Blue exhaust smoke on overrun (2 Viewers)

[snapdragon]

Hi
Its been a while since I have posted here.

Rebuilt my 1fz engine last year, all has been well, already put 25k km on it with no issues until now.
I am getting blue exhaust smoke when coasting downhill in gear, and a little on cold starting first thing in the morning.
The only thing I have not replaced in my rebuild where the guides, was told they are good.
Any ideas where I should look? Not interested in tearing motor apart again.

Cheers
Warren

 

[TYM4FUN]

Sounds like the guides seals. They definitely should have been replaced, bummer...

 

[BILT4ME]

Hi
Its been a while since I have posted here.

Rebuilt my 1fz engine last year, all has been well, already put 25k km on it with no issues until now.
I am getting blue exhaust smoke when coasting downhill in gear, and a little on cold starting first thing in the morning.
The only thing I have not replaced in my rebuild where the guides, was told they are good.
Any ideas where I should look? Not interested in tearing motor apart again.

Cheers
Warren

^^^ What he said.

Blue smoke on deceleration is valve seals / guides
Blue smoke on start-up is valve seals / guides
Blue smoke on acceleration is rings
White smoke on acceleration is head gasket
Black smoke on acceleration is fuel

 

[snapdragon]

^^^ What he said.

Blue smoke on deceleration is valve seals / guides
Blue smoke on start-up is valve seals / guides
Blue smoke on acceleration is rings
White smoke on acceleration is head gasket
Black smoke on acceleration is fuel

Yes, I have read this before, however cand oil smoke on overrun also be rings? And what fault in the ring pack causes it?

 

[BILT4ME]

Yes, I have read this before, however cand oil smoke on overrun also be rings? And what fault in the ring pack causes it?

Overrun. I assume you mean coasting or deceleration.

That's valve guides and seals. It happens because there's no overpressure event in the cylinder to blow the oil back out of the valve guide. The valve guide is under constant vacuum with higher RPM that keeps the oiling at the head, so the oil bath is there and it sucks in the oil.


When rings are leaking, it can be worn or cracked compression rings or a broken oil scraper ring.

 

[snapdragon]

Overrun. I assume you mean coasting or deceleration.

That's valve guides and seals. It happens because there's no overpressure event in the cylinder to blow the oil back out of the valve guide. The valve guide is under constant vacuum with higher RPM that keeps the oiling at the head, so the oil bath is there and it sucks in the oil.


When rings are leaking, it can be worn or cracked compression rings or a broken oil scraper ring.

Yes, overrun I mean coasting down a long hill or deceleration.

Rings and pistons are brand new, from Toyota, and don't have any symptoms on acceleration and pulling 21-22 inches on vacuum gauge.

Thank you, will stick a camera down the ports to check them

 

[BILT4ME]

Yes, overrun I mean coasting down a long hill or deceleration.

Rings and pistons are brand new, from Toyota, and don't have any symptoms on acceleration and pulling 21-22 inches on vacuum gauge.

Thank you, will stick a camera down the ports to check them

If you have new rings, you will be using some oil until the rings "seat" in the cylinder wall. That should be under acceleration primarily, though.

If guides were not replaced, you may be OK, but valves seals should have DEFINITELY been replaced.

 

[snapdragon]

If you have new rings, you will be using some oil until the rings "seat" in the cylinder wall. That should be under acceleration primarily, though.

If guides were not replaced, you may be OK, but valves seals should have DEFINITELY been replaced.

Yes the seals where replaced, along with every wear item on this motor, except the guides. Hence my frustration here.

Surely though after 25 000 km, the rings should have seated by now? Or does this motor need longer?

 

[BILT4ME]

Yes the seals where replaced, along with every wear item on this motor, except the guides. Hence my frustration here.

Surely though after 25 000 km, the rings should have seated by now? Or does this motor need longer?

No, they should have been seated by 25K.

Ok, next thing to check is the PCV system. If it is sticking, then the check ball in it is not stopping the vacuum and it's sucking too hard on the crank case under long deceleration.

Cure any vacuum leaks too because that make it all worse.

 

[snapdragon]

Thank you.

I will check it over Easter and let you know.

No, they should have been seated by 25K.

Ok, next thing to check is the PCV system. If it is sticking, then the check ball in it is not stopping the vacuum and it's sucking too hard on the crank case under long deceleration.

Cure any vacuum leaks too because that make it all worse.

 

[TYM4FUN]

Yes the seals where replaced, along with every wear item on this motor, except the guides. Hence my frustration here.

Surely though after 25 000 km, the rings should have seated by now? Or does this motor need longer?

Edited my post as I accidentally left out the word seals. Glad you had them replaced..

 

[TYM4FUN]

@BILT4ME Can guides on their own cause oil loss?

 

[BILT4ME]

@BILT4ME Can guides on their own cause oil loss?

They can, but usually, they compromise the new seals as well.

He has 25K km on a rebuild which is no longer new.
Yes seals will wear faster on worn guides because there is more vacuum on them and more debris due to debris migration.

If guides were worn but still in tolerance at rebuild it shouldn't be an issue. However, if they were at the wide side of tolerance then and now an additional 25K, then yeah, he could be having issues.

All that said, I think there are more issues going on.


As an example, my 1FZ will drink oil if I run sustained over 3400 RPM. If I keep it below 3000 RPM, It uses little if any.

