2014 Prius v EGR Cooler & Heat Exchanger

Hello - My question is on the EGR cooler and its functionality in the Prius

Unfortunately, I recently became very familiar with the EGR cleaning, spark plug/coil packs, and head gasket issues outlined in the forum.

I've been reading threads and seem to have hit the jackpot on the 2014 Prius v (model 3) woes.

The car ran great until 137,000 miles where I received the first rattle and misfire codes. Then about a week later more severe rattle and white smoke came out of the exhaust like an old steam engine. I suspected a head gasket but my mechanic could not find any coolant in the cylinders or in the oil. Ultimately, he found coolant coming out of the tailpipe and diagnosed a cracked heat exchanger. I made the decision to bypass the heat exchanger and return the coolant vs. the cost of a new catalytic converter and heat exchanger. There was some time spent removing coolant out of the catalytic converter through burn off and draining.

All was well until a few weeks later when I got the rough start again on the first start and over the course of a week now rough starts / rattle on any start warm or cold as the vehicle moves on and off battery while driving. I've stopped driving the vehicle.

I believe I am losing coolant but it is very small (Approx 24oz over a month). On 5/17 I filled it to the full line after the heat exchanger repair and it moved approx 1/4 inch down to the seam in the reserve tank and we are 2 months away from that fill. Still well above Low.

No codes!

In the various videos, I see clamping coolant lines to the EGR cooler.

My questions are:

1. Did the Heat Exchange bypass possibly impact the EGR cooler? I'm not familiar with the flow of the coolant.

2. Would a faulty EGR cooler (or clogged most likely) be able to allow coolant into the combustion for a rough start on cold/warm startup repeatedly?

3. Any explanation of the EGR cooler in the Prius, how it functions with neighboring parts, and why it exists will help my sanity.

Considering the rough start (misfiring) and smoothing out happens on every startup and smooths out (no misfires while driving at speed) and the fact I recently changed the sparkplugs makes me less suspicious of the coils / plugs.

With the many head gasket issues and not having cleaned the EGR system, I am not ruling out head gasket repair. However, I would like to understand the EGR cooler better and the possibility of it leaking small amounts of fluid into the combustion process somehow.

Thanks for any advice you can give. The vehicle has officially stressed me out.

 

Thanks for the vote on head gasket. I seem to have hit the Jackpot as based on the coolant out of the exhaust it looked like a gen4 / steam engine from the wild west until the bypass. I wonder what causes the heat exchanger to crack? Maybe I'll take a look over in Gen 4. I'm going to look into head gasket repair at a reputable shop nearby. Thanks for the advice.

 

Thank you, I've read your links extensively and I am up against a situation where I own a 2nd Prius V (2014) with no issues at the moment (120k miles). I am debating whether to proactively complete the EGR repair (and intake) on the vehicle with no issues first (first time doing it) or gain the experience and complete the EGR (and intake) repair on the vehicle with symptoms first to gain experience. Either way, both vehicles EGR will be serviced as outlined In the helpful threads.

 

Your posts are entertaining and it seems you have many stories.

 

I pulled apart the engine this weekend and am working on cleaning the EGR system and installing an oil catch can. Since this is all routine recommended maintenance the cost is mostly labor in the garage. Interestingly, it appears a prior owner did some work on the system as the troublesome nut under the egr cooler was missing. I removed the torx stud to aid a future cleaning. In addition, the rear studs contained a 12mm and for the bottom one had a 13mm nut which had me perplexed why the socket wouldn't fit by feel alone.

Thanks to Mendel for posting of the diagram of the EGR valve, pipe, and cooler in the 2nd link of his signature. This diagram was great to reference as many of the nuts and bolts are not easily seen.

Going back to my original problem, Unlikely as it sounds the (Gen 3) heat exchanger cracked and allowed coolant to flow into the exhaust system / catalytic converter. This is bypassed near the cat with a separate hose returning coolant.

Does anyone have a diagram of the coolant flow through the heat exchanger in Gen 3? I want to rule out coolant loss flowing through the heat exchanger crack and it would be helpful to identify any hoses that feed the heat exchanger line. I might re-look at bypassing in the engine bay if my earlier bypass was not 100% in eliminating all coolant to the heat exchanger system.