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Main seal leak...or maybe something less disastrous? Need help with diagnosis.

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Hello - I am the owner of a 1999 Jetta GLX Manual transmission, 2.0 L gas engine 

I am getting about 9 square inches of oil stains overnight coming from between my bell housing and my engine - even visible drops. Sadly, this is the classic indication of blown main seals, a complex repair costing almost as much at a shop as the vehicle is worth. Assuming they do it right and nothing else goes wrong.

I have four sets of questions:


(1) any chance that valve cover or other less expensive leak could end up coming from that area?  IN particular, where would valve cover leaks manifest? I just replaced a leaking oil sensor so things are wet higher up than the bottom of the bell housing from that leak so it is not clear whether or not there is a leak higher up than the bottom of the bell housing. I assume that main seal leaks do not deposit oil higher up in the engine compartment so if I can prove that there is still something leaking up high I might be able to avoid the Main Seal issue.

(2) Is it even worth tightening the oil pan bolts at the back, on the off chance that's the issue, or is the risk of just making it worse greater than the very unlikely possibility that suddenly my oil pan gasket would leak. To be fair to this question, there are some lesser oil stains visible at the front of the oil pan too, even on a flat surface.


(3) How much time do I have before a main seal leak becomes catastrophic, ruining my clutch or causing fast leaks that make the car undrivable? I would not mind ninety days to save up for a replacement vehicle. The state of California Vehicle Retirement Program should be providing me $1500 for the car, which I paid $2,000 -2700 for depending how you count it.

(4) The Vehcle Retirement Program requires that you are able to drive the car in, which is about fifty miles from where I live. Can the main seal leak get so bad the car will be undrivable?

Note: Engine and transmission are in the car and I don't have a garage at my disposial. The pictures are ot of my stuff they are just for reference.

I will greatly appreciate any ideas that may help me stay on the road. - Jeff


RE: Main seal leak...or maybe something less disastrous? Need help with diagnosis.



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Welcome! That's a shame and sounds like it has come at a bad time.

In response to your queries:

1) It is possible that a BAD valve cover gasket leak could be the issue; leaking and filling the bell housing while being driven, and then dripping out when parked. I don't know anything about your specific car to know if it's a common leak, but it may be worth checking the bolts for the valve cover are tight, and then cleaning the area so you can spot the leak culprit better. You may also want to remove the valve cover to see if the gasket is brittle/flat if it is leaking. I think it would be very unlikely for a rear main seal leak to deposit oil up as it'd be hitting the bell housing for the most part.  

2) It is worth checking if the oil pan bolts are loose, I had a 2003 Polo with a leak on the oil pan, for some reason 7 or so bolts were less than finger tight. Once I tightened it up, it was never an issue again. Oil pan bolts will be torqued up very low in the grand scheme of things, so use a small ratchet/spanner and be careful, there's little/no danger of making it worse from just checking they're tight and snugging them up. 

3+4) It's hard to say (fortunate enough to never had this issue), but if the leak is due to the RMS, then it seems like it's not in a good way anyway. I'd presume it's pot luck if the seal worsens to being undriveable in 1, 100, or 1000+ miles. I imagine the two things that may happen that'd prevent you from driving the car to the Retirement Program location is a catastrophic blow out of the seal, no oil pressure and then spun bearings etc., or contamination of the clutch that's so bad you can't make any progress.  

I know there are also 'stop leak' products about from auto stores, this may be worth a try too if the car's destined to be recycled anyway (that's what I guess the retirement is). I quickly googled for a stop leak and found this: https://shop.advanceautoparts.com/p/bluedevil-rear-main-sealer-00234/10148609-P which seems to work for some people. 

If I were in your position, I'd be checking the valve cover and oil pan, then if that meaningfully reduces/stops the leak, and attempt to drop it off for retirement, providing the leak doesn't massively reduce the $1500 you're going to get. If the leak does not get any better, I'd be trying a 'stop leak' product (which would hopefully do something) and then drop it off for retirement. If the 'stop leak' doesn't help, I'd then be deciding between risking it to retirement (and potentially being stranded at the side of the road and losing $1500?), or continuing to use it locally for as long as it can still get you to places, so you can save up for a replacement. 

Hope this helps and you can get the car dropped off to retirement without issue. 

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  • 2 weeks later...

Props to the mods for allowing my non-Supra question. And actually my old car was a sort of an MIV this one is actually MkIII and so it is a discretionary thread rode an old school Toyota today, looked at one for purchase last week, and used to drive one and TBH did not realize what I was doing here  so thank very  much for taking the question. Ditto @ Izaak. But....


YikES! I was hoping  to at least keep the car through new year's did not realize there was high risk of sudden catastrophic blow out. Seems like it has been leaking for quite a while. Not valve covers. Probably not oil pan. Why would it start leaking it is just metal. Seals of some kind more likely.

The good news - not leaking from direct bottom dead center of bell housing but higher up toward the back of the car. Oil around the distributor base, might be an o ring there but other stuff too. Maybe even oil from dizzy is blown back. Well the motor is transverse mounted which makes it even more likely that the leak is not the seal.

Other good news: I failed smog, but found a shop that will take the 80%funding from the State of California. It is just the secondary air pump, an easy bolt on on the top of the engine .

The bad news: I now have a bad crank speed sensor causng (a) random failed starts when hot and (b) one stall at idle though it restarted right away. This is progressiveley worse as previously the condition merely required a second key turn to start, at times. The part is $50 but it is way down behind a bracket behind the starter behind the oil filter a tricky 5mmm hex and pry-off - lacking a garage I can attempt side-of-the-road but if I can't get the bolt off it's probably a couple hundred or more. Well worth it if I have a chance of driving anothre month or two or three.

But your reply has me worried. I might be better off putting 800-1200 in for seals and have a car I know runs and shifts and brakes with good tires than take the $1500 from the Vehicle Retirement Program + 1000 - where I am going to get a car for $2500 that is not likely to have its own hidden time bombs?


TO FOLLOW: Pictures/links to videos...

This car has no real front end problems runs great probablhy good for 300,000 miles right? Except...it leaks oil.


So the real question in my mind is whether - worst case scenario - if it is main seal should Id do other seals at that time and are they all likely to go - if so what other seals are involved. I sure hope you can ratchet bak the pessimism and be honest but if the reality is that these kinds of leaks can indeed create sudden undriavable oil loss I will look into that hypothesis and sit it out until at least I have the approval for the $1500 in hand.

Edited by Distressed99Jetta
typos (see edit history)
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