OIL PRESSURE SHOULD FLUSH THE CONTAMINATES OUT OF THE OPEN PLUG HOLE. KEEP REPEATING THAT PROCESS UNTIL YOU ARE DONE TAPPING THE HOLE. YOU SHOULD NOT NEED TO TURN THE MOTOR MUCH, THE OIL PUMP WILL MOVE A BUNCH OF FLUID IN NO TIME. BEST OF LUCK, HOPE YOU FIND SOME METHOD THAT WORKS FOR YOU. IF YOU RUN HEADERS, YOU MAY WANT TO RELOCATE THE SENDING UNIT TO THE TOP OF THE MOTOR. THERE IS ANOTHER PLUG ON THE DRIVER'S SIDE BETWEEN THE DISTRIBUTOR AND DRIVER'S HEAD. IT RESTS IN THE LITTLE NOTCH OF THE INTAKE MANIFOLD. IT WILL ALSO GIVE YOU THE SAME PRESSURE READING AS THE PLUG YOU ARE CURRENTLY WORKING ON.
BRIAN
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Just curious

why you did not run the oil pressure sending unit off the top of the block behind and under the distributor housing?

You can usually use an adapter with a 45 degree, or 90 degree elbow to angle it up and out from the engine where it clears and is easy to access.

The late model C4 vettes ran two sending units on the top rear of the block. ONe for pressur gauge, and one for the oil light (also to keep the fuel pump relay engaged), AND, they used the hole you are working on to install an oil temp sending unit.

Good luck. I know that is frustrating working in such a tight small area.

If you can get it, I would suggest angle grinding the nose of a new 1/8" pipe thread plug so it has a "self tapping" tip. Wrapping a good coating of thread tape on it, and just replugging the hole. Then, go up top and hook it up the other way (that is if you don't trust the threads, because you can't really muscle torque on the sending unit like you can the plug to secure a tight seal).
 
S

Stingray72

Guest
How far will the sending unit thread into the hole? I think most of those sending units use tapered threads. They will thread a few turns, then get gradually harder to turn, as if the threads were messed up. This completely dumbfounded me in the past , but it's designed to create a good seal. I would try to examine the threads as closely as possible before whipping out the tap. Try using a bright flashlight and a small mirror. A few SMALL filings in the oil should be no big deal. You always find a bunch of filings on magnetic oil plugs the first few times you change the oil on a new car, but I would still avoid the tap if at all possible.

Good luck.
 
V

vmrod

Guest
The car is up on jack stands, and I was using a flashlight. I couldn't directly see the integrity of the threads in the hole. I was able to locate the appropriate sized tap for the hole, and I am planning on doing the deed tonight.
I'll closely examine the hole first and make absolutely sure that it's OK to proceed. I'll try again to screw the sending unit in. At this point, I'll take out the oil filter, (being careful not to spill the oil), then remove the part above it. I'll should feel good at this point.
It might sound like I am over-catious, but I cannot stand the thought of some fillings possibly grinding into my cylinders or going through my valve train.:eek (I've got a set of Dart II heads with roller rockers.)
At the worst case, I'll put a plug there, install a sending unit ontop of the block, and forget about the whole bum deal.
Wish me luck!
 
V

vmrod

Guest
Still not complete!:hb

I removed the oil filter and the piece above it. (was secured by 2 bolts.) I removed the metal particles left over from the forceful plug removing project.

I was able to get real close and inspect the hole. The pressure sending unit is NOT the right size!!:bash Geez!! Now you can see why I drove with no oil pressure gauge!

I'll try something different, because I don't want to buy ANOTHER sending unit. (I already have 2!) I'll try to use a die, and make the threads on the sending unit a tiny bit smaller. So, this may get done this weekend, or early next week. Stay tuned for the outcome....

I did install my new KYB rear shocks succesfully though! (...I only didn't find the washers for the bottom, so I had to get a substitute!)
 
V

vmrod

Guest
Bob,
...on your rear shocks. At the bottom, the shock bolts to the shock mount. Are there supposed to be 2 washers down there? (1 on each side of the shock bushing?) ...or only 1 washer? (between the bolt and the shock bushing?)

