namasgt

Well putting the oil in the cylinder fouled the plugs, so I had to take them out and clean them then try again, until all the oil was gone. How strong is your battery, if it cranks the engine slow it will not show good compression numbers.

Hilton

You said on the other site that the car, once started, will run as long as you keep it above idle - I got the impression you mean it runs indefinitely, as long as you keep the revs up?

Is that the case? If so, I'm still questioning the K-jet injection system. More description on how it dies when idle drops would be good - does it die immediately on revs dropping, or will it idle for a few seconds before dying? (e.g. 5 seconds).

Seriously, I don't mean to patronise, I think we've all been to the point of jumping to conclusions and throwing mass parts replacement at our cars as a strategy at some point. You've got so far on this 928-save, that it sounds like you're getting a bit desperate. I'm guessing you're going through some crazy emotions right now with respect to the car?

Steady methodical checking is the way to solve this.. Working through each test carefully will help inform diagnosis, and prevent tailspin

IIRC, the price of new rings for a 4.7L engine is high - so its worth being very sure you need them before you have to buy them.

James Bailey

If you do end up putting in rings DO NOT hone the cylinders !!!! That will ruin the block...... neither the 30 lbs or the 160-240 would be reasonable for that engine. Get a decent compression gauge use it on a couple OTHER cars then do ALL the cylinders on the 928....hold throttle open do 1-8 then do 1 AGAIN to see how much the loss of battery is changing the cylinder to cylinder readings. Putting oil into the cylinders is often done to confirm that the rings are shot since bad valves do NOT get better with oil. You need about 100 lbs of compression for an engine to run.

928 at last

It's been oiled and fired now, and let run for a bit. For insurance, I'd still run a compression test (warm) on all eight, and not expect miracles.

gbgastowers

It runs smooth and smokey. I was going to set in there and run it for a long time but my wife was asking me stuff and I accidentally let off the gas and it died after about 5 minutes. It dies immediately when I let off the gas and will not restart. It started earlier the first time and ran for about 20 seconds and I never touched the gas pedal. The second time it started I used the gas pedal and kept it revved up a little for about 3 minutes before it died when I let off the pedal. The 3rd start was the one where my wife was asking me questions. Each time it wouldn't restart till I added oil to the plug holes and cleaned plugs. It didn't require starting fluid and started on the first hit of the starter.

neilh

Hilton has good points,.
You need to get a good fuel pressure gauge on there and see exactly what is happening. If i had one that would work i would send it to you, to put us all out of our misery :-)

928 at last

Are you oiling all the cylinders, or just some on these attempts?

gbgastowers

All on the 1st 3 starts. Then I put the airbox on for the long run I attempted. I am going to try to see if it will run by just oiling the front 6 since the airbox is in the way for the back 2.

namasgt

I don't know much about the mechanical fuel injection system, but I truly believe that your rings are fine.
Have you connected the vacuum lines on the throttle plate correctly? It could be that you have 2 vacuum lines switched wrong so that when the plate is closed you don't get any air, so no idle, but when you push on the gas pedal you get air and your engine runs.

928 at last

It's going to be a process of elimination now. It's your call. Warm it up a little and run a compression test with a fully charged battery. Test all cylinders and make very clear notes on the readings you get from each. Do a search and follow the directions for doing a proper compression test on these cars. It's on here somewhere, I've read it before. If that goes well, and hopefully it does, then you're going to have to suck it up and read up on the fuel system for your car and locate (Beg Steal Borrow) a set of gauges and test/calibrate the system properly.
Good luck with it!

Hilton

This is an excellent point - compression test should be carried out on a warm engine.

As you can get it running, and keep it running, give it 15-20 minutes to properly warm up. Unfortunately the best indicator of it being properly warm is idle oil pressure dropping to below 5bar, which you can't check without killing the engine.

So just give it another 10 mins after the coolant gauge stops climbing.

Some other questions - whats your oil pressure gauge showing when the engine's running? What oil are you using?

Given the bottom end came from an unknown engine, it may be something as simple as the rings aren't seated properly, so even if compression shows low, you might just need to follow the ring seating procedure with some non-synthetic oil.

James Bailey

This assumes the fan clutch still works...."So just give it another 10 mins after the coolant gauge stops climbing. " or it may not stop climbing

namasgt

Do you mean the ring end gaps? I have read that when the engine is running the rings rotate in the ring lands, so I would think that would not matter.
Also if your going to go trough the trouble of taking the pistons out don't reuse the rings just replace them.

gbgastowers

I don't know if oil pressure gauge is working correctly since the cluster is having some issues but the needle swings all the way to the top while running (and goes all the way to the bottom when I turn the headlights on). Oil is Mystik 15W-50 synthetic blend. http://www.docs.citgo.com/msds_pi/663004002.pdf I'll take a look at the ring seating procedure and maybe change the oil to full dino.

928mac

Hmmmm I was going to say to FILL the cylinders with some dexron and let it sit over night with the plugs out.

Turn it over by hand the next day, clean up the mess and then with a blanket over the engine to stop oil spray,
crank it 10 times over (plugs still out) to remove all the oil in the cylinders so it dose not hydraulic when you crank it with the plugs in.

You should drain the engine oil and replace it to remove all the dexron before running it for the 10 min.

Hold it above 2000 rpm for 10 min.
check compression (with a 100 psi it should at least start and run)
It may smoke for days
If the compression dose not come back, its bad.