Engine oil burning smell - prius 1.5 even after engine swap

[dua3346]

Salam, i am pissed off at this problem as i spent over 150k for new engine on my prius 2007 which has run 180k KM mileage.
My car gives strong burning smell at high RPM / speed, more smell if windows are open.
My mechanic (i trust) said the engine has a lot of wear and should be changed with new one, he showed me signs of wear by disassembly of the original engine. I agreed to engine swap as I wanted to save the car. He took me to a scrapyard (kabadia) which tried to give us refurbished engine, even offered my mechanic extra cash but he refused that engine from the first look, he said he is sure the engine is refurbished, i researched for new engine assembly and took my mechanic there, he saw the engine and said it's genuinely new looks like zero meter so he accepted that engine, i paid and got the receipt.
My mechanic put that engine in my Prius gen2 and everything's great. He tested and got no smell, after that i also tested the car and got no smell. But after few weeks, the smell starting to come back.
All of the time and money feels wasted, and i have yet to do the 15 police / MTMIS alteration khwari.
I am feeling hopeless in pakistani engine oils / mechanics / parts everything.

Some extra information:
The issue existed in my car when I bought it used 1 year ago at 169k KM from a friend, my first ever buy.
It kept increasing at a normal rate, i was changing Liquimoly 10w40 oil at regular 8k KM intervals.
But last time at 178k KM, i changed to Mobil1 3-in-1 5w30 with a local oil filter (i still regret) as the salesman said toyota geniune/copy oil filter have same performance.
The issue started rising faster, the burning smell raised a lot than it used to.
Which led me to go to my mechanic for engine change.

After engine change, i bought toyota engine oil 5w30 taglonX 3.5ltr and gave to mechanic, with same local oil filter.
I wasnt present at engine oil change as i trust him and am mostly super busy with job but it is possible he used another cheap kind of oil instead of taglonX.

How to diagnose the problem properly?

[dua3346]

some extra concepts from people:

"even the so called official seller of engine oils are using re-filtered oils + cans from local market"

"you can find LiquiMoly cans original repacked from Raja bazar with re-used filtered oil and not differentiate between real/fake"

"almost all oil filters "toyota genuine" are made by kids in local bazar and their uncles pack them in genuine cans"

[Xulfiqar]

Your entire engine swap was based on “burning smell”?

If the engine was burning oil to the extent that it was smoking from the exhaust pipe then it probably has a ton of oil coated inside the exhaust which needs to be burned out.

Its not only just using liquid molvi or gaseous priest oil - you need to find out the actual issue then fix it

In my experience of repairs, these prius engines are beaten to death rather harshly because of the way the car is designed, its a lot of start/shutoff and low rpm lugging which causes very bad wear,

Good thing is that its rebuild is not too bad and will result in a new engine. However by reading the usual customer rants and mechanics/workshop owners experiences, the swap game is preferred as it pays same day and customer loves “kabul ka item”

[dua3346]

I had strongly pushed that the catalytic needed cleaning or renewal from my internet research but my friend + mechanics denied it as the cause and kept blaming the engine assembly, I also got it tuned / MAF sensor cleaned / PCV cleaned / recirculation or whatever they call head assembly cleaning.. but engine oil burning didnt go.
I will push my mechanic tomorrow to look at the exhaust pipe / catalytic, i had been using different mechanics in past but this one is better than a lot and listens to me.

thanks for the very quick response, it is really helpful.

[Xulfiqar]

Cleaning the cat doesnt do anything, its a self cleaning thermal reactor, the oily residue from a bad engine gets stuck in the mufflers and will need to be burned out or washed out like a 2 stroke exhaust with caustic soda ash.

Before any of this, can you literally identify where the burning smoke is emanating from? Just smelling it doesnt mean much.

[msabbasi]

I have zero experience with Prius so what I am about to say may be utter nonsense. Check to see if any oils is leaking onto the exhaust manifold. Sometimes the valve cover gaskets leak a bit oil that ends up on the exhaust manifold and smells. Just my 2c worth.

[Xulfiqar]

Thats the usual culprit, most mechanics dont want to clean the tarry oil off either.

[dua3346]

update:
the mechanic washed the whole exhaust pipe with a catalytic cleaner (sasta wala 350rs), it was quite dirty so black liquids came out.. my friend told me i messed up because there is a jaali / web in catalytic which can burn from the catalytic cleaner which is a kind of acid in most cheap products, i dont know if that part was taken out but it was a long pipe, single that attaches from 2 sides in the car.
Anyway, the smell is no more but only if i put my nose near the back of the exhaust / muffler of the car.

[mgalaxy3]

Engine swap is something I never recommend because of technical and legal/docs issues.

Should always go for engine rebuild from a competent person if engine is really really shot.

Otherwise minor oil burning is fine and can be dealt with oil top ups.

[dua3346]

a surprise that makes me wanna fck myself, I SMELLED THE OIL BURNING AGAIN, even after the exhaust cleaning. I swear when I was going to mechanic I could not smell it at all, also when returning, but whenever I go with car filled 6 persons, i can smell the oil burning slightly.

i cfm the engine is the new one in the car, just checked to be ultra sure

[Xulfiqar]

If you can smell oil burn, you will need to find the source, good thing is that burning engine oil emits smoke, find it, best done at night with help of a torch or strong aimed light.

[dua3346]

i will try to find the source some time soon, you gave very good idea to use flashlight in dark..

ANOTHER crap i noticed: When i floor the gas pedal from 0-100, my car misses like 2-3 times feeling like unable to get enough power or something.
transmission fluid was changed 1 year ago,
have been using petrol (no hi octane),
battery cells recently replaced, the battery is fine enough as it stays 75% on charge, when it was bad it used to stay 60% charge,
tyres have less traction though (which i am most tilted towards as the cause of acceleration missing).

i will do a simple test on inclined road to cfm it's the tyres/traction problem (i hope so).

[abbasqamar3166]

Waiting for update

[dua3346]

UPDATE:

i could not see any smoke other than from the exhaust / muffler at the rear.
when i returned after a normal drive, i smelled the burning from all sides of the car quickly, i felt like the sides of the car are most smelly, the rear is not much, the front is also fine.

Car missing 2-3 times on max gas pedal:
I tested this on an inclined road, my car missed 2-4 times when going uphill.
While hardly missed 1 time when going downhill.
I think it's about the road traction / tyres.

[abbasqamar3166]

Did u resolve this issue

[dua3346]

Nope, I can smell the burning oil after trips outside my car, but i dont get the smell inside cabin anymore or maybe it's too low.