2nd Gen Project

So today I bought an auctioned 2007 Prius with 210K miles for 1,000 bucks. Body and interior are very good but there are rat droppings under the hood, oil filler cap is missing (not sure why that is), and it has the Red Triangle of Death. I'm hoping to put a good deal of work into it, replace broken stuff with used by serviceable components, and save it from the junkyard while hopefully turning a profit. Wish me luck!

 

I brought the Prius home and spent an hour cleaning out rat dropping under the hood. I thought, wow, that looks like a clean engine bay now! Then, I found there is apparently a high power drain somewhere or the 12v battery (less than a year old) is toast. I couldn't get the Prius to stay in neutral so I put the fonts wheels on dollies to move it into the garage. Two 2 inch curbs at the garage door meant I had to Mickey Mouse the situation with plywood ramps and blocks to get the thing into it's new resting place, sideways near the back of the garage so I can still park 2 cars inside and have room to work on it. Then, I pulled the dipstick, which was clean and dry. Ooops, I'm betting the engine is seized. Yep, it's seized. Anyway, I probably would have still bought it as I can pick up a motor for 200 bucks if I pull it myself. And, I can likely get one with less mileage.

 

I picked up a motor today but it only has compression in cylinder 2 and that's not every cycle, either. While turning the crankshaft, the timing chain alternates between tense and slack so I'm guessing that or stuck valves? I assume it should be tight throughout rotation.

 

I'm hoping I'm not irritating anyone here but here's an update on the 2007 rehab project. I did a leakdown test, sort of, on the motor I found in the junkyard prior to installation. I wasted a good 3 hours pulling the motor and found only 1 cylinder that could hold any compression at all. I think my leakdown guage may not be working properly so I just injected compressed air at 100 psi into each cylinder when it was at TDC on the compression stroke.

Today, I took the motor back and check others in the yard with my compression tester. I pulled each plug from potential motors and checked for free rotation through at least 2 cycles. Then, I attached the compression guage to the cylinders in series and turned the motor by hand with a ratchet through several cycles each. Unfortunately, I didn't block the throttle body open which is a requirement for compression tests. Generally, these tests are done with the engine cranked by the starter (about 300 RPMs) but I've done them by hand and even with a large powerful drill attached. I find generally that the starter gives the highest values, the drill comes in second, and hand cranking is last. Today, when I finally figured out my mistake and opened the throttle body on the last motor, I got values of 4, 30, 40, and 20 PSI. I assume that motor need some work as these values vary too much. I didn't add oil to each cylinder to check whether the rings were bypassing air.

I've heard some say that rotating the engine for this type of test can cause crankshaft scoring but I would assume some debris or contamination would be needed there. The slow speed of rotation is not enough to build up any heat either. I don't really like the idea of putting the motor all the way in and then finding out the rings are bad.

 

I should add that I believe the best compression method is on a warm engine using the car's starting system. Numbers with hand cranking would be lower but could still show cylinder head or ring problems, holed piston, etc. And, adding oil to each cylinder would pinpoint a ring/cylinder wall problem. Leakdown test is good for cylinder head issues, assuming you have a compressed air source, but it doesn't indicate the condition of the cylinder wall over the range of piston travel.

 

I'm not sure how much of it's talent. No formal mechanic training so it's YouTube and Google. I kind of screwed up on a Gen 3 I put back together. One cylinder had polishing on opposing surfaces and curiously better compression than the other 3. I asked all over everywhere what this meant and nobody knew. 3K miles later, the great Car God showed me. A bent connecting rod broke and blew several holes in the engine block.

 

I've pulled my 3rd Gen 2 ICE now. There wasn't able to find any compression in The first. The 2nd was from a front end crash in which an engine mount bolt was sheered off which I didn't see until it was on the ground.and I was worried the block might be cracked. The 3rd car also had front end damage. I'm going to check this one for compression and either use it as is or rebuild the top end or bottom end as necessary. It only set me back $140 or so.

 

They do seem thin. But, after a connecting rod breaks, the engine is done. The only question is whether you'll leave souvenir fragments on the road or have them all for yourself when the tow truck gets to your house.

 

This brings up my latest idea on testing valve/piston timing and overall cylinder health before installing the motor. With a given cylinder at TDC on compression, I'm planning to fill the spark plug tube with gasoline or another fluid. Then, depending on the time to drain cylinder, I would have an idea of how effective compression might be. Would it be correct that the valves should be completely closed at that point? I'm also planning to position all cylinders at the mid stroke point and then evaluate fluid loss past the rings.

These ideas are more related to leakdown than compression testing. I have done compression tests on a Gen 3 motor using a high torque 1/2 inch drill out of the car. I found the values about 40 PSI below standard expected values and figured the drill RPM was maybe a third slower than an with the engine installed in the car.

 

I was able to get the Internal Combustion Engine completely removed and the replacement completely installed from the top and without removing the rest of the power train. I had not read previously that this was possible and I don't think it's the shop manual procedure. I think it was easier than the other options, but then again, I haven't done it other ways so I'm not sure. I'm including some of what I did here although this is not a comprehensive step by step.

1. I removed the 4 mounting bolts of the inverter assembly and moved it slightly toward the driver's side fender...maybe 1/2 an inch.
2. The power train must be supported from below as the center and passenger side engine mounts must be removed. In fact, the passenger side mount and the complete bracket assembly must be removed.
3. The water pump drive belt, pulley, and tension adjuster must be removed along with the crankshaft pulley.
4. Both studs at the exhaust manifold were removed. It's not possible to tilt the power train forward enough to clear these.
5. After all bolts attaching the engine case are removed, the power train might need to be rocked forward on the passenger side slightly as the engine block is pulled off of the splines. The hardest bolts to remove are the top two engine case bolts. Moving the inverter slightly toward the driver's side fender and removing all hoses and connectors from the end of the cylinder head is absolutely required to get these two bolts.

A shout out to the Toyota people for those nasty spring hose clamps! I wound up cutting several off with my Dremel tool since there was no way to get any pliers in there to squeeze them. I will be replacing them with the screw on hose clamps. The overall spare left to right clearance for separating the engine case is about 1/16 of an inch, so there's not a bunch of extra room between the frame rails.

 

That is definitely something to think about. I hear there is a clamp removal tool that makes it much easier.

 

I've gotten everything back together after putting the motor in, except windshield wipers, windshield washer reservoir, air intake, etc. I put the orange safety plug back in and hooked up the 12v battery. The panel indicates no charge level for the hybrid battery and Red Exclamation Point in red triangle. Motor does not turn over. Any suggestions are appreciated.