Discovered oil leak *need assistance*

[llennium]

Since it was nice out today I decided to clean the 4R up before attending a meeting at work. Once the meeting was over and I was back home I crawled under the 4R to make sure things were in good shape after the last few outings and also to check the oil filter as my local shop has a tendency to not tighten the filter enough. Once under I was surprised to find an oil leak. I checked the filter first and there was minimal oil leaking from the filter but not enough to have reached the bottom of the trans bell housing and covering the sway bar and steering rack.

Provide any feed back you can. Is this something I should be worried about. I watch my oil levels and haven't needed to add oil between changes. I'm thinking of pulling the skid plate and cleaning everything thoroughly, then leaving the skid off and drive a few days. I'm hoping this migh help pinpoint where the oil is coming from.

Here are a few pics that I thought might help.

 

[NickF]

If you're not needing any oil between changes, then its not a leak. They probably spilled oil when tehy changed it. This is why you should change your own oil :shrug:

 

[durrell]

Looks like a rear main seal leak to me. My Frontier had one and it looked just like that.

Have you switched to a synthetic oil recently?

 

[llennium]

If you're not needing any oil between changes, then its not a leak. They probably spilled oil when tehy changed it. This is why you should change your own oil :shrug:

Yea, no oil needed during changes. Thanks for the suggestion, I had pretty well made my mind up it was time to start changing my own oil. I think I'm going to pull the skid and see if I can pin point where its coming from.

Looks like a rear main seal leak to me. My Frontier had one and it looked just like that.

Have you switched to a synthetic oil recently?

I purchased the runner about two years ago and started running synthetic in it then, is that a bad thing?

Thanks for the suggestions.

 

[cougar428]

NO.The only problem when switching to synthetic is that it
cleans up some of the gunk and build up in your engine. Sometimes
that gunk is whats preventing an oil leak and once it gets cleaned off it starts to leak

 

[llennium]

NO.The only problem when switching to synthetic is that it
cleans up some of the gunk and build up in your engine. Sometimes
that gunk is whats preventing an oil leak and once it gets cleaned off it starts to leak

Yea, thats probably my luck. Once the weather is better I will have to dig into this further. Replacing the rear seal doesn't sound like it would be fun.

 

[Diagram14]

Easy on the the rear main diagnosis there cowboy. The way the motor sits in the engine bay it has a slight tilt to the back and any leak you develope on the back half of the motor (namely your valve covers, which are substantially more prone) is going to run off the back side and down the bellhousing. A rear main would only be leaking out of the bottom of the bellhousing. You have oil going all the way up the side. I would follow it all the way up first...

 

[J-money$$$]

Easy on the the rear main diagnosis there cowboy. The way the motor sits in the engine bay it has a slight tilt to the back and any leak you develope on the back half of the motor (namely your valve covers, which are substantially more prone) is going to run off the back side and down the bellhousing. A rear main would only be leaking out of the bottom of the bellhousing. You have oil going all the way up the side. I would follow it all the way up first...

good advice. And do not run synthetic, unless your motor has had it in it younger years. I tried the switch and had my motor burn off oil and start leaks all over.

my advice is make sure your oil filter is on tight, and try out some high mileage oil. that stuff really helps. Its supposed to make seals swell and slow leaking

 

[durrell]

Easy on the the rear main diagnosis there cowboy. The way the motor sits in the engine bay it has a slight tilt to the back and any leak you develope on the back half of the motor (namely your valve covers, which are substantially more prone) is going to run off the back side and down the bellhousing. A rear main would only be leaking out of the bottom of the bellhousing. You have oil going all the way up the side. I would follow it all the way up first...

Sounds good. I was just throwing it out there because I've had a rear main leak before and it looked just like that. Your suggestion is better than mine. :jump:

 

[llennium]

Easy on the the rear main diagnosis there cowboy. The way the motor sits in the engine bay it has a slight tilt to the back and any leak you develope on the back half of the motor (namely your valve covers, which are substantially more prone) is going to run off the back side and down the bellhousing. A rear main would only be leaking out of the bottom of the bellhousing. You have oil going all the way up the side. I would follow it all the way up first...

My plan is to look into this further this weekend. Hopefully, you are correct and it is coming from something I might be able to correct.

good advice. And do not run synthetic, unless your motor has had it in it younger years. I tried the switch and had my motor burn off oil and start leaks all over.

my advice is make sure your oil filter is on tight, and try out some high mileage oil. that stuff really helps. Its supposed to make seals swell and slow leaking

Great suggestion. Any recommendations on a brand to use for high mileage vehicles? I'm pushing 120,000 on the runner.

 

[durrell]

Just run a synthetic blend for higher mileage vehicles. I usually run Valvoline Max Life or something like that.

 

[llennium]

Just run a synthetic blend for higher mileage vehicles. I usually run Valvoline Max Life or something like that.

Thanks for the recommendation. If the weather is acceptable this weekend I will go with the high mileage oil and do a little clean up while I'm under there and see what happens over the next couple weeks. A little Simple Green and a water hose should do it.

