Aico

In what ways can an engine be damaged from sitting for a couple of years?

I know it can rust. When it does, will the engine be worth anything? And is there any way to check this from the outside? Maybe by a compression test?

xero_xero

there is alot, depending on how long it sat, it seizes up after about 6 months but that can be fixed with a little tranny fluid. it has to be reworked after rust gets on the outer wall of the chamber because it will keep breaking your apex seals. if it sits too long, then the whole engine will need to berebuilit because of dried and craaked oil seals.

RotorMotorDriver

iTrader: (1)

A light surface rust is a possibility I suppose, but Ive never heard of any real problems from it. Most people who revive engines that have sat for a while simply put a little MMO in all the chambers as they turn it over by hand to help lubricate the seals a little. Clean or replace the spark plugs while you've got em out. Cleaning out the carb is a good idea, but not everyone does this. Also, draining the old fuel and putting fresh in is a good idea, if you cant drain it, at least put some fresh fuel in if not pump the old fuel out with a cyphon or maybe if its a small amount the stock fuel pump. Just disconnect the line at the carb and extend it somewhere to catch it. Make sure the air filter hasnt fallen apart so when you start it, it wont suck chunks of filter into it. Make sure the oil looks ok, or even if youre ambitious do an oil change on it. Some of that my not even be neccessary if its only sat a small amount of time. I was thinking more along the lines of you finding one in a barn somewhere that hasnt been touched since the early 90s. Anyway, that should give you an idea of some things you could do. Its really all case by case and how bad it looks.

~T.J.

RotorMotorDriver

iTrader: (1)

WTF? Siezes up after 6 months? Are you kidding me? I have first hand knowledge that this isnt always true, and most of the time isnt. Ive seen plenty of RX-7s that have been sitting for years and they still turn over by hand. People let them sit longer than that when they store them for winter, and some people consider "storing" it just parking it and taking the keys inside, no fuel preservative, no oiling the seals, nothing. Then, when they feel like dragging it out again for summer, it turns over (and usually starts) just fine.

Also, rust on the outter walls of the chamber? What are you talking about here? The rotor housings are aluminum and dont rust, they would oxidize, but AFAIK they are coated on the sealing surface with something, and wont. I could be wrong, but if I am, I still doubt that they would oxidize enough to cause problems, if at all. The irons might rust. A light surface rust is possible, but considering the engines burn not only gas, but also oil, water is repelled from the surface for the most part, hence me not really hearing about a lot of problems from internal engine rust, especially if the engine was "sealed" (IE All plugs in, carb on, exhaust on, etc).

And what do you mean "keep breaking your apex seals"? Once they break, theyre broken, engine rebuild time. If you tore the engine apart to rebuild it, replaced the apex seals, and put it back together with rust still inside it to "keep breaking apex seals", youre an idiot.

Youre right, the oil seals could dry out and crack, so the engine would need to be rebuilt, but your apex seal scenario would be more likely for a rebuild than a cracked oil seal. I owned a couple of RX-7s that have driven for a long, long time with cracked oil seals, they just burn more oil and smoke a bit more than they should.

To summarize, the only truth (IMO) that you put out there is the oil seals could crack and dry out which I forgot to mention. Thanks.

~T.J.

tempusfugitive

does no one coat the inside of the rotor housing with oil before letting it sit? that'll stop any rusting problems, and as long as you turn it over by hand once a month it'll never seize up on you.

thekyl

Hey guys I got a question what is the best way to get rid of some sucrafe rust if you do get some in there? I have a few housings that got some surface rust on the housings after sitting in a yard for 3 years under a tarp. And I didnt treat the engine. The rotos are really slightly pitted just at the tips of the rotors where the apex seal sits. Would they be okay to use or should I wory about getting some new rotor's? Or do you think it wont matter because the Seals are still making a god seal to the block?

RotorMotorDriver

iTrader: (1)

I would say steel wool would be what I would try, but not a harsh steel wool. See what happens after that.

~T.J.

thekyl

Yea I did that to one of the rotars with some highly nasty fuel and engine parts cleaner and it was a little pitted but not too bad. Cleaned really nice. No the housings I didnt want to scratch them up very much I dont want to uneven them out. Also I read that if you can catch your finger on any marks on the housings you should have them lapped is that really vital close to the Apex or does that really not matter that much?