Uncle_Rico

It sucks to read something like this. I've almost finished my first WP/TB job and this is is why I'm scared s***less about firing it up (even if it is a beater). There are so many things that can go wrong. I've convinced myself the first time I start this thing the engine is either going to get destroyed or it's going to catch fire (or both!). While it's fun working on this car, sometimes I wonder if I should have just let Sean R. take care of everything since he's only 30 minutes away.

All that to say, hang in there man. I might be joining you soon.

linderpat

If Sean were 30 minutes away from me, I'd spring for his hourly rate to come over and do a visual before firing up on my first TB job.

Shawn Stanford

The ironic thing is that overall, it went pretty smoothly. Certainly better than the first TB I did, which was on my '82. And I think that it will go even better then next time. I certainly know what to look out for during the reassembly.

But, yeah: just a tiny f* up, with Big Consequences.

76FJ55

It is most likely that it has at least a couple bent valves, but I have heard rumors of a few instances where they have survived intact. A leak-down test would confirm the condition of the valves, but you will need to re-time the cams and string a new timing belt to to test it. rotate the crank forward or backward to the nearest 45 degree location then align the cams to to it.

It may also be worth capturing the condition of everything with photos during the tear down, just in case you need to look back at anything for diagnostic purposes.

Keep us informed on what you find. It totally sucks that this happened, but if what is learned from this car can save someone else from suffering the same failure, it will be worth passing the info on.

And let us know what we can do to help you recover this one.

Shawn Stanford

My current plan is to get back down to the belt, get it off, and then get a scope down into the cylinders and see what's going on.

Shawn Stanford

Okay, after a day of work, here's where I'm at...

I got a scope down into the cylinders and I didn't see anything marks on the tops of the pistons; they all have a nice even coat of carbon. So, rather than immediately tearing off the heads, I decided to invest the time into putting a new timing belt on and seeing what would happen.

With my brother's help and instructions from here, we put a screwdriver into cylinder 1 and turned the motor to 45 degrees BTDC. Then we turned the cams to three teeth BTDC. We strung a new belt and turned the motor through a two complete revolutions and stopped at TDC. The driver's side cam was dead on and the pax side was within half a tooth of the mark. The motor turned free, no problems. Deciding that we couldn't do any more harm than was already done, we put the front of the motor back together and tried to fire it up. The motor turned over and almost caught once, but that was it. Now it turns over easily, but doesn't even think about starting.

Frankly, it sounds weird to me, but I'm not sure if something is off, or if I'm just hearing things. The starter seems to be turning the motor far too easily, which would lead me to believe that there's no compression. However, even if the motor did get a valve strike in one or more pistons, I would still expect the car to be able to fire and run rough on the cylinders that don't have valve damage.

My brother says the if it was his, he'd pull the motor and do a rebuild. The motor hasn't been overhauled since the car was new, and it could use a complete refresh. But a rebuild means time, and I don't feel like I have that time, and I'd like to free up the garage space sooner rather than later. And, ff course, for my money I'd rather do a Renegade LS swap than a complete rebuild of the original motor. But it's not my car.

At this point, I'm of two minds: Should I talk to Stan about dragging the car down to him to make sure that I'm not overlooking something stupid, or just start tearing the heads off?

docmirror

OK, one thing at a time. Like Hippocrates said, first - do no harm. Since that ship sailed, second - do no further harm. So far no comp test has been done, to check for bent valves, or low comp. Either on the first mis-adventure, nor on the second try. I say do some step-wise evaluation before blowing it up with a few sticks of tri-nitro toluene.

1. Check your timing marks, then check them again. TDC 0 T mark = notch marks on back of cam wheel meet tick marks in backing plate. There are gobs of photos here to verify.
2. Rent/steal/borrow/buy a compression gauge! Know what you know. Remove all plugs, and take a baseline measure. Should be > 150PSI cold on all jugs.
3. Depending on what you find in 2, you will either continue to troubleshoot, or decide on a plan to fix it. Valve crash <> 'engine rebuild'. It means the heads come off, and valves/guides/seats are renewed as needed.
4. If you have good C/R pressures on all jugs, look elsewhere for no start.

Shawn Stanford

We triple-checked the marks, hand rotated the motor, and checked again. I'm satisfied they're correct.
Yeah, so, I forgot to mention that we checked #1 and #2, and then the fitting for the compression gauge fell into the cowling and disappeared behind the blower motor (!!). But before it did, I read 0 PSI on #1 and 60 PSI on #2. Rather than run out and take the time to buy another compression gauge just to get the fitting, we decided to button the top up and see if the an attempted start would confirm what the gauge indicated.
Yep. Like I said: It sounds weird, but I don't know if it's truly weird, or if I'm being overly sensitive. I'm not in favor of a rebuild.
See #2.

