View Full Version : 1993 6.2l: "Oil Level Sensor"(?) removal?
I just got done swapping out my old g/p's for AC Delco 60G's and installed a manual g/p switch on my 1993 GMC 6.2l. While in there I noticed an item was covered in oil. This item is on the back top center of the engine, in front of the square oil filter, and looks like a black UFO with a wire connector going to it. I guess it's some kind of sensor.
I gave the part # to my guy but he came up with nothing, which I find hard to believe. The part# shown on the top of this thing is 7841996. Googling it returns as an "oil level sensor". There is a bolt securing a piece of metal shaped almost like a "Y" that seems to hold down the lower part of this item from moving. There's a thick metal ring around this part. I removed the bolt and the metal holder but that's it... I can't seem to move it at all. How the heck do I remove this thing? Thanks.
DmaxMaverick
08-08-2011, 15:43
That's a vacuum pump. The wire is for the tachometer driver. 1993 seems a bit late for a 6.2L, or a cam driven pump. It's possible the original tach driver was replaced with a pump model, if you have no use/need/plumbing for vacuum. If your truck has/had EGR, then it needed vacuum. There were 3 versions of things that got plugged into that hole: Vacuum pump; vacuum pump with tach driver; tach driver only (same thing w/o the pod).
I took a few pics and will post here for clarification. The part in question is the one in the center of the pic on the left. I don't think it's part of the vacuum system, but I could be wrong.
http://www.divshare.com/img/midsize/15481320-ffd.JPG http://www.divshare.com/img/midsize/15481315-39e.JPG
I removed the sensor wire, also the bolt and metal retainer(?), hence the hole next to the part in question. I'm hoping there's a gasket under there that I can simply replace...but nothing is ever simple, is it? ;)
DmaxMaverick
08-08-2011, 22:32
That's where the vacuum pump would be on a 6.2L, if you had a vacuum pump. What you see is the tach signal driver. These were used before the alternator was used for the signal on 6.5's.
Just like 6.2L vacuum pumps and gasser distributors, this also connects the cam to the oil pump. Be careful removing and replacing it, as the pump drive can interfere with installation (if it doesn't line up). Pull it straight up, then install it straight down. Get in there with a flashlight and look around to see what you are dealing with. No big deal, but can be a bear if you don't know what's involved.
Verify the source of the leak first. That location is right under your fuel filter, and the leak may be fuel, either from filter changes, or a leaky filter assy. The water drain is at the bottom of the filter assy, so make sure it is tight, and not wet with fuel (if so, the plastic valve or its O-ring may be damaged, or the filter assy may have a crack/leak). If it is engine oil, the O-ring at the top of the tach driver shaft may have failed, or the tach driver is leaking around the cap-crimp, or the cap is cracked or loose (happens over time). None of this is difficult or excessively costly to repair.
Thank you, sir! When the engine is running I can see oil starting to bleed up around the ring/cap of the tach signal driver. I already removed the bolt holding the retaining metal ring and the ring itself.... now I just pull up on the whole assembly....should I grab it by that thick metal ring...? Sorry for all the questions...I just don't want to make matters worse.
DmaxMaverick
08-09-2011, 07:54
It should come out easily. At most, you shouldn't need more than a little twisting. The retainer/bolt is the only thing holding it in. If you are getting oil leakage above where it and the block mate (below where the Y retainer rests), it may need to be replaced, as the internal shaft seal has probably failed. If it is only seeping at the block surface, you can usually cure this with a thin paper gasket. Some overhaul gasket sets include a gasket, some don't. Not sure why.
arveetek
08-09-2011, 20:26
This must be installed in a van, since you were able to get such clear, unobstructed pictures! ;)
Casey
This must be installed in a van, since you were able to get such clear, unobstructed pictures! ;)
Nope! It's actually on my Big Wheel (http://www.originalbigwheel.com/)! :D
OK gents, I got the whole thing out. Oil appears to be leaking from where the black plastic cap and the large metal ring under it meet. Is there any way to remove the whole black plastic cap? I'm tugging, twisting, and pulling and nothing's budging. Thanks.
DmaxMaverick
08-10-2011, 14:38
Sure, it comes right off......with a big enough hammer. Problem is getting it back on, and leaks will be the least of your problems. But, it can be removed, without a doubt.
If it's leaking at the crimp seal (where the metal meets the plastic), it's leaking internally. Rockauto has it at $154, called "oil pump drive gear", ACD part# 21597. GM part# 07849305.
Dmax, thank you again. I was hoping it was a minor $ fix but we can't have everything. Thank you for your help, sir.
DmaxMaverick
08-10-2011, 18:55
Unfortunate, but it is what it is. The shaft seal holds back full oil gallery pressure (what you see on the gage), so it isn't so simple, even if you "accommodate" a bit of a leak. It won't get better. Only worse, until you have a full-on blowout. They weren't designed to be repaired. But, on the bright side, 19 years on a $150 part ain't too shabby. At least it's easy to replace.
