Engine Knock even after cleaning EGR pipe cooler

The intake manifold is part of the egr system. There are small ports for each cylinder
underneath the large ports for each cylinder.
Yes, you do need to clean them. At least it's a lot easier and faster to remove and clean the intake
than the egr valve.

How clogged was the cooler?

 

Do you mean the "PCV valve" or EGR valve? Many owners replace the PCV valve when the intake manifold is removed for cleaning.

 

Cleaning at 130k miles, and AFTER symptoms arose, you might have left it too long.

Definitely clean the intake manifold ASAP: all the upstream cleaning is for naught till you’ve cleared the Exhaust Gas Recirculation passages in the intake.

You can check the condition of the head gasket with a leak down test. If you’re not losing coolant you may have caught it in time.

Exhaust Gas Recirculation info:

Bad Flywheel | PriusChat

 

A chemical cleaner that works well is saturated Oxi-Clean solution, with hot tap water. Cork one end and fill with solution, wait about an hour, rinse and repeat. Takes a few cycles, it froths up, eats away at the carbon. I’d only use it on the stainless steel cooler, since it’s moderately basic. Everything else can be readily cleaned with brake cleaner and brushes. For next time.

 

Use the pressure washer first to clear it out, then oven cleaner. Oven cleaner is inexpensive.
You can use "other" stuff, but oven cleaner eats the carbon build up.
Then use the pressure washer to clean it out. It will take a few times before
you'll have clear water going through, depending on how dirty the cooler is.

 

I think it's a personal choice. You take a chance with a used engine. And I would try for a
2015 engine because of the updated pistons and rings, and likely less mileage.
It would be better to get a remanufactured or new short block and have the head checked
to see if it's warped.
Replacing the head gasket is the least expensive if you are going to change it yourself.
Either way, it will take time.

 

"My car rattles slightly during warmup on cold mornings. should I scrap the car?"

Come on, man. Listen to yourself.
I had a 2010 which I bought new. I sold it in mid-2012 to get the Plug-in which I still have.
My 2010 had an odd cold-start problem: If I shut the car off before the warmup cycle completed, the next start would ALWAYS be a rough start. But if the car completed the warmup cycle, I would not get a rough start. The 2010 was the first year of the Gen III and had some issues like that.

On the other hand, you just completed some important maintenance. If you didn't remove and clean out the intake manifold, then you still need to do that. There are pipe cleaner-sized passages which easily become blocked. But all you did was maintenance. Welcome to the club; we've all done it.

 

Hello all,

I have a similar problem so maybe it fits well in your thread.

Hopefully some part of this brain trust of people like ChapmanF, Mendel Leisk and Ragingfit can help with my situation.

Like Ragingfit I have a 2012 Prius v. However, I bought mine new from the dealer in April 2012. It now has 59,000 miles on it. 100% of factory recommended maintenance has been done so far mostly by the dealer. I do a few easy things myself.

Over time my Prius has developed a kind of metallic rumble when under light acceleration.

Most recently there has also been a nasty shaking occasionally at idle which I understand is transaxle damper rattle. Based on what I have read and having received Canadian EGR valve warranty extension notice W11 from Toyota I believe the transaxle rattle is caused by a sticky EGR valve which causes uneven firing in the cylinders especially upon start up.

I tried Ragingfit’s idea of unplugging the EGR and there was a slight change but not the kind improvement that he found.

I decided to change the plugs, renew the PCV valve, and clean out the intake manifold and EGR system.

The plugs are a revised spec SC16HR11 Denso which run slightly hotter than my original SC20HR11. In the end I did not renew the PCV valve because when I arrived at my appointment to pick it up. I was told sorry someone else was given the one on order for me. The PCV was a simple metal spring loaded piston check which moved freely.

My EGR cooler, EGR pipe and the intake manifold EGR ports all turned out to be dirty and partly restricted but none were fully blocked.

My EGR valve is a 90 degree angle stop valve with a brushless electric motor drive to raise and lower the stem and there is a small spring to assist with shut off. After separating the EGR valve from the cooler and removing the black plastic stator cover and screwing of the rotor I found that yes indeed the valve had a bit of excess carbon deposit covering the stem and it was sticking in place. In my rush to get it moving freely I stupidly omitted to take note of the precise position it was in. I believe it was partly closed but not fully closed but this is not certain.

I was able to clean a lot of the valve stem by fully compressing the small spring and scraping as much carbon from the stem as possible. By adding grease and opening and closing the valve by hand I was able to restore normal spring closing.

A rhetorical question: Why make the EGR valve with stem pull up (SPU) closing rather than the more usual stem push down (SPU) closing? The only real advantage I see to SPU is pressure assist to shut-off in the fully closed position but it has the downside that the stem is fully exposed to the flow in the open position. This is only recommended for use in clean flows. Crud getting into the stem packing area is the natural result of particulate in the flow getting onto the stem which is then pulled up through the packing each time the valve closes.

Under the Canadian W11 warranty enhancement program owners who have experienced a rough idle and/or tapping noise from the HV transaxle at cold start due to a sticking EGR valve due to excess carbon build-up is eligible for a warranty repair.

I assume the Ragingfit unplug EGR solution applies best when there is more obstruction so that unplugging tells the control system correctly that the EGR is equal to closed.

Question: Has anyone contacted the dealer after fixing the problem themselves? Will the dealer supply a new EGR valve?

My other problem did not go away and must be a separate issue. There is still a metallic rumbling under light acceleration!

Questions: Could the PCV valve cause this? Is it normal that the PCV valve piston feels quite loose or should the spring be keeping the piston tight against the valve inlet?

The car has been very gently driven since purchase and I am the only driver. The only driving stress which comes to mind is a condition of my old daily commute. There is a long slight downhill slope and the car would go into electric only mode at 50 mph. At the end of the down grade as I pressed the accelerator pedal the ICE would come on but seemingly at a very low rpm. It was only a feeling since I do not have a tachometer. The low rpm may have put some stress on the engine but I did not find a way to avoid the condition and I assumed it was normal for a Prius being super fuel efficient.

I doubt there would be a head gasket issue. The dealer seemed to fill the car at the high end of the scale but the feeling seems to be a rough rumbling rather than liquid knock in the cylinder though I am no expert.

Question: Any ideas on the rumbling at light acceleration?

Thanks for any Help

Will

 

How badly clogged were the little egr holes in your manifold? Can't quite see in pic

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okay that's good, #1 inlet was blocked solid in mine, other three were 70/80% blocked ..the pipe and cooler etc about 20/30% restricted, at a guess

 

I think a going forward strategy depends on current oil burning, oil leaks, hv battery history, inverter and master cylinder status and how long you would like to keep the car.

If I have a 2010 gen3 that burns oil, leaks, is beyond the ten year inverter and master cylinder warranties (without previous replacements), has the original hv battery, occasionally cold start rattles AND I am thinking about a newer vehicle within a year, then I might do do little besides moving the newer car date forward. Doing so may preserve my private party value in the 2010.

If the engine and car is clean, no oil issues, the hv battery is hanging in there, I like it and want it to last two more years, then a head gasket now makes sense. I certainly would verify the hg with a leakdown test and block combustion gas detector.

Maybe I love the car, have oil problems but have already put in a new hv battery, the master cylinder was replaced and I would rather put the down payment into my 2010 for a rebuilt engine and no ongoing payments, then I might get a used "low mileage" gen3 engine and have an experienced independent shop do the work.

There are a spectrum of possibilities. By the way, the egr system is closed at startup and during initial warm up periods, so cleaning the egr cooler and passages before the cold start rattle is potentially preventative but is rarely curative after the rattles start.