Hydrolock from gas, possible engine damage? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Awann99 · 03-19-2021, 12:03 AM

I attempted to crank over my engine with my new carb (Quadrajet on crate 350). I guess the float was stuck from shipping so It poured gas everywhere. I didn’t realize that it also flooded the cylinders until I tried to crank it a few days later and it felt like the battery was dead and cranked over maybe two rotations and then froze. I pulled the plugs and gas came out of cylinders 6 and 7. More out of 6 then 7. I spun the engine with the starter with no plugs and cleaned out the engine. Nothing sounded off. I put the plugs back in and it was running rough. Shaking the whole truck. I thought it might be a vacuum leak or bad coil so I changed out the coil and now it only cranks and won’t fire. Is it possible that I bent a rod while trying to turn the engine over when it had gas in a cylinder?
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Greasey Harley · 03-19-2021, 12:10 AM

yes, it is possible, but I've never actually seen it. I would run a compression test. If the comp test checks out good, Change the oil and filter before you drive the truck, gas diluted oil can cause severe engine damage.
Hopefully, it just runs bad cuz of the carb.

MAC71Cheyenne · 03-19-2021, 12:12 AM

Where is the oil level? Gas in the oil? Will it turn over manually with plugs out?

Awann99 · 03-19-2021, 12:14 AM

Quote:

Originally Posted by MAC71Cheyenne

Where is the oil level? Gas in the oil? Will it turn over manually with plugs out?

Oil level seemed lightly high. Just a small run over full. I could smell the gas on the dipstick.

Bigdav160 · 03-19-2021, 07:49 AM

I've seen it happen. Compression is be slightly low in that cylinder(s)

**BigBird05** · 03-19-2021, 08:50 AM

The starter shouldn't have enough force to bend a rod. Washed out rings will make a engine run bad. Change oil, check compression, use oil in any cylinder that might have low compression to see if the compression will come up, if all of the cylinders have good compression rotate plugs and see how well it runs. Are you trying to run it with the same carb that flooded the engine? You might need to try to run it with a donor carb?

weq92f · 03-19-2021, 09:35 AM

[QUOTE=BigBird05;8896460]...<snip>...Washed out rings will make a engine run bad. ...<snip>.../QUOTE]

This is exactly what I was thinking. Sounds like the fuel sat in the cylinders for a while too.

Get some oil into those cylinders.

-klb

**HO455** · 03-19-2021, 01:00 PM

A new set of spark plugs will likely cure the rough running. It is likely the insulators on plugs have been covered in gas and any micro cracks have filled with carbon carried from the cylinder and left by the gas when it burned. This will cause misfires from the shorted electrode.
The starter alone shouldn't be able to cause damage from a hydro-locked cylinder. The literal kicker is if another cylinder fires just prior to the hydro-locking. Then its a whole different situation.
As several members have said a compression check will tell the tale. An oil change is necessary as fuel did go past the rings. It is cheaper to change oil in a SBC than it is to do a fuel dilution test of the oil.

Awann99 · 03-19-2021, 11:37 PM

Thank you for the advice fellas. I will change the oil tomorrow once I get off work and the plugs. Compression test as well. I’ll update once I get it back together.

Awann99 · 03-20-2021, 07:22 PM

I think I found the issue lol. Changing the plugs. Haven’t done a compression test yet though.

**Steeveedee** · 03-20-2021, 09:12 PM

Well, I've never broken a spark plug.

I'm curious- how long have the plugs been in that they have rust on them? Bear in mind that I live in the California desert where rust is a word "furriners" use.

Greasey Harley · 03-20-2021, 09:30 PM

Quote:

Originally Posted by Steeveedee

Well, I've never broken a spark plug.

I'm curious- how long have the plugs been in that they have rust on them? Bear in mind that I live in the California desert where rust is a word "furriners" use.

I installed leaky valve covers to keep my plugs from rusting.

Awann99 · 03-20-2021, 09:31 PM

Quote:

Originally Posted by Steeveedee

Well, I've never broken a spark plug.

I'm curious- how long have the plugs been in that they have rust on them? Bear in mind that I live in the California desert where rust is a word "furriners" use.

If I had to guess, I would say these have been on the truck for about a year maybe. I guess a combo of the rain and humidity in Tennessee makes anything that isn’t painted rust up pretty quick.

**BigBird05** · 03-20-2021, 10:22 PM

Greasey Harley, Nobody that drives a sbc should ever have rusty spark plugs.

**Steeveedee** · 03-20-2021, 10:45 PM

Quote:

Originally Posted by Awann99

If I had to guess, I would say these have been on the truck for about a year maybe. I guess a combo of the rain and humidity in Tennessee makes anything that isn’t painted rust up pretty quick.

I was pulling your leg, bud.

I once bought a '72 Le Mans that had spent it's life in Malibu. It was rusted out, bad.

**chevy71super** · 03-21-2021, 12:27 AM

Rats got under the hood of my 03 Silverado and dined on a few of the injector wires. I repaired the damage and took it to the car wash to clean up their mess. The truck ran fine but developed a miss fire shortly thereafter. Cracked plug. Apparently cold water on a hot plug is a bad idea!

