URGENT HELP - engine smoking under deceleration, EXHAUSTED

OK guys, I'm ready to tear my hair out. Have a car I have recently done an engine swap on due to a broken ring land.

Now engine is smoking during deceleration then RE acceleration.

Here is what I have done.

Hot dry compression test on engine was 160-165 across the board before engine was pulled out of donor and fitted.

Fresh rebuilt turbos fitted during the swap

All under plenum deletes completed

Pcv valves cleaned/tested and new hoses

Inhale repulled engine and redone the turbos with a full new kit as I suspected it was the turbos - this has reduced the smoke but it is still there.

Plugs/cylinders are dry and showing no signs of oil/fouling.

No change when I disconnected pcv valves and left them open.

Dry/wet test done again to double check, dry test still around 160 across the board, number 2 2 went up 10psi on wet teat and number 5 went up 15 but still well within spec in my opinion and no cause fore concern under ordinary circumstances.

No oil in intake pipes, I suspect it might still have some.residual oil in the exhaust system as it pumped a good sump worth of oil through the exhaust, but I did drain it out , block the ends off and fill it full of degrwaser and flush it out.

Now it starts up with no smoke, doesn't have smoke at idle, give it a good rev and.you get a bit of smoke once it returns to idle then clears.

Exhaust has a middle muffler fitted so is suspect it won't be a balance issue but it could be single chambers on that muffler.

I am honestly open to all and any suggestions.

 

Could be few things... What is the color of the smoke? What's your oil consumption?

Running rich?

Turbo oil return line blocked/kinked?

Valve guides seals?

 

Grey/blue smoke so oil

Both drains were clear but I will pull the driver side return off and double check that.

Oil consumption is minimal.

I suspected valve stem seals but I would expect it to smoke on start up over night and there is no smoke at all after leaving it over night.

It's almost like negative pressure is drawing the oil through as it is just whisping/swirling through, it's not pouring out

 

I didn't wanna bring the bad news on the very beginning but...

it is the sign of bad oil rings...
The high vacuum during deceleration pulls oil past the rings, the low volume of air flowing through the cylinders doesn't flush the oil out quickly, so as it sputters into the hot exhaust system it makes a lot of smoke. It will persist for a few seconds after you get back on the throttle, too. And this may not show up on a compression test either, since the oil control rings may be worn and the compression rings can still be OK.


You can drive like that for a while (just keep an eye on oil level)... Once it blows rebuilt it... Or forget it...

Other will might have something different to say but yeah those are my 2 cents...

 

You got a H/X pipe in the exhaust? There has been a few cases in the past where fitting one has fixed mysterious oil smoke problems.

 

"I suspect it might still have some residual oil in the exhaust system as it pumped a good sump worth of oil through the exhaust"

When you mention "a good sump worth of oil", this quantity is open to interpretation.
The FSM indicates the engine oil refill capacity is 3.0 litres not including the oil filter.
If the oil was pumped into the exhaust.
How much was left in the engine?
How long was the engine running once the smoke was noticed?
What did the turbo rebuilder discover or identify as a cause of the oil entering the exhaust?
There is something wrong with your engine compression test results.

You mentioned the initial test indicated 160 to 165 PSI on all cylinders prior to purchase.

When you performed the second test you mentioned.

"Dry/wet test done again to double check, dry test still around 160 across the board, number 2 2 went up 10psi on wet test and number 5 went up 15 but still well within spec in my opinion and no cause fore concern under ordinary circumstances."

You mention number 2 & number 5 cylinder pressure increased during the wet test.
What about the other 4 cylinders?
Did the pressures also increase by a similar amount of 10 to 15 PSI?

 

Yeah that's what I'm suspecting Rob.

OK, so I bought this car with a blown engine. This motor had just been fitted with a pair of cheap Chinese turbos and had not seen the road as it had a catastrophic failure straight after they had done the turbos in the workshop.

After first purchase I regularly had to start the car and drive it in/out of the driveway and move it around at the panel shop while some paint work was being done. It smoked like a cheech and chong film.

Upon pulling this motor down once removed it was discovered the cause was a broken ring land on #4 piston, and I would suggest about 2-3 litres of oil had been pushed past the turbos into the exhaust and through the intercoolers. I pulled exhaust and coolers off, flushed them with de greaser.

Donor car had engine removed and fitted, along with a pair of rebuilt Factor turbos. These turbos had been rebuilt several years ago and where wrapped up sitting on the shelf. Same exhaust and intercoolers fitted.

After first start up I straight away suspected the oil rings on the turbos were gone. I drove it for about two weeks, didn't consume any oil that I could tell, but had clouds of smoke on deceleration and reapplication of power.

