Northstar Oil Pan Leak

[Rckjaws10]

Hello everyone, just thought I would share something I have seen on several occasions. At the Cadillac dealer I am a tech at I occasionally wander about and help the more advanced techs with the big fun jobs. More so if I see work being done on a Northstar since that is what I have. One thing that always interested me was the oil pan gasket leak and the removal of the engine or transmission to fix it. I can now witness and say that no, not always does the engine or trans need to come out. I watched the tech and seen him complete the job in if I had to guess, 5 hours. Which if I had to guess he flagged many more than that.. Anyways, what he did first was support the engine and transmission with a stand and a block of wood then lowered the whole front of the engine cradle. From what I could see, the front motor mount was removed, the abs unit unbolted oil filter removed and the front exhaust manifold was completely taken off the engine. He unbolted it from the crossover going across the oil pan. Once all of that was removed he removed all the bolts from the pan and just maneuvered the pan out moving it towards the right side of the car. Seeing all this I asked if all Northstars were the same with the oil pan. He told me yes, however some of them can be "cheated" which is the way he did it, and others the only option is the transmission removal. He did not specify how or why but that was the answer. Also on the back of the crossover pipe, as it is going up an over the transmission there is a extremely difficult bolt squeezed between the pan and transmission. He told me that once the bolt is out, he never puts them back in. If he did the trans would need to be removed. He explained that the bolt is simply a hold down for the exhaust to keep it from moving, but there is no wiggle room for it anyways so its best to be left out. Funny thing is after he explained this, anytime I work with a Northstar I take a look at that bolt, and have seen MANY motors that have had the pan resealed and that bolt is missing because it was not necessary to put back. Also they do not use rubber gaskets but AC Delco engine sealant available at the dealer. All in all the job would require a few jacks and high jack stands. But did not look terribly difficult. The tech did however explain that if its the oil pan MANIFOLD that that is a 14 hours job, and in his words, not as fun. haha. Anyways maybe others can add some experiences, or talk about why the pan was designed to be so difficult to remove. This is just what I have seen. So for anyone with a leaky pan gasket, there may be hope of not pulling the motor!

[Cadillac Jim]

Isn't the "oil pan manifold" actually below the case half gasket, above the oil pan? To get at that one, you split the main bearings.

Whoops, I looked at the photos in the link given by Paul T below to the Caddyinfo "case half" page and saw that the oil manifold is on the bottom side (oil pan side) of the case half!

[joeb]

is the pan designed to be difficult to remove on purpose? no. look at the underside of motor. all you see is subframe, bottom of oil pan and trans pan. you literally cannot touch the side of oil pan or even trans. once the subframe is out than its pretty easy. but removing the subframe is like taking the foundation out from under a house. how do you do that? by holding the motor up. from above which is the factory way or getting tricky and blocking up the parts with bits of wood? i am surprised a tech would use a piece of wood. sure its a good trick and it does work but how stable is it? would your shop insurance pay for injuries due to a wood support failing? how about workers comp?

[PAUL T]

If I remember right there is a cradle to support the engine & transmission from above that mounts to the strut towers and something else so the sub-frame can be dropped and the engine halves can be repaired. There was a picture in the archives somewhere. Here's the thread with pictures.

http://www.caddyinfo.com/casehalf.htm

[BUICK11]

Do they charge less money when it is done this way?

[PAUL T]

Do they charge less money when it is done this way?

Probably not.

[Cadillac Jim]

Most mechanics go by the flat rate, which is a schedule of how much skilled, experienced mechanic's time, on the average, is needed to do the job when parts and proper equipment and tools are present, usually in decimal hours, such as 1.1 hours to change a strut. Dealers have their own flat rate manuals written by the manufacturers, while professional mechanics buy them from industry infrastructure people like Chilton's. Usually the times given are identical, or nearly identical, and the manual, and the time per mechanic-hour charged by the shop, determine the labor bill.

Ask what the mechanic's rate is at a shop you intend to do business with; they should be comfortable with that question and most shops have that rate posted on the wall for all to see (if you get evasions, leave). If you want to startle them, ask whose flat rate manual they use. To stun them, quote numbers out of it.

[KHE]

Also on the back of the crossover pipe, as it is going up an over the transmission there is a extremely difficult bolt squeezed between the pan and transmission. He told me that once the bolt is out, he never puts them back in. If he did the trans would need to be removed. He explained that the bolt is simply a hold down for the exhaust to keep it from moving, but there is no wiggle room for it anyways so its best to be left out. Funny thing is after he explained this, anytime I work with a Northstar I take a look at that bolt, and have seen MANY motors that have had the pan resealed and that bolt is missing because it was not necessary to put back.

