TheSamba.com :: View topic - Running on 2 cylinders? Need troubleshooting help

Sat Jun 13, 2015 9:20 pm

Hello All,

I'm in the middle of a road trip to Yellowstone National Park in my '64 SO35 camper. I'm having some engine troubles, I need to bounce some ideas off someone to help me troubleshoot.

Engine was just swapped out 2 weeks ago with a rebuilt 1600. Was running smooth this morning, all through Colorado. About Rawlins Wyoming, I started noticing a loss of power. Started off adjusting the timing (009 distributor) and carburetor (34PICT-3). Shut off the motor on the side of the road and got everything back to baseline (7.5 BTDC, and carb adjusted to baseline) Did all that, kept struggling. It got worse after awhile. In hindsight, I may have been on 3 cylinders, then dropped to 2.

Here's what I need advice on: At one point, I started pulling spark plug wires from the distributor. When I disconnected the spark plug wires that go to the cylinders on the right hand side, motor didn't miss a beat. No difference in what the motor sounded like with the wires connected, vs. disconnected. I did the same thing with the cylinders on the left side, and the motor stumbled until I reconnected them.

I pulled the spark plugs out of the 2 right hand side cylinders (one at a time), and ran the motor. Grounded the spark plug to the engine case, and I'm getting spark at the plugs. I did not have a compression tester with me, so I need to get that piece of information as well.

The motor runs, but I don't have hardly any power. I stumbled into Riverton WY, and I'll be troubleshooting tomorrow.

Based on the fact that pulling the spark plug wires doesn't make a difference in how the motor runs, I suspect I'm running on 2 cylinders.

Please confirm my line of troubleshooting is correct.

Here's my plan for tomorrow:

Compression test on all 4 cylinders.
Valves
check and compare spark at all 4 plugs
Check coil?

Any suggestions are welcomed, thanks!

Mike A.

Sat Jun 13, 2015 9:51 pm

A valve adjustment would be high on my list, a ghetto compression test is disconnect the coil wire and crank the engine while listening, rrrr...rrrr...rrrr...rrrr....?, or rrrr...rRRr...rrrr...RR...?, if the sound changes between each RRR or one seems shorter and faster than the rest you have a soft cylinder.

Sun Jun 14, 2015 8:48 am

It sounds like you are on the right track. As mentioned above, a valve adjust is a must before a commpression test. Would also check the condition of distributor cap, rotor and point gap to ensure a good and consistant spark. Good luck and keep us posted.

Sun Jun 14, 2015 10:46 am

Not real likely, but your rocker arm could have pulled loose a stud....

Sun Jun 14, 2015 11:09 am

busdaddy wrote: A valve adjustment would be high on my list, a ghetto compression test is disconnect the coil wire and crank the engine while listening, rrrr...rrrr...rrrr...rrrr....?, or rrrr...rRRr...rrrr...RR...?, if the sound changes between each RRR or one seems shorter and faster than the rest you have a soft cylinder.

when you are troubleshooting, do the easy things first... checking and adjusting your valves is easy and quick. you can also visually inspect the rockers while you are in there. do that first

Sun Jun 14, 2015 12:01 pm

i would inspect the points and inside of dist cap. then the spark plug wires and plugs. hopefully its just something simple, mabey try swapping the coil. mechinical problems will usally have strange engine noises that go with them.

Sun Jun 14, 2015 7:19 pm

I agree with above. Start by checking the simplest things, like points gap.

My guess would be poor high tension wires, especially if it the passenger side that has lost power, the wires leak where they pass under the generator/alternator. If you spray them down with soapy water while running and watch for spark jumping from the wires to ground.

Good luck with it and let us know how things turn out.

Gordo.

Mon Jun 15, 2015 10:11 am

If it's a dual port check to see that all the boot clamps are tight.

Mon Jun 15, 2015 2:50 pm

Check the plugs. That should help you diagnose what is going on with each cylinder. covered with gas would indicate it is not firing. Oily? something else is going on. Charred with carbon, too rich. When I traveled at elevation I had to swap jetting.

I had a BIG power drop as compared to sea level.