Pulled engine, marked everything on turbos and put a new kit from roserage turbos through them both. Didn't notice anything sinister within turbos except passenger turbo had oil throughout the the exhaust housing and also turbo air intake was flooded with oil.

Fitted the freshly sealed/kitted turbos, considerably less smoke, a completely different car, but it still had some smoking occurring during deceleration, most notably/prominently on the driver side now(which is why I suspect the middle muffler might be separate chambers or not sufficient to balance both sides of exhaust)

Bit the bullet again yesterday and did a wet and dry test as follows
Dry-
1 - 160
2 - 165
3- 160
4- 160
5- 160
6- 160

Wet-
1- 165
2- 175
3- 165
4- 160
5- 176
6- 160

Motor is running real strong, plugs have a clean burn on them, they are coppers and gasped at 1mm from memory.

Plenum had some oil residue within it on passenger side so that has been cleaned out, intake hoses have NO oil within so I don't think it will be the intercooler with some residual in it but that is always a possibility.

I think I will get a balance pipe fitted to the exhaust just as a tick off the list.
I'll also throw some seafoam through the intake and then some atf fluid in the bores over night incase it is a stuck /gummy oil ring.

It's just apart from the small amount of smoke the engine is otherwise perfect.

 

Try a balance pipe in the exhaust. Either a H or X pipe. Some members who had unexplained smoke in the past fixed it with just having the dual exhaust piping merge somewhere.

 

How many ks has the fresh motor done since install?

Despite the fact youve cleaned everything thoroughly, it will still take a while to "clean the pipes" of all the oil / cleaning products etc.

you could drop the exhaust off and run without it to elimate the exhaust as the source of the smoke.

 

Done about 500-600 km since engine change.
About 300 since doing the turbos again.

It looks like the middle muffler is conjoined so I'm doubting it is a balance issue.
Just run some upper cylinder head cleaner through the motor, no difference notices after 40km so I guess I'll just take it for a really long drive over the weekend to see if it clears up.

Knowing my luck it's going to be bloody valve stem seals, which would be surprising as when I prepped the motor to fit it appeared to have possibly been rebuilt at some point in its life, or at least the heads had been off as the top end was clean like new, no tarnishing or funk build up.

 

Could even merge by connecting the old AIV hoses together???

But he did say there was a common muffler in there at beginning of thread.

 

Bit the bullet again yesterday and did a wet and dry test as follows
Dry-
1 - 160
2 - 165
3- 160
4- 160
5- 160
6- 160

Wet-
1- 165
2- 175
3- 165
4- 160
5- 176
6- 160

A wet test by adding oil to the cylinders should identify worn piston rings or cylinder bores.
If the pressures do not increase then valve sealing is possibly the issue.

This is what I see in relation to your tests.
171 PSI is what a good engine would produce.

#1 Dry - 160 Wet 165 +5
#2 Dry - 165 Wet 175 +10
#3 Dry - 160 Wet 165 +5
#4 Dry - 160 Wet 160 NO CHANGE WHY?
#5 Dry - 160 Wet 176 +16
#6 Dry - 160 Wet 160 NO CHANGE WHY?

As the dry test pressures are relatively even.

Why aren't all the cylinders increasing by a similar amount during the wet test?

 

A wet test by adding oil to the cylinders should identify worn piston rings or cylinder bores.
If the pressures do not increase then valve sealing is possibly the issue.
As stated before....adding oil does not seal leaking valves. Number 4 and 6 have valve issues.

 

Could this be timing belt on wrong teeth?

 

I'll pressurise number 4 later this week to see if I hear any leaking but I'm highly doubtful the valves are failing to seal, Compression would be way lower than 160 I would have thought. Regardless that won't cause the oil smoke. I'll put another exhaust on on the weekend and drive it a bit more and see if it starts to clear out

 

THIS!!!
The whole story "in a Nut Shell".:agree::br:

 

Actually thinking about that and the compression results I got, 4 &6 would possibly be more indicative of a head gasket issue with a bridge/gap between the cylinders. This could indicate why they don't change, but normally you would expect a lower compression than what I got. I'm thinking I will definitely need to do a leak down teat before I keep ****ing with this any further

 

This is what I would do, prior to jumping to any conclusions.

Ensure the engine is at normal operating temperature & the battery is fully charged.

Remove all the spark plugs & the fuel pump fusible link.

Perform a compression test with the throttles wide open & record the readings.

Perform another compression test, this time injecting the same quantity of oil (perhaps use a syringe) into each cylinder immediately before inserting the gauge & record the readings.


It may be beneficial to have the vehicle on a level surface during the tests.

 

I thought it was the other way around, removal of the H/X pipe caused a funky low pressure pulse which sucked oil through the turbo seals?