Engine Rebuild!

[dkjones96]

I had a little 'accident'(experiment gone wrong) with the Tracker and ended up with some foreign debris in cylinder number two.

The head needs removed and they are going to just re-bore the cylinders because of some slight scouring on the cylinder walls that will most likely just damage the ring eventually(works for me). The engine compression tested fine at 185/192/189/184 (debris causing a little increase i guess). Engine ran 111k miles and used 0-20 full synthetic.

I'm gonna have them overbore by only .015 since I want the ability to rebuild the engine again if I happen to screw it up...again. I'm going to have them deck the head only half of the maximum allowed too for the same reason. The goal is to up compression past 10.5:1. It was 9.7:1 stock so that isn't too hard to get.

This time it gets a GOOD break-in, however, those compression numbers are pretty good for the mileage and considering it had factory-new compression specification of 195 it may have been broken in just fine. I mean, cmon, it was a rental car when it was getting broken in, nobody is ever nice to rentals.

[GasSavers_Erik]

How did they know the cylinder wall was scored? Did they use a boroscope?

If not confirmed with a boroscope, I'd keep running it for a few weeks around town and retest the compression readings. It might be OK as is.

My experience with doing engine rebuilds is that they always go over budget (even when I do all of the engine pulling/disassembly/assembly/engine installation labor myself).


Sooooo- please tell us about the "experiment gone wrong" so no one here will repeat it.

[bobc455]

Originally Posted by dkjones96

I'm gonna have them overbore by only .015 since I want the ability to rebuild the engine again if I happen to screw it up...again. I'm going to have them deck the head only half of the maximum allowed too for the same reason. The goal is to up compression past 10.5:1. It was 9.7:1 stock so that isn't too hard to get.

Buy your pistons first, and have them match the bores to the pistons. Do you know that 0.015 oversize are available?

I'm not a fan of raising compression ratios.

If you cut too much material from the heads, you may have to adjust other dimensions (for example on a traditional v8 motor you would need shorter pushrods). Maybe if you have a timing belt, you should be sure your tensioner can pick up the extra slack.

-BC

[GasSavers_Erik]

Bob- Good point on the consequences of milling head/block surfaces.

When you shave a head or deck the block of an OHC engine, you end up retarding valve timing because of the extra slack on the "pull" side of the timing belt.

I just ordered an adjustable cam gear to counteract this on the 1.3 liter Honda I just rebuilt (head was shaved and block was decked).

[dkjones96]

Yes, it was verified with a borescope. They actually saw the debris embedded in the piston and head. The scope is the only reason it went to the shop in the first place. I'm very DIY but don't have the time to do this project unfortunately.

Originally Posted by Erik

Sooooo- please tell us about the "experiment gone wrong" so no one here will repeat it.

Totally forgot to add that.

When modifying a spark plug don't dick with the center electrode. I cut a groove(not even a big groove) into the electrode to make the spark either go left or right of center when it fired to hit the edge of the ground strap. While it worked great I think it couldn't dissipate heat as well and ended up shattering the ceramic insulator which fell into the chamber. Oops.

I modify ground straps all the time. Even made a normal plug into a surface/gap discharge plug with great success but the first time I modify a plug like this I have trouble...

Weird thing is, the plug lasted almost 850 miles before this happened. It started by stumbling under load and I figured after 800 miles the plug was fine so didn't think about it. Over the course of 50 miles(2 days) the engine started stumbling more often and the night before it died it was stumbling at idle. No check engine light so I figured the fuel system was being stupid. 5 miles from home and a little under half way to work I decided to make a check egine light come on. I downshifted to second gear and pulled from 4400 to 6700 in second, it took like 20 seconds(gross) and the check engine light came on.

I reached over to my right and hit the PCMscan tab for MIL codes and pulled the code. cylinder number 2 missfire detected, about 30 seconds down the road it completely dropped that cylinder. I slowed to 55 and flipped the switch to leave the torque converter unlocked. I got to work without a single stall but my TCC override circuit burned up and stopped functioning about 2 miles from work.

I had never used it for an extended period of time like that. I want to say a rectifier burned up or something but I over-built the dummy load and everything so it would run cool and the fact that the TCC signal from the PCM was actually passing through to the transmission indicates that relay number 1 wasn't functioning anymore. The red indicator light worked still so it wasn't a loss of 12v power(complete loss anyways) and the TC locked indicator still lit up so it wasn't a loss of ground. I smelled something burning from it tho so we will see.

[dkjones96]

The engine uses two timing chains(a lower and an upper), I'm pretty sure the tensioner can take up the slack but I have them replacing it anyways because the chain slaps around on cold starts. I'm fairly sure there is a +- 3 degree adjustment on the stock cam timing gears. I'll get them to adjust it 3 degrees advanced if they can. If not, I'll have to make my own adjustable timing gears.

The shop I took it to is the only person I'd ever trust my car with. I started the engine, 2 seconds later he had me turn it off and he said there is stuff in the cylinder but the valvetrain is fine(that's what I thought the ticking was), he even knew which cylinder it was by listening. They got the pistons in this morning and it should be back from the machine shop this afternoon!

I'm driving an 80's suburban right now and even 20mpg is sounding economical to me lol.

[GasSavers_Erik]

Thanks for the explanation. It's too bad that your engine was damaged during the experiment.

[dkjones96]

Update, I actually went down there and it turns out the guy was talking to me about the wrong car(retard) MY car still needed the head removed but it was because the piece was embedded in the head to a point that they couldn't get to it. I am extremely surprised at how good the engine internally actually is. I took a few pictures but I'll post the picture of the cylinder only for now.

So, they slap the head back on and I won't need machine work done! (aside from fixing the pit in the head) Still, it's 11.6 hours for a head removal. The timing chain system on this car really sucks.

At the top left of the picture you can see the second piston's pit from a piece in the cylinder, it has two in it. This engine has 111k miles on it and the last 50k have been very hard. I'm surprised to see how little cylinder wear there is. You can see the reflection of the piston in the cylinder wall!

[bowtieguy]

happens all the time, and not just from DIYs. i'll tell anyone...

spray cleaner and use compressed on the motor BEFORE removing/installing spark plugs.

[GasSavers_Erik]

Yeah- those cylinders are in really good shape. It's nice to open up a motor and see the factory hone marks still on the cylinder walls.

You had some really good compression readings too.

I'd love to see a pic of the piece embedded in the head if you have one.