Cold-weather startup rattle revisited

No Oil Catch Can on this manifold. YUCK!!!

 

When I cleaned the intake manifold, about 15K kms post oil catch can install, there was still "some" pretty nasty stuff. I'm looking to improve the efficiency, with an extra internal baffle and increasing the hose diameters. This is with a Moroso 85474.

 

I don't think it would be that effective. Also, I'd be loath to drill into the intake manifold, assuming that's what it would take.

When I took off my intake manifold, 15K and over 2 years after the previous clean-out, and OCC install, The low point of the manifold, under the throttle body, looked semi-clean. I put the IM in a pan, ran a pipe cleaner style brush through the small diameter EGR passageways, with a shot of brake cleaner, then did some more brake cleaner shots into the 4 main ports. Tipped it and some pretty nasty stuff came out.

My impression: the gunk is reduced with an OCC. But even when the lake at the bottom is more-or-less gone, there's still accumulations all the way up. Maybe more dry and tenacious.

Maybe I've got to go to another OCC design, not sure. And the Moroso I'm using is pretty pricey. So far I've put in a small additional baffle, and reworking the plumbing, went to larger diameter hoses, thinking that might slow down the speed of the air through the can, improve the retention.

 

So the OCC gets most of the PCV Oil.
The rest of the stuff that crud's up the manifold is EGR Gunk and Condensation?

 

Maybe some, but I suspect in my case there's just a fair amount making it through the OCC.

If you watch videos, transparent OCC's in operation, the passage of air through there is VERY fast.

 

I know this video is NOT a Prius but I see what is going on.

 

Cosmo, does your engine burn oil?

Wouldn't there be condensation *only* on the cold engine parts (intake manifold)? The head and valves are warmed up by the coolant and combustion. Unless the engine wasn't warmed up prior to shutting off the car and taking that picture.

 

I have not noticed any loss of oil on my Red 2011 (148,000)
And
too early to tell on the Blue 2012 (208,000) with the 2015 engine (93,000) swap

 

I got the rattle sometimes too when car has sit for a long time. How to solve the problem.
1: make sure your EGR is nice and clean.
2: Check is it still ratteles at startup.
3: Does it? Great, now when it ratteles just FLOOR IT for a couple of seconds! The car will rev to around 2800 rpm. It doesn't hurt.
4: Yes your rattle is gone now.
Does it rattle at next startup? Repeat from step 3.

(o btw, my car has 400k on it it still runs good, original headgasket an battery so no worry)

 

Hey, I saw that bee next to the opening, are you sure it ain't honey in there?

 

Ha!
That bee Photo Bombed me.

 

"so that some of the unburned, intake charge is returned to the intake manifold rather than being compressed"

This could be why Even with a Oil Catch Can (OCC) and a super clean Exhaust Gas Recirculate (EGR)
we still get all that build up and crud in the intake manifold, as well as build up in the intake ports and on the top of the Valves.
Is it possible that all this condensation, un-burnt gas, crud (EGR crud?) and oil blow by etc is getting sucked back in to the cylinders
at startup?
So on cold starts or longer intervals between starts more build up = more knocking and rattling?

 

All correct. During winters, there are water droplets hanging on top of all my 3 fluid resivoirs so you can imagine water droplets in the interior top of manifold and everywhere else.

 

I notice water droplets on the inside of EGR pipe too, fwiw.

 

That confused me at first, when I took off the EGR pipe and saw water droplets,
I was mistaken thinking the EGR cooler was cracked and leaking .
Guess it was just condensation.

 

Is your prius garaged up? I only have a car port

 

There are advantages to a carport, in some conditions, snowy weather for example. I always think: a garage, with a carport in front of it, that would be the bee's knees.

 

Clearly somebody is going to have to run a tube from the intake horn through the firewall to the HVAC system to see if breathing only actively dried air fixes this.

(okay it would probably be easier to work out something like a thermoelectric chiller/condenser in the air box to dry the intake air)

 

Sometimes 50% - 50%

Nether my 2011 Red 148,000 nor my 2012 Blue 208,000 w/93,000 engine swap, have EVER Knocked or rattled.

So it is kind of weird that even with condensation and a pool of (whatever) at the bottom of the intake some engines rattle and knock
and others don't.

I am just here trying to help figure this out.

 

With all the conversations regarding this, is installing the OCC worth it? Should I just clean the EGR every 50k? The only reason I wanted to install the OCC was to keep the EGR clean and avoid the head gasket issue.