1993 Northstar Warped crankcase halves?

[williemacc]

My 93 STS has 165k on it and has suddenly developed a significant oil leak coming from the area above the oil filter. The oil pressure switch has been replaced, but did not improve the situation. The dealer does not think it is the oil fileter adapter. This has been a great car and had low oil consumption (one quart per oil change - 6000 to 7000 miles) before this latest development.

The dealer says it is the joint between the upper and lower crankcase, but they did not seem to be so sure. They said the worst case scenario is that the upper and lower crankcase halves would need to be replaced because they may be warped.

If I'm reading the shop manual correctly, the upper crankcase is the engine block itself. I suspect I'm getting bad info and the service advisor doesn't really understand what the upper crankcase is. He quoted me 25 hours (at $140 per) plus $500 for upper and lower crankcase halves. This doesn't compute to me as it seems highly unlikely that GM would be selling the upper and lower crankcase halves this cheap. Also, if the crankcase halves were replaced, would they be putting in the original pistons, crankshaft, etc??

Any wisdom for me? I love the car, but am concerned that it would not be wise to spend this kind of dough and still have an old engine that might blow a head gasket next month.

I'm curious if anyone has heard of this warped crankcase business??

PS: It has not overheated in the last 75k miles since I bought it.

[JimD]

It would be worth the effort to replace the oil filter adapter O rings as a test.

[Scotty]

When I did my AC compressor I replaced the O-rings behind the oil filter adaptor, tight spot but its doable. I highly doubt this warped business. He may be talking about the case-half leak....

[Barry94]

I've been chasing leaks in the case half area (front and rear) on mine for years now.

In the front of the engine it was a couple of things.

One was the oil level switch/sensor. When the oil got hot it would run thru the unit and out the wire connector. Strange problem. A new switch/sensor cured that leak.

The other front leak was coming from the lower crank sensor. I replaced the "O" ring on both of them.

The rear leak was in the seam of the lower case half to oil pan.

I thoroughly cleaned/degreased the seam and applied a generous amount of RTV, pressing it well into the seam and it hasn't leaked in four years.

If you do have a case half leak and can access it, then with proper cleaning, RTV will seal it from the outside.

Barry

[growe3]

Common oil leaks sources are:

1. The O-ring seals on the oil cooler lines to the adapter, the radiator, and the dipstick tube.

2. The dipstick tube has an O-ring on it where it enters the engine case.

The half-case leak is usually a nuisance, more than a real oil loss problem. The silicone seal is not expanding enough to seal the halves any more. Using oil for high mileage cars has had good effect, for some; use the same viscosity as normal.

In any case clean the entire area thoroughly before committing to a repair job.

A simple way is to spray a cool, not cold, engine with Wesley’s Bleche-Wite tire cleaner Tire cleaner. This works great for degreasing, and is non-flammable. It does not appear to hurt paint, but I would be careful to keep it off of the exterior paint. If it does get on the exterior paint rinse it with water, do not wipe off. I do this cleaning a couple of times a year, and have not encountered any problems.

1. Jack the car up and support it in a safe manner.

2. Spray everything around the side and undersides of the engine.

3. Spray the frame rails, mounts, linkage,transaxle, etc. Anything that has oil or grease accumulated on it.

4. Allow to set a few minutes, do not allow the spray to dry, or it will need to be re-sprayed for best effect.

5. Hose off using a garden hose and spray nozzle. Flush the driveway off, after the car is rinsed, to keep the residue from making a mess.

Allow to dry. Repeat if necessary after the area has dried. If you re-spray on a wet surface, the cleaner won’t work well at all.

Drive the car for a few miles then re-examine carefully. Try to determine the real source of the leak, before doing or ordering repairs.

-George

[jackc]

If you're feeling really adventurous, you can get some engine oil dye and pour it in your oil. Drive for awhile with it in there, then look around underneath with a black light. Leaking oil will show up bright yellow. If you clean as George described and then look around with it running, you can go right to the spot(s) where its leaking. If you google "engine oil dye" you should be able to find some.

[Poobah]

I have been a member of this board for a long time and this is the first time I've heard of this problem. It sounds fishy to me! The upper and lower crankcase halves comprise the engine block. I can't imagine replacing that! Maybe the gasket, maybe the entire engine, but not just the block. In any event, I wouldn't start into a project like that without being certain that it is, in fact, the problem! I would get a second opinion. There are a lot of reputable shops out there that charge about half the $140 that your dealer does.

[williemacc]

Thanks very much to all who provided wisdom, insight and motivation in responding to my post. You guys are great, and now I'm going to go after this hopefully minor problem with a passion.