It's because the RPM increases the flow of oil to the top of the head and it can't run back fast enough so it "pools" up there and then the PCV system does its job and it sucks oil out with it, thus burning lots of oil Similar to what's happening for long sustained downhill runs on deceleration.

 

[TYM4FUN]

They can, but usually, they compromise the new seals as well.

He has 25K km on a rebuild which is no longer new.
Yes seals will wear faster on worn guides because there is more vacuum on them and more debris due to debris migration.

If guides were worn but still in tolerance at rebuild it shouldn't be an issue. However, if they were at the wide side of tolerance then and now an additional 25K, then yeah, he could be having issues.

All that said, I think there are more issues going on.


As an example, my 1FZ will drink oil if I run sustained over 3400 RPM. If I keep it below 3000 RPM, It uses little if any.

It's because the RPM increases the flow of oil to the top of the head and it can run back fast enough so it "pools" up there and then the PCV system does its job and it sucks oil out with it, thus burning lots of oil Similar to what's happening for long sustained downhill runs on deceleration.

Thank you very much. Your explanation confirmed my thoughts/guess of worn guides causing alignment wear issues regarding the seals. Agree on the PCV system. Also I note that the valve cover was redesigned, having a much larger flow back system. My guess here is to mitigate the oil backup in the baffle.

 

[BILT4ME]

Thank you very much. Your explanation confirmed my thoughts/guess of worn guides causing alignment wear issues regarding the seals. Agree on the PCV system. Also I note that the valve cover was redesigned, having a much larger flow back system. My guess here is to mitigate the oil backup in the baffle.

I tested this theory last week out here in windy Kansas.

I regularly travel to one shop that is 3 hours away with 75 MPH rated interstate drives. I normally run 83 MPH (allegedly) and that's pushing about 3000 RPM until it downshifts out of OD on the Flint Hills area, then pulls about 3600+ for over a mile before it can kick the OD back on.

Then it runs that way until the next hill about a mile away and repeats throughout the trip. I will frequently use 1/2 qt oil on this trip doing this.

Last week the wind was blowing so hard (headwind) that the OD couldn't even hold and maintain 70 MPH in those conditions.
So, I acquiesced to Mother Nature and slowed down and ran 60-65 the rest of the trip, both ways. I used no oil at all.

On my other shop trips that are a max of 65 MPH roads and about 1.25 hours, I never use oil because I'm typically in the 2600-2800 RPM range, even when I'm pushing it.

 

[TYM4FUN]

I tested this theory last week out here in windy Kansas.

I regularly travel to one shop that is 3 hours away with 75 MPH rated interstate drives. I normally run 83 MPH (allegedly) and that's pushing about 3000 RPM until it downshifts out of OD on the Flint Hills area, then pulls about 3600+ for over a mile before it can kick the OD back on.

Then it runs that way until the next hill about a mile away and repeats throughout the trip. I will frequently use 1/2 qt oil on this trip doing this.

Last week the wind was blowing so hard (headwind) that the OD couldn't even hold and maintain 70 MPH in those conditions.
So, I acquiesced to Mother Nature and slowed down and ran 60-65 the rest of the trip, both ways. I used no oil at all.

On my other shop trips that are a max of 65 MPH roads and about 1.25 hours, I never use oil because I'm typically in the 2600-2800 RPM range, even when I'm pushing it.

To add test data, my head has new guides, valve seals and the new style valve cover on original bottom end of 200k. Before was almost a qt on every fuel up and now zero oil loss. I am a huge proponent of high RPM's for cooler engine and trans temps, so I always see at or over 3k to avoid excess load when needed. Currently 2.8k on new... items.

Prior, I also recorded increased oil loss above 3k or loaded as well.

 

[SNLC]

I have no issues running mine at 4k rpms for miles.

Nearly 8,000 miles on a new engine. Consumes zero oil. I run Mobil1 full synthetic.

Cheers

 

[snapdragon]

My engine doesnt burn a lot of oil. Maybe half a litre of mobil 1 in 7500km.
Just have the deceleration blue smoke issue.
I do a lot of highway driving running around 130km/h.
Will check PCV this weekend and see if anything changes.

 

[BILT4ME]

I tested this theory last week out here in windy Kansas.

I regularly travel to one shop that is 3 hours away with 75 MPH rated interstate drives. I normally run 83 MPH (allegedly) and that's pushing about 3000 RPM until it downshifts out of OD on the Flint Hills area, then pulls about 3600+ for over a mile before it can kick the OD back on.

Then it runs that way until the next hill about a mile away and repeats throughout the trip. I will frequently use 1/2 qt oil on this trip doing this.

Last week the wind was blowing so hard (headwind) that the OD couldn't even hold and maintain 70 MPH in those conditions.
So, I acquiesced to Mother Nature and slowed down and ran 60-65 the rest of the trip, both ways. I used no oil at all.

On my other shop trips that are a max of 65 MPH roads and about 1.25 hours, I never use oil because I'm typically in the 2600-2800 RPM range, even when I'm pushing it.

For data:

My engine has 327K miles on it with the HG done at 145K and a full head rebuild.

So, I am using the oil at high RPM on an engine that has 182K miles on the head rebuild. I think that's pretty damn good.

I use Quaker State Dino oil 5W-30.

 

[snapdragon]

A bit of an update......
Cleaned out PCV and drained a little oil from sump( was a bit overfilled) and the problem has become significantly better.
Still there though.