spec miata valve rust

Here is a rather strange situation, its My sons car, so I "may" get the facts bent a little, but he wanted to have some opinions, and asked if I could post here.

91 miata, Engine/ head replaced last year with a crate motor from Mazda speed. The motor "may" have 5-700 miles on it since replacing.

We went to a race on labor day together, and his car was running great, I think he even took a 4th out of a LOT of cars.

Brought car home, put in the shop as always, and worked on our regular business.

about 3 weeks later he goes to move the car and its running real ruff, he finds a bad igniter, (by swapping with my car) but still is running bad, changes the cas, coil, all the easy stuff. Still bad running.

Pulls out the leakdown tester and its showing some real problems. Im thereand we can hear the air in the head where it shouldnt be. go around to the back and can hear air in the exhaust (yes he knows to have the piston on the compression stroke at tdc) So he pulls the head.. hmmm not good, valves are stuck open. So he decides to send it in to Steward Engines to get rebuilt. they call and let him know that it looks like the car got water in it. as the valves are RUSTED. wth? My sons race procedure is to drain his tank before every session and then add the specific amount of weight of fuel he believes he needs. when we were at Milwaukee Mile he bought some Race fuel from the only place around that had any, I believe it was a shell station. But the race fuel was a seperate pump of 110, and I can not member the brand. (I bought some too but I didnt get a chance to use it, as I had a crash at T1, doh)

The Place was run by Indian people, seemed okay, but the pump looked a little sketchy.

We are wondering if water in that gas seems like a resonable assumption. or if his habit of draining and filling the tank has an impact?

the car is stored in our shop, and never left unattended, nor does anyone except him and I and maybe his GF have access (they are getting along fine btw LOL) So I don't see sabotage being an issue.

Anyone have any ideas?

What's the humidity like where you live?

I wonder how long the crate motor sat in a warehouse, and if the valves were given any sort of anti-corrosion coating. I would expect that they were, but was the head removed prior to you installing the new engine to check it out?

Humidity. hmm sometimes its rather humid here, nothing like the southern states, for sure. its Wisconsin

remember the car ran Great Labor day weekend, the next 3-4 weeks its been chilly here, and low humidity

Crate motor from Mazda speed/ California. they cut racers super deals, so that we will race their brand. Not saying its non-existent, but that scenario doesn't seem to fit the program what they are trying to do (give us great deals to race their brand, I put that idea way at the bottom, not saying it isn't a possibility)

I am a Mazda Speed Motorsports member. Familiar with the program. Just saying that it is possible that the damage was there before you got the engine. It's not like they pull the head before they ship it. They wouldn't have done it on purpose (that I could think of), but it is possible that one sneaked through the line.

I also wonder how much 110 goes through that tank, and if it had water in it. Not many people are lining up to get their 110 at ~6.00 a gallon.

Not sure what other options there are.

Even if the fuel had water in it.. the heat of the engine would have burned it off long before the engine cooled.

Honestly, I find this suspecious. The head I pulled off of a 30 year old fiat had little to no rust in it.. and that engine had not run in 10 years

The bad news is that all parts sold through the Mazda Motorsports program have no warranty. I really doubt that this was intentional, but it is possible that there was an issue with the valves. Thinking about it, the engine is hot when shut down, and any moisture in the head would condense as it cools, though I don't know how you would get enough in there for any serious rust to develop. Heck, I just went out to my shed, where I have had a head sitting, unprotected (and the shed leaks) for nearly two years, and the valves in it are rust free. Not sure what to tell you.

I honestly cannot think of a single reason for the valves to rust.. unless they were submerged in saltwater for a while.

I'd call Mazda Comp and talk to them about this. They're friendly people and may have some ideas as to what happened or if there's a problem with a batch of motors.

thats a pretty good idea, cant hurt. ;)