[Scotty]

Thanks very much to all who provided wisdom, insight and motivation in responding to my post. You guys are great, and now I'm going to go after this hopefully minor problem with a passion.

Stick with us, and run any SPIN by us. Good Luck, Mike

[Scotty]

They said the worst case scenario is that the upper and lower crankcase halves would need to be replaced because they may be warped.

I have re-read this statement a few times and each time I am amazed by this dis-information. This is a time we miss the guru. This is a time we would look to him for the definitive answer to quell this type of dis-information.

Personally, I can not imagine that a half block that is BOLTED to another half could warp at all let alone warp enough to leak. I am no engineer but I can NOT imagine that happening. So for someone to make a statement about warping to explain a case half leak assuming there is one is outrageous. To date I don't think we have ever heard of this issue.

What do all of you engineer types out there think about this? Specifically whether you think a two piece block could warp?

Maybe the Guru will appear through a chosen median....and impart his knowledge on this issue.

[Scotty]

I put this out to cadillacforums:

http://www.cadillacforums.com/forums/showt...6143#post496143

[Ranger]

I don'y buy it. Worst case scenario is the seal, which in itself will be an expensive job but warped case and block. No way.

[CBOYLE15]

We had a similar leak on our 1999 seville. dealer replaced the following parts under warranty which corrected the problem.

plug assembly 24100042

adapter 12555007

filter 25014377

good luck

Charlie

[Scotty]

A member named chevelle over at cadillacforums (see link above) responded the following to this thread:

Block warp...???....nonsense.

Have them remove the oil filter adapter and replace the seals between the oil filter adapter and the block. If there is a leak in that area then that is the likely source.

The upper/lower crankcase splitline does not seal pressurized oil so there is rarely a "leak" per se from that joint. Oil will wick from the joint...more a seepage than a leak. It will make a mess and look nasty but rarely leak enough to drip on the ground. A leak big enough to drip is most often pressurized oil and that would most likely be the oil filter adapter seals with that much age and miles on them.

[JimD]

A member named chevelle over at cadillacforums (see link above) responded the following to this thread:

Block warp...???....nonsense.

Have them remove the oil filter adapter and replace the seals between the oil filter adapter and the block. If there is a leak in that area then that is the likely source.

The upper/lower crankcase splitline does not seal pressurized oil so there is rarely a "leak" per se from that joint. Oil will wick from the joint...more a seepage than a leak. It will make a mess and look nasty but rarely leak enough to drip on the ground. A leak big enough to drip is most often pressurized oil and that would most likely be the oil filter adapter seals with that much age and miles on them.

Anyone else recognize this writing style????

[rbrantlee]

Yes. Very familiar.

[Ranger]

Hmm, now that you mention it.

[KHE]

Yes! You beat me in posting but I immediately recognized the style. Hopefully, he migrates back to this board!

[loucar1]

Why did he leave??

[adallak]

A member named chevelle over at cadillacforums (see link above) responded the following to this thread:

Block warp...???....nonsense.

Have them remove the oil filter adapter and replace the seals between the oil filter adapter and the block. If there is a leak in that area then that is the likely source.

The upper/lower crankcase splitline does not seal pressurized oil so there is rarely a "leak" per se from that joint. Oil will wick from the joint...more a seepage than a leak. It will make a mess and look nasty but rarely leak enough to drip on the ground. A leak big enough to drip is most often pressurized oil and that would most likely be the oil filter adapter seals with that much age and miles on them.

Anyone else recognize this writing style????

Yep!

[mtflight]

A member named chevelle over at cadillacforums (see link above) responded the following to this thread:

Block warp...???....nonsense.

Have them remove the oil filter adapter and replace the seals between the oil filter adapter and the block. If there is a leak in that area then that is the likely source.

The upper/lower crankcase splitline does not seal pressurized oil so there is rarely a "leak" per se from that joint. Oil will wick from the joint...more a seepage than a leak. It will make a mess and look nasty but rarely leak enough to drip on the ground. A leak big enough to drip is most often pressurized oil and that would most likely be the oil filter adapter seals with that much age and miles on them.

Anyone else recognize this writing style????

Yep!

I say kill the topic, and appreciate a knowledgeable individual "silently." Don't call attention to it because the alternative is silence again.

[jhall]

Hi Guys,

Just a thought. I had a similar style leak at the rear of the engine on my '97 Deville and traced it to a valve cover leak.

The oil can migrate down the block and give the appearance that something else is leaking - especially if it has a chance to collect in an area on the way down.