03-19-2021, 12:03 AM	#1
Awann99 Registered User Join Date: Jan 2018 Location: TN Posts: 257	Hydrolock from gas, possible engine damage? I attempted to crank over my engine with my new carb (Quadrajet on crate 350). I guess the float was stuck from shipping so It poured gas everywhere. I didn’t realize that it also flooded the cylinders until I tried to crank it a few days later and it felt like the battery was dead and cranked over maybe two rotations and then froze. I pulled the plugs and gas came out of cylinders 6 and 7. More out of 6 then 7. I spun the engine with the starter with no plugs and cleaned out the engine. Nothing sounded off. I put the plugs back in and it was running rough. Shaking the whole truck. I thought it might be a vacuum leak or bad coil so I changed out the coil and now it only cranks and won’t fire. Is it possible that I bent a rod while trying to turn the engine over when it had gas in a cylinder? Posted via Mobile Device

03-19-2021, 12:10 AM	#2
Greasey Harley Registered User Join Date: May 2013 Location: Post Falls, ID Posts: 884	Re: Hydrolock from gas, possible engine damage? yes, it is possible, but I've never actually seen it. I would run a compression test. If the comp test checks out good, Change the oil and filter before you drive the truck, gas diluted oil can cause severe engine damage. Hopefully, it just runs bad cuz of the carb. __________________ Insert clever text here:

03-19-2021, 12:12 AM	#3
MAC71Cheyenne Registered User Join Date: Aug 2020 Location: Mount Pleasant Iowa Posts: 303	Re: Hydrolock from gas, possible engine damage? Where is the oil level? Gas in the oil? Will it turn over manually with plugs out?

03-19-2021, 07:49 AM	#5
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: Hydrolock from gas, possible engine damage? I've seen it happen. Compression is be slightly low in that cylinder(s) __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

03-19-2021, 08:50 AM	#6
BigBird05 Senior Member Join Date: Aug 2019 Location: Cheraw Posts: 1,305	Re: Hydrolock from gas, possible engine damage? The starter shouldn't have enough force to bend a rod. Washed out rings will make a engine run bad. Change oil, check compression, use oil in any cylinder that might have low compression to see if the compression will come up, if all of the cylinders have good compression rotate plugs and see how well it runs. Are you trying to run it with the same carb that flooded the engine? You might need to try to run it with a donor carb?

03-19-2021, 09:35 AM	#7
weq92f Registered User Join Date: Oct 2016 Location: Dallas Texas Posts: 2,881	Re: Hydrolock from gas, possible engine damage? [QUOTE=BigBird05;8896460]...<snip>...Washed out rings will make a engine run bad. ...<snip>.../QUOTE] This is exactly what I was thinking. Sounds like the fuel sat in the cylinders for a while too. Get some oil into those cylinders. -klb __________________ 67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold

03-19-2021, 01:00 PM	#8
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 10,820	Re: Hydrolock from gas, possible engine damage? A new set of spark plugs will likely cure the rough running. It is likely the insulators on plugs have been covered in gas and any micro cracks have filled with carbon carried from the cylinder and left by the gas when it burned. This will cause misfires from the shorted electrode. The starter alone shouldn't be able to cause damage from a hydro-locked cylinder. The literal kicker is if another cylinder fires just prior to the hydro-locking. Then its a whole different situation. As several members have said a compression check will tell the tale. An oil change is necessary as fuel did go past the rings. It is cheaper to change oil in a SBC than it is to do a fuel dilution test of the oil. __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

03-19-2021, 11:37 PM	#9
Awann99 Registered User Join Date: Jan 2018 Location: TN Posts: 257	Re: Hydrolock from gas, possible engine damage? Thank you for the advice fellas. I will change the oil tomorrow once I get off work and the plugs. Compression test as well. I’ll update once I get it back together.

03-20-2021, 07:22 PM	#10
Awann99 Registered User Join Date: Jan 2018 Location: TN Posts: 257	Re: Hydrolock from gas, possible engine damage? I think I found the issue lol. Changing the plugs. Haven’t done a compression test yet though. Attached Images

03-20-2021, 09:12 PM	#11
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,104	Re: Hydrolock from gas, possible engine damage? Well, I've never broken a spark plug. I'm curious- how long have the plugs been in that they have rust on them? Bear in mind that I live in the California desert where rust is a word "furriners" use. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

03-20-2021, 10:22 PM	#14
BigBird05 Senior Member Join Date: Aug 2019 Location: Cheraw Posts: 1,305	Re: Hydrolock from gas, possible engine damage? Greasey Harley, Nobody that drives a sbc should ever have rusty spark plugs.

03-21-2021, 12:27 AM	#16
chevy71super Registered User Join Date: Jan 2002 Location: So Cal Posts: 658	Re: Hydrolock from gas, possible engine damage? Rats got under the hood of my 03 Silverado and dined on a few of the injector wires. I repaired the damage and took it to the car wash to clean up their mess. The truck ran fine but developed a miss fire shortly thereafter. Cracked plug. Apparently cold water on a hot plug is a bad idea! __________________ 71 Cheyenne Super 4X4 SB 72 Cheyenne Super 4X4 SB 72 Cheyenne 4X4 SB



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