Starts great when dry, but will not start when left out in the rain?
1999 Chevrolet S10

Starts great when dry, but will not start when left out in the rain?

(1999 Chevrolet S10)
1999 Chevy S10 4x4 truck starts within one revolution when dry, but if left out in the rain it will not fire up except for a brief moment when the key is released.

There seems to be excessive moisture under the hood, coating most of the components on the top of the engine. There is no indication of leaks allowing water to enter directly on the engine.

It has been in the repair shop for three days without any results? I believe they have changed every thing in sight. Plugs, Wires, Distributor Cap, etc..

What could we be missing that may solve the problem?

Best Regards,
What seems to make the problem better or worse? better when dry / worse when wet
How long have you had this problem? stated last year, but is in the garage most of the time
Tags: won t start when wet, chevrolet, s10
1 answer & 1 comment
Popular Answer
on June 28, 2019

Google > spray ignition sealer.

There is also a small ‘screened’ vent in the bottom of the distributor - that need to be cleaned with a cleaner and compressed air.

Good luck!
Sign in to reply
on June 28, 2019

Spraying silicone or WD-40 *INSIDE* the distributor cap will also help.


This is actually sweat - condensation rather than rain leaking inside the engine bay - the same sorta stuff that get on the inside of the windshield when it rains .. Then the defrosters ‘VENTS’ are used to clear the windshield.

Sudden changes in ambient temperatures (daylight to nightfall) within the time vehicle is parked until next trip will also make this problem more pronounced.

PROPERLY sealing the distributor cap - wires & ignition coil + cleaning the ‘VENT’ I mentioned along with using a moisture displacement spray ‘inside’ the cap has got to help with this issue.

Do NOT use the ignition ‘sealer’ INSIDE the distributor or the distributor cap!


Note - I can’t be certain the 1999 year has the distributor vent - however it should be investigated - - MOST DO !!
General Diagnosis
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on June 28, 2019

Google > spray ignition sealer.

There is also a small ‘screened’ vent in the bottom of the distributor - that need to be cleaned with a cleaner and compressed air.

Good luck!
Sign in to reply
on June 28, 2019

Spraying silicone or WD-40 *INSIDE* the distributor cap will also help.


This is actually sweat - condensation rather than rain leaking inside the engine bay - the same sorta stuff that get on the inside of the windshield when it rains .. Then the defrosters ‘VENTS’ are used to clear the windshield.

Sudden changes in ambient temperatures (daylight to nightfall) within the time vehicle is parked until next trip will also make this problem more pronounced.

PROPERLY sealing the distributor cap - wires & ignition coil + cleaning the ‘VENT’ I mentioned along with using a moisture displacement spray ‘inside’ the cap has got to help with this issue.

Do NOT use the ignition ‘sealer’ INSIDE the distributor or the distributor cap!


Note - I can’t be certain the 1999 year has the distributor vent - however it should be investigated - - MOST DO !!

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