I'm sure the engineering team at GM Powertrain would disagree with that tech on the need for that bolt.... If the bolt was not required, it would not be there in the first place. Leaving the bolt out is just sloppy work. If I paid a dealership to re-seal my engine and discovered they left bolts out, they would be re-doing the job at their expense.

is the pan designed to be difficult to remove on purpose? no. look at the underside of motor. all you see is subframe, bottom of oil pan and trans pan. you literally cannot touch the side of oil pan or even trans. once the subframe is out than its pretty easy. but removing the subframe is like taking the foundation out from under a house. how do you do that? by holding the motor up. from above which is the factory way or getting tricky and blocking up the parts with bits of wood? i am surprised a tech would use a piece of wood. sure its a good trick and it does work but how stable is it? would your shop insurance pay for injuries due to a wood support failing? how about workers comp?

The pan is not designed to be difficult to remove - there is a lot to package a V8 engine in a FWD car.

The subframe can be removed with the engine in the car. There is an engine support that bolts to the top of the strut towers and the front radiator support. It has a chain and a turnbuckle that attaches to the lift rings on the engine.

[Rckjaws10]

Maybe I should have used other wording, I didn't mean to imply it was intentional that the pan is so difficult to remove just meant to state the fact that it is difficult. I also agree about leaving the bolt out as not a good idea I know I would want mine back in as well, that is just what he told me. I also thought about if there was a way to take it out, shouldn't it go back in? Also its not just that specific tech, I have made a habit when working on the northstars to look at that bolt and have seen many many of them missing. I wouldn't say the tech was just using a wood block. All the techs there use tall stands I would call them, specifically designed to hold up heavy parts and things. The wood block was just so the metal would not press into any parts. I simply wanted to share that there is a way to seal the oil pan without engine removal, that is just the way I seen the tech do it.

[Rckjaws10]

I will add this also.. this is from the GM service bulletins that I am able to log into and read for GM vehicles. Not sure if anyone has ever tried this.

#67-61-07: OIL LEAKS FROM OIL PAN TO LOWER CRANKCASE - (Jan 31, 1996)

SUBJECT: OIL LEAKS FROM OIL PAN TO LOWER CRANKCASE ATTACHING BOLTS (CLEAN BOLT/APPLY SEALANT)

MODELS: 1993 CADILLAC ALLANTE 1994-96 CADILLAC CONCOURS, DEVILLE, ELDORADO, SEVILLE 1995-96 OLDSMOBILE AURORA WITH 4.0L AND 4.6L ENGINE (VINS 9, Y, C-RPOS L37, LD8, L47)

CONDITION:

SOME ENGINES MAY EXHIBIT ENGINE OIL LEAKS SOURCED AT OIL PAN TO LOWER CRANKCASE ATTACHING BOLTS AND BOLTS ATTACHING THE BRACE BETWEEN THE TRANSAXLE AND ENGINE OIL PAN.

CAUSE:

THIS CONDITION MAY BE CAUSED BY POROSITY IN THE LOWER CRANKCASE AREA NEAR THE OIL PAN BOLT THREADS. THIS TYPE OF LEAK WOULD SHOW OIL LEAKING AT OR NEAR THE HEAD OF THE FASTENER AFFECTED.

CORRECTION:

TO CORRECT POROSITY LEAKS IN THESE AREAS, USE THE FOLLOWING PROCEDURE:

1. REMOVE THE BOLT WHICH IS LEAKING. 2. THOROUGHLY CLEAN THE BOLT HOLE WITH BRAKE CLEAN OR SUITABLE EQUIVALENT CLEANER. 3. THOROUGHLY BLOW OUT BOLT HOLE WITH SHOP AIR (20 PSIG MAXIMUM PRESSURE). 4. THOROUGHLY CLEAN THE BOLT WITH BRAKE CLEANER OR SUITABLE EQUIVALENT CLEANER. 5. APPLY A MODERATE AMOUNT OF LOCTITE®, P/N 12345382 (BLUE SERVICE REMOVABLE) THREADLOCKER/SEALANT TO BOLT. 6. INSTALL BOLT AND TORQUE TO 9.5 N.M (85 LB IN).

ENGINES PREVIOUSLY RETURNED THROUGH THE ENGINE EXCHANGE PROGRAM FOR THIS TYPE OF LEAK SHOULD INSTEAD BE REPAIRED USING THIS PROCEDURE.

[rockfangd]

weird. Mine seeps exactly like that. but it leaks so little it doesnt even bother me. thanks for sharing

[hjb981]

Thanks for sharing, Rckjaws10.

Jim: do you know of any way for us non-shop-owners to get a hold of those standard flat rate lists?

