Interesting: what's causing an oil leak on a new engine?! ;)

Had a wonderful trip to Buena Park, CA to visit Hybrid Pit Stop... who swapped out our 218k mile 2011 engine for their "gold" comprehensive rebuild/upgrade engine, including almost-everything-new (yes, including 2015 pistons and rings)... for US$4500. (The closest deal I found here in CO was in Boulder, for $9000, and no warranty. VS 2 year/24k mile warranty from HPS! My mechanic urged us to do the crazy thing and drive to CA to get it done.

As recommended, we had a relaxed trip back home, with huge speed variations... three overnights... and a 500 mile oil change in Phoenix, done by an independent cert'd mechanic who told me everything looked great.

Got home. Not a drop of oil gone. Whew. Engine running and sounding great. Lots of potholes in NM, but that's nothing new. Extreme temp swings in CO (60's to teens), but that's nothing new.

Last weekend, I noticed an oil puddle under the car. What??!! Losing what appeared to be almost a quart a week, even while sitting in the garage. We've driven about 100 miles since getting home.

I jacked it up. Oil plug isn't leaking, nor is the new spin-on oil filter.

I was given a set of things to check... did what I could and found nothing.

This morning, my mech friend finally had a chance to get it up on his lift. His diagnosis: everything is dry except there's oil below where the lower oil pan connects. A bad oil pan seal??!

The puzzle: what could have gone wrong?

I'm told:

• The engine build was complete well before we even showed up in SoCal
• Hybrid auto's not seen this before

My plan:

• Wipe it down carefully
• Image all around
• Use my FLIR to see if I can discover any anomalies before disassembling
• Carefully disassemble, to maximize opportunity to see any flaw

I'm curious if anyone here has other ideas on what could have caused it!

 

Pulled the main under-engine plastic.
Everything dry above the pan; leak clearly from pan gasket.
Hybrid PitStop is now reviewing their QA process... because here's what I found:

• Every other bolt is tight (I'm about to use a high quality older SnapOn torque wrench to check current torque)
• But the in between bolts easily need more torque
• And worst of all, when I went to semi-tighten the bolt where the leak is worst... the head came right off

That tells me that bolt had been tightened at some point w/ an air wrench. A pain waiting to happen.

Yep, Hybrid PitStop is being great -- they'll reimburse any parts needed.

My local mech buddy is also awesome. Loaned me his fave low-torque wrench and a $50 set of Mac (lifetime warranty) left-hand extraction screws. With the other parts I just received overnight from Amazon I should be good to go on getting this done.

BTW, I also learned... Toyota charges around $20 for a tube of their oil pan sealant 029500103. I'll use the Ultra Black.

 

UPDATE: The torqued bolts/nuts ranged from 8.5 to 19 ft-lb. Air gunned. And the other ones never had been torqued at all. With it apart, the impact of that is obvious:

• Where not torqued, oil worked its way through. The seal fell apart. There's oil on the mating edges and just a mess of sealant bits. Useless.
• Where seriously overtorqued, all of the sealant was squeezed out. Bare clean metal-to-metal with a tiny ridge of sealant along the edges.Yes, not leaking now but who knows how long that would last especially if/when another bolt head pops.

Hybrid Auto actually mentioned to me while I was visiting that they were hoping to upgrade their operation from outsourcing the block and head operations... to doing more/all in house. This may push them in that direction: their outsource "block shop" obviously got lazy.

 

Yep, I'm fixing it, with the experienced help of a mech friend here.

It's all cleaned up now, and waiting for a full set of new parts to arrive at my local dealership parts counter on Tuesday. Lessons learned / hints from this unusual (?) experience (seems to me not many repairs require pulling the oil pan!)

• Getting the pan off: not at all easy. I tried several methods. What actually worked, quickly and well:
  • Order an oil pan separator tool. They are all similar, all have similar strengths and weaknesses. I bought the linked one because it was available next-day.
    
  • (Remove all of the bolts and nuts)
  • Use a flex blade metal putty knife to start. On the leading edge (towards car front) there's an area with flat metal from the engine perfectly aligned, so one can push the knife directly into the seam. Work it until it goes through, then wiggle sideways a bit to grow it.
  • Now hammer (literally) the separator tool into the gap. I was unable to do this without using the putty knife first.
  • Hammer it sideways along the oil pan. It easily stays in the slot with just a little pressure, even around the corners.. I didn't even need the handle most of the time. You'll only get three sides due to the posts in the back corners. That's fine.
  • Now gently pull the pan down with fingers, and pull down/off the two posts. Be Ready: there's still oil in the pan!
• Cleaning the surface to prep for re-sealing/installing: also not easy until I found a good combo of tools for the job:
  • The bulk of old sealant can be removed with a strong/sharp object. I happen to have lots of woodworking chisels; a one inch chisel worked great! Just be sure it is sharp/smooth. No scratches.
  • Now you've got the remaining stuck-on goop. I tried several less-than-satisfactory things: various scrubbers, solvents (cleaner, brakleen, etc). Too ineffective, easily scratched.
  • What worked great was borrowing a technique I've used (carefully) on our stainless steel gas cooktop:
    • Get a heavy duty (green) scouring pad. About 1/4-3/8 in thick is best. NO sponge. Available cheap at grocery stores. (I have a pack of larger ones for all-purpose use.) Caution! You do NOT want a pad that scratches.
    • Pull out your vibrating multitool (!). Attach either the flex triangle sanding surface, or any other strong flat non-cutting blade (this time I used a triangular rough-sanding blade.)
    • Cut a piece of scouring pad, larger than the multitool blade (you do NOT want the multitool to touch anything directly!)
    • Place the scouring pad on the surface, hold it in place with the multitool blade.
    • Run at a reasonably high vibration level. You'll quickly get the feel: the multitool makes the scouring pad a zillion times more effective! For this task, with this non-abrasive pad, you can press pretty hard except near the bolts.
    • I had the whole surface cleaned off in a few minutes.
  • I did a final cleaning swipe with some Brakleen. (Suggested by mech friend.) That stuff easily removes residue of almost anything from metal. (I tried removing thicker amounts. Not fun: it evaporates very quickly, before it has time to melt the bad stuff. And it is pretty strong/dangerous. Don't want to have a lot of it around!)

One more hint: I started cleaning up the oil pan, thinking I would reuse it. But then I discovered it was subtly but seriously bent near the hole that had the broken-off (likely overtightened) bolt, which also had the main leak. Hint: a nice way to visualize flatness of a surface is to run a straight laser beam along it, edgewise. I used my laser level beam. Made the unevenness quite obvious!

 

In this case (Prius), FelPro only has a cork gasket. Totally a matter of opinion. My opinion: no thanks. Cork has a more limited lifetime, tends to spread over time, can dry (on the non-wetted surface) and crack, etc etc.

There are several RTV options, depending on your working speed:

• Toyota: 5 minute working time
• Permatex Right Stuff: available in one minute black or 90 minute black
• Permatex Ultra Black: 24 hour

I'm going with Ultra Black myself.

 

Dumb (??) question: if using RTV sealant, are small scratches actually a big deal? I would think the RTV would fill in such things. Would be interesting to see testing to demonstrate how much of an imperfection will be fine