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burning smell

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Old 07-28-2018, 11:46 PM
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burning smell

Burning smell that is getting stranger...1400 kms since rebuild.
ive ruled out...
no leaks or not enough from rear eccentric shaft.
no other leaks
cat is not on fire .
i didn't run over a plastic bag
engine has been steam cleaned. No oil spilled anywhere....tried with a new cabin filter...and without a cabin filter
so here's the problem. ..
when i turn down the temperature as low as it will go without turning on the ac and on fresh air ..i get a slight burning plastic smell through the vents...
However. .i tried an experiment today..
it doesn't happen on recirculation. .
it also doesn't happen on fresh air but with the heating on...
is the heater core starting to melt something around it...only happens after a prolonged drive..thr car has been run and examined underneath when.hot..
anyone experiencenced this.

Last edited by dalippy; 07-28-2018 at 11:48 PM.
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Old 08-02-2018, 10:03 PM
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Just bought an 05. I notice a distinct rubber smell coming from the engine when I first start it up. While driving and coming to a stop I occasionally get a wif of the same smell. The only thing I can figure is maybe the belts.
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Old 08-03-2018, 02:45 AM
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If your belts are that loose, you will be able to tell by pressing your finger on the belts. They normally shouldn't have a lot of play.
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Old 08-03-2018, 09:40 AM
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dalippy: check for oil leaks at the OMP to engine block joint. They're almost invisible but end up flinging oil onto the exhaust manifold at speed. Best seen from underneath.

I don't think it would be the heater core, it doesn't get hotter than coolant, and that's around water boiling temp, not enough to melt anything.

If it doesn't happen on recirc, then the smell is from outside I recon.

Anything sitting close to the exhaust manifold? Loose wires maybe?

@petscar: when you first start it up, everything is cold, so whatever you're smelling would have to come from the exhaust gases. How is your coolabc level?
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Old 08-03-2018, 09:58 AM
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Did you mean coolant level? If you did, I haven't but I will. It should be ok because the guy I bought it for just had it serviced at Mazda in April. Is there a reason you suggest checking the coolant?
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Old 08-03-2018, 10:02 AM
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Originally Posted by Petscar View Post
Did you mean coolant level? If you did, I haven't but I will. It should be ok because the guy I bought it for just had it serviced at Mazda in April. Is there a reason you suggest checking the coolant?
Because if you have coolant seeping into the combustion chamber, the exhaust will smell sweet on start up. Depending on your sense of smell, that may be what you're sensing.
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Old 08-03-2018, 10:06 AM
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I will definitely check that. But wouldn't you smell that at the back of the car? Mine is from the engine compartment.
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Old 08-03-2018, 11:41 AM
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re

Just an update thanks for the suggestions..no the belts are not loose..and I've another thread about omp pumps...had some trouble. .it is now perfect
.
its just good old fashioned engine fumes. .The heat here got a bit much this summer 30.c or 90.f in old money. .wasn't helping
i bought an activated carbon cabin filter..
mazda are very expensive. ..here in Europe mazda use mahle for filters..so got a mahle carbon filter ...
problem solved. .
​​​​​​​because there is absolutely nothing else it could be
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Old 08-03-2018, 11:47 AM
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Originally Posted by dalippy View Post
Just an update thanks for the suggestions..no the belts are not loose..and I've another thread about omp pumps...had some trouble. .it is now perfect
.
its just good old fashioned engine fumes. .The heat here got a bit much this summer 30.c or 90.f in old money. .wasn't helping
i bought an activated carbon cabin filter..
mazda are very expensive. ..here in Europe mazda use mahle for filters..so got a mahle carbon filter ...
problem solved. .
​​​​​​​because there is absolutely nothing else it could be
@ pets car..put it on a ramp and check absolutely everywhere for leaks before you do anything else. ..don't miss the front oil cooler. .they can leak too.
I've a funny feeling that intake manifold is blowing out some fumes of the engine ..that oil that collects before the maf intake pipe is a quirk of that engine. .the rotors throw droplets of oil up through the intake.. (all the engines are like this I've seen loads..its not inconceivable that gas is escsping through a slightly aged o ring in the same spot..considering the odd foibles of these engines as regards heat transfer and half the raw fuel being spat out the exhaust port i wouldn't be surprised

Last edited by dalippy; 08-03-2018 at 11:50 AM. Reason: mistake
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Old 08-03-2018, 04:38 PM
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Thanks.
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Old 08-03-2018, 07:36 PM
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The rotors are not throwing oil up the intake against transsonic airflow. That oil is forced into the intake via the PCV by excess blowby pressure. If all the ones you've seen are like this, then they're all broken. A healthy car's intake is bone dry.