[Cadillac Jim]

Chilton sells them, among others. Here's the Chilton page on the 2012 flat-rate manual, book and CD-ROM:

http://www.auto-repair-manuals.com/automotive-labor-guide.htm

Note that they aren't shy about pricing. Part of it is the obvious - if you are making money off their book, not doing a DIY project, then they want a piece of the action. Less cynical is cost, because it costs the same to produce, typeset, and print a book that sells 2,000 copies as it does to produce, typeset, and print a book that sells 200,000 copies, up to the few dollars a copy printing and binding costs.

Note that the cost of the manual decreases as you go to earlier years. I did click the link for the CD-ROM for 2012 and the blurb says it covers model years 1981 through 2012. Coverage on 2012 models is "limited." The date 2012 refers to the edition, not the model year as fully covered.

Thus it pays to get the oldest CD-ROM that covers your model year fully. For example, if you have a 1997 Deville, get the 1998 edition on CD-ROM - whoops, the earliest manual available on CD-ROM is the 2004 edition. But I see a 2000 edition, hard copy, for $31.95:

http://www.auto-repair-manuals.com/2000-chilton-labor-guide-manual.html

It doesn't say what the shipping is but you can figure $5 to $10.

[joeb]

The oil leakage may be due to seepage around bolts? Hmm. Applying sealer to bolts seems easier than dropping subframe, engine case bottom, oilpan and so on. I was at Midas yesterday and store manager was telling lady how they were going to remove trans to fix rear main seal leak on her ranger pickup. $712 and she had a glazed look in her eyes. Yes any shop with lift can fix rear seal I suppose.

[Cadillac Jim]

I changed the transmission in my 1952 Henry J (to get overdrive) when I was in high school, alone, and without my parents knowing; the car was parked out front at the curb and I jacked it up, put it on stands, and did the job after school while they were still at work.

Could I have unbolted the bell housing, clutch, pulled off the clutch plate, and pried out the seal, then tapped a new one in? I suppose so. Would I still have been done before my parents got home? I suppose so.

[PAUL T]

I remember another solution was to loosen all the oil pan bolts and carefully work sealant into the crack.

[kcd1184]

I will add this also.. this is from the GM service bulletins that I am able to log into and read for GM vehicles. Not sure if anyone has ever tried this.

#67-61-07: OIL LEAKS FROM OIL PAN TO LOWER CRANKCASE - (Jan 31, 1996)

SUBJECT: OIL LEAKS FROM OIL PAN TO LOWER CRANKCASE ATTACHING BOLTS (CLEAN BOLT/APPLY SEALANT)

MODELS: 1993 CADILLAC ALLANTE 1994-96 CADILLAC CONCOURS, DEVILLE, ELDORADO, SEVILLE 1995-96 OLDSMOBILE AURORA WITH 4.0L AND 4.6L ENGINE (VINS 9, Y, C-RPOS L37, LD8, L47)

CONDITION:

SOME ENGINES MAY EXHIBIT ENGINE OIL LEAKS SOURCED AT OIL PAN TO LOWER CRANKCASE ATTACHING BOLTS AND BOLTS ATTACHING THE BRACE BETWEEN THE TRANSAXLE AND ENGINE OIL PAN.

CAUSE:

THIS CONDITION MAY BE CAUSED BY POROSITY IN THE LOWER CRANKCASE AREA NEAR THE OIL PAN BOLT THREADS. THIS TYPE OF LEAK WOULD SHOW OIL LEAKING AT OR NEAR THE HEAD OF THE FASTENER AFFECTED.

CORRECTION:

TO CORRECT POROSITY LEAKS IN THESE AREAS, USE THE FOLLOWING PROCEDURE:

1. ReMOVE THE BOLT WHICH IS LEAKING. 2. THOROUGHLY CLEAN THE BOLT HOLE WITH BRAKE CLEAN OR SUITABLE EQUIVALENT CLEANER. 3. THOROUGHLY BLOW OUT BOLT HOLE WITH SHOP AIR (20 PSIG MAXIMUM PRESSURE). 4. THOROUGHLY CLEAN THE BOLT WITH BRAKE CLEANER OR SUITABLE EQUIVALENT CLEANER. 5. APPLY A MODERATE AMOUNT OF LOCTITE®, P/N 12345382 (BLUE SERVICE REMOVABLE) THREADLOCKER/SEALANT TO BOLT. 6. INSTALL BOLT AND TORQUE TO 9.5 N.M (85 LB IN).

ENGINES PREVIOUSLY RETURNED THROUGH THE ENGINE EXCHANGE PROGRAM FOR THIS TYPE OF LEAK SHOULD INSTEAD BE REPAIRED USING THIS PROCEDURE.

I s this just a tightening of the pan process, and does it matter if the engine is warm or cold?