Suddenly getting misfires on all four cylinders

I was going to reflect about one of my previous employers that makes very large airplanes, and how very smart people can still make very dumb collective decisions, but I think I'll leave that incredibly vague and call it a day. I'll just leave it as a thought that I fully believe that a room full of Toyota engineers could miss a lot and still be brilliant people. But, I do want to try to keep it back on the topic of this particular Prius V and why it is misbehaving even though it has a new engine in it..... Having multiple problems certainly makes diagnosis more difficult, that is for darned sure... But it seems like the consensus here is validated by empirical test results (shudder, then no shudder, then shudder, the only real difference being a temporary blockage of the EGR). So, I'm planning on replacing the EGR valve. Perhaps I should do the same with the intake manifold. It is odd though. I've looked at the pictures on the internet of the intakes and they are nasty! Mine has always looked really clean. There is no blockage of the EGR channels at all. I still cleaned them out, but overall I've been kind of puzzled why mine have looked good.

 

I forgot that at least I owe a picture of a Prius getting the heart transplant!

Oh, and you know.... I tried to get that thing to go into the bay in the orientation shown in the picture... I fought and I fought, but it just wanted to go sideways!!!! .

These are the trials and tribulations when you are working by yourself. I was hoping to get help from my son, but he was on duty that day and I couldn't wait due to the weather. However, going slow and thinking things through helps a lot. It really wasn't a very difficult job. I do think that having the leveler was a worthwhile add. That and a 4x4 piece of wood to keep the engine engaged with the drive motor splines (so it doesn't slip out as you are trying to install some of the bell housing bolts) made things pretty easy.

For the prep for engine removal, I used a QuickJack 7000lbs lift. For the actual removal and installation, I just had the right front on a stand. And for the rest of the installation, I had the vehicle on 4 jack stands. Overall, I would say that the QuickJack is a very nice unit, but I don't think it was mandatory by any means. I bought it about 8 months ago because I wanted some additional ease and, well, because I got a good deal. I think I've gotten my money's worth out of it, but I'm not totally sold on it yet.

 

I'm baffled an a little embarrassed... I put a brand new EGR valve in and, although it was better, I still had a little shudder. So I took the intake manifold off an checked it. Son of a !@%^#. The right most (Closest to the EGR) port was almost completely blocked. The next one wasn't that much better. I'm baffled because I could swear on a stack of bibles that I had checked the ports and, in fact, cleaned everything. I'm so convinced of that that I'm wondering if the cleaner might not have completely flashed off and it quickly formed a goo with the exhaust. But let's face it.... That would be a lot of crap in 3 miles! So, I'm thinking that I must have missed the ports. It pains me to say that because I really really feel like I went down the correct path, but I'm absolutely capable of making mistakes. So, I'll own up to it.... My guess is that the EGR valve is probably fine.

So, I cleaned the orifices and tried 'er out.... Purrrrrrr.... I've put about 70 miles on the car in the last few days doing city errands. I have a little highway time but I want to be gentle on the engine for the first 500 miles. I also want to stay close to home for obvious reasons. But I think everything is working fine. So, with the exception of Mr Shoot Yourself In the Foot (me), I think I have a success here! And, I still don't think it was a horrible experience. In fact, I rather enjoyed many aspects of it.

With this out of the way, I have a few other (unrelated machine shop stuff) projects to finish up. After that, I plan on starting to do the forensics on the old engine. I'm curious to see what I find. I have an engine stand and I need to get the engine mounted tomorrow so that I can take the hoist apart. I think I'd like to keep it because it is pretty nice. Plus, with a second Prius V now, I figure I'll have to contact Greg again in a few years! LOL. The other Prius is going into the shop for 2 weeks tomorrow to repair the damage from the tree that fell on it during a recent storm. $3500 damage, which basically means a dent in the rear quarter panel. Welcome to California labor rates.

 

So, that is the thing that is kind of weird. I could swear that one of the comments (above, unfortunately I'm doing this on a phone right now so it is hard to check) indicated that at a quasi-static state, the EGR would be fully CLOSED. In that case, the blocked passages would not have affected the system.... I've been meaning to read up on the EGR when I get a chance. I really need to understand when it is open and when it is closed.... I can easily see how if it *were* open, then having some plugged passages would lead to an imbalance between the cylinders.