Lastly, if there is a washer(s), is it flat, or contoured to shape to the rubber shock bushing?
 
Joined
Aug 29, 2001
Messages
3,235
Location
Norcross, Georgia, United Stat
Corvette
2017 Arctic White Grand Sport
Vmrod,

As I recall, the bottom of the shock went straight against the L bolt that goes through the trailing arm. There were two washers on the outside, one large that was about the size of the bushing, followed by a lock washer and then the bolt.

Bob
 
V

vmrod

Guest
Cool!

Was the large washer slightly cup shaped or flat?
 
Joined
Aug 29, 2001
Messages
3,235
Location
Norcross, Georgia, United Stat
Corvette
2017 Arctic White Grand Sport
Vmrod

Flat and about the thickness of a penny or dime. The lock washer bit into it and actually made me have to screw it off when I replaced the camber adjustment rods.

I've still got the wheel off on the left back side replacing the spring bolts and could easily post a picture showing the washers and nut if you want.

Bob
 
V

vmrod

Guest
Thanks, but that's OK. Sounds like all I need now is a couple locknuts (no prob).

Your car is coming along nicely. If I have any more questions, it looks like you might already have the answers for me.

I have already redone my entire rear-end, but now I have alot more to go.
 
Joined
Aug 29, 2001
Messages
3,235
Location
Norcross, Georgia, United Stat
Corvette
2017 Arctic White Grand Sport
Vmrod

All it takes is money:cry

I'm getting more comfortable doing some of the mechanical and it's giving me some satisfaction to do it myself. I'm still uncomfortable if too much stuff comes off so things like the front end go to the shop. The last time I seriously worked on cars was when I was in high school, living at home and had my very mechanical father to fall back on. That was a long time ago.

Hopefully I'll have new exhaust on it and the back carpet finished before Sharkfest. I want to pull the mufflers and the spare tire off and get up their to the metal with POR 15, then take it in and have 2 1/2 inch pipes with dual cats and the delta flowmaster 50's but on the back.

Let me know if I can be of any help.

Bob
 

77-4speed

Well-known member
Joined
Apr 30, 2002
Messages
249
Location
Houston, TX
Corvette
1977 Black L-82 4-speed
Here is a picture of the rear shock assembly. Best of luck with the oil pressure sender.

Russ
 
V

vmrod

Guest
Thanx for the pic Russ. Washer 'X' is the one I was asking about. It looks kinda contoured, but it probably doesn't matter much. (I hope.)


Bob, I'm not frightened at all about the mechanic work. It is alot easier now that I found this web-site full of info!

Currently, I have my semi-stock exhaust (no cats) totally removed, and the spare tire carrier as well. I am saving for some sidepipes from JCWhitney. They look like the header system pipes, but only have one 2" input. I'll try to put in an equalizer pipe too, if possible. (I wish they had a 2 1/2" input)
 
V

vmrod

Guest
I'll phone the company (P-S-T) and ask them about those washers.
 
V

vmrod

Guest
Nope! They don't include the washers. No biggie. I really like the shocks!
 

77-4speed

Well-known member
Joined
Apr 30, 2002
Messages
249
Location
Houston, TX
Corvette
1977 Black L-82 4-speed
vmrod,

You should definitely put in an X or H pipe. Also, you HAVE to fire the car up at least once before attaching all of your exhaust components (except of course headers or manifolds). :) That bumpety bump was one of the best things I ever heard out of my car! by the way, I think that washer "X" is concave, but I'll check for sure tonight and post this evening (if I remember).

Bob, did you find a decent way to get the dual exhaust done?

Russ
 
V

vmrod

Guest
Oh, I start the car about once a week. The exhaust manifolds and the front 'Y' pipe are still there. Boy! It is loud! I don't let the car run for long though, and I really don't rev it up hardly at all. I'm scared of damaging the valves or something.

...but I will put some type of equalizer pipe in there.
 

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