Jafalex

Hi guys,

A month ago I bought my first 4wd, a '94 4Runner 3VZE auto. After the head cracked 7K miles ago, the previous owner had the head machined, new gaskets, thermostat, water pump, etc in August last year. Haven't overheated since.

It's leaked for the first time a couple of weeks ago, as it was parked nose up for a day or two in a steep street (+/- 15% grade).
Crawled underneath and noticed a bit of engine oil under the bell housing and also running all the way to the tcase. Used engine degreaser to clean as much a possible everywhere underneath. 10 days go by and not a drop on the ground, also no oil under the truck. Yesterday I parked in the same steep street, nose up, and 24h later there's another engine oil puddle. Again, oil seep under the bell housing.

I'm trying to locate the source of the leak without dropping the tranny or any other big-ish job (don't have time, money or even a garage for this task at the moment) and was hoping that with the few clues above you experts could guide me in the right direction.
I'm thinking/hoping it's the not the bottom end of the engine that needs planing/machining, but I'm not expert by any means. I've also read on here that it could be valve covers but don't really know how to make sure?

I've attached a picture of the leak as far as I can trace it. Any idea on where and how to look would be very much appreciated.

Thanks in advance...

stefanc

Most likely culprits are:
-The rear of the valve cover near the firewall (recommend getting a little mirror in there to check it out)
-Half-moon cam-shaft plug (I think that's what they're called)
-Possibly the rear main seal?

If you don't have one yet, I would recommend getting one of these. They're indispensable when it comes to the 3vze...

http://www.oreillyauto.com/site/c/de...0722&ppt=C0374

RBX

^^^ What he said.
you can also use a dry deodorant spray around the areas you think it may be leaking.

If it were my truck....
I'd clean all the areas you suspect the leak to be coming from, then I'd drive it to the step hill and park it. grab a beer, or several, and crawl around the truck till you see any areas getting wet from oil seepage.

scope103

You can check the rear of the valve cover with your fingers; I find they work better than the mirror (but get the mirror anyway; you'll use it all the time. And in the same place you'll see a magnet-on-stick; also very handy).

With all leaks, remember that gravity is not your friend. EVERY leak works its way down to the back of the engine, and tries to make you think it's the rear main seal. You need to get the engine squeaky clean (I have success with spray-on degreaser and a garden hose, but be careful around the distributor and other electrical items), then park it on the hill.

89fourrunner

See the red triangle you drew on the picture? Follow it from the highest point and go about half way down. See the metal ring at the end of the valve cover? Those plugs leak very often. Run the engine for a few minutes and then stick a rag back there against the firewall and the metal ring. If it comes out with fresh oil on it, then it is leaking there and running down.

If you find this is the source of the leak. I have fixed it two ways. Once it was fixed by removing the valve cover, and the necessary bolts to slide it out and slide a new one in. Worked. The second way I have done this is to remove the metal protection ring (by feel, without even removing the valve cover) and put a thick coat of "The Right Stuff One Minute Gasket" over the top of the ENTIRE plug and them put the protection ring back on and bolt it down. I did this and it was leak free forever. Took ten minutes.

Jafalex

Thanks so much guys, you're a true source of invaluable knowledge and I didn't expect this much guidance.. I've taken 10 minutes before going to work this morning to investigate a bit more, pictures attached.

Rear of the valve cover, likely, although I didn't spot any leak along the side of the gasket. I'll get myself a mirror asap to check the firewall side as you said, cheers for the tip!
There's no cylinder half-moon plugs on the 3VZE, as mentioned in this post (see post #2 for valve cover diagram), however it looks like it could very well be the camshaft plug
Don't think it's the rear main seal as it's never leaked whatsoever until I parked on that angle. Assume rear main seal would like no matter the angle of the car given it's right at the bottom...?

I guess I know what I'm doing this weekend

I think you've nailed it mate, see pictures below. I'm still doubting a little bit because the oil around it is quite sticky and doesn't look super fresh, but hard to say... All I know is that it's not clean around there...

I'll take all your guys advice and report back asap.

Hey at least it doesn't look like it's the head

Cheers

Jafalex

Update

Bought a mirror to look behind the camshaft plug/cap, found oil (see first picture).
Spent an hour or two cleaning everything around both valve covers using engine degreaser and water. Drove 10kms. Parked on steep road, saw fresh oil coming out of valve cover bolts on both sides! Nothing behind camshaft plugs.

