SS LS1 Rear Mains Leak - how common?

[BarelyHoldenOnTogether]

Gday commo fans,

Recently bought a nice condition 170,000km VU SS manual that was pretty immac with everything ok apart from an oil leak down the back of the Ls1. Didn't worry me when I bought it because I've read that often the rear oil sender and/or camshaft sensor can leak oil and look like a rear mains.
Usually if I keep a car for a bit I don't mind the odd leak and eventually fix it during my tenure of ownership.

I'm being made redundant in the next few months and I lose my company car so I need to sell my VU to clear up funds to buy a boring daily. I dont want to sell the VU for pittance so hoping to fix up any issues - oil leaks don't bode well for roadworthies as well.

I've replaced both the oil sender about two weeks ago and camshaft sensor two days ago with AC Delco replacements and found a stack of oil around both of the sensors, so I assumed that was the cause of the leak.
Unfortunately I'm still finding a few drips of oil that appear at the transmission bellhousing after each drive, so I'm starting to think that I've got a dreaded rear mains oil leak.

I was wondering is rear mains leak common for the LS1? I read some places that it's very common and other places that it's not. I know it was common as anything for the ecotec's but I was under the impression the LS1 leak in every other aspect but not rear mains.

I've read that sump gasket's can leak as well.
I do seem to see some oil build up around the sump bolts as well. Could a leak from the rocker cover gaskets look like a rear mains / sump gasket?

The engine was rebuilt at 140,000km and I can see an entry on the the receipt of "remove engine sump + remove pick up and clean", but f**k knows if that means they replaced the sump or not.
The clutch was definitely also recently done. Fella I bought the car off claims he had it for about 5,000km and it was done very recently before him. The clutch has good bite and sometimes will burn if not perfectly changed which again indicates a fresh clutch to me. Surely when a clutch was done - if the mains was leaking they would've replaced it?

I'm just trying to ensure I dont waste a day of labour on my back to replace a rear mains only to find it ain't the problem.

Any ideas what else could cause the minute build up of oil? it's no more than a few drips at worst, but annoyingly its right at the bellhousing to engine meeting point, with a slight build up of oil around the sump bolts.

Any other suggestions on where to look?

Thanks for the help fols

 

[ant797]

Could be the rocker cover gasket working its way to back of engine best way is to look around both rocker covers if theres no oil there degrease everything and see if theres tny oil coming from sump if not then you can assume its your rear main if its coming straight from the botom between box and block

 

[gtrboyy]

Give everything a good clean then run car in neutral then get under car you'll see it leaking down 2 bolts at back of sump where it meets bellhousing...if still don't believe it take plastis cover off side of sump oil will run out of those too.

Quite common for rear main seal to leak at 200k but it's usually metal plate seal sits in has warped or no longer sealing properly at top bolts so best way to do it is replacement kit that has revised plate with seal already in it.

A lot of people would just replace rear main & not plate that is main cause for the leak.

 

[BarelyHoldenOnTogether]

Could be the rocker cover gasket working its way to back of engine best way is to look around both rocker covers if theres no oil there degrease everything and see if theres tny oil coming from sump if not then you can assume its your rear main if its coming straight from the botom between box and block

Thanks for the guide there. I can see a very minor bit of build up around the rocker covers but it does seem to be fairly old. Can't see any fresh oil.

I've cleaned the hell out of the back of the engine, top of gearbox and at the join b/w engine & gearbox. I'm still seeing a few drops of oil build up at the box and engine connection point after every drive which is I'm guessing means I likely have a rear mains / rear seal plate .

Give everything a good clean then run car in neutral then get under car you'll see it leaking down 2 bolts at back of sump where it meets bellhousing...if still don't believe it take plastis cover off side of sump oil will run out of those too.

Quite common for rear main seal to leak at 200k but it's usually metal plate seal sits in has warped or no longer sealing properly at top bolts so best way to do it is replacement kit that has revised plate with seal already in it.

A lot of people would just replace rear main & not plate that is main cause for the leak.

Thanks for that info! I'll run her tomorrow in neutral and see if I can isolate where the leak is coming from. Dont you just love old cars giving you drama when you want to sell them!

I've read on a few places that it's more likely to be the seal plate than the rear mains seal itself. Is there any special tools required to replace the seal plate?
If my sump gasket is leaking - do I need to remove the bell housing/gearbox to get access or can the sump gasket be done with gearbox attached?

Thanks for the advice folks - very much appreciated!

 

[gtrboyy]

Tbh I've never seen leaking sump gasket on these.

Between leaking rear main plate/seal & front crank seal they'll easily make a complete mess of the engine bay when looking at it from underneath....

Most people want it to be simple fix like oil pressure switch or sump gasket....oil leaks & lifter noise is normal for old aging ls1

 

[someguy360]

"LS1 rear main seal leak, how common?"

About as common as Herpes on a Hooker mate.

 

[BarelyHoldenOnTogether]

Tbh I've never seen leaking sump gasket on these.

Between leaking rear main plate/seal & front crank seal they'll easily make a complete mess of the engine bay when looking at it from underneath....

Most people want it to be simple fix like oil pressure switch or sump gasket....oil leaks & lifter noise is normal for old aging ls1

My mechanic is adamant that even the sump gasket can leak on these old girls.

Should I add potential front crack seal too to the list?

Both rear mains and sump gaskets are a pain to get too.

I’ve done the oil pressure switch and camshaft sensors and while there was a sh*ttonne of oil up there, there’s still oil leaks developing at the bell housing and engine joint.

"LS1 rear main seal leak, how common?"

About as common as Herpes on a Hooker mate.

talking from experience?

Anyone here done the rear main seal without a hoist?

I’ve done clutch changes, transmission conversions etc before but they were on mostly fwd hatchbacks and once on a mates VL (back when a full tank of fuel doubled their value)
Is it especially hard for a LS1 or just a pain the arse for clearance?
I might be naive but it doesn’t seem all that difficult to do - people seem to suggest it’s an enormous job?

I read the Holden service manual recommends turning the gearbox 90deg. That seems ridiculous when you can just unbolt the box from the bell housing?

Also- I read that you can buy a new Rear mains plate with the seal already in it so you don’t need the special rear mains seal tool to centre it. Any special techniques to attach it other than bolting it on evenly ?

 

[mpower]

i had the rear main done in my VXII Clubsport and was told it is common.

they did the sump gasket and the engine mounts at the same time because why not car was 18 yo and had near enough to 200k on it - i did not realise how much better the car would feel after the engine mounts were done but yeah do that while you are there. it was a big job, lots of labour in it.

degrease the whole thing too, good chance the rocker cover gaskets are leaking too if it's all over the oil pressure switch and this can contribute heavily to any oil runoff.

I mean be realistic it's not a spring chicken anymore.

 

[BarelyHoldenOnTogether]

Well, if it walks like a duck and looks like a duck, chances are it’s a duck.

Spent the last weekend on my back changing the rear valley plate & mains seal, and sure enough it was filthy with a mixture of oil and clutch dust.
Found the top of the rear mains caked in oil. Spent $160 for a new one off ebay and much the same for beer

That was one hell of a job to do without a hoist but thank f**k it’s done.

thanks for the help folks (y)

 

[gtrboyy]

Yep mongrel of a job without a hoist...if mine gets bad enough I'd rather pull engine out & do a bunch of mods like lifters,springs,front & rear seal + braided clutch line & bleeder

Rather not mess with it untill it's necessary.