More engine trouble.. again

Went for a fantastic ride yesterday. My new rebuilt engine performed like a champ. Today went for a little ride , very modest drive, suddenly something changed. The engine runs but runs rough and I think there is a knock. I am hearing impaired so listening is troublesome for me. So is describing the sound. But I tested compression and all are at 120.

If I am right, the fact that compression is good means it is likely in the bottom half of the engine... right?

I built this engine myself last month and it is my first, so I almost expect some trouble, but it seemed to be running really smoothly once I got the timing set. Only trouble is that it seemed to be running rich. And now this.
I have taken a short video with sound of the engine today, but I am having trouble with the downloading, and posting it. I found it on my realplayer software but I can't seem to save it where I can find it to post it. I will keep trying. In the mean time, any suggestions on where to start are appreciated.

This is a recent rebuild so all internal parts should not have to be replaced.... at least I think.
I believe the sound is coming mostly from the rear of the crankcase. I have a small exhaust leak as well at where the exhaust crosses the crossmember.

My list of possible problems

Bent rod
Failed rod bearing
Failed main bearing(rear)
Broken Crankshaft

Anything else?


Anybody else work on their jeep for 2 years for every 4 hours worth of driving it?

 

it's easy to get frustrated...BTDT over the years.
does it make the noise at idle ?
if so, removing one plug wire at a time might isolate the specific cylinder with the problem.
if it's a knocking sound, that is.

 

Also, can you elaborate on "runs rough" ... rough at idle, at mid speed, at WOT, or all speeds?
Any lack of power, or just "rough"?

 

I will try that now. Give me a minute

 

The thing sounds like a tractor motor initially, sound stays the same, but interestingly then engine at idle dies when plug wire 1 and 2 are removed. The idle speed increased slightly when 3 and 4 are removed and only the rubber insulator is touching the top of the plug, and slows down again when fully removed.:?

 

Yea lack of power, and what ever happened, did so suddenly. Runs rough like a tractor motor at idle, seems to hesitate a lot with acceleration and does smooth out a bit at higher rpm, but still much less power than before the event.

 

it seems at this point like fouled plugs-ignition problem, you say it was running rich, pull all the plugs and see what they look like, with a stock point ignition they should tan-or white-grayish, if they are black or sooty, they are fouled, try a new set of plugs if thats the case, if it runs well right away after that, you need to fix the carb rich issue.

start with that and let us know how you do

Duane

1963 cj5
1945 gpw

 

They are black and sooty for sure. I'll have to wait till am to change plugs, see if that helps, but the problem seemed to start instantly from running good, to crapy and reduced power in a split second. Fouled plugs do that? If this is fouled plugs, I'll not here the end of it from blevisay!

I hired a local guy who works on carbs. He came over while I was gone and did some work. I came home and sure enough it ran much better, after I adjusted the valves the other day I pulled a plug and still rich. My mixture screw does nothing, zero, zip! I can turn it down to seat and the thing stll runs the same as turned out to 3 turns.
I put new plugs in 3 days ago fyi.

 

First thing that comes to mind is a bad power valve. From reading, Webers are known for that and IIRC, yours is several years old. And, as I understand it, they do just "go out". I have also heard of clogged air bleeds, but don't think they cause nearly as big of a leak as you must have.

 

Update:

Carb was running really rich, and after a long ride which required engine braking for the entire last 40 minutes, the plugs fouled on the rear 2 cylinders. All plugs were black and sooty. After having 2 mechanics "fix" the carburetor with no luck, I went ahead and bought a new one for around 250.00 , got it and bolted it on. Changed plugs. Started it up and adjusted the idle speed a little. Seems to run great, no knock, no roughness.

Got to attach the emergency brake cable though after my wife said "what's that thing dragging underneath?"

 

:iagree: On the Carter YF the idle mixture screw not responding, rough running and fouled plugs are generally a sign that the Pump Diaphragm is beginning to leak fuel. Out of curiosity what did the Mechanics say was done to the carb?................do you still have the old carb?

 

Great! Congrats!!!
How much do you want for the old Weber?