BajaRunner

Well I've had a slow oil leak ever since I swapped to synthetic oil, and now is starting to bug me.

I brought it down to my buddy who knows quite a bit more about cars than myself, he took a look and found I had THREE (3) leaks. Two were basically just "sweating" and the other one "gushing".

1) Gusher - Rear main seal near bellhousing
2) Front main seal @ oil pan
3) Passenger side valve cover gasket

Sooo... I got another family friend who works on cars for a living and will be bringing it down to him to do another check and see if its really leaking from those areas.

I don't think I want to do the rear main seal due to dropping the tranny. The other stuff I could probably do, but, am not too stoked about.

Anyways, whos had to replace the rear main oil seal? I've never even seen this topic covered in much detail. Is this a pretty common problem?

The oil leak isin't all that bad. I probably get 4-5 drops a day. But, still just annoying as hell now that its streamlined the entire bottom of my truck.

Comments, suggestions?

BajaRunner

So no one has heard of this?!

Localmotion

Ive had the valve cover gaskets but not rear main seal.

I am interested as well, I have a feeling somethings going to break soon.

BUMP!

kmchby76

I too am interested in this topic. Anyone hve any advice on the removal of the tranny. i have the 3.4l 4x4 auto. I would like to attempt this on my own if possible as I can not imagine having to pay about $700 to have it done.

BajaRunner

LocalMotion, how bad was it to replace the valve cover gasket? Mine is on the passenger side, so it looks as if I do not need to remove the plenium (? silver assembly next to throttle body).

I used to have a bookmark to a PDF file of the Toyota service manual now I can't find it! Grr...

Localmotion

I actually had my service guy do it for me. He only charged me 120 for both sides. From what I've read, its not too hard to do it as long as you have the time. In my case, i didnt have the time. It was easier for me to wait 2 hours than spend the whole day.

BajaRunner

Yeah, I might do the same...I really don't trust myself around the engine components.

My family friend actually works for the Ford dealership in SD...hes the guy who fixes up all the trade-ins and resale as "Certified used cars". Apparently, he's able to sidework on Toyota's at the Ford dealership... haha.

BajaRunner

Oh and found the FSM online... its for a 2003 Tacoma, but, close enough.

http://www.deserted1.com/FSM/

Localmotion

awesome..that will definitely be useful in the future!

good luck!

progress4m

When my valve covers started leaking I just tighten the valve covers bolts.
It was more then 2 years ago and no leak yet.
Just when you do tight them be careful and do not overdo it.

kmchby76

When I was replacing a fuel injector, I noticed oil leaking from the valve covers. I just tightened the bolts which were surprisingly loose.

nrgetic99

If its not been asked before, what oil were you on before you switched to synthetic, what is your synthetic ? How many miles

David

BajaRunner

I was using Castrol GTX dyno oil.

I then did the Amsoil "flush" product which supposidly cleans your engine of dyno. Then added Amsoil, ran that for a while till I couldnt find it at my store anymore and now running Mobil 1 10w30.

I think the dyno oil had a nice "sludge" buildup around the gaskets, and kept the oil in. Once the synthetic was added, i think its slightly "thinner" and seeped out.

Who knows.

As for tightening the bolts.. I might as well try that first.

kmchby76

I had the same problem when I tried mobli1. The oil was just a dripping like a leaky faucet. I switched back to valvoline high mileage. I still have a leak, so I added some Lucas oil additive. It's a bit thicker and slows it down a bit. I do really need to change the rear main seal.

nrgetic99

Ok,

Here is the skinny. A regular non synthetic uses a base oil or base oil blend that naturally helps the seals swell and keep the oil where its supposed to.
Over time, seals will tend to dry out and can develop small cracks around the lips. However, a good non synthetic will tend to keep leaks in these situations to an absolute miniumum.

Syntehic base stocks, by thier nature, do not have the naturally occuring waxy compounds that keep the seals swelled due to the process of making them that essentially removes all of the wax or in the case of a true synthetic (Amsoil Series 2000), was never there in the first place.

You need to add seal swell agents to synthetics to make them swell the seals enough to stop leaks and most of the time, its not an issue.

However, in higher mileage vehicles, with tired seals, the synthetic with its added seal swell agents just cannot swell the old inflexible seals enough to stop the leaks. This does not happen if a synthetic is used when the seals are new and in a lot of cases with older vehicles...just combine the wrong set of tolerances and you get unlucky.

I am using a fluid that is designed for older vehicles with some leaks and its Castrol's High mileage 10W-30. Its meets all the specs required (API SJ) and also has a dyno oil base stock PLUS seals conditioners.

My truck has 135k and does not leak a drop. As long as I change every 3k with a filter, in my mind and from what I know, I am getting the same protection as a synthetic. Now I may run a 5W-30 or even a 0W ( I used to use Amsoil's OW in the winter in my 99 SC) synthetic but sticking with a
10W-30 high mileage works for me.

There used to be a lot of myths about switching to a synthetic after running non synthetic for a while but nowadays, most synthetics are fine... you just got unlucky.

Seriously, if you are concerned, try a 10W-30 high mileage for a while and see what happens. Ultimately, replacing the seals is the cure but in the interim, keep what oil you have INSIDE the block.

I don't work for Castrol or Amsoil but I do work for a company that supplies additives used by ALL of the major oil companies in thier engine oils and ATFs and Gear Oils..... that and I stayed in a Holiday Inn express last night

David

BajaRunner

Good post, and info. Thanks for the advice.

BajaRunner

Bumping this up again.

Its gotten much worse, I still cannot really tell where the hell this oil is coming from. I don't know if its really a combination of 3 leaks anymore. There just seems as if I am loosing oil from the oil-pan gasket!?!

If anyone please post up where the problematic areas were on the 3.4, I'd be stoked. I've taken it to 3 mechanics, and they have told me different things.

The valve covers appear to be loosing a very small amount... or is it possible that the oil is being burned off, and appears to be less than it is? I tightened the bolt heads with no difference.

I switched back to high-mileage dyno with a quart of lucas oil treatment... was good for a while, but, still running out.

lexustech

if ya don't mind me asking,who changes your oil?- i work at a dealer and we see 4runner trade in's that have aftermarket oil filters-if you don't take the shields off underneath the engine you can't really clean the residual oil from the oil filter removal and then the oil will blow back along the oil pan and appear the rear main or oil pan is leaking,i would pressure wash the entire area then drive it and keep checking it to see where exactly it is coming from,the source will be from the highest point running down

5-spd for life!

I actually went from the normal dealership stock 5w-30 to royal purple at 153,000 miles and here I am at 168,000 miles and still have no leaks and have been running Mobile 1,500 extended preformance fully synthetic ever since with no problems.

I bet that your problem could easily be coming from the oil pan, but a good way to tell is to crawl under the toy and look for the little port on the front of the tranny( it is a very small rectangular hole to let oil out in case of a leak) and see if it is coming out of there. If it is than that is a rear main seal but if not then trace it back further. I very well could be an oil pan gasket which is just rtv sealent from the factory. The only other one that is on the bottom of the engine is the front seal and if your pouring out of that then replace it!!! I think that if you pull the crank pully then you can get to it but it may be harder than that.

ARB1977

Some leak when switching to synthetic and some dont...the ones who do generally have leaks already. Switch back to dino and see if it goes away or try a high milage oil that contain seal swellers.