Nor is half the fuel spat out the exhaust, the cars run near stoich AFR just like any engine. On a healthy engine, obviously.
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Old 08-04-2018, 04:08 PM
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Originally Posted by Loki View Post
The rotors are not throwing oil up the intake against transsonic airflow. That oil is forced into the intake via the PCV by excess blowby pressure. If all the ones you've seen are like this, then they're all broken. A healthy car's intake is bone dry.

Nor is half the fuel spat out the exhaust, the cars run near stoich AFR just like any engine. On a healthy engine, obviously.
...its all over this website about the oil sitting in the air intake. .
I've seen a mazda workshop bulletin about the fact if cars come in experiencing this problem its a normal quirk of the engine. ..not a symptom of a worn engine..
...blow by ?what the f##k are you talking about its not a piston engine...
and you are talking through your *** about not spitting half burned fuel...
why is there a leading and trailing spark plug..
it was an unsuccessful attempt by mazda to burn all the fuel ...
spitting flames out exhaust?
cats going on fire...
19 mpg
i could go on but i couldn't be bothered
thanks for trying to help but you haven't a clue..
ill give you some marks for effort but try to stop talking through your ***..it exposes your ignorance

Last edited by dalippy; 08-04-2018 at 04:13 PM. Reason: spelling
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Old 08-04-2018, 06:53 PM
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Lol. Ok.
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Old 08-06-2018, 10:41 AM
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Originally Posted by Loki View Post
Lol. Ok.
You tried. He'll figure it out eventually.
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Old 08-07-2018, 06:24 AM
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Originally Posted by MikeTyson8MyKids View Post
You tried. He'll figure it out eventually.
​​​​​​​keyboard warriors.../armchair mechanics
nothing constructive to add...
​​​​​​​

Last edited by dalippy; 08-07-2018 at 06:28 AM.
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Old 08-07-2018, 02:19 PM
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Originally Posted by dalippy View Post


keyboard warriors.../armchair mechanics
nothing constructive to add...
​​​​​​​
Ok, one last shot to help get you in the right direction.

1) If you are feeling much at all come through the breather, that's a problem. On both of my engines, even with the one that was failing, there was no flow (more on this later). I never experienced oil in the intake either.
2) My engine failed on one of the rotors with 2 weak pulses, one strong pulse. What does this mean? Apex seal damage. Compression bleeding from one side of the rotor to the other.
3) We've also seen plenty of example of 1 weak pulse, 2 strong pulses. What does this mean? That means there's either a side seal failure or a corner seal failure. Compression is bleeding through the side/corners seals.

Which...brings me to my point. Where does that compressed air go when it is bleeding around the side/corner seals?

It has to go somewhere.....and that's out the PCV. It goes around the side/corner seals, around the oil control rings...into the crankcase raising the pressure. That pressure is bled off through the PCV tube, right back into the intake. Because that air is traveling through the crankcase, it takes oil/oil mist with it...which is why you find oil in the intake accordion. As of note, its also possible to get oil in the intake by simply overfilling. What you are describing though is air flow out the PCV, which simply shouldn't be there to the level you are describing.

Like Loki was saying, oil doesn't come back up through the jet air nozzles and back into the intake. That is high velocity air with a large pressure delta...all the air/oil is traveling INTO the engine at high velocity.

Now, unless I've never seen it, there's not an allowable PCV flow spec called out in the factory service manual. The way to find out for sure is compression test, which Mazda references many times. That'll give you an overall health report on your engine. And from the pulse patterns, can see what is wrong. Apex seal, side seal, or just generally worn out.

In summary: Get a compression test.
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Old 08-08-2018, 06:58 PM
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Originally Posted by MikeTyson8MyKids View Post
Ok, one last shot to help get you in the right direction.

1) If you are feeling much at all come through the breather, that's a problem. On both of my engines, even with the one that was failing, there was no flow (more on this later). I never experienced oil in the intake either.
2) My engine failed on one of the rotors with 2 weak pulses, one strong pulse. What does this mean? Apex seal damage. Compression bleeding from one side of the rotor to the other.
3) We've also seen plenty of example of 1 weak pulse, 2 strong pulses. What does this mean? That means there's either a side seal failure or a corner seal failure. Compression is bleeding through the side/corners seals.

Which...brings me to my point. Where does that compressed air go when it is bleeding around the side/corner seals?

