Engine dies when weather is wet - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Husker · 12-01-2018, 12:34 AM

My 68 Chevy
250 6cyl
single barrel carb
HEI ign (new wires, new cap and rotor)
Stock air cleaner and filter is good, has heat tube down to manifold
Manual choke
manual trans
On my way to work about 7 miles or so about 2/3rds way there the last couple of days it has been raining or heavy fog, when I come to stop or just in neutral coasting the engine is sputtering, idling low and it will die. Starts back up OK but if I want to continue running I have to give it gas or pull choke out a bit. I cleaned the Distributor cap with electrical parts cleaner and used carb cleaner around carb and manifold. No apparent vacunm leaks. Not sure what is causing this, any help would be great.
Thanks
Ron

geezer#99 · 12-01-2018, 01:11 AM

You’ve got a cold intake plenum!
Check that the heat riser is working?

hjewell2 · 12-01-2018, 11:06 AM

Quote:

Originally Posted by geezer#99

You’ve got a cold intake plenum!
Check that the heat riser is working?

BINGO we have a winner.

Husker · 12-01-2018, 11:18 AM

The tube from air cleaner to the exhaust manifold?
Ron

geezer#99 · 12-01-2018, 12:12 PM

Quote:

Originally Posted by Husker

The tube from air cleaner to the exhaust manifold?
Ron

Look in here for a pic of the heat riser.

http://67-72chevytrucks.com/vboard/s...d.php?t=313227

davepl · 12-01-2018, 11:46 AM

Need a pic so we can see if the air cleaner, heat stove, stove pipe, and thermac are all present. If they are and the thermac is working (check to ensure it's not sucking air through the snorkel, should be pulling it up the bottom when cold), then check the heat riser valve to ensure it's still there and operating freely.

Husker · 12-01-2018, 12:17 PM

Here ya go. Thanks
Ron

Husker · 12-01-2018, 12:28 PM

I have one like in pic but no heat coil, and it was stuck open( just like in pic) so I closed it Moved the weight to the bottom. may need to replace it
Thanks Borrowed pic from other post
Ron

davepl · 12-01-2018, 01:19 PM

Yup, I'd replace the heat riser valve to get it working. Did closing it improve the problem though?

You don't want to leave it closed permanently, I think you can burn exhaust valves that way. So a working one is a better choice!

I'm surprised the way the snorkel is, with no valve! It just mixes some warm air in?

Husker · 12-01-2018, 02:18 PM

No have not driven it yet. I will try to find a good one. Thanks Love you guys and this board
Ron

**jocko** · 12-01-2018, 03:39 PM

If this doesn't solve your problem, I'd check for a hairline crack in the distributor cap - or just replace it and see if it helps.

12-01-2018, 12:34 AM	#1
Husker Registered User Join Date: Dec 1999 Location: Mid NE USA Posts: 2,212	Engine dies when weather is wet My 68 Chevy 250 6cyl single barrel carb HEI ign (new wires, new cap and rotor) Stock air cleaner and filter is good, has heat tube down to manifold Manual choke manual trans On my way to work about 7 miles or so about 2/3rds way there the last couple of days it has been raining or heavy fog, when I come to stop or just in neutral coasting the engine is sputtering, idling low and it will die. Starts back up OK but if I want to continue running I have to give it gas or pull choke out a bit. I cleaned the Distributor cap with electrical parts cleaner and used carb cleaner around carb and manifold. No apparent vacunm leaks. Not sure what is causing this, any help would be great. Thanks Ron __________________ Member #111 68 C-10 Daily Driver 70 4x4 Project 76 Jeep CJ-5 Help Support the Board: http://67-72chevytrucks.com/vboard/payments.php He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors. Thomas Jefferson

12-01-2018, 01:11 AM	#2
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,736	Re: Engine dies when weather is wet You’ve got a cold intake plenum! Check that the heat riser is working?

12-01-2018, 11:18 AM	#4
Husker Registered User Join Date: Dec 1999 Location: Mid NE USA Posts: 2,212	Re: Engine dies when weather is wet The tube from air cleaner to the exhaust manifold? Ron __________________ Member #111 68 C-10 Daily Driver 70 4x4 Project 76 Jeep CJ-5 Help Support the Board: http://67-72chevytrucks.com/vboard/payments.php He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors. Thomas Jefferson

12-01-2018, 11:46 AM	#6
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: Engine dies when weather is wet Need a pic so we can see if the air cleaner, heat stove, stove pipe, and thermac are all present. If they are and the thermac is working (check to ensure it's not sucking air through the snorkel, should be pulling it up the bottom when cold), then check the heat riser valve to ensure it's still there and operating freely. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

12-01-2018, 12:17 PM	#7
Husker Registered User Join Date: Dec 1999 Location: Mid NE USA Posts: 2,212	Re: Engine dies when weather is wet Here ya go. Thanks Ron Attached Images __________________ Member #111 68 C-10 Daily Driver 70 4x4 Project 76 Jeep CJ-5 Help Support the Board: http://67-72chevytrucks.com/vboard/payments.php He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors. Thomas Jefferson

12-01-2018, 12:28 PM	#8
Husker Registered User Join Date: Dec 1999 Location: Mid NE USA Posts: 2,212	Re: Engine dies when weather is wet I have one like in pic but no heat coil, and it was stuck open( just like in pic) so I closed it Moved the weight to the bottom. may need to replace it Thanks Borrowed pic from other post Ron Attached Images __________________ Member #111 68 C-10 Daily Driver 70 4x4 Project 76 Jeep CJ-5 Help Support the Board: http://67-72chevytrucks.com/vboard/payments.php He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors. Thomas Jefferson

12-01-2018, 01:19 PM	#9
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: Engine dies when weather is wet Yup, I'd replace the heat riser valve to get it working. Did closing it improve the problem though? You don't want to leave it closed permanently, I think you can burn exhaust valves that way. So a working one is a better choice! I'm surprised the way the snorkel is, with no valve! It just mixes some warm air in? __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

12-01-2018, 02:18 PM	#10
Husker Registered User Join Date: Dec 1999 Location: Mid NE USA Posts: 2,212	Re: Engine dies when weather is wet No have not driven it yet. I will try to find a good one. Thanks Love you guys and this board Ron __________________ Member #111 68 C-10 Daily Driver 70 4x4 Project 76 Jeep CJ-5 Help Support the Board: http://67-72chevytrucks.com/vboard/payments.php He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors. Thomas Jefferson

12-01-2018, 03:39 PM	#11
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: Engine dies when weather is wet If this doesn't solve your problem, I'd check for a hairline crack in the distributor cap - or just replace it and see if it helps.



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