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Loss of cylinder after engine wash

Tiny
HAZMAT
  • MEMBER
  • 1981 SUBARU BRAT
  • 234 MILES
I did a degrease and pressure wash on the engine and fired it up. It started missing on one cylinder. After I stopped in an auto parts place I started it back up and put it in gear and heard a clunk and the engine died. The engine fired right back up but only on 3 cylinders. When I got it home I replaced the wires, plugs and distributor/rotor and it still only had 3 cylinders. I pulled the wires one at a time from the spark plugs and found one cylinder to not have any effect once plug wire was pulled. It does have spark to the plug. There are no unusual noises when it is running and driven. It just runs on 3 cylinders. The no noise thing and having spark is really throwing me off on diagnoses.
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Monday, October 10th, 2011 AT 3:07 AM

7 Replies

Tiny
DAN_K
  • MECHANIC
  • 213 POSTS
I would perform a compression test. Were you very careful in preventing water from entering the engine?
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Monday, October 10th, 2011 AT 3:20 AM
Tiny
HAZMAT
  • MEMBER
  • 4 POSTS
Yes, pretty much the only place water could get in would be thru the breather which I made sure I avoided. The thing that throws me off is the lack of clatter or any other noise when it is running. If there were strange noises such as clatter or clunks or rattles etc. I would be thinking many things such as a rod, bearing, wrist pin etc.
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Monday, October 10th, 2011 AT 3:35 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Have a comppression test performed as suggested and if the compression is low, it could be someting else.

The cylinder compresion could have failed due to weak rings, and that is not because of water getting into the cylinders. It could be that the cylinder was misfiring due to water contamination to the spark plug wires etc and the continued misfiring had caused the loss of compression due to excessive fuel getting to the cylinders and cleaning off the oil.

Check for vacuum leaks at the intake manifold for the particular cylinder.
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Monday, October 10th, 2011 AT 12:42 PM
Tiny
HAZMAT
  • MEMBER
  • 4 POSTS
I did a compression test earlier today and all cylinders were above average and grouped pretty close together. I thought maybe the new plugs/wires/cap/rotor might have been a problem so I replaced them again with all new. It fired up and ran great, but after a mile or 2 of test driving it it went back to running like crap again. I'm thinking tomorrow I may check the timing to see if it may have jumped on me. Maybe check the coil, resistor and capacitor as well to see if maybe one of them were damaged?
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Tuesday, October 11th, 2011 AT 7:21 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Recheck the distributor cap and ensure there is no water condensation inside it.

Have you checked for vacuum leaks. Not likely to be a skipped timing as it ran great for a certain period.
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Tuesday, October 11th, 2011 AT 10:49 AM
Tiny
HAZMAT
  • MEMBER
  • 4 POSTS
You are going to love this one. 3 NEW sets of plug wires later and 2 NEW rotor/caps later it is back to running great! I checked the coil/capacitor/resistor/vacuum lines, among other things and all checked out good. Did some reading on the timing and thought it unlikely it skipped a tooth as the old subarus are gear to gear instead of belt or chain. Guess it just goes to show you that you cannot always trust new parts. Thanks for all the ideas and help. It was much appreciated.
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Tuesday, October 11th, 2011 AT 11:56 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
That I sone of the reasons I never like to use after market ignition parts and would rather go to the junk yard for used genuine parts.

Glad to know you have fixed the problem.

Have a great day.
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Wednesday, October 12th, 2011 AT 4:28 PM

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