My brother isn't a 928 guy, but he seemed to think that once I pull the cam covers, I should be able to see if the valves look wonky before going further. Does that sound correct?

jej3

@Shawn Stanford - this is probably all the info you need to know you have bent valves. Since part of your compression tester is lost, go RENT one at AutoZone. Do the compression test again with a bit of motor oil in those cylinders through the spark plug hole. My guess is you bent valves on one of those two. Pull the heads with low compression (probably both) and get a valve job done.

With all the talk of Renegade conversions, etc... The money paid to a machine shop for the re-made heads is pennies vs the pounds of craziness that might go into a motor swap.

Alternatively, source a working used motor. Install it and don't touch it again

Shawn Stanford

A compression tester from HF is $20, so it's really no big deal to pay for another. It was more the 45 minutes to get there and back that pushed us in the direction of buttoning up and turning the key. It was later on Saturday afternoon and it was in the 90s. There was a pool and beer waiting.

I agree: Having the heads and some new valves done is way better than rebuilding the motor.

If it was my car (remember: it's not), if the motor came out because it needed a rebuild, an LS would be going in. I've never done serious motor work, either pulls, installs, or rebuilds. The idea of rebuilding any motor is daunting, but the 928 motor is much more so. As far as I can tell based on my meager experience with 928s and what I've read here, installing a recovered LS with a Renegade kit would be cheaper than having the original motor rebuilt. And if I'm doing the rebuild myself, then it's also going to be both easier and faster.

But, that's a discussion for another thread...

Thanks for the advice, everyone. I very much appreciate it!

76FJ55

Seems like most of the points have been covered above, but it still may be worth posting pics of your timing marks at TDC. I know you've verified several times, but sometimes others may notice something you missed, and it wont cost you anything.

Shawn Stanford

Just time. It's actually kind of stupid how much crap you have to remove in order to hand turn the motor and view the timing marks on the cams. Turning the motor means removing the throttle cable bracket and the fan to get a wrench on the crank bolt. The passenger-side upper cover isn't too bad, other than having to maneuver around the radiator hose, but the lower corner of the driver-side upper cover is under the top of the cassette. As we found out: It will come out with the cassette in place with a bit of moderate twisting, applied force, and creative vulgarity, but it wasn't easy.

GregBBRD

1. You are going to have multiple bent valves. Quit wasting more time.

2. The cylinder heads do not come off with the engine in the car in a 1985 model....the engine needs to be removed.

3. If you can't do a timing belt without it turning into a disaster, there's not a snowball's change in hell you are going to be able to get the engine in and out of the car and get heads on and off, given the complexity of the camshafts, which have no "reference" marks in 1985.

4. You and your buddy need to figure out what to do, next....and who is going to write the check.

Shawn Stanford

While hobbies are, by nature, wastes of time, this wasn't. I had a very enjoyable day Saturday wrenching with my brother, something I haven't had a chance to do for many years. My brothers and I are very different people and lead very different lives; wrenching is one thing this brother and I have in common (although he's better at it than I).

Hmm... I was told differently. Hopefully you're mistaken. (Does it help that I have small hands?)

I can do a timing belt without it becoming a disaster, I just didn't manage it this time.

Other than the fact that I'd like to have my garage back, neither of us is in any hurry.

GregBBRD

When it's your own car, it's a hobby. When it's someone else's car, it's a job.

It's a good thing thing you're enjoying it. I'll check back in three months and then after another three months, after that and see how you are enjoying it.

The very first 1985 928 engine I rebuilt came to me in boxes, with one head off and the other loose, but still on the block. The A/C lines had been bent to crap and removed, the engine was loose on the motor mounts, and the torque tube had been loosened, so the engine would twist. They still could not get the head off. The engine compartment was missing more paint than a World War II destroyer sitting in mothballs. The fenders needed to be repainted.

While almost anything is possible, not everything makes sense.

The '85/'86 engines are the most difficult of all of the various 928 engines to take apart and put back together....by a huge margin. I can't imagine bending over the fenders for days on end, just installing the cams and getting them timed correctly.

Pop the thing out of the car, put it on an engine stand, start taking all the digital pictures you can, and start praying.

This is going to rock your world.