 

Shoot. I'm not at home right now I realize that I need to buy some bolts that I can use to mount the stand pivot to the engine bell housing. Does anyone know the size/thread that is used for that area? I hope to get these tomorrow or the day after before I return home. The goal is to have these bolts so I can put the engine on the stand and take it apart. Ideally I'd use the two threaded holes on the top of the bell housing as when I looked at this before, those seemed to be better situated for my pivot. The lower half has the threads on the drive motor side so the bell housing just has holes. I can use any bolt for that.

 

I don't have any spares. The existing bolts were used with the new engine

 

I have information! I took the engine apart and it was interesting. But story-telling is my game, so you have to bear with me a bit.... Prius #2 is in the shop for the tree dent (after just 3 weeks of ownership). They upped the cost to repair to just shy of $5000. Thankfully, I have a $250 deductible. Prius #1 is working through its first 500 since its heart transplant. Aside from the initial depression of shuddering, which was the EGR system, it is doing nicely. My wife is even beginning to believe that the car might work... meaning that she has (albeit suspiciously) taken it out a few times.... She knows how to hit my pride when she jumps for one of the other cars! :-(

Now to the motor.... I got it up on a stand so my 60 year old bones didn't have to stoop (God, am I really that old? What happened?)... I popped the top cover and then the side cover. The chain was tight but when I removed the tensioner guide, I noticed that I could rock the intake cam back and forth about 10 degrees with no effort. Not correct. Then I looked down at the crank it is was immediately obvious. The crank timing gear was cracked in 3 places. The crank position sensor disk was able to free-wheel and there was obviously not a positive correlation between crank and cam positions.



So... of came the head. The gasket actually looks like it is in fantastic condition, to the point where you could probably use it again, although I don't think I would. There is absolutely NO evidence of any current or pending issues with the head gasket job I did, thankfully.

HOWEVER.... When I looked at the valves, it became immediately apparent why the rockers were loose. Now, if you know this is an interference engine, you will already have guessed the issue. With a broken crank timing gear, well worse... one that partially worked, the intake valves are bent like a spaghetti noodle. Oddly, though, they are all bent in one direction (and I don't mean the music group)



You can see some fairly minor damage to the block, and also see the strikes on the pistons. It also looks like the exhaust side hit too, which would make sense. I'm not sure why the exhaust side doesn't look as bad as the intake, to be honest.



The lack of steam cleaned pistons is nice. it is also consistent with what I had seen with the spark plugs. But now the big question.... Why did the gear break? I don't really believe in coincidences, so I am guessing that *I* must be the culprit, but I don't really know where/how. The best guess I have is it is when I replaced the tensioner to try to diagnose the misfire. But, I put the tensioner in, then did a small reverse turn to release the clip... that is all. That is pretty standard and, more to the point, I don't see how I could have caused the tensioner to somehow become too tight. It did feel pretty tight, but again, the normal operation of the engine would, I am reasoning, tighten the tensioner to anything I could have done. But I *have* to strongly assume that this must be the root cause... or maybe it is just bad luck?

The other curiosity here is the original misfire. Given that I now have pretty conclusive proof that the head gasket was fine, that means we don't know the cause and, worse, I might get it again.... I am *thinking* that it might be related to the plugged EGR passages? It usually gave me the service light when I was at a steady state throttle, kind of the same thing as when I was getting the shudder.

Anyhow, getting a new engine isn't the worst thing in the world. In 20K, the engine clogged up one and a half of the EGR cylinder feed tubes, so I'm guessing the car was starting to burn more oil (although it never showed on the dipstick). And, now I have the better pistons and rings. With luck, this engine will give me another 120K, and at 240K total, I'd call that the most successful vehicle I've ever owned. So, it is all good.

I welcome your thoughts on the root cause or anything else. Learning is about discovering what you've done right and what you've done wrong. I have done a blend of the two throughout my entire life.

Also, does this kill the head? Is it possible to replace the valves and have a good head again, or are the seat likely to be all buggered up? I suspect that even if it were OK, though, replacing 16 valves (I'm assuming that both sides are bent) is probably not cost effective.

 

Both posts make sense. I was thinking that the gear was more the *problem* than the weak link. The car drove for 20K miles before the catastrophic failure, and about 2000 after the chain tensioner replacement. Both are a pretty long time to run without hitting the pistons (i.e. missed link), I would think. Of course, in the end it is impossible to know for sure. Once the gear broke, any ability to verify the correct timing went out the window.

 

When I recycle the old engine, should I pull the VIN tags off the block? Is there a reason I need to keep these? Will I have issues recycling the engine if there is no VIN tag (hence not able to prove I own it), etc?