Speculating on the Source of Oil Leak

Just got a pre-purchase inspection on a 2006 Tundra 4x4 (4.7L V8, 78k miles) and my only major concern is the mechanic noted, "wet oil left lower under truck". The guy I spoke with in the shop said it's likely to be a line or valve cover, but no guarantee that it's not something more serious like the head gasket. Someone in the First Gen Tundra Facebook group pointed out that cam seals are a common issue on VVTi engines.

What do ya'll think? Would you be hesitant to purchase without a more definite diagnosis based on these photos?

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Have to find out how much it will cost to fix it…

 

@Winning8 that's what I'd like to do. Going to try to have it brought back in for a closer inspection tomorrow but that assumes the shop has a same day opening. Dealer isn't going to wait around if I have to schedule it several days from now.

 

Hit everything with degreaser, scrub the wettest bits, then give it a week, the leak will be there bright & early. If you cant find it, you didnt clean enough. Pull the skidplate and clean everything you can reach.

 

If head gasket, engine will over heat and smoke coming out exhaust. Coolant mix with oil in radiator…those are sign for head gasket.
Valve cover gasket is easy fix, cam seal should be easy too…

 

My only worry is rear main seal or crank seal, those cost a lot to change for seal.

 

but its a one and done with a warrantee if you use a reputable shop. Plus, what an excellent excuse to find a 2500 stall converter, maybe a quick and easy trans rebuild without having to source worn or broken parts. The trans shop that built my s10's 700r4 to corvette spec woulda done my main/crank seal for cost.

 

Good to know those symptoms, thanks @Winning8. I'll add that there's no evidence that the timing belt's ever been done, and I don't have any maintenance records, so even the the mileage is still low, figure I should go ahead and get that done on a 16 year old truck. While they're at it, from what I understand, doing cam and crank seals might make sense too, right?

@Mr.bee, wish I had the time for your cleaning suggestions, but I'm going to have to decide whether to buy this one based on the evidence I can gather between now and tomorrow.

EDIT: thanks for the suggestion re: trans rebuild. Does that still make sense in the context of the timing belt work I mention above? Don't know anything about the stall converter but will look into it.

 

Are you scared of replacing seals? Nothing is really difficult on these trucks, you just have to make time to inspect and repair. Part of owning a 20 year old truck. Plus, everything you repair can be optimized for your usage. Wanna be cheap, you're good for a while (top off fluids). want a new truck? Get a new truck. Its a toyota, theres 2 dozen folks willing to help within about 5mins. And they used lots of similar parts from '00-'06 ('05-06 is more difficult, but so are newer trucks).

 

@Mr.bee I definitely plan to make time to inspect and repair, but I don't own this truck yet! Trying to decide if I should go ahead with the purchase without knowing the cause of this leak. That said, appreciate your suggestions, and I hope to have a chance to start implementing them soon.

 

Timing belt, water pump, crank and cam seals are a must for no record vehicle.

 

Balljoints should be on that list. Do the '06's have driveshaft zerks?

pretty sure the '06 doesnt have a trans dipstick, so you gotta check the hard way.

i think the drain and fill schedule is something like 4 quarts every 1000 miles, but someone that knows should chime in.

 

@Mr.bee

Based on what I found here, looks like they do:
https://www.tundras.com/threads/2005-06-driveshaft-lube-zerk-locations.74500/

 

that image is super helpful if you change your carrier bearing without marking the driveshaft because each junction is dependent and balanced.

 

That pre inspection didn’t give you no info, at lease wipe the oil and see if it’s engine, tranny or diff fluid…

 

The leak is showing too far up on the skid plate to be anything other than driver side cam seal or, more likely, the driver side head gasket. OP will very easily be able to spot either. Just check this for the kind of evidence you'll find. The first two pics are what you'll see for a cam seal leak. The 2nd two pics are what you'll see for a valve cover leak, which is basically residual oil on the heat shield flange, and if the corner beads are leaking because someone didn't FIPG correctly last time the valve covers were off, you'll find it all over the oil dipstick support.

