Rough start after extensive cleaning and replacement parts

Wedging a breaker bar and holding it to ensure it didn’t move or slam into something was what i did. I resorted to having it point upward. My breaker bar was not long enough to point downward and reach with my foot. It might not have technically been a breaker bar. It was a non-ratcheting 1/2 drive, about twice as long as most 1/2 ratchets you’d get in a set, but not as long as some of the pics I’ve seen illustrating various items. I think the readings i have a pretty good. I used a wooden dowel that i marked the top location on one of the cylinders. Once i determined which one of the cylinders was was in the up position i then determined easily which one was in the compression stroke vs power stroke. I then went from than cylinder to the next one in the firing order after rotating that next piston to the top of the cylinder.

I read in another thread somewhere that the prius valves are a little finicky to determine exactly where both are closed due to the narrow window between compression and power.

 

Hi RJParker. In answer to your question about any further rattles on start up, yes. For about a sec or so and then would stop. Nothing like before where it would do it for 20-30 seconds or longer.

Definitely will make sure cylinder is clear of liquid before starting back up.

 

Hey rebound, thx for the reply. Just sent the car back with my son. No codes. Generally running well. Rattles briefly at start up but then goes away about as quickly. Still a little puzzled by that one. I guess I would expect another CEL if it was an actual misfire. Still not seeing coolant leaks and really cleaned the EGR valve and cooler well. I may have him run a few takes of higher grade gas to see if that has any affect.

The rattle is not anywhere close to the level previously experienced. We’re going to monitor the oils consumption of the next 1,000 miles and see how it goes. I’ve got him laser focused on it now. Running seafoam in the gas and then running MMO in the crankcase. MMO is much cheaper so finishing out the last of the seafoam. Hopefully no more CEL’s for a bit. I think I’ll take a peak at the pistons again when he brings it back.

I’m guessing new piston rings are probably warranted at some point. Not sure I’m ready to tackle that one yet. But may be close…working on another family members car this weekend which may push me even closer to that task.

thx Mendel, I’ve watched a few of his. I think his trick was a screwdriver if it’s the same video of the Chevy Tahoe or suburban. I personally like the wooden dowel. DIY Dave had a good trick for marking TDC on the dowel, which is what I did. Unless there’s something to the Atkinson cycle in the Prius affecting where TDC actually occurs, I think I found it.

 

Looks like we’re back to the possibility of a blown head gasket. Noticed the coolant was all of a sudden low. A couple of short start-up rattles but no CEL. No white smoke or discoloration in oil. Possible it just a minimal head gasket issue at the moment (if there’s such a thing)? Are white smoke or discoloration not always a given when a head gasket fails?

Going to double check for any other obvious coolant leak possibilities, but planning to do a head gasket replacement this weekend. Everything seems to generally point to it.

BTW, oil consumption has dropped since the other work. Close to 2k miles before having to add oil. Normally would have been 600 miles or so.

 

Thx Mendel. I found that video over the weekend and gave me enough info/confidence to tackle it myself.

Also, thx for the part #. I had narrowed it down to that on as well. Thx again!

Here's to a positive experience this weekend...and not issues on the head bolts.

 

Appreciate all of the feedback on this.

This car is my son’s so trying to help him out with the repairs and teaching some maintenance along the way. First car for him to own. The gasket kit / new head bolts…OEM, about $260.

I was also doing some checking on cost of a replacement engine…just for comparison purposes. Cost of a replacement engine (long block, used, not rebuilt), found one with 73k miles for $2500 and one with 26k miles for $3200, delivered from wherever to GA, no core charge. Both come with 6 month warranty. Confirmed US sourced and not JDM. Thoughts on these? These seem a little on the high side based upon other posts I’ve seen.

178k miles on current one. My math says try the $260 repair first and see if / how long that helps. Based upon everything we’ve found so far, the piston rings are worn out, given the oil consumption issues we were originally having.

We’re doing all of the work ourselves.

 

As a conclusion to this thread, here’s an update on what we did and how it turned out:

we replaced the head gasket with OEM gasket set, which had gaskets for most other parts: changed gaskets on tensioner, water pump, thermostat, EGR, and top engine cover.

All went well, until we broke a camshaft assembly bolt. We ended up getting sealant in one of the bolt holes. My conclusion was that that affected our ability to properly torque the bolt or rather allowed for over torquing. We replace that bolt and a couple of additional ones where threads looked like they we stretched.

abilty to get parts was challenging. Dealers were limited on stock. Had to use a regular bolt and washer rather than the flanged OEM style for one of them.

Upon reassembly we cross threaded a bolt that fastens engine mount to fender well. We fixed that with that with no issue.

after start up, we had a significant leak at the chain tensioner. After reading several threads we put the engine at TDC and removed, applied a thin layer of sealant and reinstalled and ensured it was properly torqued. Leak fix…for now. (Also notice this was present before we did any work. So it was an existing issue.

threw P0351-P0354 on start up. Although these all reverted to inactive permanent codes. My conclusion is that since inactive and not pending or current were good.

Will the permanent aspect go way after drive time is experienced?

thanks for all of help on this. It was quite a journey and very satisfying to have fixed this issue.

 

I did do a seafoam soak again for a couple of days while we were working on other things but didn’t do Berryman B12…what’s your thought on Berryman vs seafoam? This was also done a couple of months ago as well and we noticed some marginal improvement.

Do to timing and logistics, we opted against the machine shop this go round. I would have preferred to not do that but we were very limited in time. Definitely a gamble but after checking for flatness, Nothing appeared warped. We also checked the valves for any leaking. Everything appeared good there too.

we ended up using Toyota’s seal packing rather than Permatex. Seems like it had a faster cure time.