Surprisingly clean intake valves at 187k miles

[VeryNoisyPoet]

I have the manifold off to install an oil pressure sender and to service/inspect the PCV system. Quite surprised to see how clean all the valves look. I expected at least some deposits or varnish. This car will get some PEA-based fuel system cleaner run through maybe once per year. I tried MMO for a few tanks earlier in the year but stopped when it didn't give any noticeable improvement in engine smoothness or fuel economy (though it did make the exhaust smell nicer on a cold start!)



The intake runners themselves have a fair bit of crud so the manifold and throttle body are getting cleaned while I'm at it. Really tough baked carbon that smells evil and seems to resist anything but a dousing of carb cleaner. Really wish I had a big parts washer tank so I could soak the darn thing overnight.

 

[Snagglefoot]

Great valves. Which gasoline do the typically buy?

 

[VeryNoisyPoet]

Originally Posted By: Snagglefoot
Great valves. Which gasoline do the typically buy?

Whoops forgot to add that info in the post.

I use the cheapest midgrade gas that Gasbuddy brings up that's not too far out of my way. I don't thrash it but I'm not afraid to put the hammer down when safe and necessary.

 

[Snagglefoot]

Over there do they tend to give you more fuel injection cleaner in mid grade than regular?

 

[VeryNoisyPoet]

Originally Posted By: Snagglefoot
Over there do they tend to give you more fuel injection cleaner in mid grade?

Not sure about detergent levels in midgrade vs regular. Some brands do advertise better detergents in their premium fuels, however.

I use midgrade because turbo. Manual recommends premium; says regular is ok but it definitely reduces power and I can see the timing retard more under boost. I can't see a performance difference between midgrade and premium so I save a few bucks per tank.

 

[daves87rs]

Looks pretty good for midgrade!

 

[FermeLaPorte]

Use MMO

 

[VeryNoisyPoet]

Originally Posted By: FermeLaPorte
Use MMO

What benefit do you think it will give me? Pump and injector lube?

I saw no measurable increase of fuel economy averaged over several tanks. Engine felt just as smooth with and without. Obviously I don't have a valve buildup issue.

Only exterior difference I noticed was the exhaust smelled nicer when the engine is cold, and I don't make a habit of inhaling engine fumes.

 

[SZR48207]

Mid grade? So you buy 89 or 90 octane? Is the car spec'd for 87?

 

[VeryNoisyPoet]

Originally Posted By: Reddy45
Mid grade? So you buy 89 or 90 octane? Is the car spec'd for 87?


87 is ok but timing gets pulled more under boost and engine feels down on power. 91 is recommended and wakes it back up after a while to adjust and reset. Going back down to 89 doesn't trigger the reduced performance, so that's what I use.

 

[mehullica]

How often do you change the oil?

 

[Nick1994]

Wonder if my Sonata's intake valves are that clean

 

[The_Nuke]

The valves are surprisingly clean, but the intake runners are surprisingly dirty. I don’t know much about that engine or how it’s fuel injection is design/implemented, but it looks like however it is set up makes it so to the runners what would normally happen to the valves in newer MPFI engines.

It’s still good though since you can remove the intake and clean the runners, so congrats on that one!

 

[Revving2Redline]

Just run a PEA cleaner once a oci and avoid anything else.

 

[Kira]

Add any PEA cleaner before a stint of local driving not a long highway trip.

 

[SHOZ]

Put a catch can on it inline between the PCV valve and intake manifold to catch the oily vapors that make the crud.

 

[VeryNoisyPoet]

Originally Posted By: mehullica
How often do you change the oil?

Generally around 5k miles (manual specified interval). Mostly ran on conventional for first 160k miles; switched to high mileage synthetics after that.

Will start doing UOAs to get a better idea of how I'm doing and if I can extend the interval.

 

[VeryNoisyPoet]

Originally Posted By: The_Nuke
The valves are surprisingly clean, but the intake runners are surprisingly dirty. I don’t know much about that engine or how it’s fuel injection is design/implemented, but it looks like however it is set up makes it so to the runners what would normally happen to the valves in newer MPFI engines.

It’s still good though since you can remove the intake and clean the runners, so congrats on that one!


MPFI, batch fired twice per revolution. Turbocharged so a bit more blowby / oil vapor can make its way through the intake. I'm not all that surprised given how many thousands of shutdowns and heat soak cycles that area sees where the fuel can mix with the oil residue and wind up as that hard as concrete carbon.

Hard to see in the picture because the light falls off too quick, but the crud gets much thinner further up the runners. The plenum itself just has a very thin layer of honey-colored varnish.

Taking the manifold off is actually easy here, so I'm glad of that.

 

[VeryNoisyPoet]

Originally Posted By: SHOZ
Put a catch can on it inline between the PCV valve and intake manifold to catch the oily vapors that make the crud.


Easier said than done because of the forced induction. PCV is sent either directly into manifold or into turbo inlet depending on operating conditions. Would take some hacking to get a system that behaves correctly in both modes (two catch cans?), and I'd have to deal with being CARB compliant because I may end up moving to California in the near future.

Good news is the factory PCV system does have a built-in oil separator that drains oil to the sump, and the intercooler has a weep hole that ejects some of the oil that makes it through the turbo.

It definitely could be better, though I'm not surprised at how much crud is there after two decades of use.

 

[VeryNoisyPoet]

Originally Posted By: Kira
Add any PEA cleaner before a stint of local driving not a long highway trip.

Is this to make sure the engine is heat cycled around town with frequent shutdowns to let the cleaner soak, vs lean and hot on the highway without a chance to soak?