 

[THEREALTOR1]

Provide any feed back you can. Is this something I should be worried about. I watch my oil levels and haven't needed to add oil between changes. I'm thinking of pulling the skid plate and cleaning everything thoroughly, then leaving the skid off and drive a few days. I'm hoping this migh help pinpoint where the oil is coming from.

Wow, alot of great info in this thread. I'm in the exact same predicament as you llennium. I recently noticed a come and go oil leak with oil in pretty much all the spots as what it appears in your pics. I switched over to synthetic about a year ago (about the same time just before I started to notice small spots on my garage floor every so often). I too was thinking maybe VCG, or worse a rear main. I did stop into a shop today to try to get an estimate, and the guy I talked to said he really doubts it would be a rear main because these T4Rs' aren't known for those going bad, but could possiby be a VCG. I'm thinking now it might just have been the synthetic, and maybe I should just take it to a buddy of mine that has his own shop and have him switch it out for some high mileage such as durrell suggested.

Again, great info guys. Really got me thinking now.

EDIT, mine also isn't leaking at a great rate, nor does it appear to be burning, still well within the acceptable limits.

 

[durrell]

Yeah, synthetic oils are great if you run them early in the life of a motor. But running synthetic oil in a 100k+ mile engine after it has ran petroleum-based oils is just not a good idea. As someone said earlier, it softens the seals and the detergents clean up deposits that may be helping fill some cracks. I've been running a synthetic blend since I got my 4Runner (15k miles ago) and I've yet to see the first oil leak.

Leaky valve covers are pretty common on the 3.4's, so that would be a good place to start and I wish I had thought of that before suggesting rear main. It just looks so similar.

 

[quicksilvr]

good advice. And do not run synthetic, unless your motor has had it in it younger years. I tried the switch and had my motor burn off oil and start leaks all over.

my advice is make sure your oil filter is on tight, and try out some high mileage oil. that stuff really helps. Its supposed to make seals swell and slow leaking

You're the first person I've heard say that.

I'm getting ready to switch my sister's '97 with 235K miles over to full synthetic for the first time. It's had standard Castrol GTX or GTX high mileage it's whole life.

I still think I'm going to switch to Valvoline SynPower, since it's what I use in all my vehicles, and what my dad uses in all his vehicles: and we are the ones that change her oil. I'm not expecting any oil leaks after the switch.



To the OP: leaky valve covers are definitely the place to start. The aformentioned '97 has some slightly leaky vc's....and it looks like the pictures your posted.

 

[llennium]

I can't express how much I appreciate everyone's input on this. It's great to have a community so willing to help. I looked through my records and realized I have had the 4R for 3 years and due to my employment/lack of time had the local shop take care of changing the oil with a synthetic blend, not full syn. I recently changed jobs and now have time to perform my own work so I will start taking care of change the oil myself. I'm going to go with the high milage oil and see if it helps.

I recently decided to start my build of the 4R and was able to find some reasonable parts for the lift, so I'm hoping this is minor so the funds can go into the build and not repairs. Again, thanks for everyone input. :thanks:

 

[Diagram14]

Somebody on here linked me to this page at YT: Oil Leaks. Awesome write up on the common leak spots for the 3.4. I had a major one this thread helped me locate... Good luck in the search.

 

[etc.]

Theres some wrong information in this thread about oils...

However, since I began my Auto RX treatment, I developed a similar leak(s). I tried to find it but was too high up and near the firewall to find.

What I could see was a leak on the pass. side valve cover. Simple replacement. The only thing I didnt do was remove the rear piece that looks like it should hold the cam (name?) and the half moon.

Well the leak continued and could even be smelled when at a stand still.

So today I finally got the chance to remove the drivers side valve cover. Its not too hard. Well I removed everything and got down to the cover. This gave me a chance to finally get my hand between the firewall and the cover to check for leaks....and BINGO! I located what I hope to be the oil leak.

When removed, I poped off the half moon I noticed very very little RTV forming a seal. The cam support piece came off a little harder, but when removed, I noticed a ton of oil on the outside of both pieces.

To be honest, going the extra couple steps maybe only added a 30 minutes to the time (4 hours total at bum speed). Most of the time spent was cleaning and applying the RTV, then waiting for it to set.

When looking at the valve cover gasket, it was almost what I could call dry cracked. I also found the location of the pin hole leak. It was where the half moon meets the gasket...

 

[durrell]

Theres some wrong information in this thread about oils...

Well why not fill us in?

I realize not everyone agrees on oils, but it's pretty commonly accepted knowledge that synthetic oil has detergents that soften seals and cause leaks in older engines.

Or is that not what you're talking about?

 

[kball]

Myths About Synthetic Motor Oils

And I'm sure all other synthetic manufacturers would agree. If you engine leaks now it will leak with synthetic oil, if it does not leak now, it's not going to start.

I've been running synthetic in mine for about 10,000 miles now. I have 189,000 on the truck. No new leaks that I'm aware of.