So I'm thinking both valve cover seals are screwed, but the amount that I'm seeing leaking off the valve covers is nowhere near enough to create the puddles I've had (after sweeping around the gaskets, barely any more oil is coming out). I've waited 10 minutes under the car and not seeing anything dripping too....

Second picture is of the leak after the drive.

Kind of clueless about what's going on... should I even be worried?

millball

Small leaks are only a nuisance, not a real operatiing concern. You could use a pan or some sort of absorbent where you park, if there is environmental concern.

Some leaks are very difficult to find and fix, and are maybe best left alone. Monitor your oil consumption, and if it is minimal, as is likely. You might choose to let this leak go for a while.

I have a power steering leak in one of my Fords that has existed for more than 80,000 miles without getting substantially worse. I probably haven't put 10 dollars worth of ATF in it in that time.

I figure that any cheap rebuilt pump I might have put in would already have worn out. I am money ahead by leaving well enough alone and just topping up the fluid once in a while.

scope103

Leaks from the back of the valve covers are actually pretty common. (and because of gravity, have fooled some into thinking a rear main seal is leaking).

The trick to installing them is to (duh!) follow the manual. http://web.archive.org/web/201208130...68cylinder.pdf (page 80) Particularly the part about "seal packing" (use RTV; I like Permatex Ultra Black) in the corners. RTV doesn't stick well to oil, so if you do this job make sure you get the surface squeaky clean.

Jafalex

Thanks for the PDF Scope, very helpful.

I agree, not a big leak, the only thing is that the oil end up dripping along one of the differential mounts and has completely disintegrated it. I failed the roadworthy inspection and had to replace it. They're hard to find! Got one from the wrecker and was a bit of a pain to replace.

I'll get that leak fixed I guess. I bet the mechanic who did the HG job didn't put any RTV under the covers...

Jafalex

Forgot to ask, anything else worth maintaining while I've got the plenum / cylinder head covers off?

Had this done less than 5K ago (which makes me wonder about the leak since brand new gaskets...):

millball

Valve cover gaskets are one of those parts where OEM parts are greatly superior.

On the 3.slo. there are metal spacers under the valve cover bolts that are designed to space the valve cover slightly higher than flush with the sealing surface of the head.when the bolts are tight. Perfect sealing depends on the continued elastic rebound of the valve cover gasket itself. (and the end rings too)

Genuine Toyota gaskets, and Ishino Stone Japanese made valve cover gaskets seem to remain elastic and pliable longer than many aftermarket gaskets do. These gaskets live in a hellish environment and the materials used by some cheaper manufacturers get hard as a rock before they are very old. Then, they begin to leak.

Some people resort to doping the valve cover gaskets with RTV, or FIPG goo, and while this sometimes works, Toyota manuals do not call for it except a tiny dab at the cam bearing cap corners.

The best insurance against leakage is use of the highest quality OEM gaskets, installed on thoroughly degreased surfaces.

Jafalex

Thanks Millball, that's once again very helpful information.

I've just rang Toyota NZ and they want US$70 per gasket and that excludes all the washers you've mentioned (16 washers for another US$70). Called the mech who did the job, said he used OEM gaskets.
Not wanting to sound cheap but I'll have a first go at opening them up, giving these almost new gaskets a good clean and put them back up with some RTV. See what happens then.

Thanks again.

89fourrunner

I highly recommend you use permatex's The Right Stuff 1 Minute gasket. Its what shops use and sets in moments, you can drive the vehicle immediately. A lot of people end up doing the job twice if they use something else.

Also, you asked what to replace while you are in there, consider replacing the fuel pressure damper. They are prone to leaking gasoline and require the intake plenum to come off to replace. Replace the PCV valve as well.

Jafalex

Looks like there's only the Grey one in NZ, can't seem to find the Black, so that'll have to do.

Just ordered the , will look into fuel pressure damper later today.

If I manage to fix this leak and fix the newly discovered tranny bottom pan leak then she should be all good to go. That's given that under 5K ago, the PO also did the work shown in the attachment.
I recently flushed the radiator to get rid of the clog and put some green antifreeze back in, I read it only takes the Toyota longlife red coolant...

89fourrunner

You will be fine with ethyl glychol green. The previous owner of my 89 ran it for a decade before I changed it back as the new owner. Half the guys on here are running traditional green. They just wont speak up about it haha.

Jafalex

Ha, sweet, thanks!