It has to go somewhere.....and that's out the PCV. It goes around the side/corner seals, around the oil control rings...into the crankcase raising the pressure. That pressure is bled off through the PCV tube, right back into the intake. Because that air is traveling through the crankcase, it takes oil/oil mist with it...which is why you find oil in the intake accordion. As of note, its also possible to get oil in the intake by simply overfilling. What you are describing though is air flow out the PCV, which simply shouldn't be there to the level you are describing.

Like Loki was saying, oil doesn't come back up through the jet air nozzles and back into the intake. That is high velocity air with a large pressure delta...all the air/oil is traveling INTO the engine at high velocity.

Now, unless I've never seen it, there's not an allowable PCV flow spec called out in the factory service manual. The way to find out for sure is compression test, which Mazda references many times. That'll give you an overall health report on your engine. And from the pulse patterns, can see what is wrong. Apex seal, side seal, or just generally worn out.

In summary: Get a compression test.
thanks for the info...yeah more constructive
but the car was checked pre rebuild for compression ..it was very low...i can't remember what it was. ..its on another thread i left
but the engine has been rebuilt and compression tested pre and post break in period and is showing very healthy numbers. ..
and as regards the oil in the intake. .its not much. ..
and i really was shown two workshop bulletins direct from mazda...i took a picture of the bulletins ..if i find it ill post it...
but 1st bulletin was that mazda recommend now...After research using mineral oil instead of synthetic. .because of its ability to burn cleaner and not stick to the ports/walls of rotor housing. . (Synthetic /semi doesn't burn well. ..causing gumming of the ports and or rotor tips...
This in turn extends rotor tip and or housing life..
The bulletin came from Japan with pictures of research
The 2nd bulletin may be related to the first. .causing unexpected 'blow by'
but basically as i said before mazdas outlook on a little oil in the intake is "don't worry about it ..its normal ". .im not talking about a litre. Only a thimble amount...
now if you want to disagree with me and tell me im lying. ..or just plain old wrong. .thats fine im not really too bothered im not gaining much from this site...all my problems I've had so far have been solved by professional rotary engine builder's and talking to mazda trained mechanics.
i understand what you are saying. ..oil can push past worn side seals ,rotor tips and oil rings...resulting in a worn engine pushing oil out in a nutshell. ..
but my engine isn't worn...and some oil in the intake is normal. .
don't forget im in Europe here and the specs are slightly different here
..we have little or no autos and a lot of 190 manuals. .all our cars come with lsds etc..so the specs are not the same. ..the fan housing isn't even on the same side

Last edited by dalippy; 08-08-2018 at 07:15 PM. Reason: spelling
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Old 08-08-2018, 09:34 PM
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Originally Posted by dalippy View Post
thanks for the info...yeah more constructive
but the car was checked pre rebuild for compression ..it was very low...i can't remember what it was. ..its on another thread i left
but the engine has been rebuilt and compression tested pre and post break in period and is showing very healthy numbers. ..
and as regards the oil in the intake. .its not much. ..
and i really was shown two workshop bulletins direct from mazda...i took a picture of the bulletins ..if i find it ill post it...
but 1st bulletin was that mazda recommend now...After research using mineral oil instead of synthetic. .because of its ability to burn cleaner and not stick to the ports/walls of rotor housing. . (Synthetic /semi doesn't burn well. ..causing gumming of the ports and or rotor tips...
This in turn extends rotor tip and or housing life..
The bulletin came from Japan with pictures of research
The 2nd bulletin may be related to the first. .causing unexpected 'blow by'
but basically as i said before mazdas outlook on a little oil in the intake is "don't worry about it ..its normal ". .im not talking about a litre. Only a thimble amount...
now if you want to disagree with me and tell me im lying. ..or just plain old wrong. .thats fine im not really too bothered im not gaining much from this site...all my problems I've had so far have been solved by professional rotary engine builder's and talking to mazda trained mechanics.
i understand what you are saying. ..oil can push past worn side seals ,rotor tips and oil rings...resulting in a worn engine pushing oil out in a nutshell. ..
but my engine isn't worn...and some oil in the intake is normal. .
don't forget im in Europe here and the specs are slightly different here
..we have little or no autos and a lot of 190 manuals. .all our cars come with lsds etc..so the specs are not the same. ..the fan housing isn't even on the same side
I wouldn't too concerned about the very small amount of oil. For all I care, I could have just overfilled a small amount anyway.

As for synthetic versus conventional, some members here use synthetic and seem to do just fine. I use conventional, but mainly because at 3000 mile/5000 km interval, any advantage of synthetic oil goes out of the window. If you use a SOHN adapter and inject 2-stroke into your engine, then using synthetic is fine since it's no longer being burnt.
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Old 08-09-2018, 07:48 AM
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Originally Posted by UnknownJinX View Post
I wouldn't too concerned about the very small amount of oil. For all I care, I could have just overfilled a small amount anyway.