Don't settle on a cheap knock-off part. The money saved will be repaid in headache, and a deeper dent in your wallet later. Get the Delco.
Finally got the part and she's in. No leaks, everything's good, except!.... all of a sudden I now have a small leak from the metal tubing going to the radiator, just about the lower radiator hose, on the passenger side. I guess I shouldn't be surprised since it's pretty darn corroded. Happy happy, joy joy. :mad:
DmaxMaverick
08-17-2011, 21:45
That's the oil cooler line. Fix that one, ASAP. If it blows, all your oil goes onto the ground, in a hurry. Not good, as you can imagine.
Yeah I thought so. The fun never stops. ;) Thanks Dmax.
I called around and I can't believe shops don't have the schematics on the PC like they used to. No one can tell me if it's the oil or tranny lines. The leak actually looks more like tranny fluid.... redish. Could those lines on the passenger side be for the tranny fluid?
DmaxMaverick
08-18-2011, 19:27
It could be for the tranny. Your application is somewhat unique. Follow the line to its origin. If it's the oil cooler, it'll go to the area of the oil filter. If it's the tranny cooler, well....
Or..... Verify the line you see is actually leaking. If the radiator bung is leaking, it may actually be Dexcool that you are seeing (often looks like ATF). If so, then a radiator repair is in your future. If there's a lot of scale and build up in the area and around the fitting, it's probably coolant, and not oil.
Dmax, thank you for all your help. God bless you, brother. I'll look into this tomorrow.
It's a tranny line. Looks like it's leaking about 1" back from the connector at the radiator. It's pretty corroded and wrenches just slipped around the coupling nut. I might have to go with vice grips.
DmaxMaverick
08-19-2011, 13:55
Vise grips should be the last resort. If you don't have tubing wrenches, and can't beg, borrow or steal one, use a pipe wrench or water pump pliers (channel lock). With these, you don't have to apply any more clamping than necessary to loosen it. Watch the fitting on the radiator. If it twists, you can damage the cooler core, and it can't be repaired from the outside. Better yet, if the line isn't in too bad of shape within about an inch of the radiator, you can use a tubing cutter and just cut the line and splice in a hose, at least temporarily. If you do this, use double clamps on each end. Make sure you use ATF hose, and NOT fuel or coolant line (or anything else that isn't ATF hose, it will turn to goo).
I was wrong. It's leaking right at the nut. Line wrenches, no gots, but pipe wrench, yes. I applied some PBB to it..waiting a bit now. The upper line is actually more corroded than this one. I might as well do them both while in there. Thanks Dmax.
DmaxMaverick
08-19-2011, 19:38
ATF is a fairly decent penetrating oil. If it's been soaked for a while, the PBB probably won't give you any advantage.
If only the radiator ends are corroded, you can repair the line for 1/10th the cost of new lines. The fittings are the same type and size as many 70-80's brake lines from many vehicles. You can get a short brake line for a few bucks and splice them in (flare or compression coupling). They often have the same fitting at both ends. Or, you can fab your own with some steel line (stainless if you have some extra cash) and fittings, which are still available. If they are bare steel, I suggest painting them to minimize future corrosion.
The lines are pretty bad shape so I'm pulling both. I already got the first one totally off and the second line at the tranny pan but it started raining and lightening like crazy. I think I saw ducks going by in a row boat. :D I'll finish her tomorrow.
DmaxMaverick
08-19-2011, 19:55
If they're bad, replace them, of course. They aren't cheap, but will be a permanent fix. Most of them are bare steel, so I still suggest a little time with some paint, especially if you are in the salt belt. If you plan on keeping the vehicle for a long time, it will be time well spent and a minimal expense. Good luck with those nuts, and the weather.
Would it be OK to use ATF-rated hose pipe-clamped onto brass barbs with male pipe thread on the ends instead of messing with bending new hardlines? If it's OK I assume getting a hose with same internal diameter would be ok? Thanks.
DmaxMaverick
08-20-2011, 09:28
It isn't ideal, but would work fine. A lot of aftermarket coolers are installed this way, and they do fine. If you are using a barbed nipple, you don't need to double clamp it. Double clamping is suggested if you are clamping hose onto straight tubing, but not necessary on a barb. Be sure to insulate the hose at vibration and chafing points, and be aware of high heat sources. If the hose has to run within about 6" of an exhaust manifold or pipe, use some heat sleeve or glass wrap. Heavy duty aluminum foil works well for temporary protection (no more than 6 months to a year).
OK. Got the other line off. I'd rather use the metal tubing but I've no bender now. I think heat sources won't be a problem but I'll check how the hoses will run. Thanks Dmax.
She's done. :) Using a 8" 5/16" hardline I cut it in half, inserted the ends into the ends of the ATF-rated hose, double-clamped both ends and carefully routed it. For chafing I used a couple of wraps of duct tape around the hose where I secured it. Took her for a spin and it's all good. ATF's a little low, of course, but otherwise.... that's it for now! :)
Dmax, if you're ever coming to central NJ let me know. Beers are on me. :)
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