That's too complicated. Just do what I did, take any absorbent cloth, old underwear, t-shirt, shop towel, whatever. Start at the top of the engine and wipe your way down. Last link shows what my shit looked like before I just used a basic towel. This is what it looked like after. I had to do this process in that thread to find out that my issue was a poorly reinstalled valve cover, and while the vc gaskets were hard, the

$15 AT-205 Re-Seal Stops Leaks, 8 Ounce Bottle

AT-205 did actually refurbish them enough to quell 75-80% of the leaking.

@olshaggy truth is, it may just be the valve covers just need to be re-torqued. But all the places I'm seeing oil coming out of your skid plate suggest valve cover leak most likely, possibly cam seal. And with a low-mileage truck, that's apparently really common. No oil coming in contact with seals for longer periods = seals deteriorating = leaks.

It's originating way too far forward for that IMHO.

Get all that done on a low mile truck? Not unless they're leaking, and even then, AT-205 appears to have stopped my driver side cam seal leak, safely, without clearly over-swelling any gaskets and causing even more leaks.

Driveline zerks are only on 4WD, which this appears to be, and they're often neglected

I suspect this is nothing more than a valve cover leak. But location of the oil origin is the big thing. Replacing them really isn't hard.

Timing belt is a 9yr/90k mile recommendation. No reason you can't stretch that to 10yr/100k miles. Some people have gotten 150k+ out of their belt. I wouldn't trust a 16yo belt though. If it snaps, your engine is toast.

Since I didn't see it skimming over this thread, frame rust is the big thing you need to be concerned about. Most mechanical stuff can be easily fixed. Just know, these engines run for 500k+ with basic routine maintenace.

Also know, low-mileage trucks, especially with the 4.7L, come with their own set of problems. At 73,500 miles today, ask me how I know Things get nasty, especially with short-trip drivers like the grandpa who only drives it 2-5 miles and puts it away to cool, then repeats, but doesn't increase oil change intervals.

 

But really, check this flange on both sides, the lines in red, along the bumps and the folded metal ridge just below them. Then check the dipstick. Then check the timing covers. I don't see drips on passenger side skid plate, for cam seal leak there look behind PS pump/alternator, left of the harmonic balancer. I was shocked how much oil a basic valve cover leak could output.

 

Thanks for all this info! Super helpful @Shifty. Re frame (and beyond) rust, here are some more photos:

Bed

spare/frame 1

spare/frame 2

frame 3

front brakes

rear brakes

brake lines

coolant

What do ya'll think about the extent of the rust? Anything else jump out at you?

 

Honestly, it looks about like a Kentucky/Missouri truck to me, like, you can tell it's seen salt, but nothing outlandish like you'd have driving around NY or MA. Nothing is jumping out at me, but I see a number of spots I'd personally like to treat if I were buying it.

You'll want to look closely at the X-shaped crossmember above the spare tire, paying attention to where it attaches to the long framerails. I think others have said to check the frame 12" before/after the forward leaf spring attachment.

 

Talk about @shifty` chiming in with a gong. That's really good info, and agree. VC gaskets are most likely culprit, but always be thorough.
Rust doesn't seem too bad. Granted we aren't getting the full view, but all that looks pretty treatable. I would check the frame around where the bed meets the cab. There's some overlaid metal there and some of that can get bad. As well as the cross member above the spare like mentioned above.
Bushings on sway bar look toast, but not a big deal. Probably some more maintenance involved depending on what condition you want the truck to be in. Check for other dried out rubber (Carrier bearing, hoses down low, shock bushings, steering rack bushings, etc.) but probably not dire.

 

Thanks for all the feedback ya'll. I told the dealer today that I was going to pass on this one. Too many concerns for a truck I can't check out in person without flying across the country on a day's notice, but all your suggestions will still come in handy for the next one I consider. In case anyone here in the PNW is interested in a First Gen RCLB 4x4, here it is. I'm sure it'll make a good truck for someone with the know-how and time/space to work on it. https://www.dwaynelane.com/inventory/-5TBKT42116S475460/