As for synthetic versus conventional, some members here use synthetic and seem to do just fine. I use conventional, but mainly because at 3000 mile/5000 km interval, any advantage of synthetic oil goes out of the window. If you use a SOHN adapter and inject 2-stroke into your engine, then using synthetic is fine since it's no longer being burnt.
full synthetic is a no no
no one that has anything to do with mazda recommends it even with the sohn adapter a certain amount of residual oil will still be burned
...engine class 1st day...synthetic oil doesn't burn well
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Old 08-09-2018, 08:22 AM
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but maybe guys fiddling in their sheds know be

Mazda spent 40 years development and countless millions with experienced automotive engineers on this engine. .i think they know what they are talking about
​​​​​​​
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Old 08-09-2018, 08:31 AM
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Originally Posted by dalippy View Post
full synthetic is a no no
no one that has anything to do with mazda recommends it even with the sohn adapter a certain amount of residual oil will still be burned
...engine class 1st day...synthetic oil doesn't burn well
Mazda recommends 5w20 here in the US....and all 5w20 is a GF4 synthetic blend by necessity to reach that viscosity. So, Mazda isn't exactly giving a clear direction there.

There's 13 years of arguing about synthetic oil on this forum.

I've run at least 5w30 GF4 synthetic in mine since day 1, along with premix after a while. First engine went to 99k miles..had no specific issues with it, but it failed compression test so I got a reman. The reman now has 60k on it. All premixed, all synthetic. Stock cat too with 160k...and its just fine. Other people have done similar to me, and can't get an engine to go 20k.

Point is, engine life on these cars is more about oil change intervals, ignition health, drive cycle, OMP function, and engine build quality.
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Old 08-09-2018, 08:41 AM
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Really, I thought in the 1st day of engine class they'd at least explain different oil groups and how polymer deposits are formed and resorbed. Maybe touch on the definition of "synthetic" and how it's a marketing term more than anything else. Maybe even explain exactly what kind of synthetic was tested and found to produce deposits under what conditions. Are you sure it wasn't dogma class?

Some synthetic oils create deposits. Some are fine ( higher quality group V's). Many mineral oils polymerize if you just look at them wrong, but at least they resorb their own deposits. It depends on the base stock and additive chemistry. Mazda even sold their own blend of synth for the Renesis specifically at some point. The Mazda manuals were written 14 years ago at this point. Oil chemistry has moved on, for example metallic ash content has been heavily diminished with the last 2 API specifications.

So yeah, we can play the condescending game all day here, so do you want help with your car or not?

P.S. I like how the very evidence you linked says "don't use any synthetic that Mazda hasn't evaluated". Do you think Mazda has evaluated all of them? Or any at all produced in the last 8 years?

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Old 08-09-2018, 11:05 AM
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Originally Posted by Loki View Post
Really, I thought in the 1st day of engine class they'd at least explain different oil groups and how polymer deposits are formed and resorbed. Maybe touch on the definition of "synthetic" and how it's a marketing term more than anything else. Maybe even explain exactly what kind of synthetic was tested and found to produce deposits under what conditions. Are you sure it wasn't dogma class?

Some synthetic oils create deposits. Some are fine ( higher quality group V's). Many mineral oils polymerize if you just look at them wrong, but at least they resorb their own deposits. It depends on the base stock and additive chemistry. Mazda even sold their own blend of synth for the Renesis specifically at some point. The Mazda manuals were written 14 years ago at this point. Oil chemistry has moved on, for example metallic ash content has been heavily diminished with the last 2 API specifications.

So yeah, we can play the condescending game all day here, so do you want help with your car or not?

P.S. I like how the very evidence you linked says "don't use any synthetic that Mazda hasn't evaluated". Do you think Mazda has evaluated all of them? Or any at all produced in the last 8 years?
Agreed. There's much more important items to do, like keeping ignition coils fresh, than worrying about "synthetic" oil.
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Old 08-09-2018, 02:07 PM
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Originally Posted by dalippy View Post
Mazda spent 40 years development and countless millions with experienced automotive engineers on this engine. .i think they know what they are talking about

https://www.rx8club.com/series-i-tec...ne-oil-249264/
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Old 08-09-2018, 02:19 PM
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Looking at the date, this was published in 2006.

Synthetic oil has changed a bit. Some older synthetic oil actually ate seals in some older piston engines and those manufacturers also said no synthetic.

Personally, my decision is simply based on cost and that conventional is adequate for my use.
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