What Cylinder Pressure for 9.0-1 Compression - Engine Pics Page 3

[ZOSO]

What was the verdict?

 

[70_Steve]

What was the verdict?

Won't know until next Monday or Tuesday. I wasn't able to get the engine to the machine shop until last Tuesday. And the machine shop has been in the process of moving to a new location for the past two months. They're still trying to get organized and have a bunch of catch-up work to do, so I agreed to wait 'till next week for them to disassemble the engine. They may do a leakdown test before I get there, but they have no problem with me being there when they disassemble the engine, and seem just as curious as I am to find out what went wrong.

I will post here, hopefully with pictures, after the disection.

 

[70_Steve]

Finally got with the machine shop to check out the engine. They started by doing a leakdown test. Cylinders 1, 2, 3, 5, 6 and 7 were "acceptable" considering the engine only had about 100 miles on it. Cylinder 4 and 8 were really bad. All the leakage was into the crankcase, indicating a problems with the rings, which is what I suspected.

I had problems with the fuel injection system when I first started the engine, not ever fully testing the EFI system with the engine before deciding to rebuild it. Although working through several issues with the FI, and the final issue being that it was running lean, apparently on startup it was running very rich. The indications were that excess fuel was washing the oil off the cylinder walls, and caused the rings to score the cylinder walls. The machine shop will disassemble the engine, rehone the cylinders and reassemble.

Here's a couple pics of the results.

 

[av bronco]

Damm, what size injectors? was it chipped or tuned? Ive had really good luck with fi stuff from the classifieds at corral. Also the guys at eectunig are pretty helpful.

 

[73azbronco]

Steve, have they verified proper bore size? Bore hone? Piston size? Ring type for the method of honing?
And you were there for the measuring?

I would think in the short time it took to realize you didn't have compression, that to much fuel from injectors would not be the primary issue. Think about it, if it ran, it was burning the fuel. How much fuel was in the oil? If no fuel in oil, I doubt their claim of fuel scavanging the oil. If anything, it looks to me like the bore was not sized correctly, the hone was incorrect for the rings, or the rings are the wrong size.

Last thought, possibility of no/poor oiling to the piston rods/spray hole? Spin the oil pump with a drill motor and see if you get oil spray into the bores.

 

[ZOSO]

I agree. It takes a lot to wash out the cylinders. So much infact that they barely run and smoke like crazy. Im still leaning towards wrong parts/bad install. How did the oil smell? was there more coming out that the 6qts you had in there? The only way an efi set-up can do that is if the injectors are basicly wired to stay on at 100% duty cycle all the time.

 

[hartbronco]

Steve, have they verified proper bore size? Bore hone? Piston size? Ring type for the method of honing?
And you were there for the measuring?

I would think in the short time it took to realize you didn't have compression, that to much fuel from injectors would not be the primary issue. Think about it, if it ran, it was burning the fuel. How much fuel was in the oil? If no fuel in oil, I doubt their claim of fuel scavanging the oil. If anything, it looks to me like the bore was not sized correctly, the hone was incorrect for the rings, or the rings are the wrong size.

Last thought, possibility of no/poor oiling to the piston rods/spray hole? Spin the oil pump with a drill motor and see if you get oil spray into the bores.

I agree .... A buddy of mine ran his Bronco with a 5.8 L and didn't hook up the O2s and it took 4 years before he was able to wash out the cylinder walls !!! What were the compression # on the "acceptable" cylinders ? For only 100 miles on a rebuild , It looks like more then just a fuel problem to me JMO Good luck .

 

[73azbronco]

Steve, i think it's time to take the motor to another shop and have them spec the bore/pistons/rings/hone, sorry buddy.

 

[Arniep]

I wouldn't take anything apart on the engine, take it to the shop complete. Disassembling anything relieves the shop of any legal responsibility.

 

[73azbronco]

Ditto, take it like it's shown in the photo, have the other shop spec the cylinder, dermine bore diamter, hone type, then pull worst piston out and determine ring gap size type, etc.

 

[Rustytruck]

I'm glad they are going to fix it.
Funny thing with cylinder 8 the scuffing at the top of the bore above the ring travel the piston doesnt touch that area so how did it scuff? It is also scuffed on the back side not on the load side of the piston while it rotates. I would check the main bearing thrust clearence or endplay in the crank before I put it back in.

 

[70_Steve]

Thanks all for the comments. I took a drive back to the machine shop this morning to ask a couple more questions.

They haven't disassembled the engine any farther than was done the other day, and that was just to pull the heads. I did question Rich, the machinist, about the piston to skirt clearance, and, although he doesn't remember the exact numbers, for my engine he honed for a .002 clearance.

We did measure the bore on a couple cylinders and they were all within .0003, including cylinders 4 and 8.

I was most interested in the scuffing above the top ring on cylinder 8, and found that the marking is not scoring of the cylinder wall. Rather, it's aluminum from the top ring land. The #8 cylinder, which shows this most prominently in the pictures, has that scuffing about 90° around the "bottom' of the cylinder. The #4 cylinder has this same scuffing around the top. I even took my pen knife and was able to scrape away the aluminum.

As I said, I do appreciate all the comments and suggestions. They really did make me think, mostly about how little I know about putting together, and diagnosing mechanical engine problems. But, I do have confidence in this shop. It's run by two brothers, one of whom has been a mechanic all his working life, and his brother has been an automotive machinist most of his life. Twenty years ago they decided to open their own shop. They must have been doing something right because they were recommended to me by several people fifteen years ago when I had thoughts of restoring an old El Camino that I had drug out to Phoenix with me. Most of their business now is in performance engines, both for dirt and asphalt circle track racers, and drag racers. I think, because of that, they seem pretty comfortable diagnosing engine failures. Plus, considering the number of engines they had stacked up around the shop waiting on them, they must not have too bad a rep among the racers.

I now have all of my fuel injection issues resolved. I'll let these guys put the engine together again, and start all over. If I have another problem, it will be time to just do this myself.

 

[73azbronco]

Steve "doesn't remember" doesn't cut it. He should have a build sheet detailing what was done to include clearances. Elsewise, he has no proof anything was done correctly and by the book.

I appreciate they are well known and liked, mistakes do happen, but unless they are going to buy the rebuild at no cost to you, please consider going elsewhere for at least a diagnoses. You owe it to your pocket book and sanity. For less than $100, another shope can mic and spec the parts in question and give you a damage report. I have lots of accident investigation experience, what your showing me tells me there is a motor problem, not a fuel problem, i really doubt fuel is the problem unless you had fuel in the oil, and if you did, that would be a lesson for the rest of us.


I do admit I'm a week or two from finishing my motor, and I'm starting with a carb for breakin, just so I don't go through the EFI and NEW motor issues your having. Sorry again pardner.