Starting problem

Tiny
CARPETMAN1759
  • MEMBER
  • 2002 CHEVROLET S-10
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
After two days of rain the truck will not start. It takes more then one complete day of rain before it will not start. Will turn over but sounds like the distributor is 180 degrees out, coughs and back-fires. Had to replace the distributor due to the top plate rusted off the shaft. I think water is getting in the cap but cannot figure out how. Installed new cap and rotor and that fixed it for a month. It started to do it again. The two screens on the bottom of the distributor are clean and not plugged. No water runs through the hood seal and hits the cap that I can tell. What else can I look at to stop this problem? I purchased this truck new and it just started doing this about a year ago.
Monday, March 26th, 2018 AT 9:02 AM

13 Replies

Tiny
THORPEDO
  • MEMBER
  • 1 POST
If you really think it is the distributor, then try putting a plastic bag/Ziploc over it next time it rains. If you still have the issue, then it is probably not it. I had an issue on a GMC van that was similar to this. It turned out to be the engine computer. Rain would get past the hood seal, and drip onto the computer, which was under the hood. Visually, you could see that the computer was not sealed, and how water was getting in. A mechanic found a re-manufactured unit through NAPA for about $250.00 to $300.00 and it ran great after that.
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Monday, March 26th, 2018 AT 10:11 AM
Tiny
CARPETMAN1759
  • MEMBER
  • 81 POSTS
Well it did it again. So I took the cap off and I can see very small drops of water all over the inside of the cap. A lot of moisture on the center contact in the middle of the rotor button. The first cap was the original then I put an Eccel brand on it, then I installed a new after market and now I just reinstalled my original back on it and it runs fine.
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Monday, March 26th, 2018 AT 11:15 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,240 POSTS
This is a somewhat common problem with these. The most common reason is the vent in the distributor gets plugged with crud and then the system condenses moisture inside the distributor. As you say those are clean the next reason is that there is moisture getting on the cap. On some this comes from the AC line on others it can simply be very high humidity. One thing you can try, pull the wires one at a time, dab some dielectric or silicone grease in the tower and reinstall the wires. The grease will block moisture entry if it is wicking in through the contacts.
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Tuesday, March 27th, 2018 AT 10:27 AM
Tiny
CARPETMAN1759
  • MEMBER
  • 81 POSTS
On this model the towers comes out the sides on all plug wires and I have done the dielectric grease thing the first time. The caps are flat on the top of these engines. I am in Maryland and coming into the rainy spring time weather right now. Would like to start figuring this thing out before I have no car. Is there anything I could spray inside the cap to keep the moisture out? The distributor is new and clean and both screen holes are open, but I can tell that under the rotor button the plate is starting to rust.
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Wednesday, March 28th, 2018 AT 5:41 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,240 POSTS
The low caps get water in them from wicking as well. This issue only happens when it rains correct? The rest of the time it is Okay?
Nothing that I know of that actually works. Wiping it out with WD40 on a rag might slow it down.

Does it use any coolant? Asking because these engines have intake leak issues and they tend to leak internally first. If it was using a bit the condensation could actually be from coolant in the oil coming up through the distributor. It is also possible this is where the rest of the moisture is coming from. Might want to check and replace the PCV valve and make sure the system is not blocked.
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Wednesday, March 28th, 2018 AT 9:10 AM
Tiny
CARPETMAN1759
  • MEMBER
  • 81 POSTS
I have done every thing you stated. I have no leaks at all. This only happens when the truck has been setting for two days or more. I can drive in the rain all day and then park it and the next day it will start up with no issues. But if I park it on a sunny day, then it rains the next two days. It will not start on the third day. Will do this every time like clock work.I have an 2003 Blazer with the same miles on it and the same motor and has never done this. It parks right beside it.
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Wednesday, March 28th, 2018 AT 1:45 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,240 POSTS
Well that is definitely unique. Okay here is an odd test but? Take some baby powder and dust the distributor and around the intake manifold seams so it is fairly well covered. Close the hood. Now take a hose and make it rain. Not just around the hood but into the cowl and all along the top of the windshield. Do one section at a time like the drivers side of the hood seam, then the center then the passengers side. Then the cowl area and then around the top. After each area open the hood and see if any of the powder is wet or any puddling around the intake.

If you find nothing the only other thing would be to coat the vent screens and the cap seam with some silicone grease and then see if it still gets water inside. If it does then, you are getting water from inside the engine that it is pulling in either through the air cleaner or possibly a leak at the rear of the intake and vacuum draws it in.
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Wednesday, March 28th, 2018 AT 7:23 PM
Tiny
CARPETMAN1759
  • MEMBER
  • 81 POSTS
I will try that and see what happens. Thank you for your time and input on this matter. Like my dad would always say "two heads are better then one" on trying to figure out a problem!
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Thursday, March 29th, 2018 AT 6:18 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,240 POSTS
I have owned a bunch of GM's with the 4.3 and 5.7's with this same style cap (have an 2002 sitting twenty feet away at the moment). I only had one that would get water inside the cap and that was due to the way the AC line was routed. The factory fix was to add a piece of pipe insulation over the line to stop the condensate from dripping onto the cap.
Never had an issue from just rain though. I am sure it can be fixed, just need to figure out what the cause is first, that is always the "fun" part.
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Thursday, March 29th, 2018 AT 7:24 AM
Tiny
CARPETMAN1759
  • MEMBER
  • 81 POSTS
The AC lines start at the compressor and swings to the front on top the radiator and does not come close to the back of the motor on a S10. The heater hoses are next to the cap but there is no leak there. I am still testing, I will get back to you soon on what I have found with the water test.
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Thursday, March 29th, 2018 AT 12:23 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,240 POSTS
Yep, the ones that had the issues were full sized and the early 4.3 in the Blazers. Even those were rare for water intrusion. Good luck testing, hopefully something will show up.
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Thursday, March 29th, 2018 AT 5:35 PM
Tiny
CARPETMAN1759
  • MEMBER
  • 81 POSTS
Steve W. Found the problem but you are not going to believe what it was. On these years S10 They have a vacuum hose that starts at the intake and goes to the vacuum tank in the driver side fender. It branches off and one line goes back over the brake booster. That line goes down the back of the fire wall and goes to the trans. That hose sets on top of the electric plug which hooks into the side of the distributor. So, When it rains water leaks thru the hood seal and drops on the top of the brake booster and runs off the back onto the hose, down the hose and then onto the plug and wicks into the distributor that way. The reason the blazer does not do it is because the hose runs under the electric plug on the distributor. So I changed the hose routing and I'll see what happens. Thank you for your time that you spent with my problem! My truck will not get any diaper rash with all the powder I got on it now. Thanks again!
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Thursday, March 29th, 2018 AT 7:07 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,240 POSTS
I have seen many "strange issues" so not much is unbelievable anymore. Especially with the newer computers with wheels.
Good to hear you found the culprit. The baby powder is a cheap trick for finding leaks. Works for coolant, oil, fuel or most others. Plus it cleans up easy.
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Friday, March 30th, 2018 AT 9:40 AM

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