To ok4450 - New thread for the oil seal discussion

Well, thought it would be worth a shot, sorry for all the reposts you’ve had to do, but if you don’t mind trying once more here, I’d appreciate it.


Oil seal? Is this a newly-discovered species of marine mammal? Perhaps richcrisler can tell us how to raise them and convert them into free fuel. (Sorry, I guess I’m a bit cranky today.)

Haha you had me thinking I misspelled something there. I’m sure richcrisler will have an opinion, no doubt.

personally i think clubbing is the way to go. no holes in the fur.

what were you thinking?

Can’t we just melt them down into crude oil?

What was the oil seal problem again?

ok, refresh old tired minds.

what about the oil seal?

was this about the oil drainplug?

or the valve covers?

i forget

i figured the previous comment would get rid of some tree huggers, looking for free gas, and a novel way to propel their fantasies.

Well, I’ve finished up clubbing oil seals for the fur market so we’ll try this forum again.

About your Northstar odds are that a simple seal replacement will repair it. Rear mains can leak because of excessively worn main bearings but in most cases it is something else; groove worn into the crank where the seal rides, aged seal with hardened rubber, PCV valve clogged up, etc.

In some engines with a lot of miles a groove may be worn into the crank and this can cause a seal leak on an aged seal.
Most of the time a new seal will compensate for a light groove. In severely grooved cranks it’s time to call a time out before replacing the seal. It’s the responsibility of the person replacing the seal to make an educated guess how bad that groove is. If it’s bad enough there are products called Seal Savers that can be installed and will give the seal a new surface to ride one.

As to measuring crank movement in the car at the rear main it could be done with a dial indicator with the transmission out. The problem is that only one in a million mechanics may even think about this or consider it.
Did that answer your question?

Here goes the post and we’ll see if it takes or not.

Hallelujah! There is a higher power at work here.

Haha thanks OK! Good stuff to know. And glad it posted.

Well the guy working on seals just called me - says he found out where the oil was really leaking from - the shop that replaced the head gaskets snapped off one of the oil pan bolts, and oil was coming out of that corner. He says it looks like they did the lower seals, but since he has new ones for it, he’ll put them in, even though they look like they aren’t leaking.

However, he’s a bit perplexed about how tight they torqued this bolt to snap it off, and is worried about the rest (he has 5 loosened, there are 20 total). He said something about how he’s surprised the engine was ok up to this point since these bolts have something to do with the main bearings? Went over my head…says he’s surprised it didn’t spin a bearing.

I told him to continue with the rest and to drill and retap any other bolts that snap (hopefully none!) and he agreed that’s the best thing to do since he’s in there…said he’ll take a look at the bearing after he gets all the bolts off.

If you can explain better than he did about how the oil pan bolts affect the bearings, I’d appreciate it! (again! :slight_smile: Will let you know what he finds.

I’m not very familiar with the Northstar engine at all but I don’t see how oil pan bolts affect main bearings. Will have to think a bit about that one. ???

Well, I found this on the Net, maybe it explains it:

"This engine (the Northstar) is kind of different in that it has an engine block, an all-in-one main bearing lower section instead of individual bearing caps and then the oil pan that all bolt together to form the outside of the engine. "

Apparently the bolts that hold the oil pan on extend down through the top of the engine and cannot be accessed to drop the oil pan unless the engine/trans is removed?

A couple of pretty good pics here.

The one view from the side is pretty clear and I understand it completely now. All aluminum can have its bad points.
I would be somewhat nervous about main bearing fit over time since aluminum is prone to distortion.

I think it’s a good move to go over all of those bolts. If one was snapped off due to ham hands there’s no telling what the others went through.

Wow those are good pics…wish I knew what all the different areas were…thanks for those.

Glad you agree about the bolts, since it’ll be costing me a bit extra if any of the other bolts snap. I hope the bearings are ok, most of all! Will know tomorrow.

I asked the guy working on the engine if he thought the bolt was snapped off due to someone rushing, or just stupidity. He went with option #2 right away…

Sorry, this was from another thread I hijacked:

hey cappy, see the link above to get the context of this oil seal issue.

Well, thank God, the rest of the work went well, here’s some excerpts from the email my mechanic (a.k.a. lifesaver) sent me just now:

“All the rest of the bolts loosened with A LOT of effort. Luckily the piece of that one bolt that broke in the engine block came out with a hammer/punch. Everything assembled well, I had a replacement bolt from an engine I tore apart- lucky for me I hang on to every little part! I torqued the bolts according to the Cadillac Northstar service manual. The bolts had more than twice the specified torque.”

Apparently 3 other oil pan bolt holes were stripped…

He also said this:

"They did timesert the engine when they did the head gaskets. The evidence was all over the engine- metal shavings all over the outside, under the intake manifold, and I found a few chips on the inside- BIG mistake on their part. I tape up the entire engine when I drill/tap the block/heads for a HG job. I cleaned the engine up as best as I could.

The bearings looked great so you should be fine there. And in my honest opinion, the engine should NOT leak again. Along with the new gaskets I run some RTV sealant along the gaskets and in the corners- not much, just enough to make the gaskets stick- basically extra insurance."

So, hopefully it’s smooth sailing from here. Just thought you might find the above interesting.

As a somewhat final update, everything went back together without any problems, I no longer have any oil leaking and lots of fluids were changed, too.

I’ve attached a photo showing the broken oil pan bolt and the spot where a crankshaft bolt broke, too. Now I just gotta figure out the full throttle/no shift at redline problem.