As the title says, can bad gas be the cause of a headgasket to blow?

I have a shop working on my 23 vanguard mud buddy mini. They are doing a complete valve job and replacing head-gaskets. One of the head-gaskets was bad(you could see carbon spray on the back of the motor where the head sits). They are saying it is all caused by bad gas, and thereby is not covered under warranty. The only determined "bad gas" by finding some residue in the carburetor. No octane test was done.

I contacted Micah at Mudbuddy and Hank Johnson with the Boat Doctor, and both seem to think something's fishy.

What do you guys think? Can bad gas be a cause of bad head-gasket in any way, shape, or form?

bad gas is a way for they to not warranty the motor.

I vote no possible way bad gas can cause a head gasket to blow.

Yea bad gas can ruin a high compression high horse power race motor, I got some bad gas in my airboat and the octane rating wasn’t right and it sucked the exhaust valve right out of the head because the exhaust gas temperatures were so high the valve stems basically were past the melting point and that 502 sucked the red hot valve right of the valve stem. High compression motors with advanced timing need slower burning fuel which is a higher octane rating…
so we are basically running lawnmower motors on our mud boats…right…they are made to run on cheap gas, 87octane, and to me bad gas means water in da fuel…right…and I see no way bad gas could cause an head gasket to blow…I hate to hear that they are using the old “bad gas” excuse on you…depends on what kinda guy you are…you could call their bluff and make them prove it was bad gas and ask them why are they doing a valve job! “they are trying to Take Advantage of U”

WBG - the shop said they are going to do a valve job because bad gas gunked up the valves and it all caused the head gasket to blow. On the side where the head gasket blew, the compression was 75. On the other cylinder, it was 115 psi. Should have been around 150 on each cylinder. That shows that SOMETHING is up with the valves on the cylinder that the headgasket did NOT blow.

Hank at the boat doctor said that more than likely "carbon deposits" built up on the valves and the increased pressure finally caused one of these thin gaskets to break. The repair consists of doing a complete valve job on both sides and replacing the headgasket.

So, the work they are doing is correct, just not the REASON they are claiming.

HERE'S THE MILLION DOLLAR QUESTION:
If carbon deposits can build up on the valves/seats and cause enough increased pressure to blow a head gasket, can BAD GAS cause build up on the valves and cause this same increased pressure???????

Ever heard of water injection?

In my youth we would turn the garden hose on at a slow trickle and let it drip into the carb on my fathers stock cars at half throttle. Basically having the effect of steam cleaning the carbon deposits out of the engine.

i had a 23 gdsd an 07 model and i blew a head gasket on it and briggs said they had sent out a batch of motor with the wrong style head gasket . They never did send out a recall leter though. But bad gas does not cause a head gasket to fail.

spiderbeaver - did they replace it without question? And did you have a warranty or not?

it happened like the week befor duck season so i was in a big rush so i asked them if they could send it to me so i did it myself . but they sent it to my house no questions asked . covered under waranty.

I had a 23 vangard on a godevil surface drive about 3yrs ago and it blew a head gasket with 10 hours. I brought it back to CoCo and he said vanguard had a bunch of motors with faulty head gaskets and fixed me right up. Sounded like a 22lr rifle next to my ear when it went!

Bad gas won't blow a head gasket on a stock motor.. 75/115 is real reasonable and PSI will be the big cause of blowing a head gasket.. Tell those *ucktards to quit fillin ya full of sh!t and do the right thing.. I think the other guys that have experience saying bad gaskets were sent out is a much more realistic scenario..

There have been several post's that referenced BAD GAS causing head gasket failure resulting in the repair center claiming voided warranty. This seems to be a theme some reair shops use to bypass contacting the Motor Mgf. for warranty work payment. How do you deal with this?

Thats what I gathered when talking to Briggs shops here. I was told there is not much money in warranty work so it should come as no surprise if they didn't try to find a way to get out of it to charge full price. I got the run around from several shops. Finally someone would look at it but after a couple weeks tells me I would probably have to fight with Briggs because a lower case "does not just crack within weeks of the warranty running out". And that it could take 4-6 weeks to settle and I might have to pay him full price anyway. PD hooked me up with their now inhouse Briggs warranty repair in just a weeks time.