Terrible idle after water crossing

[duffontap]

Highway was flooded on the way to work yesterday so I had to drive a couple hundred yards through a foot and a half of water. Took it slow.

A couple miles later I noticed a really lousy idle--fluctuating rpms, nearly kills at a stop light. Took the dissy cap off last night and didn't see any moisture but left it open to dry out all night in a warm garage. Just as bad or worse today. Runs fine when it gets up to speed.

Checked for obvious vacuum leaks. Checked for loose ignition connections. Points, plugs, timing, dwell, cap and rotor are fine. Maybe water in the fuel? Any other suggestions?

Thanks! JD

 

[bikersmurf]

In a stock 40 you should fine to 3-4'. Do you have any computers, fuel injection, or other mods?

Water in fuel could be a possibility. Methal Hydrate is sold up here as gas line antifreeze, it helps with water in fuel (frozen or not).

Your exhaust system may also have water in it. How much have you driven since the water crossing?

 

[camcruiser13]

Sounds like you swallowed a little bit of water

 

[lostmarbles]

Spray the plug/distibutor high-voltage leads/wires with silicone and then wipe the excess off with a clean rag.

 

[rsbcruiser]

What Tom said. Also, what might have happened is your dizzy cap got wet and cracked from the sudden change in temp. You might or might not be able to see these cracks. Start her up and check for acring by veiwing the idling motor in the dark.

 

[45Kevin]

Take a look at your air filter. Water way have gotten in the air filter box.

 

[mydogpea]

bummer

 

[duffontap]

Thanks everyone for the suggestions. The symptoms got worse on the way home. I ended up finding that I could get the truck to run right if I put just a little pressure on the engine side of the cap; if I put pressure on the battery side it would immediately shut off. Switched caps and no change. Didn't have a spare rotor so I'll go grab one. Perhaps the water crossing was just a red herring? JD

 

[psreno]

WD-40. Water Displacement - formula 40.

It works better than silicone.

Is the dizzy loose (twist)?

 

[cjgoode]

Use to happen to me on my 1970 all the time, water on/in the distributor was always the cause. A wipe down and coat of wd40 inside and out always cleared it right up. My 1976 had such problems with rain water coming through the hood vents I had to tape the one off on the passenger side. Water on the ignition areas can cause this if stuff is old.

 

[lostmarbles]

I hate WD40 (for this particular use) because I know it attacks/damages rubber (and rubber-like materials). Hence my reference to using silicone rather than suggesting using any "common penetrating oil".

But I know common penetrating oils (like WD40) are sold for this use and I admit they may even be better at "getting an engine running" when "tracking/arcing" has become an issue. (But I value long-term reliability.)



I restrict my use of WD40 to "loosening seized fasteners".

 

[duffontap]

Well, I don't know how satisfying this 'solution' will be for anyone, but the truck is running great again. I mentioned that I could control the symptoms by putting light pressure on one side of the cap or the other. Pull it gently away from the engine block and it ran perfectly, push it gently toward the engine block and it would shut off, and somewhere in the middle it would just idle terrible as I originally said.

I loosened the retaining bolt on the distributor clamp, wiggled the whole assembly back and forth a little and re-tightened the bolt (this is the bolt that holds the clamp to the block, not the one that you loosen to adjust the timing). Runs perfect now. I just can't figure out what was going on. Maybe my distributor is so worn and sloppy the shaft was being pulled slightly to the side and the rotor was no longer making contact on side of the cap? Maybe time for a rebuilt or lower-mileage unit.

Thanks for the help and thoughts on the 'solution' appreciated. JD

 

[lostmarbles]

Normally when rough running is experienced after water crossings (petrol engines) we all assume "tracking". (The electricity "zap" that is supposed to jump across your spark plug gaps is going elesewhere.)

Hence most of went in that direction for proposing a remedy JD.

I agree that it now sounds doubtful that your problem was really caused by the water ..... unless somehow you're making the tracking-path more difficult by moving the cap slightly.

(As you can see ... Because it occurred at the same time as a river crossing, I'm still having a hard toime believing its not water-related. )

But Hey. ... You got it running great again so that's all that matters.

Well done!

 

[Mark W]

Your problem is a worn out distributor. The shaft is sloppy causing erratic opening of the points and poor ignition. The water crossing has nothing to do with this.


Also...

Water in the fuel would not produce the symptoms you mention.

Wet air filter would not cause this either.

Water immersion will not make a cap crack.

Water in the exhaust system will not affect anything.

WD40 was developed as a Water Dispersant. This is the most appropriate use of it. It is a terrible lubricant. It will not damage any rubber or plastic that should ever be found under the hood of a '40.


Mark...